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Ecological Monitoring Progress Rept,Jul-Dec 1979.
	ML19344D470
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Site:	Fort Saint Vrain
Issue date:	02/04/1980
From:	Glover F; THORNE ECOLOGICAL INSTITUTE
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i l PROGRESS REPORT

! JULY 1,1979 - DECEMBER 31, 1979 s

ECOLOGICAL MONITORING FORT ST. VRAIN GENERATING STATION 1

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FORT ST. VRAIN NUCLEAR GENERATING STATION ECOLOGICAL MONITORING PROGRAM Progress Report for the Period July 1, 1979 to December 31, 1979 Prepared by:/s M' /-M~

r. Fred A. TTover, Project Director, Thorne Date Ecological Institute

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Fort St. VraW REETJh~ Physics D nt / Date Reviewed by:/s/ Mg#

kuclear Project Department a

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r Progress Report July 1,1979 to December 31, 1979 s.

ECOLOGICAL MONITORING FORT ST. VRAIN NUCLEAR GENERATING STATION 4

for i Public Service Company of i Colorado i

by i

] Thorne Ecological Institute 4860 Riverbend Road t

Boulder, Colorado Dr. Fred A. Glover Project Director l

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TABLE OF CONTENTS Page S uma ry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Introduction ........................... 6 Investigator Reports ....................... 8 Aquatic Section ....................... 9 Invertebrates . . . . . . . . . . . . . . . . . . . . . . 10 Algae . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Avian Section ........................ 66 Terrestrial Section ..................... 75 Vegetation Monitoring . . . . . . . . . . . . . . . . . . 76 Ecophysiological Characteristics ............ 90 Mammals, Amphibians and Reptiles ............ 101 In ve rteb ra te s . . . . . . . . . . . . . . . . . . . . . . 117

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SUMMARY

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General Sumary The non-radiation, environmental data in this report continue to indicate minor, local variations in the Ft. St. Vrain environs. Back-grou1d monitoring data are presented for the environmental components, some for a background period of eight years. Generally, environmental quality tends to be about the same. To date, no dircernible, measurable harmful effects on the environment have been evident from the intermittent, limited operation of the Nuclear Generating Station (1977--137 days for 38%; 1978--201 days for 57%; and 1979--77 days for 21%).

Aquatic Section Invertebrates Significantly fewer taxa of aquatic invertebrates were collected in

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1979 than in 1978. Positive and negative factors believed to be influencing aquatic invertebrate populations in 1979 were: Goosequill Pond effluent (positive), extensive ice cover (negative), high spring runoff (negative),

and channel alterations (negative).

Fish The most important difference between the 1978 and 1979 fish fauna was the presence of several species of game fish in 1979, primarily due to a greater effort expended in collection. Otherwise, the fish fauna apparently has remained about the same.

Algae A total of 119 species was identified in 1979 consisting of 60 diatoms, 37 green algae, 6 euglenoids, 9 blue-green algae, 4 golden-brown algae,1 cryptomanad, I undescribed dinoflagellate, and 1 yellow-green

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algae. The greatest species diversity occurred in the diatoms but the overall low species diversity was characteristic of polluted (dystrophic) aquatic habitats. The low species dive.sity is also typical of past observations. Generally, the same species occur in both rivers but the dominance and time of appearance of certain species varies. The algal pooulations were higher in 1978 than 1979; a response attributed to increased spring runoff and river flows. The dominant algae were the same in 1979 as 1978 with similar trends of succession and appearance.

In Goosequill Pond Scendesmus quadricauda and Rhizoclonium hieroglyphicum were the most comon algae, continuing the trend of previous years.

Avian Section During the periods of census from 1972-1979, populations have fluc-tuated widely and no specific trend is apparent. The effects of environ-mental factors (heavy grazing, fluctuating water 'vels, hunting) other than the Nuclear Generating Station appear to be more detrimental to the birds than the Station.

Terrestrial Section Vegetation Most of the exclosures showed no significant difference for species cover or dry weight means of the major species for inside vs. outside.

However, several of the exclosures apparently had local situation varia-tions. Differential grazing pressures have contributed significantly to vegetation changes. It is felt that operation of the Generating Station to date has not been sufficiently consistent nor for an adequate period of time to evaluate probable effects on vegetation.

4 Ecochysiological Characteristics Leaf injury for kochia aopeared to be greater near the Generating Station. The reverse was true for cottonwood. Variations in leaf injury were caused more by microclimate, site variations, insects, and species differences than by Station influences. No consistent trends were noted in extent of brown leaf tipping for cheatgrass or kochia nor for leaf spotting of cottonwood as related to the Station.

Mammals, Amphibians and Reptiles With minor differences and variations early in the program, the same species of mammals, amphibians, and reptiles are present in the Station environs. Populations have shown annual variations but none seem related to operation of the Generating Station.

Terrestrial Invertebrates Population levels of Formicidae and Siloha ramosa were substantially higher in 1979 than in recent years, particularly so in the vicinity of the Generating Station. Collembola seasonal distribution, as well as spiders, Heteroceridae and Tricoptera populations were generally comparable to previous years. No detrimental effect by the Station has been noted on the terrestrial invertebrates.

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FORT ST. VRAIN Generation Summary - 1979 Dates With Nuncer Of Gross Electric Days Without Generation Month Generation Generation MWH January 1-19, 23-31 3 109,306 Feb ruarj* 1 27 546 March

O 31 0 April

O 30 0 May* O 31 0 June

0 30 0 July

23, 26-28, 30, 31 25 4,522 August 3-17, 20-24, 25-31 5 88,079 Septerrter 1 29 1,828 October 2-14, 24-26 15 46,367 November 0 30 0 Cecemcer 0 31 0

'Cefueling Cutage February 1 - July 22,1979 .

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INTR 000CTI0ti e

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b Introduction This progress report presents non-rs' > logical, environmental monitoring information and activities concerned with the period July 1,'

1979 to December 31, 1979. Environmental studies have been conducted on the St. Vrain Site environs since 1971 with monitoring data available and analyzed 'for most of the environmental components for eight years.

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8 INVESTIGATOR REPORTS e

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AQUATIC SECTION l .

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10 AQUATIC INVERTE3 RATE MONITORING s,

by Clarence A. Carlson David L. Propst r

11 INTRODUCTION Monitoring of the aquatic biota in the area of the Fort St. Vrain Nuclear Generating Station in 1979 was conducted by Graduate Assistant David L. Propst. Data resulting from analysis of timed collections of macroinvertebrates from the natural substrates and fish collections made f

in October and November are the primary components of this report.

STUDY AREA DESCRIPTION Stations SP48 and C1 were described by Cressy, Carlson and Frank (1974). Station SP4U was described by Stacey, Carlson and Frank (1975).

Station SP4 was described by Carlson et al. (1977). To assure com-parability with early program sampling, two stations, SV2 and SV4, were re-established to the biweekly macroinvertebrate sampling sites in July 1979 (Figure 1). No discharge was observed from the upper Goosequill outlet. The lower outlet at SP48 had intermittent discharge throughout the year. A culvert was installed near the mouth of the lower outlet of Goosequill Ditch in October.

The extensive ice cover on the South Platte River in early 1979 and the high and extended spring runoff caused much channel alteration, particularly in the vicinity of Stations SP4A and SP40. Channel modifi-cation at all otner sites was only moderate.

Fishes were collected at Stations SP4A and SP48 on the South Plaite River and at SV2 and SV5 on the St. Vrain River.

METH005 Macroinvertebrate samples wore collected by methods described by Eder, Carlson and Frank (1974). The samoles were composed of macroin-verteorates collected in 10-min samples (witn a triangular dignet)

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l 13 comoined with 5 min of debris picking. No sites were sampled in June because of the high water levels. Station SV2 was not sampled on 28 November because of the heavy snowfall.

Physical and chemical parameters were determined according to methods described by the American Public Health Association (1971), with the exception of total hardness. Total hardness determinations were made by use of a Hach Water Chemistry Kit (Model AL-368). Other equip-ment used included a mercury themometer, a Hach turbidimeter, a Beckman conducting bridge and pH meters (Corning and Orion Research). Malfunction-ing of the Hach turbidimeter forced the discontinuation cf measurement of this parameter, April - December.

RESULTS SP4A Thirty-five aquatic macroinvertebrate taxa were collected from Station SP4A in 1979 (Table 1). Cladocera were the most abundant organism (28.1 percent). However, cladocerans were only collected on 14 and 27 October and on 28 November; and the great majority were collected on 27 October. No explanation can be given for the unusual presence of the cladocera. 011gocnaeta were found more censistently throughout 1979 (Figure 2) and comprised 2S.1 percent of the organisms collected at SP4A. 5,imulium sp., Cricotoous sp. and Paralautercorniella sp. were the most common dipteran macroinvertebrates collected (13.0, 11.3 and 4.5 percent, respectively). Almost all Paralauterborniella sp. were found on 29 July and 6 August. Simulium sp. and Cricotocus sp. (Figures 3 anc 4) were collected througnout the year. Dicrotenoices sp., Concnacelooia sp., Chirenemus sp. (Figure 5), Microosectra so and Polycedilum so. were collected infrecuently, but in relatively hign

14 Table 1. Total organisms collected at Stations SP4A, SP4U, SP48, Cl, SV2 and SVG from January through December 1979.

Station Organism SP4A SP4U SP48 Cl SV2* SV5* Total Isotomurus palustris 8 8 16 Baetis sp. 78 72 108 48 744 72 1122 Heptagenia sp. 26 1 7 18 37 26 115 Tricorythodes sp. 6 75 29 8 309 64 491 Caenis sp. 1 1 Isennura sp. 1 1 1 3 Opniogomphus sp. I 1 Ar ia sp. 10 10 3 23 na agma sp. 1 1 Amphiagrion sp. 1 1 Corixidae 8 16 8 32 Agabinus sp. 8 8 Oytiscidae 1 1 Dytiscidae larvae 1 1 Dytiscus sp. 3 1 4 Laccophilus sp. I 1 Laccobius sp. 1 1 Hydroporus sp. I l Noteridae 1 1 2 Hydropsyche sp. 126 132 134 89 180 143 804 Ochrotrichia sp. 15 16 27 65 39 162 Tipulidae 33 96 121 72 322

,Tipulidae pupae 16 8 8 8 40 Hexatoma sp. 24 24 Pedicia sp. 1 1 Psycnoda sp. 9 8 24 41 Ceratopogonidae 8 8 Stratiomyiidae 8 8 8 8 32 Simuliidae pupae 22 41 51 47 64 7 232 Simulium sp. 966 958 508 629 1507 308 4876 Chironomidae 1169 17 32 51 3 26 1757 Chironomidae pupae 196 243 320 120 456 48 1383 Cricotopus sp. 841 1395 1631 662 1320 267 6116 Chi ronomu sp. 68 399 206 58 105 137 973 Dicrotend >.as sp. 23 41 11 14 6 ,95 Conchapelopia sp. 28 55 43 25 24 6 181 Paralautercorniella sp. 344 233 240 232 104 88 1241 Polypedilum sp. 180 215 119 97 191 39 8/'

Diamesa sp. 9 2 11 Cryptochironomus sp. 16 1 8 25 Thienemanniella sp. 8 8 Tricnoclacius sp. 16 9 1 26 Glyptotendices sp. 30 62 21 62 40 13 228 Smittia sp. 2 1 3 Goeldichironomus sp. 16 8 24

15 Table 1. Continued.

Station .

Organism SP4A SP4U SP48 Cl SV2* SV5* Totai '

Psectrocladius sp. 9 9 1 19 Paracntronomus sp. 17 1 18 Rheotanytarsus sp. 8 1 18 27 Micropsectra sp. 120 240 176 9 21 566 Trissociadius sp. 8 8 Phaenopsectra sp. 8 8 Brillia sp. I l Nematomorpha 16 24 8 48 Nematoda 8 24 9 8 8 10 67 Hirudinea 8 1 9 Oligochaeta 1868 1862 1775 1030 2251 329 9115 Planaridae 2 1 1 10 14 Daphnidae 88 232 152 120 592 Daphnia sp. 8 16 24 Cladocera 2088 1784 3176 1216 32 8296 Copepoda 8 8 Cyclopidae 8 8 Hyalella azteca 122 177 321 216 33 18 887 Asellus sp. 7 20 26 26 16 95 Crangonyx sp. 16 1 8 3 28 Gammarus s 9 9 Vnysa sp. p. 34 3 2 2- 41 Lymnaea sp. 1 1 Total # individuals 7430 9623 9403 4931 8105 1676 41168 Total V taxa 35 37 48 39 36 25

Sampling at SV2 and SV5-was not initiated until July 1979.

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8 5 3 2' O r 8 " E Figure 6. Fluctuations in Hydroosyche sp. numbers near Fort St. Vrain Nuclear Generating station, January through December 1979.

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20 numbers when present. Baetis sp. , Heptagenia sp. and Hydroosyche sp.

were the most abundant non-dipteran insects (1.0, 0.3 and 1.7 percent, respectively). Hydropsyche sp. (Figure 6) was the only taxon of this group to occur fairly regularly throughout the year. Hyalella azteca was frequently present, but never in large numbers (Figure 7).

Tricorythodes sp., Corixidae, Ochrotrichia sp., Hexatoma sp., Nematoda, Planaridae, Asellus sp. and Crangonyx sp. were uncommon during the sampling period and were generally collected on only one sampling date.

SP4U Thirty-seven macroinvertebrate taxa were collected from Station SP4Uin1979(Table 1). Station SP4U was unique among the South Platte River sampling sites as more oligochaetes were collected than Cladocera.

011gochaetes composed 19.3 percent of the macroinvertebrates collected (Figure 2). Cladocerans represented 18.5 percent of individuals collected and were found primarily in October and early November.

Several dipteran groups were present at SP4U in relatively large numbers.

Simulium sp., Cricotoous sp. (Figures 3 and 4) were present on most collection dates. However, very small chironomids, Chironomus sp.

(Figure 5), Paralauterborniella sp., Polypedilum sp. and Micropsectra sp. occurred in relatively large numbers on only a few sampling dates.

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Psectrocladius sp. and Phaenoosectra sp. were rare organisms that occurred on one or a few sampling dates. Baetis sp. (Figure 8),

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were collected at SP4U in 1979.

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DN @ N =* N =* =*N =* N =* N NW CO N == N W Figure 8. Fluctuations in Baetis sp. number; near Fort St. Vrain Nuclear Generating Station, January througn December 1979.

High water prevented sampling.

.. l 22 SPaB The greatest numcer of taxa (48) we're collected at Station SP48 (Table 1). In addition, a number of the taxa collected at SP4B were unique to this station, i .e. 00hiocomohus sp. , Laccochilus sp. , Laccobius sp. , Hydrocorus sp. and Lymnaea sp. Taxa that were relatively rare but which occurred at least two sampling sites were typically found at Station SP48, e.g. ,

Arcia sp. , Ischnura sp. , P_sychoda sp. , Dicrotendices sp. , Trichocladius so. ,

Parachironomus sp. , Thectanytarsus sp., Planaridae, Cranconyx sp. and Physa sp. Interestingly, SP48 was the only station at which no Ochrotrichia sp. were found. Cladocerans were the must abundant organism collected at SPdB in 1979 (33.8 percent) but were found almost exclusively in October and November. 011gochaetes, the second most comon organism (18.9 percent), were found throughout the year (Figure 2). Simulium sp. (5.4 percent, Figure 4),

Cricotoous so. (17.3 percent, Figure 3), Chironomus sp. (2.2 percent, Figure

5) and Paralauterbornfella sp. (2.6 percent) were the most abundant dipterans found at Station SP48. Baetis sp. (1.1 percent, Figure 8) and Hydroosyche sp.

(1.4 percent, Figure 6) were the most comon non-dipteran insects. More Hyalella azteca (Figure 7) were found at Station SP4B than any other site in 1979. The draining of Goosequill Pond in May might have had a beneficial subsequent influence on species number and diversity in the pond effluent, wnich in turn could have affected the collections at SP48.

C,1 Station Cl was the second-most speciose station (39 taxa) in 1979.

However, numbers of macroinvertebrates (4931) collected at Cl were icwer tnan any other station except SV2. Station Cl had only one taxen (Copepoda) unique to it. Cladocera were the most ccmmon organism found at C1 (24.7 percent). Gligocnaetes were seconc-most abundant (20.3 percent, :igure 2) and were found more consistently througnout the year

ai 23 than cladocerans. Simulium sp. (12.8 percent, Figure 4), Cricotoous sp.

(13.4 percent, Figure 3) and Paralauterborniella sp. (4.7 percent) were the most abundant dipterans at Cl in 1979. Chironomus sp. (1.2 percent,.

Figure 5) were not particularly comon at Station C1. Baetis sp. (1.0 percent, Figure 8) and Hydropsyche sp. (1.8 percent, Figure 6) were the most comon non-dipteran insects. Hydroosyche sp. was more comon through-out the year than Baetis sp. Hyalella azteca (4.4 percent, Figure 7) was collected on most sampling dates but generally in rather low numbers.

SV2 Although Station SV2 was sampled only during the second half of 1979, it had the second highest number of organisms (8105),(Table 1) and was rather speciose (36 taxa). Oligochaetes were the most abundant organism (27.8 percent, Figure 2) at SV2. Cladocerans were rather rare at Station SV2. Simuliumsp.(18.6 percent, Figure 4) were the second-most comon organism collected at SV2 in 1979. Cricotopus sp.

(16.3.vercent, Figure 3) was rather common. Station SV2 had the dis-tinction of having a greater abundance of several non-dipteran insects than any other station in 1979. Baetis sp (9.2 percent, Figure 8),

Tricorythodes sp. (3.8 percent), Hydropsyche sp. (2.2 percent, Figure

6) and Ochrotrichia sp. (0.8 percent) were among these insects. Caenis sp., Enallagma sp. and Trissocladius sp. were unique to Station SV2.

Hyalellaazteca(0.4 percent, Figure 7) were not comon at Station SV5 and occurred,only from July through October.

-SV5

, Station SV5 was re-established the last half of 1979. This station had the fewest taxa (25) and the fewest organisms (1676), Table

1) of.any station samoled in 1979. Oligochaetes were the most

24 comon organism found at Station SV5 (19.6 percent, Figure 2). No cladocerans were collected at Station SV5.Simuliumsp.(18.3 percent, Figure 4), Cricotopus sp. (15.9 percent, Figure 3), Chironomus sp.

(8.2 percent, Figure 5) and Paralauterborniella sp. (5.3 percent) were common dipterans at Station SV5. B_aetis sp. (4.3 percent, Figure 8),Tricorythodessp.(3.8 percent)andHydroosychesp.(8.5 percent, Figure 6) were the most common non-dipteran insects. Brillia sp. was the only organism unique to Station SV5.

Hyalella azteca (1.1 percent, Figure

7) occurred in low numbers and rather infrequently.

Fish Collections Nineteen species of fish were collected from two sampling stations on the South Platte River and from two sampling stations on the St.

'?ain River.

Hybrid Catostomus commersoni x C. catostomus were collected in the South Platte River but not the St. Vrain River. Station SV2 had the greatest number of species (16) and Station SP4A the fewest (11)

(Tables 2, 3, 4 and 5). The greatest number of fish were collected at Station SP4A and the fewest at Station SP48. Notropis stramineus was the most comon fish at all stations except SP4B where Cyprinus caroio _

was the most abundant.

Notropis lutrensis, N. dorsalis, Pimechales promelas and Catost_omus commersoni were relatively common at all sa

stations.

Rhinichthys cataractae and Lepomis cyane11us were present at all sites but in rather low numbers. Fundulus kansae was present at all sites except SV5.

Semotilus atromaculatus was found at all sites except SP4A.

Hytognathus hankinsoni, Culaea inconstans, Pomoxis annularis, I

Microoterus salmoides, Lecomis humilis, Pm flavescens and Ictalurus melas were found at only one site and/or in very low numbers at two sites.

-25 Table 2. Number,.mean' length and range, and mean weight and range of ichthyofauna collected at SP4A on 16 November 1979.

N L(mm) L Range N'(g) W Range Notropis stramineus 1726 39.786 18 - 75 0.712 0.054 - 4.356 Notropis lutrensis 278 30.972 19 - 62 0.306 0.059 - 2.824 Notropis dorsalis 138 43.931 36 - 55 0.691 0.377 - 1.326 Pimephales promelas 73 45.393 28 - 69 1.283 0.190 - 4.190 Rhinichthys cataractae 1 52.000 -

1.378 -

~'

-Cyprinus carpio 51 136.204 69-554 189.958 5.462-2155.000 Catostomus connersoni 20 154.800 56-325 93.279 2.100 - 382.719

--C. commersoni x C,. catostomus 1 83.000 -

6.055 -

Fundulus kansae 26 51.423 39 - 72 1.454 0.564 - 4.116 Culaea inconstans' 2 60.500 59 - 62 2.069 1.837 - 2.303 Lepomis cyanellus 1 66.000 -

5.009 -

Total # individuals 2317

' Total # species 11 O

,e l

26 Table 3. Number, mean length and range, mean weight and range of ichthyofauna collected at SP48 on 6 October 1978.

N L(am) L Range 7(g) W Range Notropis stramineus 33 50.5 32 - 73 1.610 0.233 - 4.000 Notropis lutrensis 12 44.2 31 - 69 1.010 0.196 - 2.963 Notropis dorsalis 9 39.0 36 0.447 0.330 - 0.562 Pimephales promelas 50 58.1 36 - 74 2.344 0.470 - 4.710 Rhinichthys cataractae 4 56.0 50 - 68 1.798 1.336 - 2.993 Semotilus atromaculatus 2 149.5 123-176 38.980 18.541 - 59.419 Cyprinus carpio 82 170.272 65-610 324.887 3.952-3062.00 Catostomus connersoni 34 111.5 64-330 36.708 2.695 - 395.000 Catostomus catostomus 2 124.0 107-141 23.298 14.264 - 32.331

--C. commersoni x C,. catostomus 1 165.0 -

44.890 -

Ictalurus melas 2 76.5 76 - 77 6.578 6.421 - 6.735 Fundulus kansae 2 49.0 42 - 56 1.122 0.616 - 1.627 Lepomis cyanellus 28 57.0 32-112 4.961 0.576 - 25.537

.Lepomis macrochirus 8 56.6 36-100 4.608 0.579 - 17.946 Micropterus salmoides 1 102.0 -

12.507 -

Total # individuals 270 Total # species 15

r 27 Table 4. Nunber, mean length and range, and mean weight and range of ichthyofauna collected at SV2 on 6 October 1979.

N C(mm) L Range 7(g) W Range Notropis stramineus 1690 43.826 25 - 73 0.808 0.107 - 4.021 Notropis lutrensis 96 35.049 24 - 59 0.427 0.081 - 2.282 Notropis dorsalis 29 43.804 36 - 51 0.642 0.391 - 1.044 Pimephales promelas 79 51.399 32 - 74 1.744 0.307 - 4.966 Rhinichthys cataractae 60 58.930 45 - 89 2.289 0.827 - 7.430 Hybognathus hankinsoni 5 57.800 30 - 74 2.248 0.259 - 4.044 Semotilus atromaculatus 1 167.000 -

51.477 -

Compostoma anomalum 4 75.000 68 - 89 4.457 3.200 - 7.096 Cyprinus carpio 41 87.145 65-186 13.098 4.062 - 98.341 Catostomus commersoni 76 103.378 63-274 18.039 2.620-231.00 Catostomus catostomus 7 100.286 81-125 10.513 5.154 - 16.572 Ictalurus melas 5 105.00 50-148 20.281 2.087 - 30.593 Fundulus kansae 11 40.000 29 - 48 0.600 0.205 - 0.974 Lepomis cyanellus 22 65.318 36 - 97 6.464 0.687 - 16.978 Lepomis humilis 2 61.000 58 - 64 3.692 3.148 - 4.235 Pomoxis annularis 1 67.000 -

3.291 -

Total # individuals 2129 Total # species 16

30 [

28 Table 5. Number, mean length and range, mean weight and range of ichthyofauna collected at SV5 on 16 November 1979.

N L(mm) L Range W(g) W Range Notropis stramineus 1598 48.090 26 - 79 1.273 0.049 - 5.005 Notropis lutrensis 499 34.036 21 - 65 0.453 0.078 - 3.576 Notropis dorsalis 44 62.175 31 - 79 2.172 0.377 - 3.927 Pimephales promelas 27 48.074 31 - 75 1.644 0.387 - 5.458 Rhinichthys cataractae 2 64.000 57 - 71 3.113 1.809 - 4.417 Hybognathus hankinsoni 7 72.429 68 - 83 3.995 2.976 - 5.889 Semotilus atromaculatus 2 179.500 162-197 64.215 48.353 - 80.077 Cyprinus carpio 21 179.143 78-515 259.694 7.548-1185.000 Catostomus canmersoni 12 135.2500 67-270 49.107 3.582-226.000 Catostomus catostomus 1 185.000 -

84.449 -

Culaea inconstans 1 62.000 -

2.615 -

Lepomis cyane11us 12 74.412 35-130 11.125 0.742 - 44.356 Micropterus salmoides 1 116.000 -

22.875 -

Pomoxis annularis 3 137.333 112-151 40.705 20.404 - 53.910 Perca flavescens 3 106.333 69-165 19.736 3.645 - 48.695 Total # individuals 2233 Total # species 15

~

u

, as 29 Chemical and Physical Data Chemical and physical data for Stations SP4A, SP4U, SP48, Cl,-SV2 and SV5 are presented in Tables 5, 7, 8, 9, 10 and 11, respectively.

Meaningful comparison of the relative abundance of aquatic macroinverte-brates to the chemical and physical data is possible only when physical and chemical data are collected continuously, i.e., by constant recording devices. Since the chemical and physical data are collected bi-weekly, no relationship analysis was made.

Statistical Analysis Statistical analysis of the data has not been completed but will l

be reported at a later date.

ISCUSSION Significantly fewer taxa and organisms were collected in 1979 than in 1978. This is particularly noteworthy as two stations were re-established (SV2 and SV5) in July 1979. Only Station SP48 had more taxa

, in 1979 than in 1978 (44 and 48, respectively). Station SP48 was also the l

l only station at which more organisms were collected in 1979 than 1978 i

(9403 and 6780, respectively). An additional confounding factor was the very high number of cladocerans collected from all Sovth Platte River sampling stations in 1979 (Table 1). In 1978 cladocerans were a rela-tively unimportant component of the total aquatic macroinvertebrate co'm-l L

munity of all South Platte River sampling stations. Station SP4B had the greatest number of c'adocerans of any station in 1979. Station SP4B had the greatest number of taxa unique to one station. Although it is imoos-sible to isolate one factor as the single most important cause of the

~

Table:6a. Sunanary of chemical and physical data for Station SP4A, January through June 1979.

Parameter 1/9 1/28 2/8 2/22 3/11 3/27 4/13 4/26 5/13 5/28 6/

6/

Air Tenp. (C) -1.0 -6.5 1.0 13.5 17.0 13.0 18.5 18.0 25.0 ****

Water Temp. (C) 0.0 1.0 3.0 5.5 9.0 9.0 8.5 13.0 18.0 Dissolved 02 (ng/1) 8.0 8.1 9.5 8.7 6.9 7.1 7.0 5.3 4.4 4.9 Dissolved CO2 (ng/1) 17.5' 14.0 30.0 33.0 -- - --

4.5 *f**

[dl 7.8 8.0 7.5 7.5 -- -- --

8.0 7.8 Total Alkalinity (ng/1) 388 488 358 474 354 330 280 216 247 252 Filtrable Solids (mg/1) 608 696 672 776 656 632 880 480 720 80 Dissolved Solids (ng/1) 798 872 892 854 864 802 1040 1040 820 500 liardness (ug/1) 308 325 308 325 325 325 222 310 360 257 Conductivity (micromhos/aa) 420 370 450 380 390 375 200 230 220 340 Turbidity (JTU) 14.0 15.5 23.0 13.5 20.5 26.0 -- -- --

liigh water levels prevented sampling

- pil meter malfunctioning.

- - Turbidimeter malfunctioning.

- - - Broken thernaneter.

I Table 6b. Sununary of chemical and physical data for Station SP4A. July through December 1979.

Parameter 7/9 7/29 8/6 8/30 9/10 9/29 10/14 10/27 11/11 11/28 12/7 12/31 Air Temp. (C) -

34.0 33.0 32.0 30.5 25.5 27.0 18.0 15.0 4.0 -8.0 0.0 -1.0 Water Temp. (C) 19.5 20.0 22.0 22.5 23.0 18.5 15.5 14.0 6.0 0.1 4.0 2.0 Dissolved 02 (ng/1) 5.5 6.3 10.0 8.9 6.4 5.0 4.8 6.2 6.0 5.6 8.0 Dissolved C02 (ug/1) 14.5 13.5 14.5 14.5 13.5 20.0 20.0 , 26.5 81.0 74.0 51.0 40.0 pil 7.6 7.9 7.8 7.8 7.8 7.7 7.7 7.6 7.2 7.3 7.4 7.6 Total Alkalinity (ng/1) 196 590 508 542 512 532 498 520 522 498 508 576 Filtrable Solids (mg/1) 480 104, 100 80 760 100 850 500 400 800 600 200 Dissolved Solids (m9/1) 460 860 580 860 1020 780 800 840 820 820 840 780 liardness (mg/1) 172 342 291 308 291 325 360 325 360 360 377 308 Conductivity (micrombos/cm) 520 610 550 540 560 560 600 600 580 600 580 Turbidity (JTU)* -- -- - -- -- -- -- -- -- -- -- --

Turbidimeter malfunctioning.

- D0 8ottles broken in transit.

- - Water sample inadvertently disposed.

~

I Table 7a. Sunanary of chemical and physical data for Station SP40, January through June 1979.

Parameter 1/9 1/28 2/8 2/22 3/11 3/27 4/13 4/26 5/13 5/28 6/

6/

Air Temp. (C) -l.0 -7.5 8.0 13.0 23.0 11.5 18.5 18.0 26.0 27.0 Water Temp. (C) 0.0 0.5 3.0 6.0 10.0 8.0 8.5 12.5 19.0 24.0 Dissolved 02(mg/1) 7.7 8.0 9.3 8.7 7.0 7.1 6.9 5.2 4.6 4.2 Dissolved C02 (mg/1) 45.0 4.0 28.0 36.0 ** -- -- --

4.5 5.5 pil 7.3 8.4 7.5 7.4 *! -- - --

8.0 7.9 Total Alkalinity (mg/1) 306 372 342 372 314 294 276 212 245 250 Filtrable Solids (ng/1) 592 728 640 712 656 624 480 640 640 480 Dissolved Solids (ng/1) 762 868 864 842 876 826 680 740 800 700 liardness (mg/1) 308 325 308 308 325 325 240 310 360 291 Conductivity (micrombos/cm) 380 355 435 320 500 480 210 260 215 290 Turbidity (JTU) 11.0 12.5 24.5 15.0 20.0 26.0 -- -- --

liigh water levels prevented sampling.

- pil meter malfunctioning.

- - Turbidimeter malfunctioning.

'i Table 7b. Sunsaary of chemical and physical data for Station SP40, July through Decensber 1979.

Parameter- 7/9 7/29 8/6 8/30 9/10 9/24 10/14 10/27 11/11 11/28 12/7 12/31 Air Temp. (C) 25.5 33.0 31.0 27.0 27.0 17.0 25.5 14.5 4.0 -1.0 0.5 3.5 Water Temp. (C) 19.5 21.0 23.0 21.5 23.0 18.5 15.5 14.0 6.5 1.0 4.0 2.0 Dissolved 02 (ag/1) 5.5 5.9 *! 8.6 8.2 6.5 5.0 4.8 6.2 6.4 -4.3 6.0 Dissolved C02(mg/l) 12.0 20.5 7.3 19.5 11.5 15.0 18.5 27.0 78.0 84.0 50.0 40.0 pil 7.6 7.7 8.1 7.7 7.9 7.8 7.7 7.6 7.2 7.2 7.4 7.6 Total Alkalinity (mg/1) 236 580 526 554 538 518 482 544 508 488 508 588 Filtrable' Solids (mg/1) 480 160 100 80 810 200 800 600 600 600 700 400 Dissolved Solids (mg/1) 460 760 500 980 1040 740 740 860 800 800 840 740 liardness (mg/1) 172 291 291 308 308 325 394 325 360 342 377 325 Conductivity (niicromhos/cm) 580 540 560 680 520 525 600 600 580 600 580 Turbidity (JTU)* -- -- -- -- -- -- -- -- -- -- -- --

Turbidimeter malfunctioning.

- D0 bottle broken in transit.

- - Water sample disposed inadvertently.

e 9

Table 8a. Sunniary of chemical and physical data for Station SP48, January through June 1979.

Parameter 1/9 1/28 2/8 2/22 3/11 3/?7 4/13 4/26 5/13 5/28 6/

6/

Air Teny. (C) -2.0 -8.5 7.5 10.5 21.0 9.0 11.0 18.0 23.0 26.0 Water Tenp. (C) 0.5 0.0 2.5 4.5 8.0 5.5 7.5 13.0 16.0 20.5 Dissolved 02 (mg/1) 8.0 7.8 9.6 9.5 7.2 7.3 7.0 4.5 4.4 4.9 Dissolved C02 (mg/1) 12.0 4.5 17.5 40.0 88 -- -- -- 5.0 7.4 pil 7.9 8.4 7.8 7.5 -- -- --

8.0 7.8 Total Alkalinity (mg/1) 338 400 402 526 414 296 264 222 255 254 Filtrable Solids (ng/li 600 752 664 760 744 648 720 640 720 560 Dissolved Solids (ne/1) 840 722 892 862 858 840 760 1760 840 580 liardness (ng/1) 342 342 308 325 325 342 257 325 360 291 Conductivity (microudios/cm) 390 400 390 350 365 465 260 230 215 360 Turbidity (JTU) ***

10.0 9.5 22.5 10.0 16.0 25.0 -- - --

liigli water prevented sampling.

- pH meter nulfunctioning.

- - Turbidimeter malfunctioning.

S

Table 8b. Suusuary of chemical and physical data for Station SP48, July throu9h December 1979.

Parameter 7/9 7.29 8/6 8/30 9/10 9/24 10/14 10/27 11/11 11/28 12/7 12/31 Air Temp. (C) 28.0 33.0 33.0 24.0 29.0 23.5 25.0 14.0 3.0 -6.0 1.0 1.0 Water Temp. (C) 20.0 20.0 22.0 21.0 24.0 16.5 15.5 14.5 6.5 0.5 4.0 3.0 Dissolved 02 (ng/1) 6.5 5.3 9.6 9.3 6.8 5.0 5.0 5.6 6.2 3.4 4.0 Dissolved CO2 (mg/1) 9.0 21.5 3.8 15.0 13.5 8.3 25.5 22.5 79.0 70.0 52.0 40.0 pil 7.6 7.6 8.4 7.d 7.8 8.1 7.6 7.7 7.2 7.3 7.4 7.6 Total Alkalinity (ng/1) 190 518 524 538 514 546 512 562 520 490 510 612 Filtrable Solids (mg/l) 560 120 100 120 300 100 700 500 700 800 769 700 Dissolved Solids (ng/1) 440 830 600 960 820 680 700 860 800 840 820 780 liardness (ng/1) 172 308 326 274 308 308 394 325 342 360 360 325 Conductivity (micrombos/cm) 600 550 580 620 650 660 600 610 580 600 580 Turbidity (JTU)* -- -- -- -- -- -- -- -- -- -- -- --

Turbidineter malfuncticaing.

- 00 bottle broken in transit.

- - Water sample disposed inadvertently.

I.

Table 9a. Sunenary of chemical and physical data for Station C1, January through June 1979.

Parameter 1/9 1/28 2/8 2/22 3/11 3/27 4/10 4/16 5/13 5/28 6/****6/3***

AirTemp.(C) -4.0 -8,5 1.0 14.0 21.0 10.0 12.5 18.0 24.0 28.5 Water Temp. (C) 0.0 0.0 2.0 4.5 9.5 7.0 7.5 15.0 16.5 19.0 Dissolved 02 (ag/1) 7.8 8.0 9.4 9.0 -* 7.6 618 4.7 4.7 4.7 Dissolved CO2 (mg/1) 15.0 14.0 28.0 34.0 -- -- -- 4.5 7.5 pH 7.8 8.4 7.6 7.5 -- -- --

8.0 7.8 Total Alkalinity (mg/1) 328 396 404 430 344 298 26G 206 245 256 Filtrable Solids (ug/1) 656 744 720 704 784 672 480 740 160 320 Dissolved Solids (mg/1) 840 912 834 854 872 826 760 1440 900 600 liardness (mg/1) 325 325 308 325 342 342 240 257 34 2 257 Conductivity (micromhos/cm) 340 375 385 350 405 440 250 245 210 330 Turbidity (JTU) 9.5 10.5 22.0 12.0 16.0 27.5 -- -- --

Dissolved 02 bottle broken in transit.

- pH meter maf functionin9

- - Turbidimeter malfunctioning.

- - - lligh water prevented sampling.

Table 9b. Sunenary of chemical and physical data for Station C1, July through December 1979.

Parameter 7/9 7/29 8/6 8/30 9/10 9/24 10/14 10/27 11/11 11/28 12/7 12/31 Air Tenp. (C) 29.0 34.0 33.0 30.5 30.0 20.5 23.0 15.0 4.0 -5.0 1.0 4.0 WaterTemp.(C) 19.0 19.0 21.0 20.5 23.0 18.0 15.5 15.0 6.5 1.0 4.0 3.0 Dissolved 02 (mg/1) 5.6 6.4 8.1 10.4 9.3 6.7 5.0' 5.0 4.6 6.2 4.3 8.2 Dissolved CO2(ng/1) 10.5 15.5 9.5 50.0 11.5 11.9 25.5 21.0 96.0 54.5 39.0 32.0 pil 7.6 7.8 8.0 7.8 7.9 7.9 7.6 7.7 7.1 7.4 7.5 7.7 Total Alkalinity (ng/1) 218 510 536 548 524- 514 512 534 512 492 496 618 Filtrable Solids (m9/1) 88 80 100 110 300 700 700 700 700 700 800 600 Dissolved Solids (ng/1) 440 800 540 920 720 860 700 880 800 880 820 800 liardness (mg/1) 154 308 308 291 291 308 394 308 325 360 360 325 Conductivity (micrombos/cm) 560 640 620 610 700 620 600 610 600 600 580 Turbitity (JTU)* -- -- -- -- -- -- -- -- - -- -- --

Turbidimeter malfuntioning.

- Water sample disposed inadvertently.

.. - .., .~ , .. . - . . . - . -.

Table 10. Summary of chemical and physical data for Station SV2, July through December 1979.

Parameter 7/9 7/29 8/6 8/30 9/10 9/24 10/14 10/27 11/11 11N8'12/7 12/31 Air Temp. (C) 26.0 33.0 30.0 18.0 23.0 24.5 18.5 14.0 0.0 0.0 0.25 WaterTemp.(C) 19.0 19.0 21.0 20.0 20.0 16.0 15.0 14.0 5.0 2.0 2.0 Dissolved 02 (mg/1) 7.8 6.2 6.4 13.4 6.0 7.6 7.0 6.8 7.6 5.2 8.6 Dissolved C02(mg/1) 11.0 *t 10.0 7.8 15.0 14.0 10.5 11.5 30.5 34.5 24.5 pil 7.8 7.9 J.0 8.1 7.9 7.9 8.0 8.0 7.6 7.6 7.8 Total Alkalinity (mg/l) 364 538 584 562 518 578 534 562 502 518 576 Filtrable Solids (mg/1) 144 700 220 500 400 700 500 500 820 100 DissolvedSolids(mg/1) 820 f* 1220 1220 1020 1100 820 920 880 860 520

'llardness (mg/1) 496 462 582 479 548 462 531 445 496 479 411 Conductivity (micrombos/cm) 720 540 630 580 740 660 550 625 580 620 610 Turbidity (JTU)* -- -- -- -- -- -- -- -- -- -- --

Turbidimeter malfunctioning.

- Water samples disposed inadvertently prior to determination.

- - SV2 inaccessible due to heavy snowfall.

I

-Table 11. Summary of chemical and physical data for Station SVS, July through Decenber 1979.

Parameter 7/9 7/29 8/6 8/30 9/10 9/24 10/14 10/27 11/11 11/28 12/7 12/31 AirTemp.(C) 22.0 32.0 30.0 22.5 29.0 19.5 17.5 10.0 0.0 -5.0 0.0 2.0 Water Temp. (C) 20.0 19.5 21.0 20.5 20.5 17.0 15.0 13.5 5.0 1.0 2.0 0.0 5.1 6.3 8.8 6.6 7.1 6.0 6.0 4.0 5.0 6.4 8.2 Dissolved 02 (m9/1)

Dissolved CO2(ug/1) 6.0 !! 8.0 7.4 8.3 10.1 9.5 6.3 31.0 34.0 33.0 20.0 pil 8.0 7.9 8.1 8.1 8.0 8.0 8.0 8.0 7.6 7.6 7.6 7.8 Total Alkalinity (mg/1) 344 514 598 534 492 574 482 306 500 492 500 544 filtrable Solids (ng/l) 480 400 150 700 100 720 760 700 1000 700 200 Dissolved Solids (mg/1) 940 f* 1080 1160 1140 1060 860 920 920 1040 880 620 lic.:diess (mg/1) 479 462 565 514 548 479 565 445 496 616 514 428 Conductivity (micromhos/cm) 670 640 660 580 750 600 580 625 580 620 620 630 Turbidity (JTU)* -- -- -- -- -- -- -- -- - -- -- --

Turbidimeter malfunctioning

- Water samples inadvertently disposed prior to determination.

- - D0 bottle broken in transit.

O*

.. l 40 distinctiyeness of Station SP48 (Carlson et al.1979), the influence of the effluent from Goosequill Ditch must be considered a primary cause of the high diversity and large number of organisms found at Station SP48.

Station SP48 also had more taxa in 1979 than in 1977 or 1978 (35 and 42,

- respectively). Significantly, the difference in number of taxa between Station SP4B and any other site in 1979 was at least twice the difference in number of taxa between SP4B and any other site in 1977 or 1978. The rather extensive ice cover of much of the South Platte River in early 1979, high spring runoff, and channel alteration certainly contributed significantly to the lower numbers and diversity (except at SP48) in 1979.-

Comparison of the aquatic macroinvertebrate community of the St.

Vrain River to previous years is difficult as sampling at SV2 and SV5 has been intermittent and irregular over the years and was re-established to a regular sampling basis in July 1979. The rather high diversity and l large number of organisms at SV2 is, at least partially, attributable to the varied substrate. In contrast, SV5 had primarily. a sand substrate.

The most important difference between the fish fauna of 1978 and 1979 was the presence of several game fish species in 1979. However, their numbers were never great, and all individuals captured were rather small. Hyboqnathus hankinsoni and Culaea inconstans are evidently permanent deni_zens of the South Platte and St. Vrain Rivers in the vicinity of the Fort St. Vrain Nuclear Generating Station as they were captured in 1978 snd 1979, albeit in low numbers. Fundulus kansae was found at all stations except SV5. Pimechales oromelas, Notroois dorsalis, Cyorinus carcio'and Catostomus commersoni occurred at all stations in moderate numbers. The much greater number of fishes collected in 1979 than'1978 was completely a function of a more inte.1sive collection effort.

l

c<

i, 0, 41 The inclusion of game fish species in the 1979 collections was also probably due primarily to the greater effort expended in collection. The greater number of species collected in 1979 is a result of the capture of the game fish species (Ictalurus melas, Lecomis cyanellus, k. humilis,

k. macrochirus, Microoterus salmoides, and Perca flavescens) (Tables 2, 3, 4 and 5). No other fish species were collected in 1979 that were not collected in 1978.

LITERATURE CITED American Public Health Association, American Water Works Association and Water Pollution Control Federatior. 1971. Standard methods for the examination of water and wastewater. 13th ed. American Public 3

Health Association, Washington, D.C. 847 pp.

Carlson, C. A. and L. D. Propst. 1979. Aquatic invertebrate component, Fort St. Vrain Ecological Investigations. 1979 Semi-annual Report.

Reoort to Thorne Ecological Institute. 23 pp. Mimeo.

- Carlson, C. A. , W. D. Frank, D. L. Propst, R. L. Rohrer, and P. E. Stacey.

1977. Aquatic invertebrates component, Fort St. Vrain Ecological Investigations. 1977 Semi-annual Report. Report to Thorne Ecological Institute. 23 pp.

Cressey, S. , C. Carlson, and W. O. Frank. 1974. Aquatic invertebrate component, Fort St. Vrain Ecological Investigations. 1974 Annual Report. Report to Thorne Ecological Institute. 17 pp. Mimeo.

Eder, S. , C. Carlson, and W. 0. Frank. 1974. Final report, aquatic invertebrate component and fish food habits component, Fort St.

Vrain Ecological Investigations. Report to Thorne Ecological Institute. 30 pp. Mimeo.

-Stacey, P. E. , C. A. - Carlson, and W. D. Frank. 1975. Aquatic inverte-brates component, Fort St. Vrain Ecological Investigations. 1975 ;

Semi-annual Report. Report to Thorne Ecological Institute. 21 + i viii pp.

Weber, C. I. (ed.). 1973. Biological field and laboratory methods for measuring the quality of surface waters and effluents. U. S.

Environmental Protection Agency, Cincinnati, OH.

1 1

y i .. J 42 ALGAL MONITORING by l

Paul Kugrens I

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43 INTRODUCTION The data in this report consist of a comprehensive species list (Table 1), a comparative table that provides monthly dominants, relative abundances, population sizes, and general water conditions at the time of collection (Table 2); a list indicating the percentage of a population comprised of various algae (Table 3); a table of species diversity at each site (Table 4); and a table listing species ratios of the four most prominent algal divisions (Table 5). Sampling techniques have remained the same, although during low or high water conditions, alternate sub-strates were chosen. These do not alter the results significantly since previous observations indicate little difference in algal growth on the concrete samplers vs. other substrates. As in the past, only living cells are included in actual counts, to represent actual site conditions.

If dead cells were included the numbers would be greatly inflated and inaccurate. Figure 1 presents the algal sampling sites.

OBSERVATIONS

1. Species Oiversity Tables 1 and 4 incidate that a total of 119 species was identified during 1979. The algal populations consisted of 60 diatom species, 37 green algae, six euglenoids, nine blue-green algae, four golden-brown algae, one cryptomonad, one undescribed dinoflagellate, and one yellow-green alga. The greatest species diversity occurs in diatoms at all sampling sites and reflects past observations. However, an overwhelming l dominance in diatom species at site GQ is absent. The lowest speciea diversity is found at SP and might be caused by the swifter currents at

44 this sampling site. By any species diversity index, all sites represent a low species diversity, a characteristic of polluted or dystrophic aquatic habitats. As in past years, the number of species at any given time is dependent upon temperature, ice, water level, and scouring by swift currents (Table 2). Table 5 indicates the relative number of species from the four most prominent divisions and shows that diatom species dominate, qualitatively and quantitatively, the algal populations.

As the temperature increased during March and April, a corresponding increase in species also took place. Except for a de' cline in May and June, species numbers remain ' .c high levels the remainder of the year.

Euglenoids were present in January through April at various sites, dis-appeared during subsequent months, and began to reappear in December at sites SPGQ and SP. Blue-green algal species were occasionally present but for the most partwere absent during the colder mcnths. However, in August blue-green algae constituted a significant portion (SPGQ - 32%)

of the population. Green algae also were low in species numbers except in Goosequill Pond. The decline in species during May and June is attributed to the high, swift water created by spring runoffs. These scour the substrates of algae and do not allow populations to become established. This trend is also noted in the quantitative aspects of this monitoring period.

2. Alcal Populations and Succession All river sites had large proportions of Nitzschia calea throughout this monitoring period with Navicula cryotocechala also being prominent.

Euclena viridis made its appearance in the winter flora as it has in

45 past years, generally growing in large numbers from January to April (Table 2). Diatoms, in general, are most prominent in the rivers (Table

3) whereas green algae represent the dominants in Goosequill Pond, a characteristic noted in previous annual reports. Euglenoids appear during mid- to late winter depending on the river conditions. Blue-green algae are generally absent during the winter months (Table 5).

St. Vrain River The St. Vrain River had, as its most caninon dominant, Navicula cryptocephala with Nitzschia palea being dominant at SCI in March, July, September, October, and December, and at SV during March, April, and Septemoer. While Euciena viridis never became dominant, it constituted a significant portion of the algal population during March and April at both St. Vrain River sites. This is somewhat later than the appearance of E_. viridis in the South Platte River, which occurred in January through April (Table 3).

The highest number of algae also occurred during March, April, and October indicating favorable temperatures and more stable water conditions at these times. Prior to and after these months, water was either frozen (SVI in January and somewhat in December) or several runoffs created extremely swift and high water conditions (Table 2).

Gooseouill Pond With the exception of November and December, Scenedesmus cuadricauda dominated the algal population in Goosequill Pond and as the water tempera-tures increased, so did the proportion of dominance by this alga. Popula-tion numbers also increased with the warmer water, even when the pond was

l 46 beind drained during April and May, eventually increasing to 224,786 individuals /ml. In November, however, as the temperatures fell below ,

10 C, Scenedesmus growth decreased drastically (Tabla 2). During November and December ice covered the pond, but a large sub-ice population of the diatom, Steohanodiscus hantzschii became dominant (90%) in a sizeable copulation of 204,197 individuals /ml . In December, a snow cover over the ice probably restricted light penetra :on, therefore decreasing the population to 13,025 individuals /ml.

South Platte River The 1979 monitoring period began with Euglena viridis being the dominant during the first three months, except at SPI during January and SP during March. During the remainder of the year Nitzschia palea was the dominant at all sites with N. palea being the only constituent of the algal populations during May at SP and SPGQ. 1 The number of periphyton remained low throughout 1979 due to the l

continually swift currents present, even eliminating all living repre-sentatives during June (Table 2). Only empty cell walls were collected and identified through their ornamentation. The swift high water condi-tions during May and June eliminated algal growth at all sampling sites in the South Platte River, apparently by scouring available substrates.

Unusual populations of Hydrodictyon reticulatum and Enteromarcha, intestinalis occurred at SPI during the summer months. These algae are l l

free-floating, macroscopic forms that generally grow in ponds and lakes. I I

Their presence indicates the lake-like conditions that are present at )

this collecting site.

g ,,

47

3. Comparison of Alcal Populations Between Rivers In general, the same species occur in both rivers but the dominants and the time of appearance of certain species vary. For instance Navicula cryotoceohala is generally more dominant in the St. Vrain River whereas Nitzschia calea dominates periphyton in the South Platte River. In addi-tion, Euglena viridis was never dominant in the St. Vrain River but dominated for three months in the South Platte River. Furthennore Euglena.

_ viridis grows later (March-April) in the St. Vrain River than in the South Platte (January-March). Other algae that occur sporadically during certain months in both rivers are of little significance. However, the presence of Enteromarcha and _Hydrodictyon in rivers indicates the altered conditions at this collecting site (SPI).

4. Effects of Fort St. Vrain Nuclear Generating Station on Alcal Populations Two collecting sites appear to be affected by activities of the generating station. The first is site SV1 (Tables 1 and 2) where stationary water collects debris and sedimentation of dead cells, creating a dystrophic and anaerobic situation, resulting in proportionally more dead cells than

, living algae during late summer and fall.

The second affected site is SP. As reported previously, the effluent t

from Goosequill Pond modifies the algal population significantly. The population often contains large numbers of algae that are representative of Goosequill Pond but are not found at any other river site.

5. Comoarison with 1978 Monitorino Period The algal populations in both rivers were considerably higher in 1978, reaching population numbers of 2 million or more by June in the South

s

..a f 48 Platte River, but considerably lower in the St. Vrain River. The decrease in the St. Vrain River was attributed to fast water in 1978. The South Platte River, on the other hand, did not exper.ence any significant spring runoff in 1978 which allowed populations to build up to high levels (Tables 3, 4, and 5).

This year the spring runoff was greater in both rivers, either eliminating algae or greatly reducing their numbers. In fact, the rivers remained high throughout 1979, therefore keeping algal populations at a lower level.

The dominant algae were the same as last year with similar trends of succession and appearance. Similar conditions at the various river sites, namely SPI, SP and SVI also occurred in 1973 and previous years with similar lentic algal growths.

Scenedesmus Quadricauda and Rhizoclonium hieroglyohicum are the most commonly-occurring algae in Goosequill Pond, continuing the trend of pre-vious years. Scenedesmus was the dominant phytoplankton for 10 months in 1979 with Stephanodiscus hantzschii dominating the November and December sub-ice samples. Rhizacionium on the other hand forms extensive floating mats along the perimeter of the pond during the warmer months of the year.

Factors that affect the size of algal populations and dominants include temper-b2.ae, water level, nutrients, water movement, and ice cover.

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SV = 'St. Vrain below Intake ,

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= South Platte River below Intake but above effluent 4

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51 Table 1. Algal Soecies List and Sites for 1979 Sampling Sites Genus or Species SVI SV S PI SPGQ SP GQ Division Bacillariophyta ,

Achnanthes lanceola n AB AB AB AB AB AB Achnanthes minutissims A A A A A Amphora ovalis A A AB A AB B Asterionella formosa AB AB A AB Biddulphia laevis A AB B A Caloneis amphisbaena AB AB AB AB A AB Cocconeis placentula AB A A A A Cyclotella meneghiniana AB AB A A AB AB Cymatopleura solea A A B A A Cymbella minuta A A B Cymbella tumida AB B Cymbella turgida A B A AB Diatoma elongatum A A A A A A Diatoma vulgare AB AB AB AB AB Entomoneis ornata A Fragilaria capucina A B B A Fragilaria construens B A B B Fragilaria crotonensis A AB AB AB B

Gomphonema constrictum A Gomphonema lanceolatum A Gomphonema olivaceum A AB AB B Gomphonema parvulum AB AB A AB AB AB Gomphonema truncatum A Gyrosigma acuminatum A AB A AB AB A Gyrosigma scalproides A AB A Hannea arcus B A Hantzschia amphioxys AB AB A AB B Melosira sp. B Melosira granulata AB AB B AB A AB A Melosira varians AB B A Navicula cryptocephala AB AB AB AB AB AB

' Navicula cuspidata AB A AB A AB AB Navicula exigua~ AB A A B AB A Navicula minima B B Navicula pupula AB AB B A A AB Navicula pygmaea B AB '8

! Navicula radiosa AB AB '

AB A Navicula rhynchocephala A AB A AB AB AB Navicula viridula AB AB A Neidium iridis A A AB AB Nitzschia acicularis AB AB AB AB A B Nitzschia fonticola A A Nitzschia gracilis AB AB A l

l 52 Table 1. Algal Species List and Sites for 1979 (continued)

Samp1.F~- Si tes Genus or Species SPI SP SVI SV GQ SPGQ Nitzschia holsatica B AB AB A Nitzschia hungarica. AB AB AB AB AB AB Nitzschia palea AB AB AB AB AB AB Nitzschia 3igmoidea A B A A Nitzschia vermicularis A AB A A Pinnularia latevittata B A B Pleurosigma s~p. B Rhoicosphenia curvata AB AB B AB Rhopalodia gibba B B Stephanodiscus hantzschii AB AB AB AB AB AB Surirella angustatum A Surirella capronii A A AB AB A Surirella ovalis A AB Surirella ovata - AB AB AB AB AB Synedra acus B B Synedra-rumpens B B B Synedra ulna AB AB AB AB AB AB Division Chlorophyta Actinastrum hantzschii B B A Ankistrodesmus falcatus AB B AB AB A B Chlamydomonas sp. AB A AB A AB Chlorogonium elongatum A AB Cladophora glomerata A A A A Closteriopsis longissima B B Closterium sp. A Closterium lunula A A A Coelastrum microporum AB A B B Cosmarium sp. B Cosmarium botrydis A A Dactylococcopsis raphidioides A A A Dichotomosiphon sp. A Dictyosphaerium pylchellum A B Enteromorpha intestinalis A A Glecocystis gigas A B Golenkinia ra 'iata A B B Hydrodictyon reticulatum A A -

Micractinium pusillum B AB Oedogonium sp. A AB A Occystis lacustris A B AB B Pediastrum simplex A A Pediastrum duplex A AB A B

l 53 Table 1 Algal Species List and Sites for 1979 (continued)

Genus or Species Sa ing S s gyg 3y SPGQ SP Protosiphon botrydioides A Pteromonas aculeata AB B Rhizoclonium hieroglyphicum A A Scenedesmus acuminatus B AB B B Scenedesrc is armatus AB AB AB B A Scenedesmus bijuga B B Scenedesmus quadricauda A AB AB AB A AB Selenastrum lacustris AB Spirogyra sp. A AB A Staurastrum sp. 3 Stigeoclonium tenue B A A A Ulothrix sp. A Volvulina steinii B A Zygnema sp. A A Division Chrysophyta Anthophysa vegetans B Chrysameba sp. B Dinobryon sp. B B B B AB B Gonyostomum semen B A Division Cryptophyta Cryptomonas ovata B B AB AB B AB Division Cyanophyta

Anabaena sp. AB A A AB AB Aphanizomenon flos-aquae AB B AB AB AB AB Merismopedia sp. B Oscillatoria sp. AB Oscillatoria limosa AB A B A Oscillatoria minnesotensis B Oscillatoria princeps A A AB A AB A Phormidium sp. AB A Rivularia sp. A Division Euglenophyta Astasia sp. A B Euglena acus AB A AB AB AB AB Euglena viridis AB AB AB AB AB AB Peranema sp. B A B Phacus brevicauda AB B Trachelomonas hispida B B B

.* l 1 54 Table 1. Algal Species i.ist and Sites for 1979 (continued)

Sampling Sites Genus or Species SPI SP SVI SV GQ SPGQ Division Pyrrophyta Undescribed dinoflagellate B B B Division Xanthophyta Vaucheria sp. A 1

1 i

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Table 2. Comparison of Algal Populations and their pominants as Influenced by Certain Physical Conditions at their Respective Sites. Results in Total Population. Dominant Species and Percent of each Species in the Population in parenthesis. River Populations Represent Periphyton whereas GQ Represents Phytoplankton Counts, Fort St.- Vrain,1979.

Months Site Janua ry February March SVI Frozen completely 4,622 813.430 No samples. Navicula cryptocephala (64) Nitzschia palea (49)

Navicula viridula (14) Havicula cryptocephala (28)

Euglena viridis (17)

Euglena acus (5)

SV 115,554 18,718 104.452 Navicula cryptocephala (56) Navicula cryptocephala (67) Nitzschia palea (47)

Surirella ovata (20 Nitzschia palea (22) Navicula cryptocephala (34)

Nitzschia palea (10) Euglena viridis (12)

Navicula viridula (6) ,

u, GQ 7,423 10,084 26.050 Scenedesmus quadricauda (62) Scenedesmus quadricauda (67) Scenedesmus quadricauda (87)

Stephanodiscus hantzschii (30) Euglena viridis (20) Chlamydomonas sp. (8)

SPI 16,176 113,233 136,342 Euglena viridis (43) Euglena viridis (24) Euglena viridis (53)

Hitzschia palea (29) Navicula cryptocephala (13) Euglena acus (19)

Gomphonema parvulum (14) Hitzschia palea (11) Nitzschia palea (12)

Navicula cryptocephala (14) Navicula cryptocephala (8)

O W

I Table 2. (continued)

~.

NntP.s Site . January February March SPGQ 6,932 286,549 198,736 Nitzschia palea (33) Euglena viridis (60) Euglena viridis (47)

Achnanthes lanceolata (11) Navicula cryptocephala (27) Nitzschia palea (24)

Euglena viridis (11) Nitzschia palea (6) Navicula cryptocephala (20)

Surirella ovata (11)

Synedra ulna (11)

SP 16,176 67,015 76,259 Euglena viridis (71) Euglena viridis (38) Navicula cryptocephala (42)

Nitzschia palea (21) Gomphonema parvulum (17) Euglena viridis (27)

Navicula cryptocephala (14) Nitzschia palea (15)

Nitzschia palea (7) Nitzschia acicularis (6)

E General GQ - 4.5" C: Completely frozen GQ - 6.50 C: Open water in GQ - 9 C: High water, slightly entering and exiting.

Water SV - Cgmpletely frozen cgnter only. greeg,C: Low, clear. Algal Conditions SP - 2 C: Clear, swift water. SV - 7 C: liigh, turbid, swift. SV - 10.5 Some ice along banks Considerable ice along popufations evident.

hanks. SP 11 C: liigh, swift, SP - 10 C: liigh, turbid, swif t. turbid.

Table 2. (continued)

Months Site April May June SVI 494,528 23,108 4,044 Navicula cryptocephala (46) Navicula cryptocephala (80) Havicula cryptocephala (57)

Euglena viridis (21) Navicula radiosa (10) Nitzschia palea (29)

Hitzschia palea (16) Scenedesmus quadricauda (10) Helosira granulata (14)

SV 1,261,740 9,243 2,889 Nitzschia palea (37) Navicula cryptocephala (75) Navicula cyrptocephala (20)

Navicula cryptocephala (33) Melostra granulata (25) Melostra granulata (20)

Euglena viridis (10) Nitzschia acicularis (20)

Nitzschia palea (20)

Synedra ulna (20)

GQ 19,957 46,848 224,786 Scenedesmus quaridauda (98) Scenedesmus quadricauda (96) Scenedesmus quadricauda (99+)

Navicula cuspidata (3)

SPI 11,957 23,109 Nitzschia palea (46) Nitzschia palea (100) No living cells.

Navicula cryptocephala (33)

SPGQ 88,234 190 Nitzschia palea (50) _Nitzschia palea (100) No living cells.

Navicula cryptocephala (25) 4

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Table 2. (continued)

~.

Months Site April May ,

June SP 238,230 4,622 Nitzschia palea (56) Nitzschia palea (100). No living cells.

Navicula cryptocephala (26)

Nitzschia acicularis (7)

General 0

GQ - 18 C: Green water, no GQ - 22.5 C: Green, no water GQ - 30 C: Deep green high Water wagerenteringorexiting. entering but some exiting. water, exiting over con-Conditions SV - 15 Extremely swift, cretgdam.

SP - 18.5 g:C:liigh, swift, turbid.

liigh, swi f t, SV - 16 C:

high, turbid. No algal SV - 17.5 C: Extremely high, turbid. pogulationsvisible. mugdy, swift.

SP - 20 C: Extremely swift. SP - 20 C: Extremely high, high, turbid. No algal muddy, swift. g; populations visible.

2

' Table 2. (continued)

Months Site July August September ,

SVI 810,909 340,330 471.420 Nitzschia palea (70) Hitzschia acicularis (35) Hitzschia palea (R3)

Navicula cryptocephala (16) Nitzschia palea (33) Navicula cryptocephala (9)

Navicula cryptocephala (25)

SV 210,080 63,024 573,098 Navicula cryptocephala (60) Nitzschia acicularis (40) Hitzschia palea (70)

Nitzschia palea (26) Navicula cryptocephala (30) Navicula cryptocephala (10)

Nitzschia palea (27) Nitzschia hungarica (8)

GQ 142,644 107,771 176,887 Scenedesmus quadricauda (94) Scenedesmus quadricauda (75) Scenedesmus quadricauda (86)

Cryptomonas ovata (2) Oscillatoria limosa (8) Nitzschia acicularis (5)

Pteromonas aculeata (7) Nitzschia palea (5)

SPI 764,691 18,907 258,819 Nitzschia palea (86) Nitzschia palea (44) Nitzschia palea (75)

Navicula cryptocephala (11) Navicula cryptocephala (22) Nitzschia hungarica (9)

Aphanizomenon flos-aquae (22) Nitzschia acicularis (7)

Surirella ovalis (11)

SPGQ 756,288 16,806 896,621 Hitzschia palea (81) Nitzschia palea (68) Nitzschia palea (91)

Navicula cyrptocephala (4) Aphanizomenon flos-aquae (32)

W*

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- Table 2. (continued)

~.

Months Site July Augu'st September SP 152,308 25,210 360,497 Nitzschia palea (613) Nitzschia palea (58) Nitzschia palea (70)

Stephanodiscus hantzschii (15) Aphanizomenon flos-aquae (8) Stephanodiscus hantzschil (15)

Nitzschia acicularis (9) Nitzschia acicularis (8)

Navicula popula (8)

Oscillaforia princeps (8)

General GQ - 28 C: Lower, green water. GQ - 25 C: Deep green, high GQ - 18".C: Green water.

Wager entering and exiting, water. Water entering Water entering and SV - 24 C: High water, swift angexiting. exftingpond.

Sv - 23 C: Swift, turbid, high Sv - i8 C: siow, iow and SP - cuSr*"ts.

26 C: Low, clear water, water. No visible algal clear. Large mats of g slow current. pogulations. Hydrodictyon at SVI. 44%

SP - 24 C: High, swift, turbid ligingalgae.

water due to rain. Sub- SP - 18 C: Slow, low and clear strates scoured. water. Large, floating mats of Enteromorpha ,

Hydrodictyon A DIcTdlo-mosiphon at SPI. 23%

living algae.

Table 2. (continued)

Months Site October November December SVI 1,839,460 166,383 46,218 Nitzschia palea (53) Navicula cryptocephala (39) Nitzschia palea (30)

Nitzschia acicularis (35) Navicula viridula (26) Navicula cryptocephala (25)

Navicula cryptocephala (7) Navicula radiosa (21)

Nitzschia palea (7)

SV 647,046 43,907 17,332 Navicula cryptocephala (46) Navicula cryptocephala (58) Havicula cryptocephala (33)

Nitzschia palea (44) Nitzschia palea (26) Nitzschia palea (20)

Navicula radiosa (11) Navicula radiosa (13)

GQ 126,048 204,197 13,025 Scenedesmus quadricauda (92) Stephanodiscus hantzschii (92) Stephanodiscus hantzschii (55)

Scendesmus quadricauda (5) Peteromonas aculeata (16) m Scenedesmas quadricauda (14)

Cryptomonas ovata (7)

Euglena viridis (6)

SP1 152,518 64,705 11,554 Nitzschia palea (70) Hitzschia palea (96) Nitzschia palea (60)

Euglena viridis (9) Gomphonema parvulum (10)

Stephanodiscus hantzschii (6)

SPGQ 254,196 249.575 108.611 Nitzschia palea (85) Nitzschia palea (94) Nitzschia palea (53)

Stephanodiscus hantzschii (5) Navicula cryptocephala (6) Euglena viridis (32)

Euglena viridis (4) 9

Table 2. (continued)

~,

Months Site October November December SP 62,394 4,622 32,352 Nitzschia palea (59) Nitzschia palea (50) Hitzschia palea (50)-

Scenedesmus quadricauda (22) Navicula cryptocephala (50) Euglena viridis (21)

Nitzschia hyngarica (7) Navicula cryptocephala (14)

General GQ - 13 C: High, green water. GQ - 3 C: No water entering GQ - S C: Completely frozen.

Water Water flowing over cement or exiting. Two inch ice Water entering and exiting-Conditions overflow dam. Rhizoclonium cgver. Water brown. Over concrete dam. Open mags. Little water entering.SV - 1 C: liigh, swift, clear water near ditch and dam.

SV - 13 C: Low, slow, turbid. water. Ice along banks Diatom populations on Digtom populations evident. (gverhanging). sgbstrates.

SP - 13 C: liigh, swif t, turbid. SP - 2 C liigh, swif t, clear SV - 4 C: liigh, swi f t , turbid.C3 Some algal populations visi- water some filamentous green No visible algal popula-ble. Large growths of algae visible on substrates. tions. Some ice along Enteromorpha & ilydrodictyon. Some Euglena populations hgnks.

30% living algae. evident. SP - 6 C: Clear, high, swift.

No visible algae. Channels changed, especially at SPl.

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64 Table 4. Species Diversity According to Taxonomic Divisions during 1979.

Sites Total Species Division Identified SVI SV GQ S PI SPG0 SP per Division Bacillariophyta 45 53 28 38 43 35 60 Chlorophyta 18 12 23 14 18 14 37 Chrysophyta 2 1 3 1 2 1 4 Cryptophyta 1 1 1 1 1 1 1 Cyanophyta 6 4 5 4 4 4 9 Euglenophyta 3 4 4 4 3 4 6 Pyrrophyta -- -- 1 1 -- 1 1 Xanthophyta -- 1 -- -- -- -- 1 Total Number of 75 76 65 63 71 60 119 Species per site I

1 1

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l 1

' Table 5. Diatom - Green - Euglenoid - Blue-green Algal Species Ratios at Sampling Sites ! 'ing Monthly Fluctuations in the Species Diversity of these Four Dominant Divisions, Fort St. ain, 1979.

Sites Total. Number Months SVI SV GQ SPI S PGQ SP of Species January 0-0-0-0 14-1-1-0 5-5-2-0 ;4-2-2-1 9-1-2-0 9-1-1-0 24-6-3-1 February 16-0-1-0 10-6-6-0 4-3-1-0 9-0-1-0 15-0-2-0 12-1-1-1 29-3-2-1 March 14-0-2-1 17-5-2-0 11-4-3-0 16-2-2-1 13-0-2-1 8-2-2-0 25-8-3-2 April 21-1-3-0 19-0-1-1 9-3-1-0 16-2-2-0 15-0-0-1 14-1-1-0 31-4-4-2 May 16-1-0-2 12-0-1-0 5-5-0-1 8-1-0-0 11-0-0-0 11-3-0-0 22-6-2-3 June 14-0-0-0 11-2-0-0 9-5-0-0 14-0-0-0 7-0-1-0 10-3-0-0 28 7-1-0 July 20-4-1-4 22-2-2-3 6-11-1-3 16-3-1-4 25 10-1-2 23-4-1-3 36-19-3-6 17-2-1-3 7-13-0-3 12-2-1-1 18-2-0-3 10-3-2-2 32-15-2-7 OI August 18-10-1-4 September 19-5-1-3 12-5-2-0 7-6-1-2 10-7-1-1 13-12-2-2 10-5-2-1 26-21-5-5 October 17-3-0-2 22-3-1-0 12-9-0-1 11-6-1-0 11-1-1-0 6-5-1-0 33-17-1-2 November 10-0-0-1 14-1-0-0 9-6-1-1 13-1-3-1 13-1-1-1 9-1-1-0 25-6 3-2 December 19-3-1-0 16-0-0-1 9-2-2-1 10-2-1-0 13-0-1-1 13-0-1-0 31-5-2-1 Total Number of Species 45-18-3-6 53-12-4-4 28-23-4-5 38-14-4-4 43-18-3 4 35-14-4-4 60-37-6-9 per Site

66 AVIAN SECTION l

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, mo 67 AVIAN MONITORING t

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by Ronald A. Ryder l

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68 INTRODUCTION Data regarding oopulations of resident, migratory and breeding birds are cvailable from April 1972 through December 1979. Avian populations of 1979 are compared to those from past years of the study.

DESCRIPTION OF STUDY AREAS Avian populations were monitored on 3 designated study areas. Briefly, these are (1) the St. Vrain River study area, 71,6 ha (177 acres), located northwest of the Nuclear Station and bordered on the west and north by the St. Vrain River, on the east by County Road No. 38, and on the south by pasture land; (2) the Goosequill Pond study area, 8.5 ha (21 acres), northeast of the reactor site, bordered on the south, east and north by the South Platte River and on the west by agricultural land; and (3) the South Platte River study area, 52.2 ha (129 acres), immediately east of Goosequill Pond, bordered on the north, south and east by the South Platte River and by agricultural land and Goosaquill Pond on the west (Figure 1).

CENSUSING PROCEDURES Each census began at sunrise on relatively clear and calm mornings.

Goosequill Pond was censused from the road encompassing its perimeter. The St. Vrain and South Platte River study areas were systematically searched by walking a loosely defined route through each area and identifying every bird observed within the boundaries of the area. Identifications were aided by use of 7- or 8-power binoculars. Birds seen were immediately recorded on standardized field forms. During the breeding season " spot maps" were made of territories of breeding males. Additionally, nesting birds around Goose-quill Pond and in the sloughs on the St. Vrain area were followed closely to i

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determine nesting density and success. All 3 areas were censused 16 times each in 1977,1978 and 1979. Earlier census numbers were over 20 per year.

FINDINGS Total individuals and species seen are summarized in Table 1. Summer, fall and winter populations have fluctuated widely, and no specific trend is apparent. Spring populations, however, show a fairly distinct pattern of an overall decline in avifauna in 1973 followed by a steady recovery to 1977, with declines in 1978 and 1979. The sharp decline in 1973 can probably be attributed to habitat deterioration due to flooding. The reco/ery is probably attributable to a natural return to pre-flood conditions. Grazing of live-stock was reduced in 19'77 but increased in 1978 and 1979.

The spring migration in 1979 was delayed somewhat by late snowfall, a. .

the fall migration was somewhat earlier than normal. The non-breeding seasons for all eight years were marked by irregular fluctuations of popula-tions, but breeding bird numbers are believed to be a more sensitive indicator of the state of the habitat. Results regarding breeding bird populations were reported in the January 1 - June 30,1979 progress report. Briefly, breeding birds were scarcer in 1979 than 1978. Yellow-headed and red-winged blackbirds, particularly, had a very poor oreeding season with low hatching success. Most other species fared somewhat better. See Tables 2 and 3.

Weather in fall 1979 was more severe than in 1978, with considerable snow in November and December 1979.

Environmer,tal disturbances increased in 1979. Rather heavy grazing of the areas was seen in early spring and late summer. Goosequill Pond was drained completely in May "in an effort to control muskrat and beaver activity in the peripheral dike." The low water level of the pond favored the migrants but not the nesters. Waterbirds were able to feed there most of the winter and much of the fall. Wa'terfowl hunting

71 probably affected local wood duck production in the South Platte area. Irriga-tion in the adjacent fields caused prcnounced fluctuations in the water levels of the beaver ponds throughout the summer. Efforts were made during the summer by the ranch manager to poison prairie dogs. Prairie dog numbers, however, recovered by fall, so it is believed the prey base they provide for raptors such as great horned owls was not seriously altered. Deep snow cover in much of November and December made unavailable most grasses and forbs, so granivorous birds such as juncos and native sparrows were hard-pressed for food.

Overall, avian use of all three areas declined the past two years.

Similar declines in nesting red-winged blackbirds were reported in the Dakotas by U.S. Fish and Wildlife Service Biologis'_s (J. F. Besser, personal comm.).

We also noted reductions in yellow-headed blackbird nesting populations in 1978, and to a lesser extent in 1979, in an intensive study of a large marsh approxi-mately 13 miles to the east (Ryder, unpublished data). There drawdown, burning and hailstorms seemed responsible. Declines on Goosequill Pond were, no doubt, largely due to drawdown during the territory-establishment phase of nesting.

Continued heavy grazing of the St. Vrain River study area is considered more detrimental to nesting birds than effects of the Nuclear Generating Station operation so far observed.

Table 1. Ei9ht-year tabulation of species numbers and population levels from monitoring at the Fort St. Vrain Nuclear Generating Station (number of species seen per count followed by total individuals).

Time Period 1972 1973 1974 1975 1976 1977 1978 1979 January No count 19(762) 19(319) 20(335) 10(340) No count No count No count February No count .19(2884) 24(15,474) No count 23(41 :) 24(4/8) 30(1121) +

29(847)

March No count 32(709) 25(14,063) 29(709) 33(627) 30(715) 31(546) early April 28(823) 26(326) 32(487) 34(688) 38(720) No count 43(622) 34(498) late April 50(871) 34(561) 37(441) 44(719) 46(903) 40(717) 1st wk May 47(574) 33(381) 45(534) 45(591) 48(729) No count U 37(488) y 2nd wk May 47(583) 39(382) 62(833) 52(533) 47(777) 50(640) 54(510) 3rd wk May 48(593) 45(543) 43(563) 55(728) 54(855) 43(522) 38(397) 45(466)E 4th wk May 48(691) 38(450) 46(523) 50(635) 49(656) 45(565) 44(451)

Ist wk June 35(500) 39(373) 40(641) 42(491) 38(569) 49(614) 43(518) 40(426) 2nd wk June 41(558) 33(414) 42(583) 40(419) 42(513) 46(660) 42(450) 40(416) 3rd wk June 38(551) 38(426) 33(469) 34(340) 39(585) 44(635) 40(457) 43(536) 4th wk June 37(509) 32(324) 34(426) 37(373) No count 40(589) 41(510) 37(378) 1st wk July 36(704) 33(421) 32(537) 32(483) 38(731) No count 40(560) No count 2nd wk July 37(681) 29(433) 34(541) 36(522) No count No count No count No count 3rd wk July 36(680) 34(437) 37(478) No count 41(600) 38(534) 37(503) 4th wk July 37(588) 30(779) 36(550) 40(1145) No count No count No count

Table 1, continued.

Time Period 1972 1973 1974 1975 1976 1977 1978 1979 1st wk August 37(658) 28(838) No count No count Ho count No count No count 38(750) 2nd wk Au9ust 38(851) 34(1123) 40(386) Ho count No count 34(571) No count 3rd wk August 42(757) 33(997) 35(565) 46(685) 37(2289) No count No count 36(377) 4th wk August No count No count No count No count No count No count 37(1299) ist wk September 43(1080) 36(1287) 40(879) No count No count No count No count 2nd wk September No count No count No count 43(1917) No count No count No count 3rd wk September 45(605) 43(879) 47(2392) fio count 37(1046) 41(980) 33(468) 31(1008) ,

4th wk September No count 39(963) No count Ho count; No count No count No count October 36(1190) 29(1402) 29(532) 31(442) 46(596) 34(856) 30(1692) 25(1737) U November 32(1642) 23(455) 23(2057) 27(387) 33(580) 26(458) 26(565) No count December 23(611) 22(283) No count No count No count No count No count 22(192)

N Hay 1973 counts probably not comparable to those in 1972 and 1974. Due to floods, it was not possible to complete counts of all 3 areas weekly in May 1973.

Early May count in 1978 delayed by unusually late snowstorm.

i

.. e 74 Table 2. Summary of the 1979 intensive nest search on the St. Vrain Study Area and Goosequill Pond.

Total Percent Percent Percent Area and Species Nests Successful 1I Unsuccessful Unknown St. Vrain Study Area American Bittern 2 0.0 100.0 0.0 Yellow-headed Blackbird 6 0.0 83.3 16.7 Red-winged Blackbird 22 4.5 77.3 18.2 Mourning Dove 3 0.0 66.7 33.3 Goosequill Pond Yellow-headed Blackbird 3 0.0 0.0 100.0 Red-winged Blackbird 3 0.0 0.0 100.0 MEggs to fledglings.

Table 3. Total nestings of Red-winged and Yellow-headed Blackbirds at the Fort St. Vrain Nuclear Generating Station, 1972-1979.

Number of Nests Followed Species 1972 19731/ 1974 1975 1976 1977 1978 19790 Red-winged Blackbird 27 25 27 16 26 68 23 25 Yellow-headed Blackbird 54 20 31 56 53 100 33 9 MoosequillPondwas drained in May 1973 and May 1979.

75 4

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! TERRESTRIAL SECTION I

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76 VEGETATION MONITORING by Charles D. Bonham Larry Larson Ann Morrison h

77 INTRODUCTION Vegetation communities at the St. Vrain Nuclear Generating Station were monitored to detect changes in species which might occur. Changes-to date are interpreted as natural fluctuations since the Generating Station has not been operational continuously nor for an adequate period of time to evaluate probable effects on vegetation. Data on species characteristics of plant communities at the St. Vrain Nuclear Generating Station have been collected since 1972 for analysis of environmental effects of the station on these communities. This year,1979, is the third year of a planned three-year monitoring effort for the native plant communities.

Fenced exclosures were built in 1972 and 1973 to exclude livestock from grazing'the vegetation study areas at the site. These exclosures also serve as protection from other man-manipulated disturbances. How-ever, various circumstances have reduced the number of exclosures to six that are still intact and suitable for monitoring purposes (Figure 1).

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79 METHODS Field sampling was conducted during 1979 in June and August. The June data results were reported in July 1979, and this report contains^

only results of the August 1979 collection period. Cover values for all herbaceous plants and shrubs were estimated by the Daubenmire method l from systematically placed 20 x 50-cm quadrats. Twenty-five samples for each period were obtained f rom each exclosure and an additional 25 samples were taken from an area adjacent to each exclosure.

I Standing crop values for aboveground biomass were obtained in i

August only by clipping 15 quadrats inside the exclosure and 15 quadrats l

i outside the exclosure. Species were clipped according to dominant species inside the exclosure. All other species were grouped under "Other species." Fresh weights for species were measured in the field and one sack of fresi terial per category per exclosure was collected and oven-dried to detennine dry matter percentage for the categories.

Statistical analyses were performed on dry weights.

Statistical analyses were conducted on exclosure data and the t-test was used with a probability level of 0.05 to detennine significance.

RESULTS i Means and standard errors for standing crop data are presented in

! Tables 1 through 6. Also presented in Tables 1 through 6 are the levels of significance for t-tests between inside and outside the exclosures.

l Exclosure 1 (confluence) had no significant differences (P < .05) for dry weight means of major plant species inside and outside the exclosure.

Exclosure -2 had more standing crop inside for other species, Acrooyron elongatum, Bromus inermis, and Polyconum coccineum. Festuca elatior had

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80 more standing crop outside the irrigated pasture exclosure than inside (Table 2).

No significant differences were found for dry weight means of major plant species inside and outside the Goosequill exclosure (exclosure 3)'

(Table 3), or the exclosure north of the plant (exclosure 4)(Table 4).

The exclosure south of Ben Houston's (exclosure 6) had more standing crop for other species and Distichlis stricta outside the exclosure, and more standing crop for Agropyron elongatum inside the exclosure (Table 5). The South Platte River exclosure (exclosure 8) had no significant differences

-for dry weight means of major plant species inside and outside the exclosure (Table 6).

-In the St. Vrain River loop (exclosure 5), sampling was stratified because a fenced exclosure was not present. An association of Lepidium latifolium and Cirsium spp. was sampled as though inside an exclosure and the adjacent area sampled as though outside. Lepidium latifolium and Cirsium spp. standing crop was greater inside the exclosure than out, and other species dominated the area outside the exclosure (Table 7).

Cover data for species by exclosure is preserted in Tables 3-14.

Also in Tables 8-14 are the levels of significance (P < .05) for t-tests between inside and outside the exclosures. Agropyron trachycaulum and Symphoricarpos occidentalis had greater ccver inside exclosure 1 (confluence) and Bromus tectorum had greater cover outside (Table 8).

In the irrigated pasture exclosure, Bromus inermis, Lactuca ,scariola,'

. Polygonum coccineum and Helianthus spp. had more cover inside the exclosure, while Festuca elatior had more cover outside the exclosure (Table 9).

81

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In the Goosequill exclosure (Table 10) Salsola kali and Sporobolus cryptandrus had significantly greater cover outside the exclosure than inside. In the exclosure north of the Station, Melilotus -officinale had greater cover outside the exclosure (Table 11). The exclosure south of Ben Houston's (Table 12) had greater cover values for Agropyron elongatum inside and greater cover values for Mtichlis stricta, Kochia scoparia, and Hordeum jubatum outside.

The South Platte River exclosure had no significant differences for cover values of species encountered during sampling between inside and outside the exclosure (Table 13). Cirsium spp. and Lepidium lat' folium had greater cover values inside the St. Vrain River Loop exclosure (Table 14) while Carex p aegracilis, Distichlis stricta, Panicum virgatum, and Spartina pectinata had greater cover outside the exclosure.

No changes that occurred in an exclosure over the years can be attributed to the presence of the Station since major changes occurred between outside and inside exclosures. Cattle grazing the areas has contributed to vegetation changes that are reflected in exclosure data.

On the other hand, any changes that have occurred within any exclosure must be attributed to natural species fluctuations and secondary plant succession, since the Station has not been operaticual continuously nor for an adequate period of time to evaluate probaHe effects on vegetation of.the area.

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Table 1. Standing crop (gms/m oven dryweight) for plant species in the confluence exclosure (exclosure 1) compared to outside, August 1979.

In (n_= 15) Out (n = 15)

Category x s x s P x x Other species 44.4 18.39 36.8 15.86 .73 Agrooyron trachycaulum 66.3 16.65 45.9 18.32 .42 Bromus japonicus and Bromus tectorum 36.5 13.2 40.9 23.0 .16 Cirsium spp. 4.3 4.33 23.3 15.97 .26 Rhus radicans .

4.7 4.69 0.0 0.00 .33 Symphoricarpos occidentalis 16.6 11.94 22.7 17.95 .78 '

2 Table 2. Standing crop (gms/m oven dryweight) for plant species in the irrigated pasture exclosure (exclosure 2) compared to outside, August 1979.

Other species 95.2 36.72 9.5 3.19 .03 Agropyron elongatum 31.8 12.53 0.0 0.00 .02 Ambrosia coronopofolia 4.5 4.51 0.0 0.00 .33 Bromus inermis 68.2 32.85 C0 0.00 .05 Festuca elatior 73.7 35.40 275.2 31.46 .00 Polygonum coccineum 38.9 17.86 .4 .41 .04 2

Table 3. Standing crop (gms/m oven dryweight) for plant species in the goosequill exclosure (exclosure 3) compared to outside, August 1979.

. Other species 9.5 3.25 9.5 3.74 1.00 Agropyron trachycaulum 14.4 4.94 5.4 4.26 .,13 Ambrosia coronooofolia 10.1 10.05 5.2 3.62 .65 :

Bromus inermis 1.8 1.33 4.6 3.51 .47 Bromus jaoonicus and Bromus tectorum 62.5 13.2 110.6 30.2 .54 Sporobolus cryptandrus 10.4 8.02 24.8 9.90 .27 e

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83 Table 4. ' Standing crop-(gms/m2 oven dryweight) for plant species in the' north of plant exclosure (exclosure 4) compared to outside, August 1979.

In (n = 15) Out (n = 15)

Category x s x s P' x x Other species 41.9 22.72 17.9 10.46 .35 Bromus tectorum and Bromus japonicus 28.4 6.57 19.3 2.55 .21

-Soorobolus cryptandrus 11.7 3.81 19.2 6.09 .31 2

Table 5. Standing crop (gms/m oven dryweight) for plant species in the exclosure south of Ben Houston (exclosure 6) compared to outside, August 1979.

Other species 3.6 3.60 19.3 4.39 .01 Agropyron elongatum 273.3 42.28 34.2 15.34 .00 Distichlis stricta 59.7 17.89 107.5 15.82 .05 2

Table 6. Standing crop (gms/m oven dryweight) for plant species in the South Platte River exclosure (exclosure 8) compared to outside, August 1979.

Other species 40.5 13.29 32.2 12.12 .71 Acrooyron trachycaulum 21.7 5.87 21.7 10.38 1.00

.Bromus japonicus and Bromus tectorum 48.5 18.26 55.2 16.51 .79 Cirsium spp. 2.' l.74 0.0 0.00 .24 Rhus radicans 17.2 7.83 12.7 6.62 .66 Symphoricarpos occider.talis 32.6 19.33 58.6 29.13 .46 2

Table 7. Standing crop (gms/m oven dryweight) for plant species in the

Saint Vrain River Loop (Point 5) with stratified sampling,

-August 1979.

Other species 8.2 4.38 58.6 5.84 .00 Cirsium spp. 153.2 22.14 4.4 2.64 .00

[

i Lepidium latifolium ' 192.4 39.43 9.7 6.93 .00 I .

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. 84 A

r; Table 8. Cover values (percent) for plant species in the confluence exclosure (exclosure 1) compared to outside, August 1979.

In (n = 25) Out (n = 25)

Category x s x s -P x x Agropyron smithii 0.0 0.00 .6 .60 .32 Agropyron trachycaulum 21.1 4.22 9.8 3.09 .04 Ambrosia coronopofolia 2.8 1.67 9.1 3.16 .08 Bromus inermis 2.5 1.12 .8 .61 .19 Bromus japonicus 4.4 2.16 11.0 4.40 .18 Bromus tectorum 1.3 .83 6.9 2.23 .02 Descurainia spp. 0.0 0.00 .6 .60 .32 Asparagus officinale 4.0 1.79 .6 .60 .08 Cardaria draba 13 . 1 1.22 3.5 1.73 .85 Smilacina stellata .1 .10 0.0 0.00 .32 Cirsium spp. 3.3 1.74 8.9 4.47 .25 Conium maculatum 0.0 0.00 .6 .60 .32

, Kochia scoparia .6 .60 0.0 0.00 .32 Lactuca scariola 1.9 .99 4.1 2.86 .47 Melilotus alba 0.0 0.00 3.6 2.13 .10 Medicago sativa 0.0 0.00 .6 .60 .32 Panicum virgatum 0.0 0.00 .1 .10 .32 Poa pratensis 0.0 0.00 1.2 .83 .16 Glyccyrrhiza spp. 0.0 0.00 4.5 2.49 .08 Rhus radicans 2.1 1.59 0.0 0.00 .19.

Rosa nutkana 2.1 1.59 .6 .60 .38 Spartina pectinata 0.0 0.00 5.8 3.48 .10 Symphoricarpos occidentalis 28.7 6.88 11.7 4.78 .05 Taraxacum officinale .6 .60 2.2 1.59 .35 Tragopogon dubius 1.2 .83 0.0 0.00 .'16 Xanthium italicum 4.0 2.86 1.5 1.50 .44 Rumex-triangularvalvis .6 .60 0.0 0.00 .32 Euphorbia eusula 3.4 3.40 .6 .60 .42 Lomatium 0.0 .0.00 1.2 .83 .16 Convolvulus spp. .6 .60 -0.0 0.00 .32 Aster ericoides- .6 .60 0.0 0.00 .32

-Setaria lutescens 1.2 .83 1.5 .83 .80

85 Table 9. Cover values (percent) for plant species in the irrigated pasture exc.osure (avelosure 2) compared to outside, August 1979.

-~_

In (n = 25) Out (n = 25)

Category x s x s P f x x Acropyron trichochorum .7 .60 0.0 0.00 .25 Agropyron trachycaulum .6 .60 .1 .10 .42 Bromus inermis 39.8 6.72 1.0 .61 .00 Bromus japonicus .1 .10 0.0 0.00 .32 Bromus tectorum .7 .60 0.0 0.00 .25 Descurainia spp. .2 .14 0.0 0.00 .16 Equisetum kansasum .1 .10 0.0 0.00 .32 Festuca elatior 22.3 6.75 82.1 3.07 .00 Lactuca scariola 5.4 2.23 0.0 0.00 .02 Phalaris arundinaceae 3.9 3.90 0.0 0.00 .32 Polygonum coccineum 17.0 4.66 .1 .10 .00 Spartina pectincta 2.5 2.50 0.0 0.00 .32 Trifolium spp. 0.0 0.00 1.4 .B3 .10 Helianthus spp. 4.4 2.16 0.0 0.00 .05 Hordeum jubatum 0.0 0.00 2.1 1.59 .19 Ambrosia trifida 13.6 4.98 0.0 0.00 .01 l

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. 86 Table 10. -Cover values-(percent) for plant species in the Goosequill Pond exclosure (exclosure 3) compared to outside, August 1979.

In (n = 25) Out (n = 25)

Category x s y s P x x Agropyron trachycaulum 3.9 1.70 1.8 .82 .27 Ambrosia coronopofolia .7 .60 2.4 1.12 .19 Bouteloua gracilis 0.0 0.00 1.5 1.50 .32 Bromus inermis 1.6 1.50 .7 .60 .58 Bromus japonicus 5.6 1.83 9.0 3.02 .34 Bromus tectorum 24.9 4.98 15.3 3.62 .13 Descurainia spp. 3.4 1.73 0.0 0.00 .06 Hordeum pussilum .1 .10 0.0 0.00 .32 Kochia scoparia .1 .10 .1 .10 1.00 Lactuca scariola 1.2 .83 .6 .60 .56 Polygonum coccineum 2.8 1.67 0.0 0.00 .10 Rosa nutkana .6 .60 .6 .60 1.00 Salsola kali .8 .61 10.0 3.01 .00 Sporobolus cryptandrus 2.3 1.59 12.2 3.46 .01 Symphoricarpos occidentalis .6 .60 10.0 0.00 .32 Rumex triangularvalvis 1.2 .83 0.0 0.00 .16 Euphorbia eusula .2 .14 2.7 1.67 .14 Aster ericoides .1 .10 0.0 0.00 . . - .

Setaria lutescens 0.0 0.00 3.0 2.08 .16 Echinochloa crusgalli- .6 .60 1.2 .83 .56 Ambrosia trifida .1 .10 0.0 0.00 32 b

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87

. Table'11. Cover values (percent) for plant species in the north of plant exclosure (exclosure 4) compared to outside, August 1979.

In (n = 25) Out (n = 25)

Category x s x s P' x x Aarooyron desertorum 3.0 2.08 .7 .60 .29 Bromus tectorum. 11.1 1.70 13.8 1.79 .28 Descurainia spp. .4 .19 .3 .17 .69 Lactuca scariola .6 .60 .6 .60 .1.00 Melilotus officinale 0.0 0.00 1.8 .82 .03 Salsola kali .1 .10 0.0 0.00 .32 Sporobolus cryptandrus 13.1 2.53 15.7 2.82 .50 Aster ericoides 3.0 1.22 .9 .61 .13 Echinochloa crusgallis .2 .14 .1 .10 .56 Table 12. Cover values (percent) for plant species in the exclosure south of Ben Houston (exclosure 6) compared to outside, August 1979.

Agropyron elongatum 63.5 5.92 5.9 1.88 .00 Carex spp. 0.0 0.00 3.3 1.74 .06 Chenopodium spp. .2- .14 .8 .61 .34 Distichlis stricta 22.9 5.20 57.3 3.38 .00 Kochia scoparia 0.0 0.00 7.2 2.27' .00 Hordeum jubatum .1 .10 5.1 1.87 .01 9

^^

,a e 88 Table 13. Cover values (percent) for plant species in the South Platte River exclosure (exclosure 8) compared to outside, August 1979.

In (n = 25) Out (n = 25) -

Category x s x s P x x Aeropyron smithii 1.8 .99 1.9 .99 .94

.Agropyron trachycaulum 10.2 2.77 7.5 2.24 .45 Ambrosia cq;onopofolia 2.4 1.12 4.9 2.20 .32 Bromus japonicus 6.0 2.92 14.7 3.96 .08 Bromus tectorum 7.4 3.17 3.4 1.73 .27 Asparagus officinale 1.2 .83 2.5 2.50 .62 Cardaria draba 2.3 1.59 0.0 0.0 .15 Lactuca scariola 2.1 1.59 .6 .60 .38 Mei11otus alba 1.5 1.50 3.1 2.55 .59

. Panicum virgatum 1.2 .83 4.6 2.89 .26 Poa Pratensis 1.2 .83 3.3 1.74 .28 Glyccyrrhiza spp. 0.0 0.00 4.6 2.89 .12 Rhus radicans 25.6 5.45 24.3 6.10 .87 Spartina pectinata- 4.7 2.88 0.0 0.00 .11 Symphoricarpos occidentalis 35.3 7.37 28.1 6.20 .46 Tranopogon dubius .7 .60 0.0 0.00 .25 Euchorbia eusula .6 .60 0.0 0.00 .32 Aster ericoides 1.2 .83 2.5 1.12 .36

89 Table 14. Cover ' values (percer.t) for plant species in the Saint Vrain River Loop-(point 5) with stratified sampling, August 1979.

In (n = 25) Out (n = 25)

Category x s x s P x x Agropyron trachycaulum 0.0 0.00 .3 .17 . 08 Amoros,is coronopofolia 0.0 0.00 1.4 .83 . 10 Juncus balticus 0.0 0.00 3.1 2.55 . 23 Carex praegracilis 0.0 0.00 21.7 4.05 . 00 Cirsium spp. 31.0 5.23 4.5 1.35 . 00 Distichlis stricta 0.0 0.00 17.5 4.71 . 00 Equisetum kansasum 0.0 0.00 1.7 1.50 .26 Lepidium latifolium 42.4 4.86 1.3 .83 . 00 Panicum virgatum 0.0 0.00 3.7 1.30 .01 Poa pratensis 0.0 0.00 .2 .14 .16 Glyccyrrhiza spp. 1.5 1.50 5.6 3.48 .28 Rosa nutkana 1.5 1.50 0.0 0.00 .32 Sporobolus cryptandrus 0.0 0.00 .6 .60 .32 Spartina pectinata 1.2 .83 12.8 5.54 .04 Symphoricarpos occidentalis 1.5 1.50 0.0 0.00 .32 Asclepias speciosa 1.8 .99 0.0 0.00 . 08 Capsella bursa-pastoris 0.0 0.00 .1 .10 .32 Hordeum jubatum 0.0 0.00 1.3 .83 .12 O

e

.sa- o 90 EC0 PHYSIOLOGICAL CHARACTERISTICS by M. J. Trlica Dot Helm

' ap 91 INTRODUCTION Terrestrial vegetation surrour. ding the St. Vrain Nuclear Generating Station may be directly or indirectly affected by the plant's operation.

Operation of the pc.cr plant will probably result in releases of small amounts of radionuclides. Heat, water vapor and salts will also be lost to the atmosphere as a result of cooling 1.ower operation. In addition, water effluents will be released from the station which could affect vegetation along the water courses or it irrigated pastures.

It is, therefore, desirable to have an invent.ory of the ecophysiology of the vegetation which might be affected by increased heat, water vapor, i and salt deposition as a result of cooling tower operations. Since all animal life is dependent either directly or indirectly upon vegetation as a source of food, decreased productivity or palatability of vegetation may be detrimental to animal populations. In addition, operation of the cooling towers may result in increased humidity and temperature changes in the immediate surrounding envircnment. Since the St. Vrain Nuclear Generating Station is in the Denver Air Pollution Corridor, increa:cd humidity could interact with vegetation, resulting in increased leaf injury caused by the pollutants. Numerous studies have indicated that a significantly detrimental interaction extsts between air pollutants and humidity which can cause severe damage to photosynthetically-active tissuas. ,

OBJECTIVES The objectives of this study were:

1. To determine leaf injury by pollutants, disease, and insects for certain species surrounding the Generating Station.

o

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92

2. To determine concentrations of important elements in foliage of several species as related to distance and direction from 4

the Generating Station.

METil0DS Leaves of cheatgrass (Bromus tectorum), kochia (Kochia scoparia),

and cottonwood (populus sargentii) were collected from a maximum of 32 locations on four radii at distances of 1/8,1/4,1/2 and 1 mile from the generating station during rapid spring growth from 1972 through 1979 (Figure 1). Sampling of kochia and cottonwood at these same locations was again repeated when vegetation was mature in August,1972 through 1979.

l Estima'tes were made for each leaf sampled for total leaf area, leaf area injured by chewing insects, and leaf area spotted caused by air pollutants, disease, nutrition, and sucking insects.

Chemical analyses were conducted on foliage samples of cottonwood,

, kochia, and pinto beans (Phaseolus vulgaris). These analyses indicated whether concentrations of various nutritive and toxic elements were influenced by either distance or direction from the generating station.

The chemical analyses were not completed by the time of report writing and will, therefore, be reported upon later as an addendum to this report.

l A literature search indicated that pinto bean plants are sensitive to air pollutants.- As pinto beans are an important crop produced in the I -

l area around the St. Vrain Nuclear Generating Station, they were utilized in 1973,1974,1976,1977,1978 and 1979 as a controlled experiment to-determine effects of air pollution and drift at varying distances and directions from the cooling towers.

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Figure 1. Fort St. Vrain study area showina locations of collection sites.

.a e 94 Pinto beans were planted in polyethylene-lined #10 cans in the green-house. All plants received similar treatment in the greenhouse until mid July, when plants and containers were transported to the St. Vrain study s i te . Sixty-four containers with bean plants (four containers / location) were placed at two distances and eight directions from the cooling towers.

Distances from the towers were 50 feet and 1/4 mile. The bean plants all received similar amounts of supplemental fertilizer, insecticide, and water. They were allowed to grow for approximately six weeks during each year at the study area. At that time, leaves from each plant in each container were sampled to determine leaf injury. However, because of large numbers of grasshoppers feeding on the plants in 1979, only enough samples remained for chemical analyses.

Wet bulb and dry bulb temperatures at each location for pinto beans were measured in 1976, 1977, 1978, and 1979, each time bean plants were watered. Data were collected using a portable psychrometer. Utilizing these data, relative humidity and dew point temperature were calculated to aid in determining the sphere of influence around the cooling towers.

Analyses of data for vegetation samples collected from 1972 through the 1979 growing seasons continued throhh the fall and winter of 1979.

Statistical' analyses of data for leaf injury of vegetation has been completed and is discussed in the following sections. Analyses of variance were utilized for all data analyses. When significant (p < 0.05) F-values were found, Tukey's test was utilized to separate significant (p < 0.05) mean differences.

95 RESULTS AND DISCUSSION LEAF INJURY CAUSED BY POLLUTANTS, DISEASE AND INSECTS Natural Veaetation Statistical analyses of all leaf data for each year of the study have now been completed. As expected, highly significant (p < 0.01) differences existed for all leaf measurements among the eight years of data collection.

This indicates the high degree of yearly variation that influences leaf growth and injury. Distance and direction from the Generating Station were often significant (p < 0.05) variables in affecting leaf injury, even though the Generating Station was not in full operation. This indicated that micro-climatic and site characteristics were natural factors affecting leaf growth and injury rather than relationship to the Generating Station.

In general, leaf area of cottonwood increased from May or June through August. Kochia, however, had smaller leaf area per leaf in August of 1974 through 1979. No significant trend in leaf area per leaf for cheatgrass was found as related to distance from the station. In some years, leaves were larger near the generating station, whereas in other years they were larger at the 1/2- and 1-mile distance from the station. Leaves of kochia tended to be somewhat larger during the eight years of sampling at the 1/2- and 1-mile distance from the generating station. Cottonwood leaves showed somewhat of an opposite trend, with larger leaves being found nearer the generating station during five of the eight years of study. This trend, however, was not apparent in 1975,1976, and 1979.

Cheatgrass leaves were larger in a south and southeasterly direction from the generating station in four of the eight years of sampling. Leaves of both kochia and cottonwood were often larger in a southeasterly direction.

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+ i t e 96 This may be related to intensive farming and irrigation practices occurring southeast 'of the Generating Station during the years of the study.

The percentage of leaf area removed by chewing insects increased for both kochia and cottonwood between rapid growth and maturity during six of the eight years of study. This was very evident during 1979 with large populations of grasshoppers feeding on kochia. Cheatgrass leaf area removed by insects was slightly greater near the generating station than at greater distances. Chewing insects also removed more leaf area of kochia at the 1/8- to 1/2-mile distance from the power station. In contrast, leaf area missing for cottonwood was somewhat greater at the 1/2-and 1-mile distance from the generating station during several years.

Therefore, there wes no consistent distance influence from the generating station affecting insect leaf removal among the three species.

Removal of cheatgrass leaf area by insects was greater in a south and southwesterly direction from the generating station in five of eight-years of sampling. No consistent directional trend in leaf area removal among the years was found for kochia. Insect feeding activity on cottonwood leaves was great in a southerly direction from the station from 1972 through 1974. Trees at this sampling location were cut down in 1975; thereafter, insect damage was greater in a southeastern or northerly direction.

Brown tip leaf area of cottonwood was often greatest at the 1/2- or 1-mile distance from the station. No consistent trends in brown leaf tips for cheatgrass or kochia were noted for the four distances from the station among the eight years of study.

Greater brown tip leaf area for cheatgrass appeared in a northwesterly through southwesterly direction from the station from 1972 through 1977.

97 This trend was not evident in 1978 or 1979. However, brown tip leaf area and leaf spotting for kochia was greater by an order of magnitude in 1978 and 1979 than in previous years. This resulted primarily from storage problems in 1978 and insect feeding activity in 1979. Brown leaf tips of kochia were also often greater in a south through west direction.

This same trend was also noted for cottonwood in six of the eight years of study. This trend might be related to less intensive agricultural activity in a southwesterly direction from the station.

Leaf spotting may be the better indicator of leaf injury caused by pollutants or cooling tower drift. No significant (p < 0.05) effect as related to distance from the generating staiton was detected for three of the eight years for leaf spotting of cheatgrass. However, leaf spotting of kochia was greatest near the Generating Station from 1972 through 1974 and in 1978 and 1979. This was not evident in 1975 even though water was being circulated through the cooling towers. Leaf spotting was often greatest near the Station for the June collection of kochia, but spotting was greatest at 1/2 mile by the time of the August sampling period. Leaf spotting _of cottonwood, as related to distance from the Generating Station, was greater at the 1/2- or 1-mile distances in four of the eight years of study.

Leaf spotting of cheatgrass was usually greatest in a north, northeast, northwest, and westerly direction from the Generating Station. Leaf spotting for kochia _ was usually more pronounced in a northwest through southwest direction from the Station. No trend was detected in leaf spotting for cottonwood as related to direction from the Generating Station.

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98 It appears that leaf injury of the three species during the past eight years has been occurring somewhat at random about the Generating Station. Microclimatic differences, site characteristics, and agric 1tural t- activity appear to be the major factors causing the significant distance and directional effects observed to date for leaf injury.

Pinto Bean Exoeriment Analysis of data for various leaf characteristics of pinto beans in the controlled experiment indicated that neither distance nor direction from the cooling towers significantly (7 20.05) affected all leaf charac-teristics, except for brown tip leaf area, in one of the five years of study. However, significant differences were found among the five years of data collection. Leaf area of individual leaves were smaller near the cooling towers (50 feet) in three of the five years of study. Leaf area removed by insects was greater near the cooling towers in 1976 and 1977.

In 1973 and 1974, missing leaf area was greater at 1/2 mile from the cooling towers. Spotted leaf area was greater near the towers in 1973.

Non-significant differences in leaf spotting were found in. the other four years as related to distance from the cooling towers.

. Larger leaves of pinto beans were found on the east side of the cooling towers in four of the five years of study. However, leaf area

. utilized by insects was usually greatest on the south side of the cooling ,

towers. No consistent trend during the five years of study was found for either leaf area spotted or brown tip leaf area as related to direction

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from the cooling towers. As expected,-highly significant differences (p'< 0.01) among years-for all leaf measurements were probably caused by i differences in growing conditions during the five years of study.

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99 Blowers on the towers were usually not in operation even though water was being circulated through the towers 1973-1977. The blowers operated more consistently in 1978 and 1979. Ambient environmental conditions surrounding the cooling towers were found to not vary significantly during the study in 1976 and 1977. In 1978 and 1979, dry bulb temperature was found to increase significantly with distance from the towers. Relative humidity was slightly greater and dew point temperatures were slightly lower near the towers as compared with data collected at 1/4-mile distance in 1976,1978, and 1979, whereas the reverse was true in 1977. These small differences in ambient conditions probably resulted in the small differences observed for leaf spotting of pinto beans.

CONCLUSIONS In general, leaf area injury increased with time during the growing seasons during the eight years of study. This was anticipated as leaves are more susceptible to injury while they are growing and before they reach maturi ty. The percentage of leaf area injured for leaves of cottonwood generally increased with distance from the Station. This was sometimes evident in the amount of leaf area spotted or in the amount of brown i.ip on the end of each leaf. However, leaf injury for kochia appeared to be slightly greater near the St. Vrain Nuclear Generating Station.

Most leaf injury measurements for the three naturally occurring species showed statistically significant directional effects. It appeared that. leaf injury was greater to the southwest, west, and northwest of the Generating Station, which is not downwind for the prevailing summer wind. Therefore ,

it appears that variations in leaf injury were caused by microclimate, site, insects, and species differences and were influenced little by the

' Generating Station.

a s 100 Leaf area of pinto beans in a controlled experiment were smaller when grown near (50 feet) the cooling towers. However, increased leaf

'sootting near the towers was observed only in one of the five years of study. Cooling tower blowers were usually not in operation during earlier 9

years and humidity near the towers was only slightly greater during 1978 and 1979 than at the 1/4-mile distance from the towers.

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l 101 MAMMALS, AMPHIBIANS AND REPTILES by Bruce A. Wunder Douglas C. Ure

<. o 102 INTRODUCTION AND METHODS 4

The methods and procedures involved in monitoring amphibian, reptile and mammalian populations during 1979 are those described in

, previous progress reports (see Progress Reports May 1 - December 31, 1973 and January.1 - June 30,1974). Small mammal sampling sites were the same as in past years and are indicated in Figure 1.

This report is concerned primarily with data gathered during 1979.

RESULTS AND DISCUSSIONS Mammals: Species Present The mammal species recorded from Public Service Company property since 1972 are listed in the yearly progress report for 1976. All species noted were present during 1979, with the exception of those species listed in Table 1 and no new spec'es were observed. Most ;

l of the species not observed this year have been seen only rarely in '

the area of our atudy sites in previous years, with the exception of i

the meadow jumping mouse (Zapus hudsonius). This species has been )

captured on Iransect 7 in the past, and it's current absence from the trapping records may be due to a periodic population low or the effects of habitat modification along Goosequill Ditch (as discussed in previous reports). Black-tailed jackrabbits (Lepus californicus) have been seen in previous years in the scuthwestern portion of the Public Service Company property. Visits to this area were more l l

frequent'this year but black-tailed jackrabbits were still not

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       @ GRID 0 NACSM Figure 1. Small mammal samoling areas, grids and North American Census of Small Mamal Lines or Transects (NACSM) on the St. Vrain Nuclear Generating Station property.

104 observed. Thirteen-lined ground squirrels (Spermophilus ridecem-Iinec:us) were present in the vicinity of Transect 8 and Grid 1 in the'first two years of the survey. However, they have not been found in these areas since then. Some of the small noctural species, such as shrews (Sore: sp.) have never been caught in large numbers, and there is no reason to believe that their absence from our current observations is related to the operation of the Nuclear Generating Station. A long-tailed weasel (h steIc frer.c:c) was seen near Transect 5 in 1978. Although the tracks of a small mustelid were observed in the southwest corner of the Public Service Company property in October,1979, it was impossible to identify them to species and we were not able to positively confirm the presence of long-tailed weasels near the Nuclear Generating Station during 1979. Pocket gopher (Geomjs or Tnomanys) burrows were observed on Transect 2, in the southwest corner of the Public Service Company property and along the St. Vrain River south of Transect 5. Cotton-tail rabbits (Sylvilagus sp.) were abundant on the St. Vrain River and South Platte River floodplains into early June. By late sumer, the number of rabbits seen dropped drastically and only occasional observations were made into fall. The skull of an eastern cottontail (S. floridanus) was collected on Transect 2 and a single individual . that could have been a desert cottontail (S. cadobonii) was seen south of. Transect 3 in early summer. Positive identification of the latter was not possible without collecting the individual. Two

105 white-tailed jackrabbits (;epus cunsendii) were seen in the cultivated fields east of the Nuclear Generating Station during the spring small mamal census. Fox squirrels (Seiarus niger) were present on the floodplains north and west of the Nuclear Generating Station wherever there were large concentrations of cottonwoods. Black-tailed prairie dogs (Cyncmys !adoviesanus) were plentiful in the established " town" northwest of the Nuclear Generating Station. A small additional group of burrows has been excavated on elevated ground near the *oad southeast of the main

 " town". A number of juveniles were seen through the sumer and the residents appeared to be in good condition in early autumn. A second active prairie dog colony was found in the extreme southwes.t corner of the Public Service Company property. An attempt at control of the prairie dogs through poisoning apparently was ineffective.

Muskrat (ondcrra zibe:hica) and beaver (Cascor ecn=densia) tracks were found in several places along the banks of the St. Vrain and South Platte Rivers. Greatest evidence of activity was along the outlet from Goosequill Pond and near the confluence of the St. Vrain and South Platte Rivers. Goosequill Pond was largely drained in early spring in an effort to control the muskrat population. As a result, beaver abandoned the Goosequill outflow. Goosequill Pond was refilled in mid-summer and by early fall, beaver were , reestablished on the outflow and both beaver and muskrat were seen in Goosequill Pond. Striped skunks (Nephi:us mephicus) and raccoons (Frecycn Lc:cr) were present in virtually all low-lying areas along the St. Vrain i

 .4 0 106 4

and. South Platte Rivers and on fields used by dairy cattle. The tracks and diggings of a badger (."'a-ids: : =us) were found on Transect 2 during the September small mammal census. A coyote (ccnis !c:rens) den with evidence of current use was found in the bluff southwest of Transect 2. Coyote and dog (c. f=:i!icris) tra'cks were abundant throughout the Public Service Company property. Fox (7u!,:es sp.) tracks were found in the southwest quadrant of Public Service Company property during the winter months. Domestic cats (ye!is domesticas) were seen near the dairy farm and in the prairie dog town in the southwest corner of the Public Service Company property. Deer (CdocciIsas sp.) tracks were abundant along the rivers and in marshy areas during the first half of the year. Numbers seemed to decrease in late summer and early autumn. Mule deer (O. Asmicr.as) were seen numerous times especially in the vicinity of Transect 3 and Grid 2. A doe white-tailed deer (C. virginicnus) with a fawn was seen along the Goosequill Pond outflow in July. Mammals: Pooulation Parameters In 1979., the late spring census was conducted from 27 May through 1 June and the early autumn census from 6 September through 11 September. 1 Each census consisted of 2400 trap-nights. An unusually heavy snowfall on.the first night of the late autumn census rendered all grids and l transects inaccessible for several weeks. This unfortunate natural evend led to excessive marcality of trapped animals. A meaningful comparison

s. 107 of. data from this period with previous census periods would not be possible. For this reason, the late autumn census was not ~ completed and only the two previous 1979 small mammal censuses will be discussed here. One-hundred-thirty-four individual 4 animals were captured during the late spring census, two of which were recaptures from the previous late autumn censuses. Eighty-one individual animals were captured during the early autumn census. Deer mice (Feromyscus m nicalcrus) and house mice (h a musculus) continue to be the most abundant species, accounting for 62 percent and 21 percent of the individuals captured during the early autumn census. Western harvest mice (Reichrodontomys megato is), prairie voies (Microtus ochrogaster) and meadow voles (M. pennsylvanicus) were present in very low numbers. Total numbers of individuals of the four most common species captured during the late spring, early autumn and late autumn censuses for the period 1972 through i early autumn 1979 are presented in Figure 2. Captures of all species of mice and voles were lower in early autumn than in late spring of 1979. This pattern has been observed every year for each species. Deer mice remain the most abundant species, but this year their numbers were at a low point comparable only with the population levels of 1977. This may be a result of the extremely' long and cold winter 1978-79. Population levels may not have recovered sufficiently to show a large increase before the onset of summer months when breeding is reduced relative to spring.

.O

108 Summer 1979 was relatively mild and moist and heavy ground cover had developed by early autumn. The low numbers of deer mice in September are probably not a result of an unusual lack of food or cover but rather related to low spring numbers. Harvest mice were much less abundant during 1979 than in previous recent years. The low numbers of harvest mice captured may be indicative of a cycling population. The number of harvest mice caught during each census period from 1972 through 1975 was quite low. From late autumn 1975 on, the number of captures increased reaching a peak in late autumn 1977 and has decreased since then. The observed low number of harvest mice in early autumn 1979 may be a return to pre-1975 population levels.

Very few prairie voles were captured during the first ten months of 1979, and substantially fewer were captured during the early autumn census than during the late spring census. This may be largely due to agricultural manipulation of the census grid and transect sites. Voles have previously been most abundant on Transects ?, 5, 7 and on Grids 1 and 3. The western half of Transect 2 was burnej in August 1978. The cover has not completely returned and vole captures have been sporadic since that time. The central portion of Transe t 7 was burned and the east side of Goosequill ditch was dredged and graded prior to the late spring 1979 census period. Cover was destroyed and the populations dispersed. It has yet to recover. Grid 1 was partially flooded during the late spring 1979 trapping session and about one fourth of the grid was unsuitable for voles.

o . 109 During the subsequent early fall trapping, the grid was very dry i i and again poor vole habitat. It has been shown that prairie vole l populations cycle. A low point in the cycle combined with destruction of the habitat on two of the prime sampling sites and seasonal unsuitability of a third site during the census period could easily explain the observed low number of captures of prairie voles, especially in early autumn of this year. The concept of a cyclic low in the population level of prairie voles on Public Service Company property seems likely in the view of the few captures on Transect 5 and Grid 3 this past year, although a number were caught in each site during the 1978 census. The house mouse population has stabilized at roughly the level observed prior to 1977. House mice seem to have survived the burning of Transects 2 and 7 and it was in these areas and on Grid 1 that they were most abundant, as might be expected since they thrive in disturbed areas. Meadow voles (Microtus pennsylvanicus) were also captured during the census periods. One meadow vole was caught on Transect 5 during the spring census and one each on Grids 1 and 3 and Transect 5 during the early autumn census. Amphibians and Reptiles: Species present , Table 2 lists the species of amphibians and reptiles which have been observed since 1972 in the vicinity of the Saint Vrain Nuclear i Generating Station. Two special trips (aside from our normal twice-a-month surveys) were made to the Public Service Company l1

o e 110 property in Spring 1979 to inventory reptile and amphibian presence. Additional sightings during the maanal censuses and surveys were also noted. Chorus frogs (Pseudacris criserictc), Woodhouse's toads (Eufo uoodnousei), great plains toads (Bufo cognatus), plains spadefoot toads (Secphiopus bombifrons), and leopard frogs (Renc pipiens) were breeding on Public Service Company property in late May and June. Leopard frogs, which were first seen here in August, 1977, were abundant during August and September on Transect 2, and were also seen in permanent water along the northwest Public Service Company boundary. Woodhouse's toads were seen throughout the summer and early fall along the St. Vrain and South Platte Rivers and near Goosequill Pond. Plains spadefoot toad tadpoles were numerous during July in silage pits boardering Transect 7. Goosequill Pond has been a major breeding site for toads and frogs in past years. The draining of Goosequill Pond this past spring left all shore vegetation removed from surface water. Since there were no protected breeding sites we heard no frogs or toads breeding there this spring. However, a few bu11 frogs (Ranc ecteabiana) were breeding there in late sunmer. Even given the dry state of Goosequill Pond, because of the. warm, moist spring with standing water in other places, there appeared to be more amphibian breeding activity this spring than in several previous years. Several species of snakes were captured during the warm months of 1979. Bull snakes (Picuophis meIcnoleucus) were found near Gird 1-and on Transect 7. Racers (Coluber constrictor) were on Transects I l l

111 2 and 7. The garter snake from Transect 7 was identified as a plains I garter snake (T. radie). - One painted turtle (Chrysemys picea) was seen in a small pond along county road 19 north of the Generati,ng Station. Two turtle nests were found in a mud bank along the St. Vrain River in August but the species could not be determined. Virtually all the amphibians and reptiles previously inventoried on the public Service Property were inventoried this year, with it appearing to be a good year for amphibian reproduction. The lesser earless lizard (HoIbrookia maculata) (with only one previous sighting) and western rattlesnake (CrocaZus viridia) (which probably still occur in low numbers) were the only reptiles not recorded. Spiny soft-shelled (Triony spiniferus) and snapping turtles (CheIydra serpentina) were not seen but have never been abundant on the rivers since the floods of 1973. And the tiger salamanders (Ambystoma tigrinum) (which were not recorded this year) have only been seen in the Nuclear Generating Station settling ponds which we did not census. OVERALL CONCLUSIONS With the exceptions noted above, the same species of mammals, amphibians and reptiles noted during the inventory phase of this project are still present. Although some small mammal populations show yearly variations in numbers, climatological factors and agricultural practices have probably been more important in

 . o 112 influencing these numbers than activities of the Nuclear Generating Station. At this point, we have no reason to belive that function-ing of the Nuclear Generating Station has adversely affected mammals, amphibians or reptiles on the surrounding property.

However, because of the importance of Goosequill pond for amphibian breeding in years which are not so moist as 1979, we recommend that if draining is neces:ary, it be done so as not to involve the spring breeding period of these amphibians. This year, there was probably negligible effect because of the rains and thus availability

of standing water elsewhere.

f 4 4%, ,_w _ _ _

113 Table 1. Mammal species previously noted near the St. Vrain Nuclear Generating Station that were not censused in , the first ten months of 1979. Common Name Scientific Name

1. Shrew Sore: sp.

2. Black-tailedjackrabbit Lepus californicus

3. Thirteen-lined ground squirrel Spermophitus tridecemlineatus

4. Spotted ground squirrel Spermophilus spitosoma

5. Rock squirrel Spermophilus variegatus

6. Northern grasshopper mouse Onychomys Leucogaster

7. Norway rat Rat:us norvegicus

' 8. Meadow jumping mouse Zapus hudsonius 9.. Long-ta', led weasel Rustela frenaccM

    '1/ May have been present, as tracks were recorded, but species
      -identification was not possible.

v w _ . - . _W

t 114 Table 2. Amphibians and reptiles present in the vicinity of the Saint Vrain Nuclear Generating Station. , Comon Name Scientific Name Presence N

1. Spadefoot toad Scaphiopus bombifrons 1. V-C

2. Great Plains toad Sufo cognatus 2. C

3. Woodhouse's toad Sufo uoodhouses 3. C

4. Western chorus frog Pseudacris criseriata 4. C

5. Bullfrog Ren: eccesbiana 5. C

6. Leopard frog Rana pipiens 6. V

7. Tiger salamander Ambyseoma tigrinum 7. V

8. Snapping turtle Chelydra serpentina 8. D 9 Painted turtle Chrysengs picta 9. V-D

10. Spiny soft-shelled turtle Triony spiniferus 10. V

11. Racer Coluber constrictor 11. V

12. Common garter snake Thamnophis sirta;is 12. C

13. Plains garter snake Tnamnophis radi 13. C

14. Buli snake Pieuophis meI noteuces 14. C

15. Western rattlesnake crotatus viridis 15. V ,

16'. Lesser aarless lizard RoIbrookia meuZata 16. V U i E C = captured l D ~= found dead l V = visual observation i E Identification not positive

                                                                        . 115' f

i Figure 2. Total number of small mamal individuals captured as i > the Saint Vrain Nuclear Generating Station: late spring 1972 - early autumn 1979. .I - ' 1-1' i f_ 4 + i l' [ . p l .

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117 TERRESTRIAL INVERTEBRATES by J. Wayne Brewer Judy Bodenham I i L I

118 Introduction Terrestrial invertebrates have been collected fNm three sites near the Fort St. Vrain Nuclear Generating Station since April 1972. The samples were used to establish (1) an inventory of invertebrates in the area and (2) baseline population estimates of groups selected for the monitoring phase of the study. Previous. reports indicate that minor increases in radiation probably do not adversely affect terrestrial invertebrates (Skaife 1968, Cadwell and Whicker 1972, Noordink 1970 and Bushland 1971), but that temperature changes could cause important alter-ations in species and populations (Wurtz 1969). Therefore, terrestrial invertebrate species and study areas were selected (Figure 1) that would be most greatly affected by the possible increases in environmental tem-perature. Procedures All general procedures used have been previously reported (Brewer 1973). A minor procedural change was instituted in January, 1979, when it was decided that the black light trap collections should be discon-tinued during the winter months of December, January, February and iSrch. This report sumarizes data collected from July 1 until December b,1979, and provides a comparison with data collected during the same periods of previous years. Results and Discussion Inventory: The species inventory was reported by Brewer (1973) and additional t;ecies were appended to the list later (Brewer 1978). Analyses of G,llections subsequent to the 1978 report have not revealed species new to the area.

i 1 119 l l l l

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f Figure 1. Fort St. Vrain Nuclear Generating Station and environs, showing invertebrate collection sites.

120 Formicidae: The number of Fonnicidae collected during the period is presented in Table 1 along with the range of numbers collected during

    . comparable periods of 1976-78.      The highest population levels occurred in July when over 11,000 specimens were collected from the three rows of' pit fall traps. 'This total was substantially higher than the range of previous years. After the July sampling period the number of individuals I

collected declined steadily until December when there were no Formicidt in the samples. This pattern is typical for invertebrates since the group is generally less active during periods of low temperature. Nearly i 90 per cs.at of the individuals collected occurred in samples from pit fall I row two, an area where formicids have been very abundant in prev 1ous ' years. Population levels were substantially higher in 1979 than in recent years (Table 1) with levels nearly twice those of 1978. There has been a general increase in numbers since 1977 when populations were relatively low. It appears as though the Formicidae are increasing in numbers in the vicinity of the Nuclear Generating Station but the signifi-cance of such a change in time is not known. It is possible that this population change is the result of natural population fluctuations. Collembola: A sunnary of Collembola species collected July 1 - j December 31, 1978, is presented in Table 2. These data were not pre-viously available because species identifications were incomplete. In these collections 11 species were taken of the 16 known to have occurred , in the area. The absent species included Isotomurus palustris (Muller), pseudosinella rolfsi Mills, Bouletiella arvalis (Fitch), Sminthurinus areus and Smintnurides aouaticus (Fitch). Four of these, S_. areus, ) S. acuaticas, B. arvalis and I. calustris have been collected infrequently l and appear to be quite rare. However p. rolfsi has been relatively I common-in past collections and its absence is surprising. Eight of tne

Table 1. ' Number of Fonnicidae collected from pit fall traps at the Fort St. Vrain Nuclear Generating Station, platteville, Colorado, July 1 - December 31,1979.1/ July 14 Aug 11 Sept 8 Oct 13 Nov 10 Dec 8 Totals Row 2* 10,500(3520-7103) 4872(822-3724) 5996(833-1700) 1423(604-844) 63(164-555) O(0-11) 22,854 Row 3 842(268-423) 649(285-792) 288(327-514) 209(153-327) 42(27-41) 0(0-11) 2,030 Roe 4 287(440-1230) 374(897-1239) 479(992-2069) 163(153-816) 1(7-83) 0(0-9) 1,304 Total 11,629(4965-8295) 5895(1107-5369) 6763(2198-3606) 1795(1105-1747) 106(198-678) 0(0-26) 26,188 Annual Totals - for this period 1979 1978 1977 1976 S 26,188 13,948 11,607 18,577 1/ Figures in parenthesis are ranges of numbers collected 1976-1978. Some of the traps in Row 2 were re-established, due to flooding of the South platte River in June 1979. O

122 Table 2. Summary of Collembola collected from pitfall traps at the Fort St. Vrain Nuclear Generating Station Site, Platteville, Colorado, July 1 - December 31, 1978. Species Row 2 Row 3 Row 4 Total Entomobrya nivalis 67 1,623 4,466 6,156 Entomobrya unostrigata 2,448- 17 116 2,581 Entomobryoides guthriei 2 4 16 22 Hypogastrura armata 0 1 0 1 Hypogastrura matura 6,661 103,534 108,522 218,717 Lepidocyrtus cyaneus 1 ,31 4 224 31 3 1,851 Proisotoma minuta 596 5,696 2,944 9,236 Pseudachorutes suberassoides 16 0 0 16 Sminthurides pumilis 451 112 8 571 Sminthurinus elegans 1,155 1,729 998 3,882 Tomocerus vulgaris 2 0 0 2 Total 12,712 112,940 117,383 243,035 J e w

123 species were collected at all three trap lines and seem to be common residents of the area. The remaining three species Hypogastura armata, pseudachorutes subcrassoides and Tomocerus vulgaris were collected from all areas. These species has been very numerous in the collections since the study began in 1972. Other common species included Entomobrya nivalis, E[. unostrigata, proisotoma minuta and Sminthurinus elegans. The seasonal distribution of Collemb'ola species for the July - December 1978 period was similar to that of past years. Some species, .- like Hyoogastura matura, Entomobrya nivalis, E;. unostrigata and Lepidocyrtus cyaneus occurred throughout most of the season. Others, like proisotoma minuta were abundant for only a short period and thus are " rare" species in that regard. Siloha ramosa: This carrion beetle is normally collected in rela-tively high numbers in pit fall traps in the vicinity of the Generating Station. Both the adults and larval forms feed on carrion, mainly small rodents (Brewer and Bacon 1975), and thus are higher in the food chain than many terrestrial invertebrates in the area. The high populations and food habits of this species make it an important part of the moni-toring program. Population levels of adult and inmature beetles are presented in Table 3 along with the range of numbers collected 1973 - 1977. The population levels of adult S,. ramosa were higher during this period than they have been since 1976. Collections at all samoling . periods fell within, or exceeded, the range of previous collections. Immature beetles were also collected in high numbers with population levels exceeding those of all previous years of the study. Thus it appears that population levels of S,. ramosa have increased substantially in the past year in the vicinity of the Generating Station. l

o Table 3. ha ramosa collected in pit fall traps near th F Number Nuclear Generatingof adult andStation, inmature PTatt Silp'eville, Colorado, July 1 - December 31,1979._y/ortSt.Vrain Adults

   .                         July 14                   Au9 11                       Sept. 8                   Oct. 13  Nov. 10       Dec. 8        Totals
 -Row 2                      0(0-0)                    0(0-1)                       0(0-0)                    0(0-1)   0(0-2)        0(0-0)            0 Row 3                  65(1-83)                  54(0-83)                      11(2-47)                   3(1-100) 0(0-5)        0(0-0)          133 Row 4                   50(0-45)                  41(0-55)                       8(1-16)                   3(0-7)   0(0-13        0(0-1)          102 Total                 115(1-128)                  95(0-133)                     19(6-59)                   6(1-106) 0(0-8)        O(0-1)          235 Annual Totals for this                       1979                       1978                          1977                       1976  1975          1974          1973 period                           235                        113                           185                       249   339             81*          80*

C a Inanatures July 14 Aug. 11 Sept. 8 Oct. 13 Nov. 10 Dec. 8 Totals Row 2 0(0-2) 0(0-0) 0(0-0) 0(0-0) 0(0-0) 0(0-0) 0 Row 3 577(1-623) 50(1-147) 18(0-148) 0(0-8) 0(0-0) 0(0-0) 645 Row 4 246(1-114) 42(0-28) 6(0-100) 0(0-1) 0(0-0) 0(0-0) 294 Total 823(1-694) 92(0-164) 24(1-248) 0(0-8) 0(0-0) 0(0-0) 939 Annual Totals for this 1979 1978 1977 1976 1975 1974 1973 period _939 229 547 848 475 16* 525* 1/ Figures in parenthesis are ranges of numbers collected 1973-1977.

Collection procedures differed somewhat durin9 1973 and 1974 and the data may not be directly comparable.

e . 125 Araneida: Spiders generally are collected throughout the year and thus comprise an important part of the monitoring program, particularly in winter when many invertebrates are inactive. Seasonal fluctuations of spider populations for this period are shown in Table 4, along with ranges of numbers collected from 1973 - 1977. The data for this period indicate that monthly collections generally fell within the range of that from previous years. Total population levels were slightly lower than 1978 but generally comparable to those of recent years (though substantially lower than the 1975 level). Collections for the monthly sampling dates were similar to past years with numbers gradually decreas-ing from a high in July to lower levels in December. Thus data continue to indicate a relatively stable spider population exists in the area around the Generating Station. Tricoptera: The caddisflies are aquatic during the immature stages and therefore would be adversely affected by any changes in water quality or temperature, created by the operation of the Nuclear Generating Station. The short-lived nocturnal adults are attracted to lights, and during their brief mass emergences are collected in large numbers in the black light trap. Population levels of Tricoptera for this period are shown in Table 5, along with ranges of numbers collected from 1973 - 1977. Because emergency occurs sporadically, it is difficult to accurately estimate popu-lations based on limited collections and natural population fluctuations. However, the data available 3dicate that Tricoptera populations were generally comparable to those of previous years. The total number collected was some-

 . what higher than for the comparable period of 1978 and lower than for 1977, but substantially higher than for 1976, 1975 and 1974.           It appears that i

the populations are relatively stable in the area around the Generating i f l

t

                                                                                                                                                                         . , - -e .

Table 4. Number of Araneida collected in pit fall traps near the Ft.,jt. Vrain Nuclear Generating Station, Platteville, Colorado, July 1 - December 31, 1979.H July 14 Au9 11 Sept. 8 Oct. 13 Nov. 10 Dec. 8 Totals Row 2 51(10-151) 39(7-243) 66(5-139) 41(13-76) 12(6-84) 4(0-31) 213 Row 3 265(0-288) 130(0-424) 60(71-220) 101(16-140) 20(15-105) 0(0-72) 576 Row 4 472(0-289) 211(0-376) 89(24-286) 131(5-187) 15(6-328) 1(0-32) 919 Total 788(34-719) 380(42-1043) 215(15-566) 273(34-391) 47(27-517) 5(0-135) 1708 Annual Total for this 1979 1978 1977 1976 1975 1974 1973 period T/Uli 190f 1389 Tfi6T 3237 ton alii (July 1 - Dec. 31) , _ __ m Table 5. Number of Tricoptera collected fran a black light trap near the Ft. St Vrain Nuclear Generating Station, Platteville, Colorado, July 1 - December 31,1979._I/ July 7 Aug. 4 Sept. 1 Oct. 6 Nov. 3 Dec. Totals 269(11-1278) 90(2-6617) 77(0-293) 0(0-9) 0(0-0) Trap not 436 ____________________________________________________________________________________________sg}_gg}_____________ Annual Total ' for this 1979 1978 1977 1976 1975 1974 1973 period 436 391 602 177 69 59 2497 (July 1-Dec. 31) 1/ Figures in parenthesis are ranges of numbers collected 1973-1977.

l

                                                                          . 4 127 Station. The seasonal emergence patterns have been remarkably similar for all collection periods since the study began.

Heteroceridae: These small beetles inhabit the mud shores of ponds and streams and consequently could be affected by changes in water quality or temperature. The nocturnal adults are collected in large numbers in the black lignt trap. Population levels of this group are presented in I

Table 6 along with ranges of numbers collected for 1973 - 1977. Popula-tions of this group appear to be cyclic in nature. Levels were relatively l high in 1973 then declined to a low in 1975. Numbers then increased to a peak in 1977, declining from that to lower levels in 1978 and further in 1979. As with Tricoptera it is difficult to estimate populations of these insects with limited samples because of their sporadic emergence patterns. However, it appears that population levels are continuing to fall within expected patterns for the area. Sumary The results of the monitoring program on terrestrial invertebrates in the Fort St. Vrain area indicate that populations of most groups have remained relatively stable, or increased slightly, during the period covered by this report. It seems that the intermittent and limited operation of the Generating Station to date has not affected the ter-restrial insect populations that have been studied. I

O . Table 6. Number of Heteroceridae collected from a black light trap near the Ft. St. Vrain Nuclear Generating Station, Platteville, Colorado, July 1 - December 31,1979.O July 7 Aug. 4 Sept. 1 Oct. 6 Nov. 3 Dec. Totals 573(0-2018) 122(2-1050) 39(0-186) 0(0-5) 0(0-0) Trap not 734 set out Annual Total for this 1979 1978 1977 1976 1975 1974 1973 period 734 1125 2997 989 77 188 1802 (July 1-Dec. 31) M 1/ Figures in parenthesis are ranges of numbers collected 1973-1977. e

h.

12c References Brewer, J. W. 1978. Terrestrial Invertebrates. In: Progress Report Fort St. Vrain Nuclear Generating Station Environmental Imoact Study. Thorne Ecological Institute. Boulder, Colorado. Brewer, J. W. and T. R. Bacon. 1975. Biology of the Carrion Be:tle, Silona ramosa Say. Annals of the Entomological Society of America. 68:786-790. Brewer, J. W. 1973. Terrestrial Invertebrates. In: Progress Report: Monitoring Fort St. Vrain Nuclear Generating Station for Public Service Co. of Colorado. Thorne Ecological' Institute. Boulder, Colorado. Bushland, R. C. 1971. Sterility principle for insect control: Historical development and recent innovations. In: Sterility Principle for Insect Control or Erradication. IAEA. (Available from UNIPUB Inc., Box 433, New York) 542p. Cadwell, L. L. and F. W. Whicker. 1972. The anthropod comunity. In: Radioecology of some natural organisms and systems in Colorado, tenth annual progress report on Atomic Energy Commission contract. (Available from Department of Radiology and Radiation Biology, Colo. State Univ., Ft. Collins) 84p. Noordink, J. Ph.W. 1970. Irradiation, competitiveness and the use of radioisotopes in sterile male studies with the onion fly, Hylemya antiqua (Meigen). In: Sterility principle for Insect Control or Erracication. IAEA. Vienna. (Available from UNIPUB Inc., Box 433, New York) 542p. Skaife, S. H. 1968. Experiments on the effects of radiation on ants. Australian Natural History. March 27-28.

Wunder, B. A. 1978. Mamals. In: Progress Report: Ecological Monitoring Fort St. Vrain Nuclear Generating Station for Public Service Company of Colorado, Thorne Ecological Institute. Boulder, Colorado.

Wurtz, C. B. 1969. The effects of heater discharge on freshwater l benthos. In: Biological aspects of thermal pollution. Krenkel, , P. A. and F. L. Parker, Editors. Vanderbilt U. Press. Nashville, l Tennessee. - I

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ML19344D470

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