ML20217D449

Requests Approval to Revise Scope of Aquatic Biology Assessment Program by Reducing Biological Monitoring

ML20217D449
Person / Time
Site:	Limerick
Issue date:	04/16/1998
From:	Geoffrey Edwards PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Garg S PENNSYLVANIA, COMMONWEALTH OF
References
NUDOCS 9804240320
Download: ML20217D449 (4)

Text

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. April 16,1998 Mr. Sohan Garg Bureau of Water Quality Management PA Department of Environmental Protection Lee Park, Suite 6010 555 North Lane Conshohocken, PA 19428

Subject:

Limerick Generating Station, Units 1 and 2 Bradshaw Reservoir Discharge NPDES Permit No. PA 0052221 Request for Reduction in Biological Monitoring

Dear Mr. Garg:

The Pennsylvania Department of Environmental Protection (PA DEP) issued National Pollutant Discharge Elimination (NPDES) Permit No. PA 0052221 to PECO Energy Company authorizing the discharge of water diverted from the Delaware River to the East Branch Perkiomen Creek from the Bradshaw Reservoir in support of the operation of Limerick Generating Station (LGS), Units 1 and 2.

NPDES Permit PA 0052221, Part C, "Other Requirement K," requires that PECO Energy perform post-operational biological assessments to assess the impact of the water diversion discharge on the resident aquatic communities and stocked trout population in the East Branch Perkiomen Creek.

PECO Energy developed and implemented a post-operational study plan for sampling and monitoring aquatic life in the East Branch Perkiomen Creek and in the Perkiomen Creek. This study plan was originally submitted to the PA DER by letter dated July 20,1989. The study plan was subsequently modified as documented in our letters dated September 25,1991, June 20,1994, and October 2,1995.

Biological sampling in Perkiomen Creek ceased in 1996, consistent with the study plan changes approved by the PA DEP in 1995.

In addition, we have submitted " Post-Diversion Aquatic Biology Assessment" reports covering the years 1989 through 1996, as required by NPDES Permit No. PA 0052221, Part C, "Other Requirement K." The most recent report documented the results of the studies performed during 1995 and 1996.

This report was submitted to the PA DEP by letter dated December 22,1997. These reports document the effects of the first eight (8) years of water diversion operation on the East Branch Perkiomen Creek.

In addition, data has been collected throughout 1997, and is currently being analyzed.

Based on the results of the post-diversion studies conducted to-date. the following conclusions can be reached regarding the impact of the water diversion operation.

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April 16,1998 Page 2 Post-augmentation monitoring has shown some effects as a result of the water diversion on the East Branch Perkiomen Creek. The water diversion has generally improved the water quality in the East Branch Perkiomen when compared to pre-diversion conditions. The most significant effects have been observed, as expected, in the headwaters region, where hydraulic and physical habitat changes are most pronounced. The effects on the fish community structure in this region have been evidenced by changes in cyprinid dominance (i.e., golden shiners and bluntnose minnows have been replaced by spotfin shiners, comely shiners, common shiners, and spottail shiners) and elimination of redfin pickeral.

Farther downstream, where the physical effects of the water diversion are less pronounced, patterns of species composition and trends in population density have been observed througnout the eight (8) year study period in general, both seining and electrofishing have shown a trend of increased abundance of smallmouth bass, rock bass, and redbreast sunfish in the middle and lower reaches of the East Branch Perkiomen Creek relative to the pre-diversion period. In addition, a significantly decreased incidence of blackspot parasitism at all e

sampling locations is an indication of improved water quality in the East Branch Perkiomen Creek.

Similarly, benthic macro invertebrate studies have demonstrated that the most significant effects have taken place in the headwaters region. Taxa preferring a lotic environment have replaced lentic or intermittency-adapted forms. Farther downstream, lotic and pollution sensitive taxa have replaced lentic and pollution tolerant taxa in response to the increased stream flow and improved water quality.

The survey of trout anglers in 1995 and 1996 continued to demonstrate the popularity of the stocked-trout fishery in the East Branch Perkiomen Creek as well as the ability of the anglers to quickly harvest the stocked trout.

Therefore, based on the conclusions reached during flow-augmentation studies on the East Branch Perkiomen Creek, PECO Energy is requesting approval to revise the scope of the Aquatic Biology Assessment program beginning June 1,1998. We plan to reduce the list of constituents included for water quality monitoring to those metals and phenolics presently included for monitoring in the NPDES permit (i.e., aluminum, cadmium, mercury, zinc, iron, nickel, and phenols) and reduce the number of sampling locations. Sampling will be performed on a biweekly frequency at three (3) locations, i.e.,

one (1) at the Delaware River intake, and two (2) on the upper reach of the East Branch Perkiomen Creek. Water quality sampling on the Perkiomen Creek is to be discontinued. Also, benthic macroinvertebrate sampling in the winter quarter will be discontinued. In addition, we plan to discontinue the fish age and growth, and trout creel survey monitoring tasks. PECO Energy will maintain a sample location representative of the headwaters region, and three (3) sample locations in the middle to lower reaches of the East Branch Perkiomen Creek for the reduced benthic macroinvertebrate study and the unchanged fish seining and electrofishing components. Sampling at these locations will continue to represent a gradient of increasing stream size and changes in water quality.

The ongoing aquatic monitoring program will be fully effective, and will provide all the necessary* data to perform an Aquatic Biology Assessment of the impact on the resident aquatic community in the East Branch Perkiomen Creek. Attachment i to this letter provides a summary of our revised aquatic monitoring program for your review.

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April 16,1998 Page 3 I .

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if you have any questions or require additionalinformation, please do not hesitate to contact us.

Ve truly yours, . .

)

Garrett D. Edwards Director - Licensing Attachment cc:

USNRC Document Control Desk, Washington, DC (Docket Nos. 50-352,50-353)

(w/ attachment) ,

l H. J. Miller, Administrator, Region I, USNRC (w/ attachment) i A. L. Burritt, USNRC Senior Resident inspector, LGS (w/ attachment) l l

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