Text

Endangered Species Act Section 7(a)(2) Concurrence Letter and Magnuson-Stevens Fishery Conservation and Management Act Essential Fish Habitat Response for the Issuance of a U.S. Army Corps of Engineers Permit Authorizing Pacific Gas and Ele
	ML16006A277
Person / Time
Site:	Humboldt Bay
Issue date:	07/17/2014
From:	Stelle W; US Dept of Commerce, National Oceanographic and Atmospheric Administration
To:	Hicks J; NRC/RGN-II, US Dept of the Army, Corps of Engineers
References
	SWR-20 13-9644
	Download: ML16006A277 (1)
	v • d • e

UNITED STATES DEPARTMENT OF COMMERCE

,, *\.* National Oceanic and Atmospheric Administration

NATIONAL MARINE FISHERIES SERVICE

% . West Coast Region

,,*,,o,,* 1655 Heindon Road Arcata, California 95521-4573 In response refer to:

SWR-20 13-9644 Ms. Jane Hicks Chief, Regulatory Branch U.S. Army Corps of Engineers 1455 Market Street, 16th Floor S an Francisco, California 94103-1398 Re: Endangered Species Act Section 7(a)(2) Concurrence Letter and Magnuson-Stevens Fishery Conservation and Management Act Essential Fish Habitat Response for the Issuance of a U.S. Arxmy Corps of Engineers Permit Authorizing Pacific Gas and Electric Company to Implement the Humboldt Bay Power Plant Intake and Discharge Canal Remediation Project

Dear Ms. Hicks:

On July 10, 2014, NOAA's National Marine Fisheries Service (NMFS) received your request to initiate informal consultation for the U.S. Army Corps of Engineers (Corps) issuance of a Permit (File Number 2013-00329N) to Pacific Gas and Electric Company (PG&E), under Section 404 of the Clean Water Act ( 33 U.S.C. § 1344) and Section 10 of the Rivers and Harbors Act of 1899 (33 U.S.C. § 403), is not likely to adversely affect (NLAA) species listed as threatened or endangered or critical habitats designated under the Endangered Species Act (ESA). This response to your request was prepared by NMFS pursuant to section 7(a)(2) of the ESA, implementing regulations at 50 CFR 402, and agency guidance for preparation of letters of concurrence.

NMFS also reviewed the proposed action for potential effects on essential fish habitat (EFH) designated under the Magnuson-Stevens Fishery Conservation and Management Act (MSA),

including conservation measures and any determination you made regarding the potential effects of the action. This review was pursuant to section 305(b) of the MSA, implementing regulations at 50 CFR 600.920, and agency guidance for use of the ESA consultation process to complete EFH consultation.

This letter underwent pre-dissemination review using standards for utility, integrity, and objectivity in compliance with applicable guidelines issued under the Data Quality Act (section 515 of the Treasury and General Government Appropriations Act for Fiscal Year 2001, Public Law 106-554). The concurrence letter will be available through NMFS' Public Consultation Tracking System https://pcts.nmfs.noaa.*ov/pcts-web/homep~age.pcts. A complete record of this consultation is on file at NMFS West Coast Region, Arcata, Gta!ifornia office.

CONSULTATION HISTORY Pre-consultation Activity Following an August 14, 2013 interagency meeting hosted by the Corps, the Humboldt Bay Power Plant (HBPP) Canal Remediation Project Interagency Working Group (IWG) was formed to coordinate remaining permit actions required by the U.S. Nuclear Regulatory Commission (NRC) to decommission the PG&E Humboldt Bay Power Plant Unit 3. The IWG included representatives of federal, state, and local regulatory agencies [Corps, NMFS, U.S. Fish and Wildlife Service (USFWS), California Coastal Commission(CCC), California Department of Fish and Wildlife, Regional Water Quality Control Board, and Humboldt Bay Harbor, Recreation, and Conservation District (HIBHRCD)); and representatives of PG&E and its contractors, CH2M Hill, and Stiliwater Sciences. On September 4, 2013, Stillwater Sciences provided NMFS and USFWS an electronic copy of th6 July 2013 Humboldt Bay Power Plant Intake and Discharge Canal Remediation Project (Project) Biological Assessment (BA). On September 13, 2013, PG&E provided electronic copies of materials (agenda, overview of mitigation for canal remediation activities) for the first IWG September 17, 2013, meeting.

On November 11, 2013, CH2MHill provided IWG with an electronic version of the agency review draft of the Biological Mitigation and Monitoring Plan for the Humboldt Bay Power Plant Canal Remediation Project (IBMMP), prepared by Stillwater Sciences (2013b). On November 14, 2014, CH2MHill notified IWG, via electronic mail, that PG&B has submitted various permit applications to regulatory agencies having jurisdiction for the.Project, and provided three figures intended to supplement the permit applications and provide more information about the discharge canal remediation. At the second IWG meeting on November 19, 2Q13, NMFS and others provided oral comments on the agency review draft BMMP (Stillwater Sciences 2013b),

and Stillwater Sciences agreed to revise the document. On November 21, 2013, CH2MHi~l informed NMFS that the Corps had sent a letter to NMFS requesting initiation of consultation, under section 7 of the ESA and provided an electronic copy of the letter.

Consultation Activity On November 25, 2013, NMFS received the Corps November 20, 2013, letter requesting initiation of formal consultation on the Project. The Corps enclosed several documents: a JulY 19, 2013, letter; ENG Form 4345 (Application for Department of Army permit); ENG Form 4345 Application Supplement; and the July 2013 BA (Stiliwater Sciences 2013a). The Corps also enclosed three project-related figures (discharge canal temporary stockpile, discharge outfall pipe removal, and discharge canal outfall structure profile view), dated October, 2013. The Corps stated all work will be completed in accordance with the permit application and BA.

On November 27, 2013, NMFS asked the Corps via electronic mail to provide color copies of photographs and figures in the permit application, as well as electronic copies of the other enclosures to allow for sharing with other NMFS staff to review regarding potential effects to the water quality and EFH components of the Project. On December 2, 2013, the Corps informed NMFS that the applicant would be mailing color copies of the document to NMFS. On December 3, 2013, CH2MHill informed NMFS that a CR-ROM would be sent with the entire, permit package, once some additional change to the IHBPP BMMP were completed. On December 16, 2013, CH2MHill provided IWG with an electronic access link to all the 2

environmental permitting documents developed for the Project, along with the final version of the BMMP (Stillwater Sciences 2013c).

Xn a December 17, 2013, letter to the Corps,. NMFS determined that the information provided in by the Corps in their November 20, 2013, letter and enclosures, along with the BMMP (Stillwater Sciences 2013c), was sufficient to support a "may affect" determination for ESA listed species and their designated critical habitat [50 CFR 402.14(a)]; and to initiate section 7(a)(2) formal consultation. NMFS stated that additional information may be needed to complete the consultation, however, and that NMFS would formulate its biological opinion as to whether the action is likely to jeopardize the continued existence of listed species or result in the destruction or adverse modification of critical habitat [see 50 CFR 402.14(g)]. NMFS will assume the proposed project may adversely affect EFH, proceed with MSA consultation for species managed under the Pacific Salmon, Pacific Groundfish, and Coastal Pelagic Federal Fishery Management Plans, and provide conservation recommendations if necessary. NMFS intended to integrate the ESA and MSA consultations, and expects to complete the consultations before April 30, 2014.

On Febiruary 25, 2013, NMFS contacted the Corps to discuss a potential change in the Corps effects determination for listed salmonids and their designated critical habitat. On February 25, 2013, the Corps requested via electronic mall to amend their effects determination in the November 20, 2013, letter. Because presence of individual salmonids or green sturgeon in the action area during project implementation is unlikely and the effects to critical habitat (turbidity, loss of a small amount of eelgrass habitat), would be temporary, the Corps determined that the Project would not likely adversely affect federally listed species or designated critical habitat. On February 27, 2014, the Corps requested via electronic mail that NMFS concur with the Corps determination that the prosed action is not likely to adversely affect listed species or their designated critical habitat.

On March 5, 2014, NMFS contacted Stiliwater Sciences and the applicants authorized agent CH2MI~ill about the timing of the eelgrass mitigation, required as a result of the dewatering and sediment removal in the intake and discharge canals; as well as clarification of discharge outfall pipe removal activities (e.g., area and volume of substrate disturbed, number and size of anchors for turbidity curtain). On March 5, 2014, NMFS was informed by Stillwater Sciences that the proposed action has changed since the BA (Stillwater Sciences 2013a) , and now included the site restoration of the intake canal as well as creation of the Intake Canal/Alpha Road mitigation area, and this information was part of the permit application for the HBHRCD permit, as well as the CCC permit. In the spirit of 1WG, NMFS contacted both the Corps and CH2MHil1 via electronic mail to insure that the Corps permit application was updated to include the Project changes that were included under other perrmits. On March 17, 2014, Stillwater Sciences provided details of the area encompassed by the cofferdam around the discharge pipes, the number and type of anchors employed with the turbidity curtain, and area of disturbance during discharge pipe removal via electronic mail. On March 21, 2013, CH2MHilI informed NMFS via electronic mail that the Corps recommended they submit a letter outlining the changes in the Project since the July, 2013 permit application, primarily resulting from the revised BMMP (Stiliwater Sciences 2013c); and that CH2MHill would provide a copy this letter to NMFS. On March 24, 2013, because both the Corps effects determination and the components of the Project have changed, NMFS recommended via electronic mail that the Corps reissue the letter initiating 3

ESA section 7 consultation and include a statement that the new letter replaces the earlier letter; and clearly describe the Project and the reasoning for the effects determination. Further, if the BA has not be revised, NMFS recommended the Corps clearly indicate which parts of the proposed action and effects determination are based on the BA (Stillwater Sciences 2013a) and what factors were considered in addition to the information in the BA in their effects determination. On March 25, 2014, CH2MHiII informed NMFS via electronic mail that the BA was being revised. To improve the efficiency of the consultation process, the Corps agreed to provide NMFS with a draft initiation letter for review and comment prior to signature. On April 8 and 10, 2014, the Corps provided versions of a draft initiation letter to NMFS review via electronic mail; and NMFS provided electronic comments on the draft letters on April 10, 2014.

On April 10, 2014, CH2.MI~ill informed NMFS via telephone that the cofferdam around the discharge pipes would be installed with an impact hammer rather than a vibratory hammer as described in the BA (Stillwater Sciences 201 3a); and NMES subsequently notified the Corps of this change of installation method via electronic mail. On April 10, 2014, NMFS also provided CH2MHill and the Corps with information via electronic mail on hydroacoustic effects of pile driving on fish and marine mammals, as well as contact information for NMFS staff specialists on the hydroacoustic effects of impact pile driving on fish and marine mammals. On April 11, 2014, NMFS asked Stillwater Sciences, CH2MHill, and the Corps via electronic mail to clarify the spatial extent of the action area in both the intake canal and in the vicinity of the discharge pipes in Humboldt Bay. On April 21, 2014, Stillwater Sciences notified NMFS via telephone that a vibratory hammer rather than an impact hammer would be used to install the sheet piles of the cofferdam; and also provided NMFS with an updated Project implementation schedule.

On May 9, 2014*, CH2MHiII provided NMFS an electronic copy of the revised BA (Stillwater Sciences 2014), which indicated that a vibratory hammer instead of an impact hammer would be used to install the sheet piles. On May 28, 2014, NMFS participated in a conference call with the Corps, CH2MHill, Stillwater Sciences, and PG&E to discuss the BA (Stillwater Science 2014),

and Stillwater Sciences agreed to provide additional information on the spatial extent and reasoning for description of the action area, as well more information on installation of the sheet piles and the turbidity curtain. On June 3, 2014, NMFS received a technical memorandum (Stillwater Sciences 2014b) with additional information. On June 4, 2014, NMFS contacted Stillwater Sciences b~y telephone for further clarification regarding the intake canal action area and the turbidity effects analysis, and subsequently received written explanation via electronic mail.

On July 3, 2014, the Corps notified NMFS via voicemail that the letter initiating consultation on the Project had been signed, and would be mailed. On July 7, 2014, NMFS contacted the Corps via electronic mail to acknowledge the voicemail; and to inform the Corps that, once NMFS receives the letter, clarification of statements in the letter may be necessary since NMFS had not reviewed the letter prior to signature. On July 7, 2014, the Corps provided NMFS via electronic mail a scanned copy of the July 3, 2014, letter requesting initiation of consultation on this project. NMFS subsequently contacted the Corps via electronic mail, questioning their effects determination for Essential Fish Habitat (EFH), which differed from the effects determination in the BA (Stillwater Sciences 2014); recommending the effects of both the installation and removal of the water control structure in the intake canal should be discussed and analyzed; and asking for clarification on why there were no attachments or enclosures provided along with the hard copy, as the letter suggested there were enclosures and attachments. On July 7, 2014, the 4

Corps informed NMFS via electronic mail, that thetoeffects determination for Essential Fish Habitat (EFH) in the July 3, 2014, letter (no effect EFH) is no longer valid, and should be changed to may adversely affect EFH, and provided reasoning to support this new determination.

On July 8, 2014, the Corps provided additional information regarding the effects of the removal of the water control structure in the intake to support their effects determination. On July 14, 2014, NMFS requested CH2MHill clarify the number of sheet piles to be installed, the time to remove the sheet piles, and the area to be contained within the sheet pile wall and the turbidity curtain. CH2MHill clarified these questions on July 15, 2014.

PROPOSED ACTION

Background

PG&E is in the process of decommissioning its former power generation facility at the 143-acre Humboldt Bay Power Plant (HBPP) site in Humboldt County, California, and terminating the Nuclear Regulatory Commission (NRC) license for the former HBPP nuclear unit, Unit 3. The HBPP formerly consisted of natural-gas-fired steam generation Units 1 and 2 and the nuclear unit (Unit 3), which has been shut down since 1976. PG&E has replaced the HBPP with a newer power plant using internal combustion engines, called the Humboldt Bay Generating Station (HBGS), which began generating power in 2010. The former HBPP Units 1-3 used a power plant cooling design called once-through cooling that involved piping Humboldt Bay water to cool the power generating units and then returning the water to the bay. Humboldt Bay is comprised of three sub-bays, connected by tidal channels, and the HBPP cooling water was drawn through an artificial channel connected to South Bay and then discharged into Entrance Bay (figure 1).

Figure 1. Location of HBPP (*) in Humboldt Bay, California 5

In the mid 1950's, PG&E modified a portionand of Buhne Slough located on PG&E property the by dredging, stabilizing the banks with rip-rap, installing tidegates and culverts to create Fisherman's Channel adjacent to the community of King Salmon. The purpose of the Fisherman's Channel was to provide cooling water for the HBPP via the intake canal (GHD 2013a, 2013b). Once the water passed through the heat exchangers, the heated water entered the discharge canal and was returned to Humboldt Bay. The water intake canal is physically connected to the Fields Landing Channel in South Bay by the Fisherman's Channel; and the discharge canal is physically connected to the Entrance Bay by four 48-in diameter outfall pipes (figure 2). Prior to 2010 when Units land 2 were operating, the discharge canal was not subject to tidal influence due to the large volume of water (about 52,000 gpm) that was discharged continuously (EA 1983, HBHRCD 2004). The current HBGS design does not require the use of cooling water, and Humboldt Bay water has not been drawn into or discharged from the facility since 2010. The intake and discharge canals are no longer needed for plant operation, as there is no longer a need for cooling. As a result, the outfall pipes are partially plugged with sand, and eelgrass has colonized the discharge canal.

Figure 2. HBPP Intake and Discharge Canal Remediation Sites in Humboldt Bay, California.

As part of the program to decommission Units 1-3, and terminate the NRC license for Unit 3, PG&E proposes to remove contaminated sediment from the intake and discharge canals; and remove infrastructure in the canals (e.g., concrete, pipes) associated with the past intake and discharge of the cooling water.

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The Corps proposes to issue an individual permit to PG&E to remove contaminated sediments and infrastructure from the intake and discharge canals of the former HBPP; and to restore the aquatic habitats in and adjacent to the intake and discharge canals, including compensatory wetland mitigation (Project). The proposed Project will be implemented over a five-year period (2014 through 2018); and the sequence of Project activities (table 1) has been designed so that wetland restoration and mitigation activities in the intake canal occur as soon as possible in the aquatic plant growing season after the sediment and infrastructure removal.

Table I. Estimated schedule of Project activities (Stillwater Sciences 2014a, 2014b).

Activity Approximate start finish/time to finish j

Isolate discharge canal Demolish and remediate discharge canal July 2014 July 2014 September 2014 j July 2014 October 2014 March 2015 Isolate and remove outfall structure/ pipes Place intake canal water control structure May 2018 or sooner' 1-2 months Demolish and remediate intake canal 2018 or sooner' 4-6 months Create Alpha Road parking mitigation area 2018 or sooner' 2-4 months Restore intake canal 2018 or sooner' 2-4 months

'Work in the intake canal is dependent upon the need to use the Alpha Road Parking Area for decommissioning activities. This portion of the project could start as early as 2016.

The Project is located in the community of King Salmon, south of Eureka in Humboldt County, along the east shore of Humboldt Bay just opposite of the bay's entrance, and west of Highway 101. The project is surrounded by Humboldt Bay to the west, agricultural land to the east, and King Salmon to the south. The entire project is located within or immediately adjacent to PG&E property. Construction equipment (cranes, excavators, and loaders), vehicles, and materials would be staged onsite during periods of continuous use. In addition to the major equipment listed, routine equipment already on site would continue to be used, including waste hauling trucks, forklifts, man lifts, portable generators, air compressors, portable tanks, hand tools, and other supplies and equipment already used to support decommissioning.

Discharge Canal Activities The contractor will mechanically remove the discharge head-works structure that formerly discharged cooling water to the discharge canal. The contractor will also mechanically remove an estimated 9,000 yds 3 of contaminated sediment and riprap within the 0.78 ac discharge canal, remove the outfall structure, and re-slope the sides of the canal to meet minimum safe sloping standards (Stillwater Sciences 2013a). Radiological surveys and non-radiological sampling of the sediment removed from the discharge canal will be performed after excavation and dewatering. Once tested and characterized, the sediment will either reused on site or disposed of at an appropriate licensed waste facility dependent on characterization results. The initial isolation of the discharge canal from Humboldt Bay will be accomplished by plugging the four outfall culvert pipes using inflatable pipe plugs, grout, or other suitable plugging mechanism.

The initial isolation will be sufficient to support removal of2 the intake headwall structure and sediment within the discharge canal. Approximately 815 ft (0.02 ac) of eelgrass will be removed 7

from the discharge canal along with the sediment. Any stormwater drainage currently flowing into the discharge canal will be re-routed to the Groundwater Treatment System (GWTS).

Following completion of activities in the interior of the discharge canal, the four 60-foot-long 48-inch-diameter asbestos-bonded metal outfall pipes and outfall structure (figure 3) will then be removed. Removal of discharge pipes and appurtenances will require installation of a sheet pile wall on the Humboldt Bay side of the existing revetment/levee to isolate the work area from the bay. The sheet pile wall will prevent tidal flows from Humboldt Bay and other water, such as groundwater, from entering the work area during excavation and other activities.

Figure 3. Discharge canal outfall structure (Stillwater Sciences 2014a).

A section of the existing rip-rap revetment levee and associated coastal trail will be mechanically removed to facilitate removal of the outfall structure and outfall pipes. Material excavated for access to the discharge pipes will be treated as if contaminated until demonstrated otherwise through sampling and testing. Removal of discharge pipes and outfall structure will require installation of a sheet pile wall on the Entrance Bay side of the existing levee to physically isolate the work area from tidal and wave action and provide a safe work environment. Three days prior to installation of the sheet pile wall in mid-September, the contractor will install a turbidity curtain approximately 33 ft from where the outside edge of the coffer dam (Stillwater Sciences 2014b). The turbidity curtain suspended from buoys, sealed at the bottom by weights, and anchored to the substrate by cables attached to 10 pairs of 43-lb Danforth type anchors spaced at approximately 50-ft intervals (Stillwater Sciences 2013, 2014a; Teraoka 2014). Each 4.7 ft2 , and will be anchor (20 anchors total) will disturb a benthic surface area of approximately attached to a cable that extends approximately 24 feet from the bottom of the curtain. The 8

intended to limit the spatial extent of turbidity from any sediment suspended turbidity curtain is of during installation the sheet pile wall and subsequent dewatering of the area within the sheet pile wall. The turbidity curtain will either be removed once the sheet pile wall is in place, or left in place rolled up off the bottom to allow for tidal flow and ease of replacement when the sheet piles are removed (Stillwater Sciences 2014a, 2014b). Installation of 120 sheet pile panels (22.5 in by 38 ft each) by vibratory pile driving will begin in mid-September, 2014 and take approximately 21 days (Stillwater Sciences 2014a). Piles will be installed for seven hours per day, between 0700 and 1730 hours0.02 days 0.481 hours 0.00286 weeks 6.58265e-4 months . The work area (0.17 ac) enclosed by the sheet pile wall will be dewatered by pumping water from the area into the water between the sheet pile wall and the turbidity curtain, and will remain dewatered for a maximum of 6 months. An estimated 0.42 ac of Humboldt Bay will be temporarily isolated from Entrance Bay by the turbidity curtain for a maximum of 21 days in the fall (September and October) during installation of the sheet pile wall, and in the spring (March) during removal of the sheet pile wall (Davy 2014, Stillwater Sciences 2014a).

Once the outfall pipes have been removed, the discharge canal will be re-sloped and conditioned so that it can serve as an interim stockpile area for soil generated from other Unit 3 decommissioning activities until March 2018. The former discharge canal will remain permanently disconnect from Humboldt Bay. The contractor will also restore the rip-rap revetment seawall and the coastal trail along the adjacent Humboldt Bay to their previous condition, and then the sheet pile wall will be removed. Following removal of the turbidity curtain and the 20 anchors, the substrate is expected to return to pre-Project bathymetry within eight days (Stillwater Sciences 20 14b). Once the tidal circulation is restored to the dewatered area where the outfall pipes were removed, transport of sediment within Entrance Bay is expected to fill in the area within eight days (Teraoka 2014).

Intake Canal Activities Intake canal remediation activities include: dewatering of a portion of the intake canal; removal of the contaminated sediments; removal of the intake structure (67 feet long by 52 feet wide by 26 feet tall); and creation and reconnection of intertidal habitats.

The contractor will install a water control structure (e.g., bladder dam) in the intake canal located at the pedestrian bridge about 380 ft southwest of the intake structure (figure 4) during a falling tide. The structure will prevent tidal flows from South Bay from entering the work area via the Fisherman's Channel during removal of contaminated sediment and of the intake structure. Prior to dewatering, eelgrass will be collected and transplanted outside of the work area into suitable nearby areas near the King Salmon Avenue Bridge and the Fisherman's Channel (Stillwater Sciences 201 3c). Once the water control structure is in place, the contractor will dewater the work area by pumping water over the water control structure and into the intake canal connected to Humboldt Bay, and is expected to take a maximum of 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months (Halligan 2014). Any water that may enter the work area from groundwater or stormwater during removal of sediment and infrastructure will be pumped from the work area and routed through the GWTS. An estimated 39,204 ft 2 (0.90 ac) behind the water control structure (figure 4) will be dewatered, including approximately 0.07 ac of eelgrass that will be removed and temporarily transplanted in the intake canal approximately 500 feet downstream of the cofferdam near the King Salmon Road bridge.

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The contractor will mechanically remove canal, up to approximately 1,OO0 yd 3 of contaminated sediment from the northern corner of the northeast of the pedestrian bridge and adjacent to the intake structure (figure 4). The contractor will also demolish and remove the intake structure, using heavy equipment and employ physical containment methods to prevent material from falling into the dewatered intake canal.

Direct disturbance area (approximate) U Mudfiat ~ ~~

INCoastal bluff scrub/Coastal Ursladm Open water .. .C*::

l Eetgrass

i*~rasln *

i, tr*i:

Figure 4. Location of HBPP intake canal remediation activities and associated habitats (Stillwater Sciences 2013c)

Demolition and removal of the intake structure is estimated to generate up to 4,000 cubic yards of concrete, which will be stockpiled or loaded into intermodal containers for recycle, onsite re-use, or, if contaminated, disposal offsite. Due to the proximity of the intake structures to the 10

60kV switchyard and associated structures, a physical shoring system may be necessary to safely excavate intake structures and protect existing infrastructure.

gr*y~

Mudilat coastal salt marsh Ul 1 Northern U Eelgrass benches *, 2o22 (approximate) O*t~t

.3Alpha Road park~ingarea Direct disturb~ance mitigation area rol Deep water n.2 ,I.,,

*.. 22 SCoastal bluff scrub!Coastai grassland * "k, .*it'ae S*>n 0 3 *b 22 mn wnwI2,II..SterSC, orn Figure 5. Proposed restoration and creation of tidal wetland habitat in the HBPP intake canal (Stiliwater Sciences 2013c)

Following removal of the contaminated sediment and the intake structure headwall from the dewatered intake canal, the intake canal will be also expanded to create a 1.45 ac wetland mitigation area that incorporates the adjacent Alpha Road parking area, and will create new deepwater, mudflat, intertidal eelgrass, saltmarsh, and bluff scrub habitats (figure 5). Once 3

physical construction of the mitigation area is completed, an estimated 2,000 yd of clean fill will be added to the intake canal. The intake canal will then be re-sloped and stabilized to withstand 11

daily tidal changes in water elevation and to support the infrastructure adjacent to the canal (e.g.,

road, switchyard). Once the water control structure is removed, the area will be reconnected to the unaffected portion of the intake canal and to the South Bay via Fisherman's Channel with full tidal exchange (figure 2). Once the tidal circulation is restored, eelgrass from adjacent donor beds in the intake channel and Fisherman's Channel (which may include eelgrass transplanted from the remediation area) will be transplanted into the reconnected and created intertidal habitats, and performance standards monitored to ensure successful eelgrass habitat mitigation (Stiliwater Sciences 2013c). In the 0.90 ac area that was dewatered, 0.30 acres of eelgrass will be replanted to mitigate for the loss of 0.07 ac of eelgrass lost during dewatering of the intake canal and the 0.02 ac of eelgrass removed from the discharge canal (Stillwater Sciences 2013c).

Management of Water from Dredged Sediment and Canals Contaminated sediment removed from the bottom of the intake and discharge canals will be placed on settling pads or in containers located in one or more of the upland laydown areas on the HBPP site for gravity dewatering. Any water resulting from the dewatering of contaminated sediment, including groundwater and storm water accumulated in the canals during remediation will be collected in the intake and discharge canals following the initial dewatering, characterized, and discharged into the GWTS or disposed of using appropriate methods consistent with characterization results, If necessary, additional temporary water storage and treatment, including tanks, clarifiers or filters will be installed to treat water removed from the canals prior to treatment in the GWTS.

Management of Waste from Intake and Discharge Canals The proposed project would generate construction debris, soil, and waste materials including excavated sediments and concrete rubble resulting from demolition of the intake and discharge structures. All construction on the site would implement best management practices (BMPs) to prevent soil and petroleum products from entering the bay. Construction activities on the site have the potential* to generate pollutants (e.g., sediment, concrete, petroleum products) that may be transported, during runoff of water from rain events (stormwater runoff) into Humboldt Bay.

All project construction activities will include BMPs for construction, such as those identified in the California Stormwater BMP Handbook [California Stormwater Quality Association (CSQA) 2009], to prevent discharge of pollutants. General BMP categories include: erosion control (EC), waste management and materials control (WM), non-stormwater management control (NS), sediment control (SE), and spill control (SC).

The current HBPP waste management plans for ongoing upland decommissioning operations, along with contractor-submitted waste management plans, would govern waste management activities for the proposed project. Because some demolition waste generated at the site is subject to regulation and control by the NRC, Resource Conservation and Recovery Act, and California Hazardous Waste Regulations, the HBPP waste management and radiological protection contractors would implement necessary compliance measures and contractor oversight, including screening wastes for licensed radiological materials and documenting waste characterization and shipping. It is expected that little to none of the excavated soil and sediment taken from the canals would qualify for onsite reuse and that these materials will be shipped offsite to a disposal facility; however, if removed sediment and soil meet criteria for reuse, reuse on site will be considered. If materials are not used onsite, they may be direct loaded or 12

processed for shipment to a recycle facility, or disposed of at a Class II landfill. Concrete wastes would be tested to determine eligibility for onsite reuse; however, it is currently assumed that some demolition debris generated would also require packaging into intermodal containers for shipment to a radiological disposal facility offsite disposal due to contamination.

An Erosion, Sediment, and Dust Control (ESDC) Plan will be prepared, which will conform to the HBPP Stormwater Pollution and Prevention Plan (SWPPP); and will include best management practices (BMPs) for controlling stormwater discharge to insure that runoff does not transport any sediment into Humboldt Bay. The ESDC plan will include BMPs for the handling of contaminated sediment. If dewatered sediment requires temporary stockpiling, piles would be placed on and covered with plastic sheeting or tarps that are secured safely with sand bags and bermed with fiber rolls or silt fencing to prevent stormwater runoff from leaving the area.

The SWPPP will include any additional BMPs needed for the storage and use of hazardous materials and waste from the Project, as well as spill response procedures. Hazardous materials and waste would be stored in containers that prevent the release of material or hazardous content and within secondary containment, and spill kits would be placed throughout the Project area for immediate response to spills, such as those that might occur during onsite refueling. Following initial response, follow-up investigation and cleanup to any spill would be performed in accordance with the SWPPP.

ACTION AREA Under the ESA, the "action area" means all the areas to be affected directly or indirectly by the Federal action and not merely the immediate area involved in the action (50 CFR 402.02). The action area in the intake canal remediation component of the Project includes an estimated 4.18 acres (Stillwater Sciences 2014b); and extends down the channel from the intake headworks approximately 1,700 ft, and approximately 300ft into the first residential channel off the Fisherman's Channel below the bridge (figure 6). The action area for the intake canal component of the Project includes the 380 ft of channel behind the water control structure, and extends to expected limits of the turbidity plume resulting from suspension of sediments during installation and removal of the cofferdam (Stillwater Sciences 2014b, Halligan 2014).

Of the 0.19 ac of eelgrass in the entire intake canal from the King Salmon Avenue Bridge to the intake structure, approximately 36 percent (0.07 ac) is located between the proposed location for the water control structure and the intake structure (Stiliwater Sciences 20 14a). The substrate in the in the action area is predominantly silt (GHD 2013). The most abundant benthic invertebrates in the silty substrate of the intake canal are amphipods, (Corophium spp), which occur at densities of approximately 220 per ft2 (Adams 1975), and the non-native C. insidiosunm is the dominant species (Ecological Analysts, Inc. 1983). Because of the physical connection to South Bay, planktonic salmonid prey species (e.g. Pacific herring, northern anchovy, and larval crabs) present in the waters of South Bay are passively carried into the intake canal with the tide (Ecological Analysts, Inc. 1983). The intake head works is approximately 3,800 ft from the Fields Landing Channel in South Bay (figure 2).

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The action area (figure 6) for the discharge canal remediation component of the Project encompasses a 0.64 acre (27,878 ft-2 ) area in Entrance Bay, extending 225 ft along the Humboldt Bay shoreline and approximately 124 ft perpendicular to the shoreline (Stiliwater Sciences 2014b). The substrate is predominantly medium to fine sand, and benthic fauna consists of primarily polychaetes, crustaceans, and clams (Ecological Analysts, Inc. 1983). The action area (Davy 2014, Stillwater Sciences 2014b) includes the area dewatered by the sheet pile wall (0.17 ac) as well as the area encompassed by the turbidity curtain (0.25 ac) and extends 30 ft beyond the turbidity curtain to include the 10 outside lines and anchors.

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0 IM~

100 Figure 6. Project Area and Action Area (Stillwater Sciences 2014b).

The Entrance Bay shoreline adjacent to the HBPP discharge canal and outfall pipes is protected by a rock seawall revetment having a crest elevation about 16 ft above mean lower low water (MLLW) level (HBHRCD 2004). Surface tidal currents in shallow water between Buhne Point and Elk River, which includes a portion of the action area, flow parallel to the shore line; and currents on ebb and flood tides range from 0.6 to 2.4 feet per sec, respectively (Corps 1987).

The outfall pipes are located in sandy substrate and are also subject to the high energy wave and tidal environment of Entrance Bay (figure 7). The orientation of the entrance of Humboldt Bay, the alignment of the jetties, and the prevailing wind direction results in locally generated waves that are focused on Entrance Bay and the shoreline of HBPP near the discharge canal (Costa and Glatzel 2002). Salinity in Entrance and South Bays ranges from 32 to 34 ppt (Ecological Analysts, Inc. 1983, Barnhart et al. 1992).

14

risurv *-,

Humboldt Bay Jetties Figure 7. Entrance Bay and the mouth of Humboldt Bay (Costa and Glatzel 2002).

Listed Species and Designated Critical Habitat in the Action Area The following threatened species and designated critical habitat may be affected by the proposed action: (1) Southern Oregon/Northern California Coast (SONCC) coho salmon (Oncorhynchus kisutch) Evolutionarily Significant Unit (ESU), listed on May 6, 1997 (62 FR 24588) and June 28, 2005 (70 FR 37160); (2) California Coastal (CC) Chinook salmon (0. tshawytscha) ESU, listed on September 16, 1999 (64 FR 50394); (3) Northern California (NC) steelhead (0. mykiss)

Distinct Population Segment (DPS) , listed on June 7, 2000 (65 FR 36074); (4) North American green sturgeon (Acipenser medirostris), Southern DPS, listed on April 7, 2006 (71 FR 17757);

and critical habitat for SONCC coho salmon (64 FR 24049, May 5, 1999); CC Chinook salmon (70 FR 52488, September 2, 2005); NC steelhead (70 FR 52488, September 2, 2005); and Southern DPS North American green sturgeon (74 FR 52300, October 9, 2009).

The estuarine critical habitat for salmon and steelhead in Humboldt Bay connects the freshwater habitat and the marine hlabitat of tihe Pacific Ocean. The essential habitat features of SONCC coho salmon critical habitat in the action area include adequate: (1) substrate, (2) water quality, (3) water quantity, (4) water temperature, (5) water velocity, (6) cover/shelter, (7) food, (8) riparian vegetation, (9) space, and (10) safe passage conditions. The action area serves as a potential migratory corridor, as well as habitat for feeding, for outmigrating SONCC coho salmon smolts, prior to ocean entry. For CC Chinook salmon and NC steelhead, the essential primary constituent elements (PCE) of critical habitat in the estuarine action area support rearing 15

corridor functions, areas free of namely conditions obstruction and excessive predation with watermigratory and quality, water quantity and salinity supporting juvenile and adult physiological transitions between fresh-and saltwater; aquatic vegetation, and juvenile and adult forage, including aquatic invertebrates and fishes, supporting growth and maturation. The PCE in the action area provide the rearing and migratory corridor functions for CC Chinook salmon and NC steelhead smolts, allowing for foraging and swimming through an area without expenditure of additional time and/for energy required.

The estuarine PCEs of green sturgeon critical habitat in Humboldt Bay that are essential to their conservation include: food resources; water flow; water quality; water depth; sediment quality; and migratory corridors to support feeding, migration, and aggregation and holding by green sturgeon adults and sub adults. The invertebrate prey resources for green' sturgeon are primarily found in the intertidal mudflats and subtidal channel margins; and include epibenthic and benthic invertebrates, Dungeness crab, and a variety of clams. Ghost shrimp are the preferred prey item for green sturgeon in Washington estuaries, comprising up to 50 percent of their diet (Dumbauld et al. 2008). Pinnix (2008) used acoustic telemetry to document detections of 30 individual tagged green sturgeon in Humboldt Bay from 2006 to 2007. Data provided by Pinnix (2008) indicated that 92 percent of detections (131,411 of 142,362 detections) of green sturgeon were made in the North Bay. Based on the preponderance of detections in the North Bay it is likely that green sturgeon utilize the deeper waters of the North Bay Federal Navigation Channel as a migratory corridor between the Pacific Ocean and North Bay.. Detections suggest that green sturgeon may be present as temporary residents in Humboldt Bay from June through October.

Action Agency's Effects Determination The Corps determined that the Project would not adversely affect SONCC coho salmon, CC Chinook salmon, NC Steelhead, Southern DPS North American green sturgeon or their designated critical habitats. This determination was based on the spatial extent and temporal duration of the effects of the project and the likelihood of exposure of individuals to those effects, and incorporated by reference the effects described in the iBA(Stillwater Sciences 2014a) and associated technical memorandum (Stillwater Sciences 20 14b). The Corps effects analysis the removal of the discharge outfall pipes reasoned the turbidity curtain would minimize the spatial extent of the turbidity during sheet pile installation, and adverse effects of the anchors on critical habitat were unlikely. The Corps stated the temporary (six month) loss of 0.64 acres of critical habitat in Humboldt Bay (Entrance Bay) would be minimal and would not meaningfully affect the rearing habitat function of the critical habitat. Because increased turbidity in the intake canal during installation and removal of the water control structure will dissipate after 4 tidal cycles, the Corps reasoned there will be no meaningful effect to the rearing function of the critical habitat in the action area in the intake canal. Although 0.90 ac of the intake canal would be isolated and dewatered for a period of six months and result in a temporary loss of food resources, the Corps did not expect the temporary loss to have a meaningful effect on the rearing function of the critical habitat in the intake canal. The Corps further reasoned that the habitat in the intake canal is low functioning due to the high level of historic industrial disturbance contamination with radionucleides, shallow water depths, lack of riparian zone, and overall artificial construction. Following removal of contaminated sediment, the intake canal and adjacent Alpha Road parking area will be converted into a wetland mitigation area to create 1.45 ac of new habitat including deepwater, intertidal eelgrass, mudflat, salt marsh, and bluff scrub 16

habitats. To mitigate for the loss of eelgrass in the intake and discharge canals, approximately 0.38 acres will be planted in the intake canal following removal of the water control structure.

Further, the Corps reasoned that individual fish are not likely to be present in either the intake canal or in the vicinity of the discharge pipes during Project implementation, and therefore are not likely- to be exposed to any potential effects the Project might have on critical habitat.

The Corps also determined that the Project would have a minimal adverse effect on EFH because there will be a reduction in the quantity of eelgrass and intertidal habitat in the intake canal until the remediation of the contaminated soils and implementation of the habitat restoration and mitigation plan is complete. There will be a reduction in EFH in the discharge canal during dewatering and a loss of eelgrass from the discharge canal during sediment removal. Loss of eelgrass in both the intake and discharge canals will be compensated for by the restoration and creation of eelgrass habitat in the intake canal and adjacent Alpha Road Mitigation area, respectively. The quality of EFH will be reduced by the short-term increases in turbidity during installation and removal of the water control structure in the intake canal (48 hours5.555556e-4 days 0.0133 hours 7.936508e-5 weeks 1.8264e-5 months ); and during installation and removal and the sheet pile wall in the Entrance Bay (7 hours8.101852e-5 days 0.00194 hours 1.157407e-5 weeks 2.6635e-6 months per day for 21 days in the fall and in the spring). Installation of the turbidity curtain will reduce the spatial extent of the turbidity in Entrance Bay.

ENDANGERED SPECIES ACT Effects of the .Action Under the ESA, "effects of the action" means the direct and indirect effects of an action on the listed species or critical habitat, together with the effects of other activities that are interrelated or interdependent with that action (50 CFR 402.02). The applicable standard to find that a proposed action is not likely to adversely affect listed species or critical habitat is that all of the effects of the action are expected to be discountable, insignificant, or completely beneficial.

Beneficial effects are contemporaneous positive effects without any adverse effects to the species or critical habitat. Insignificant effects relate to the size of the impact and should never r~each the scale where take occurs. Discountable effects are those extremely unlikely to occur.

The effects of the Project are reasonably likely to include changes in the physical and biological attributes of the critical habitat including: increase in turbidity from installation and removal of 20 Danforth anchors to affix the turbidity curtain to the substrate; increase in turbidity during installation and removal of the sheet pile wall in Entrance Bay; temporary (21 days in fall and spring, respectively) loss of 0.42 ac of habitat during employment of the turbidity curtain; temporary (six months) loss of 0.17 ac of habitat in Entrance Bay during dewatering for removal of outfall pipes; increase in turbidity from suspension of sediments during installation and removal of the water control structure in the intake canal; temporary (six months) loss of 0.9 ac of habitat (water column, subtidal, and intertidal mudflat and 0.07 ac eelgrass) in the upper 380 ft of the intake canal; restoration of 0.38 ac eelgrass habitat in the intake canal; and creation of 1.45 ac of wetland habitats (e.g., deepwater, mudflat, intertidal eelgrass salt marsh, and bluff scrub habitats) adjacent to the intake canal. Although projects of this type have the potential to result in a reduction of the rearing and migratory corridor functions of the habitat, for reasons described below, the effects of this Project are expected to be insignificant.

17

Effects to Salmon and Steelhead Individuals Adult SONCC coho salmon, CC Chinook salmon, and NC steelhead enter Humboldt Bay in the late summer and fall during migration to spawning tributaries in North Bay (e.g., Freshwater and Jacoby Creeks), Elk River (enters the North Bay Channel approximately 13, 225 ft to the north east of the HBPP discharge canal); and in South Bay (Salmon Creek, approximately 18,000 ft from the mouth of Fisherman's Channel). Because adult salmonids are likely to utilize the deeper waters of the Entrance Bay approximately 5,000 ft from the action area to access either the North Bay Channel or South Bay, adult salmonids are not likely to be exposed to any potential effects of installation of the sheet pile wall. Because adults entering South Bay and utilizing the Fields Landing Channel to access Hookton Slough would be approximately 2,100 feet from the action area in the intake canal, adult salmonids are not likely to be exposed to the potential effects of turbidity from installation and removal of the cofferdam in the intake canal.

Therefore, the potential effects of the Project are insignificant to adult salmonids.

Only outmigrating and rearing SONCC coho salmon, CC Chinook salmon, and NC steelhead smolts are likely to be present in the high salinity waters of Entrance and South Bays. Based on survey data from lower Freshwater Creek Slough and lower Elk River (Wallace 2006, 2007; Wallace and Allen 2007), outmigrating and rearing salmon and steelhead smolts may be moving through the North Bay Channel and into the Entrance Bay Channel from January through mid -

September; i.e., SONCC coho salmon from January through July, CC Chinook salmon from late May to early September, and NC steelhead from March through early September. Acoustically tagged coho salmon smolts outmigrating from Freshwater Creek tended to move directionally vwith the tide, and were detected in deep channel and channel margin habitats in Humboldt Bay (Pinnix et al. 2008), and it is likely that outmigrating CC Chinook salmon and NC steelhead smolts occupy the deeper channel and channel margin water column habitats. Because the action area in Entrance Bay is an estimated 5,000 ft from the deeper channels when the outmigrating smolts are likely to be present, salmon and steelhead smolts are not likely to be exposed to the potential effects of the installation of sheet piles and dewatering of the work area. Therefore, the potential effects of the Project on individual salmon and steelhead smolts are expected to be discountable in the action area present in the Entrance Bay.

Based on surveys in Salmon Creek/Hookton Slough (Wallace 2006, 2008; Wallace and Allen 2007), SONCC coho salmon smolts were collected from late March to early June, and juvenile steelhead were collected from mid- February through August. Therefore, individual SONCC coho salmon and NC steelhead smolts would likely be present in South Bay from mid- February through August. However, no CC Chinook salmon, SONCC coho salmon, or NC steelhead juveniles or adults were collected during a one year study (September 1979 to October 1980) of entrainment and impingement of fishes at the HBBP cooling water intake (Ecological Analysts, Inc. 1983). Because the outmigrating smolts would likely be using the deep water of the Fields Landing Channel (figure 2), the Fields Landing Channel is approximately 2,100 feet from the action area in the intake canal, and there is no evidence of juvenile salmonid presence in the action area; exposure of salmon and steelhead smolts to the potential effects of the installation and removal of the water control structure is highly unlikely. Because exposure of individual salmon and steelhead smolts is highly unlikely, the potential effects of the Project activities on salmon and steelhead srnolts in the intake canal action area are expected to be discountable.

18

Because it is extremely unlikely that any life stages of salmon and steelhead would be exposed to the potential effects of the proposed action, the potential negative effects to salmon and steelhead are expected to be discountable. Therefore, the Project is not expected to reduce the growth or survival of any life stages of salmon and steelhead.

E~ffects of the Action to Salmon and Steelhead Critical Habitat The presence of the turbidity curtain in Entrance Bay may temporarily reduce the rearing and migratory corridor function of the critical habitat for salmon and steelhead by preventing access to and through the water column of the 0.44 ac of the action area for a maximum of 21 days from mid-September to October during installation of the sheet pile wall, and for 21 days during removal of the sheet pile wall in March; and by the presence of the sheet pile wall from October through March, which will eliminate approximately 0.17 ac of water column and benthic habitat in Entrance Bay. The installation of the water control structure in the intake canal will eliminate 0.9 acres of water column and benthic channel habitat at the uppermost end of the intake canal for up to six months.

Because the sheet pile wall is approximately 5,000 ft from the deeper water of Entrance Bay that is the likely migration corridor for salmonid adults and juveniles, the effects of the presence of the turbidity curtain and the sheet pile wall on the migratory corridor function of critical habitat in the action area is expected to be insignificant. Because the water control structure in the intake canal is approximately 3,420 ft from the deeper waters of the Fields Landing Channel, which is the nearest likely migratory corridor, the effects of the water control structure on the migratory corridor function of the habitat are expected to be insignificant Small forage fish (e.g., Pacific herring, northern anchovy) , as well as pelagic and planktonic invertebrates (e.g.crab zoeae and megalopae) and larval fish (e.g.Pacifc herring and northern anchovy) are important salmonid prey items; and are seasonally abundant in Humboldt Bay and the vicinity of the HBBP (Cole 2004, Ecological Analysts, Inc. 1983, Healey 1991, MacFarlane and Norton 2002). Adult Pacific herring enter Humboldt Bay to spawn from December to March, and larvae are present from January through May, and juveniles in spring, summer and fail (Barnhart et al. 1992, Ecological Analysts, Inc. 1983). Northern anchovy larvae and juveniles are present in Humboldt Bay throughout the year with peak larval abundance in January (Bidridge 1970). Adult anchovies enter Humboldt Bay to feed and are present in the spring and summer (Barnhardt et al. 1992). Distribution of small forage fish is a function of swimming ability as well as physical factors (e.g., tides, currents), whereas planktonic prey are distributed by the water currents.

Approximately 66 percent of the water column habitat of the action area will be unavailable for 21 days in the fall and 21 days in March, and 26 percent of the available water column habitat in the action area near Entrance Bay will be unavailable from October through mid-March.

Installation and removal of both the turbidity anchors and the sheet pile wall will suspend sediment, which may affect the rearing function of the action area as a result of the following: an increase in turbidity, reduction in water clarity, and subsequent reduction in prey visibility for two 21 day periods. The substrate in Entrance Bay is primarily sand. At the Chevron Terminal Dock to the north of the mouth of Elk River, sediment that is 70 percent sand settles out within approximately six minutes (Winzier & Kelly 2009). Because there will be a distance of about 50 19

feet between each pair of anchors, and the sediment is primarily sand and is expected to settle out quickly (minutes), the increase in turbidity in the water column is likely limited to the immediate vicinity of the 4.7 ft 2 area of each anchor. Similarly, the sand suspended during installation of the sheet piles is expected to be localized in the vicinity of each pile, lasting for seven hours a day for a maximum of 21 days. Because the suspended sediment is sand and is likely to settle out in minutes (Winzler and Kelly 2009) and the turbidity curtain will limit the dispersion of any suspended sediment, the effects of increased turbidity and subsequent reduction in water clarity and visibility of prey in the action area outside the turbidity curtain are 1expected to be insignificant. In addition, because of the timing of the proposed action (mid-September through mid-March), the abundance and distribution of pelagic and planktonic prey items in the action area, and availability of the majority of the approximately 1,800 ac of water column habitat in Entrance Bay immediately adjacent to the action area at MLLW (Barnhardt et al. 1992), the potential effects of the turbidity curtain and the sheet pile wall on the rearing function of the critical habitat in Entrance IBay are expected to be insignificant.

if the amount and duration of turbidity in estuarine habitats is significantly elevated, in excess of what normally occurs as a result of increased turbulence from seasonal and tidal changes in water currents, the water clarity may decrease (Wilbur and Clarke 2001, Wilber et al. 2005). if

- the visibility of prey decreases as a result of decreased water clarity, the availability of prey will be reduced (Berg and Northcote 1985). Installation of the sheet pile wall will suspend sediment as each pile is vibrated into the substrate, for seven daylight hours per day for 21 days from mid-September until October. Because the sediment is primarily sand and is expected to settle out in minutes, and the area is contained by a turbidity curtain, any turbidity associated with suspension of sediments is expected to be for a short period of time and is not expected to reduce water clarity. Following installation of the water control structure in the intake canal, approximately 22 percent of the water column and benthic habitat in the action area will be unavailable for foraging for six months. Immediately following installation of the bladder dam, suspended sediments will increase turbidity and reduce in the action area for an estimated 48 hours5.555556e-4 days 0.0133 hours 7.936508e-5 weeks 1.8264e-5 months in May and 48 hours5.555556e-4 days 0.0133 hours 7.936508e-5 weeks 1.8264e-5 months in October, however the suspended sediment concentration is not likely to exceed 20 mg/i (Hailigan 2014, Stiliwater Sciences 2014b). Because the turbidity levels are low and of short duration, the availability of forage fish and planktonic prey in the water column of the remaining 3.28 ac of the action area -will likely remain unchanged, and suitable habitat is available in the adjacent Fisherman's Channel and is unaffected by the Project, the effects of the Project on the rearing function of the habitat are exPected to be insignificant.

Because of the timing and location of the Project, the limited spatial extent and short term duration of turbidity, and the abundance and accessibility of pelagic and planktonic prey in and adjacent to the action area, the potential negative effects of the Project to the rearing and migratory function of the critical habitat are expected to be insignificant.

Effects to North American Green Sturgeon Individuals North American Southern DPS green sturgeon (green sturgeon) adults and sub-adults are temporary residents in Humboldt Bay from June through October, utilizing North Bay as summer-fall holding or feeding habitat, and the deeper waters of the North Bay Channel as a migratory corridor between the Pacific Ocean and Arcata Bay (Pinnix 2008). Green sturgeon can move rapidly within an estuary (Lindley et al. 2011, Moser and Lindley 2007). In San 20

Francisco Bay, tagged green sturgeon exhibit both directional and non-directional movements (Kelly et al. 2007). Directional movements are characterized by continuous and steady swimming at a speed of approximately 1.8 ft per second, primarily within the top 6.5 ft of the water column. During non-directional movements, green sturgeon are either stationary, or move slowly near the bottom at an average speed of approximately 0.7 ft per second while making frequent changes of direction (Kelly et al. 2007). When green sturgeon swam near the bottom, they were in shallow, slow-flowing regions of the bay and were not oriented with respect to water currents. When near the surface, green sturgeon were swimming over deeper water in swift-flowing regions of the bay, and were oriented in the direction of the current. The green sturgeon in Humboldt Bay will likely exhibit similar behavior, are expected to utilize the deeper waters of Entrance Bay and the North Bay Channel for migration to North Bay (figure 4).

Because of acoustic data (Pinnix 2008) suggest green sturgeon move quickly through Entrance Bay en route to North Bay and the action area is a considerable distance (5,0,00 ft or greater) from the deeper waters where green sturgeon are likely to occur, , exposure of any individuals to potential effects of the project is highly unlikely. Because exposure of individual green sturgeon is highly unlikely, the potential effects of the Project to individual green sturgeon are expected to be discountable. Therefore, the Project is not likely to reduce the growth or survival of green sturgeon.

Effects to North American Green Sturgeon Critical Habitat An estimated 4.7 ft 2o benthic habitat and associated benthic organisms in the action area could be temporarily disturbed, and sediment will be suspended during the installation and removal of each of the 20 Danforth- anchors that will anchor the turbidity curtain. In addition, the benthic organisms associated with 0.17 acre of substrate that will perish, as the site is dewatered within the sheet pile wall for six months. Mobile epibenthic invertebrates are likely to move away from the area during installation of the turbidity curtain. Sandy substrates in Humboldt Bay are dominated primarily by mollusks (e.g., clams) and polychaetes (Barnhart et al. 1992); and peak recolonization of invertebrates in disturbed areas has been observed in spring and summer months. Because recolonization is affected by both sediment transport and densities of resident organisms, recolonization of the disturbed areas in Entrance Bay by infaunal benthic invertebrates is expected within days to months (Barnhart et al. 1982, Northeast region Essential Fish Habitat Steering Committee 2002, Turner et al. 1997, Zajac and Whitlach 1982).

Epibenthic invertebrates (e.g., crabs) are expected to quickly move in to the area from adjacent habitats once the turbidity curtain and piles are removed.

The sandy' substrate in the action area in Entrance Bay is normally subject to wave action and disturbance during the winter months. Because Project-related impacts to the benthic invertebrates would be highly localized in the immediate vicinity of each anchor (4.7 ft2), are limited to a very small area of the total substrate under the turbidity curtain, benthic invertebrates are expected to recolonize in days to months after installation and removal.

Approximately 66 percent of the benthic substrate in the action area will be inaccessible for a maximum of 21 days during installation of the sheet pile wall in the fall. However, once the sheet piles are installed and the turbidity curtain rolled up, the benthic habitat and associated organisms of approximately 66 percent of the action area in Entrance Bay will be accessible and undisturbed. Because (1) the majority of the benthic habitat in the action area will be accessible during the six months of Project implementation in Entrance Bay; (2) the 0.64 ac action area 21

represents MLLW anda Meansmall portion of therespectively approximately 1,803 and 1,952 ac of benthic habitat available at High Water, (Baruhart et al. 1992); (3) benthic invertebrates are expected to recolonize the disturbed areas in days to months; (4) the primary foraging area in Humboldt Bay is located in North Bay about six miles to the northeast, the potential effects of the Project on the rearing function of the green sturgeon critical habitat are insignificant.

Although the dewatering of silty substrate in the 0.9 acre of the intake canal behind the water control structure for 6 months will result in the loss of all infaunal benthic organisms, this area represents approximately 22 percent of the 4.1i8 ac action area in the intake canal. The majority of the benthic habitat and associated infaunal invertebrates are available and are not expected to be affected by the installation or removal of the water control structure. The amphipod Corophium insidiosum is the most abundant macroinvertebrate species in the intake canal (Adams 1975), where the life span of an individual ranges from four to six months, with several cohorts present in the population (Prato and IBiandolino 2006). Therefore, amphipods from the adjacent action area are likely to recolonize benthic substrate of the 0.9 ac within days of removal of the water control structure. Because the majority (88 percent) of the benthic habitat in the action area is unaffected by the Project, the 12 percent of the affected habitat is expected to recolonize quickly following the removal of the water control structure and restoration of tidal circulation. The distance (greater than six miles) of the action area in the intake canal from the primary sturgeon foraging area in North Bay, the potential effects of the Project on the rearing function of the critical habitat are expected to be insignificant.

Conclusion Based on this analysis, NMFS concurs with the Corps' determination that the proposed project may affect, but is not likely to adversely affect federally threatened SONCC coho salmon, CC Chinook salmon, NC Steelhead, North American Green sturgeon, and SONCC coho salmon, CC Chinook salmon, NC Steelhead, and North American Green sturgeon critical habitats.

Reinitiation of Consultation Reinitiation of consultation is required and shall be requested by the Corps or by NMFS, where discretionary Federal involvement or control over the action has been retained or is authorized by law and (1) new information reveals effects of the action that may affect listed species or critical habitat in a manner or to an extent not previously considered; (2) the identified action is subsequently modified in a manner that causes an effect to the listed species or critical habitat that was not considered in this concurrence letter; or if (3) a new species is listed or critical habitat designated that may be affected by the identified action (50 CFR 402.16). This concludes

the ESA poi-tion of this consultation.

MAGNUSON-STEVENS FISHERY CONSERVATION AND MANAGEMENT ACT Under the MSA, this consultation is intended to promote the protection, conservation and enhancement of EFH as necessary to support sustainable fisheries and the managed species' contribution to a healthy ecosystem. For the purposes of the MSA, EFtH means "those waters and substrate necessary to fish for spawning, breeding, fee ding, or growth to maturity", and includes the associated physical, chemical, and biological properties that are used by fish (50 CFR 600.10), and "adverse effect" means any impact which reduces either the quality or quantity of EFH (50 CFR 22

600.9 10(a)). Adverse effects may include direct, indirect, site-specific or habitat-wide impacts, including individual, cumulative, or synergistic consequences of actions.

NMFS determined the proposed action would adversely affect EFH for species managed under the Pacific Coast Salmon, Pacific Coast Groundfish, and Coastal Pelagics FMPs, as follows: (1) reduction in water quality as a result of increased turbidity for 48 hours5.555556e-4 days 0.0133 hours 7.936508e-5 weeks 1.8264e-5 months during installation and removal of the water control structure in the intake canal; (2) disturbance to 0.90 acres of benthic habitat during dewatering of the intake canal; (3) reduction in water quality from increased turbidity during installation of the turbidity curtain and the sheet pile wall in Entrance Bay; (4) disturbance of 2.7 ft2 of benthic habitat as a result of installation and removal of each of the 20 anchors of the turbidity curtain; and (4) disturbance to 0.17 acres during dewatering within the sheet pile wall in Entrance Bay.

As described in the Proposed Action section, the potential adverse effects are minimized to the extent practicable in the following ways: employment of BMPs during intake and discharge canal remediation and activities; restoration and creation of intertidal and eelgrass habitat in the intake canal following removal of contaminated sediment; implementation of the eelgrass mitigation and monitoring plan (Stillwater Sciences 2013); and the rapid re-colonization of the benthic habitat by invertebrates in the areas that were dewatered for six months in the intake canal and in Entrance Bay. The proposed action contains adequate measures to avoid, minimize, mitigate, or otherwise offset the adverse effects to EFH. Therefore, NMFS has no additional conservation recommendations. The Corps must reinitiate EFH consultation with NMFS if the proposed action is substantially revised in a way that may adversely affect EFH. This concludes the MSA portion of this consultation.

Section 7(a)(1) of the ESA directs Federal agencies to utilize their authorities to further the purposes of the ESA by carrying out conservation programs for the benefit of threatened and endangered species. The Corps also has the same responsibilities, and informal consultation offers action agencies an opportunity to address their conservation responsibilities under section 7(a)(1).

Please direct questions regarding this letter to Ms. Diane Ashton, Arcata, California, at (707) 825-5 185 or via e-mail at diane.ashton@noaa.gov.

Sincerely, W.

W~iam W. Stelle, Jr.

Regional Administrator cc: David Wickens, Corps of Engineers, San Francisco District, Eureka, CA AR 15 1422S WR201 3AR00 144 23

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Barnhart, R. A., M. J. Boyd, and J. E. Pequegnat. 1992. The Ecology of Humboldt Bay, California: an Estuarine Profile. U.S. Fish and Wildlife Service Biological Report 1.

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Arcata, California.

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UNITED STATES DEPARTMENT OF COMMERCE

,, *\.* National Oceanic and Atmospheric Administration

NATIONAL MARINE FISHERIES SERVICE

% . West Coast Region