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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 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 AdministrationNATIONAL MARINE FISHERIES SERVICE.West Coast Region 1655 Heindon RoadArcata, California 95521-4573 In response refer to:SWR-20 13-9644Ms. Jane HicksChief, Regulatory BranchU.S. Army Corps of Engineers 1455 Market Street, 16th FloorS 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 theIssuance of a U.S. Arxmy Corps of Engineers Permit Authorizing Pacific Gas and ElectricCompany to Implement the Humboldt Bay Power Plant Intake and Discharge CanalRemediation Project

Dear Ms. Hicks:

On July 10, 2014, NOAA's National Marine Fisheries Service (NMFS) received your request toinitiate 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 404of the Clean Water Act ( 33 U.S.C. § 1344) and Section 10 of the Rivers and Harbors Act of1899 (33 U.S.C. § 403), is not likely to adversely affect (NLAA) species listed as threatened orendangered or critical habitats designated under the Endangered Species Act (ESA). Thisresponse 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 ofconcurrence.

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 effectsof 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 completeEFH consultation.

This letter underwent pre-dissemination review using standards for utility, integrity, andobjectivity in compliance with applicable guidelines issued under the Data Quality Act (section515 of the Treasury and General Government Appropriations Act for Fiscal Year 2001, PublicLaw 106-554).

The concurrence letter will be available through NMFS' Public Consultation Tracking System A complete record of thisconsultation is on file at NMFS West Coast Region, Arcata, Gta!ifornia office.

CONSULTATION HISTORYPre-consultation ActivityFollowing an August 14, 2013 interagency meeting hosted by the Corps, the Humboldt BayPower Plant (HBPP) Canal Remediation Project Interagency Working Group (IWG) was formedto 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 includedrepresentatives of federal, state, and local regulatory agencies

[Corps, NMFS, U.S. Fish andWildlife Service (USFWS),

California Coastal Commission(CCC),

California Department ofFish and Wildlife, Regional Water Quality Control Board, and Humboldt Bay Harbor,Recreation, and Conservation District (HIBHRCD));

and representatives of PG&E and itscontractors, CH2M Hill, and Stiliwater Sciences.

On September 4, 2013, Stillwater Sciencesprovided NMFS and USFWS an electronic copy of th6 July 2013 Humboldt Bay Power PlantIntake and Discharge Canal Remediation Project (Project)

Biological Assessment (BA). OnSeptember 13, 2013, PG&E provided electronic copies of materials (agenda, overview ofmitigation 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 agencyreview draft of the Biological Mitigation and Monitoring Plan for the Humboldt Bay Power PlantCanal Remediation Project (IBMMP),

prepared by Stillwater Sciences (2013b).

On November14, 2014, CH2MHill notified IWG, via electronic mail, that PG&B has submitted various permitapplications to regulatory agencies having jurisdiction for the.Project, and provided three figuresintended to supplement the permit applications and provide more information about thedischarge canal remediation.

At the second IWG meeting on November 19, 2Q13, NMFS andothers 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~linformed 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 ActivityOn November 25, 2013, NMFS received the Corps November 20, 2013, letter requesting initiation offormal 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 threeproject-related figures (discharge canal temporary stockpile, discharge outfall pipe removal, anddischarge canal outfall structure profile view), dated October, 2013. The Corps stated all work willbe completed in accordance with the permit application and BA.On November 27, 2013, NMFS asked the Corps via electronic mail to provide color copies ofphotographs and figures in the permit application, as well as electronic copies of the otherenclosures to allow for sharing with other NMFS staff to review regarding potential effects to thewater quality and EFH components of the Project.

On December 2, 2013, the Corps informedNMFS that the applicant would be mailing color copies of the document to NMFS. OnDecember 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.

OnDecember 16, 2013, CH2MHill provided IWG with an electronic access link to all the2 environmental permitting documents developed for the Project, along with the final version ofthe BMMP (Stillwater Sciences 2013c).Xn a December 17, 2013, letter to the Corps,. NMFS determined that the information provided inby 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 ESAlisted species and their designated critical habitat [50 CFR 402.14(a)];

and to initiate section7(a)(2) formal consultation.

NMFS stated that additional information may be needed tocomplete the consultation,

however, and that NMFS would formulate its biological opinion as towhether the action is likely to jeopardize the continued existence of listed species or result in thedestruction or adverse modification of critical habitat [see 50 CFR 402.14(g)].

NMFS willassume the proposed project may adversely affect EFH, proceed with MSA consultation forspecies managed under the Pacific Salmon, Pacific Groundfish, and Coastal Pelagic FederalFishery Management Plans, and provide conservation recommendations if necessary.

NMFSintended 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 Corpseffects 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 theNovember 20, 2013, letter. Because presence of individual salmonids or green sturgeon in theaction 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 theProject would not likely adversely affect federally listed species or designated critical habitat.

OnFebruary 27, 2014, the Corps requested via electronic mail that NMFS concur with the Corpsdetermination that the prosed action is not likely to adversely affect listed species or theirdesignated critical habitat.On March 5, 2014, NMFS contacted Stiliwater Sciences and the applicants authorized agentCH2MI~ill about the timing of the eelgrass mitigation, required as a result of the dewatering andsediment removal in the intake and discharge canals; as well as clarification of discharge outfallpipe removal activities (e.g., area and volume of substrate disturbed, number and size of anchorsfor turbidity curtain).

On March 5, 2014, NMFS was informed by Stillwater Sciences that theproposed action has changed since the BA (Stillwater Sciences 2013a) , and now included thesite 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 asthe CCC permit. In the spirit of 1WG, NMFS contacted both the Corps and CH2MHil1 viaelectronic mail to insure that the Corps permit application was updated to include the Projectchanges that were included under other perrmits.

On March 17, 2014, Stillwater Sciencesprovided details of the area encompassed by the cofferdam around the discharge pipes, thenumber and type of anchors employed with the turbidity

curtain, and area of disturbance duringdischarge pipe removal via electronic mail. On March 21, 2013, CH2MHilI informed NMFS viaelectronic mail that the Corps recommended they submit a letter outlining the changes in theProject 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. OnMarch 24, 2013, because both the Corps effects determination and the components of the Projecthave 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 theBA has not be revised, NMFS recommended the Corps clearly indicate which parts of theproposed action and effects determination are based on the BA (Stillwater Sciences 2013a) andwhat factors were considered in addition to the information in the BA in their effectsdetermination.

On March 25, 2014, CH2MHiII informed NMFS via electronic mail that the BAwas being revised.

To improve the efficiency of the consultation

process, the Corps agreed toprovide NMFS with a draft initiation letter for review and comment prior to signature.

On April8 and 10, 2014, the Corps provided versions of a draft initiation letter to NMFS review viaelectronic 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 thedischarge pipes would be installed with an impact hammer rather than a vibratory hammer asdescribed in the BA (Stillwater Sciences 201 3a); and NMES subsequently notified the Corps ofthis change of installation method via electronic mail. On April 10, 2014, NMFS also providedCH2MHill and the Corps with information via electronic mail on hydroacoustic effects of piledriving 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 clarifythe 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 ofthe cofferdam; and also provided NMFS with an updated Project implementation schedule.

On May 9, 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 beused to install the sheet piles. On May 28, 2014, NMFS participated in a conference call with theCorps, 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 andreasoning for description of the action area, as well more information on installation of the sheetpiles 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 areaand 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 onthe Project had been signed, and would be mailed. On July 7, 2014, NMFS contacted the Corpsvia electronic mail to acknowledge the voicemail; and to inform the Corps that, once NMFSreceives the letter, clarification of statements in the letter may be necessary since NMFS had notreviewed 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 thisproject.

NMFS subsequently contacted the Corps via electronic mail, questioning their effectsdetermination for Essential Fish Habitat (EFH), which differed from the effects determination inthe BA (Stillwater Sciences 2014); recommending the effects of both the installation andremoval of the water control structure in the intake canal should be discussed and analyzed; andasking for clarification on why there were no attachments or enclosures provided along with thehard copy, as the letter suggested there were enclosures and attachments.

On July 7, 2014, the4 Corps informed NMFS via electronic mail, that the effects determination for Essential FishHabitat (EFH) in the July 3, 2014, letter (no effect to EFH) is no longer valid, and should bechanged 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 removalof 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 toremove 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 ACTIONBackground PG&E is in the process of decommissioning its former power generation facility at the 143-acreHumboldt Bay Power Plant (HBPP) site in Humboldt County, California, and terminating theNuclear Regulatory Commission (NRC) license for the former HBPP nuclear unit, Unit 3. TheHBPP formerly consisted of natural-gas-fired steam generation Units 1 and 2 and the nuclearunit (Unit 3), which has been shut down since 1976. PG&E has replaced the HBPP with a newerpower 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 powerplant cooling design called once-through cooling that involved piping Humboldt Bay water tocool the power generating units and then returning the water to the bay. Humboldt Bay iscomprised of three sub-bays, connected by tidal channels, and the HBPP cooling water wasdrawn through an artificial channel connected to South Bay and then discharged into EntranceBay (figure 1 ).Figure 1. Location of HBPP in Humboldt Bay, California 5

In the mid 1950's, PG&E modified a portion of Buhne Slough located on PG&E property bydredging, stabilizing the banks with rip-rap, and installing tidegates and culverts to create theFisherman's Channel adjacent to the community of King Salmon. The purpose of theFisherman's Channel was to provide cooling water for the HBPP via the intake canal (GHD2013a, 2013b). Once the water passed through the heat exchangers, the heated water entered thedischarge 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 thedischarge 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 subjectto 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 ofcooling water, and Humboldt Bay water has not been drawn into or discharged from the facilitysince 2010. The intake and discharge canals are no longer needed for plant operation, as there isno longer a need for cooling.

As a result, the outfall pipes are partially plugged with sand, andeelgrass 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; andremove infrastructure in the canals (e.g., concrete, pipes) associated with the past intake anddischarge of the cooling water.6 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 theaquatic 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 thatwetland restoration and mitigation activities in the intake canal occur as soon as possible in theaquatic 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 finishIsolate discharge canal July 2014 j July 2014Demolish and remediate discharge canal July 2014 j October 2014Isolate and remove outfall structure/

pipes September 2014 March 2015Place intake canal water control structure May 2018 or sooner' 1-2 monthsDemolish and remediate intake canal 2018 or sooner' 4-6 monthsCreate Alpha Road parking mitigation area 2018 or sooner' 2-4 monthsRestore 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.

Thisportion 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 Highway101. The project is surrounded by Humboldt Bay to the west, agricultural land to the east, andKing Salmon to the south. The entire project is located within or immediately adjacent to PG&Eproperty.

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 haulingtrucks, forklifts, man lifts, portable generators, air compressors, portable tanks, hand tools, andother supplies and equipment already used to support decommissioning.

Discharge Canal Activities The contractor will mechanically remove the discharge head-works structure that formerlydischarged cooling water to the discharge canal. The contractor will also mechanically removean estimated 9,000 yds3 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 slopingstandards (Stillwater Sciences 2013a). Radiological surveys and non-radiological sampling ofthe sediment removed from the discharge canal will be performed after excavation anddewatering.

Once tested and characterized, the sediment will either reused on site or disposed ofat an appropriate licensed waste facility dependent on characterization results.

The initialisolation of the discharge canal from Humboldt Bay will be accomplished by plugging the fouroutfall culvert pipes using inflatable pipe plugs, grout, or other suitable plugging mechanism.

The initial isolation will be sufficient to support removal of the intake headwall structure andsediment within the discharge canal. Approximately 815 ft2(0.02 ac) of eelgrass will be removed7 from the discharge canal along with the sediment.

Any stormwater drainage currently flowinginto 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 beremoved.

Removal of discharge pipes and appurtenances will require installation of a sheet pilewall on the Humboldt Bay side of the existing revetment/levee to isolate the work area from thebay. The sheet pile wall will prevent tidal flows from Humboldt Bay and other water, such asgroundwater, 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 foraccess 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 requireinstallation 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.

Threedays prior to installation of the sheet pile wall in mid-September, the contractor will install aturbidity 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 anchorsspaced at approximately 50-ft intervals (Stillwater Sciences 2013, 2014a; Teraoka 2014). Eachanchor (20 anchors total) will disturb a benthic surface area of approximately 4.7 ft2, and will beattached to a cable that extends approximately 24 feet from the bottom of the curtain.

The8 turbidity curtain is intended to limit the spatial extent of turbidity from any sediment suspended during installation of the sheet pile wall and subsequent dewatering of the area within the sheetpile wall. The turbidity curtain will either be removed once the sheet pile wall is in place, or leftin place rolled up off the bottom to allow for tidal flow and ease of replacement when the sheetpiles are removed (Stillwater Sciences 2014a, 2014b). Installation of 120 sheet pile panels (22.5in by 38 ft each) by vibratory pile driving will begin in mid-September, 2014 and takeapproximately 21 days (Stillwater Sciences 2014a). Piles will be installed for seven hours perday, 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 willbe dewatered by pumping water from the area into the water between the sheet pile wall and theturbidity

curtain, and will remain dewatered for a maximum of 6 months. An estimated 0.42 acof Humboldt Bay will be temporarily isolated from Entrance Bay by the turbidity curtain for amaximum of 21 days in the fall (September and October) during installation of the sheet pilewall, 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 3decommissioning activities until March 2018. The former discharge canal will remainpermanently disconnect from Humboldt Bay. The contractor will also restore the rip-raprevetment seawall and the coastal trail along the adjacent Humboldt Bay to their previouscondition, 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 withineight 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 isexpected 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; removalof the contaminated sediments; removal of the intake structure (67 feet long by 52 feet wide by26 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 locatedat the pedestrian bridge about 380 ft southwest of the intake structure (figure 4) during a fallingtide. The structure will prevent tidal flows from South Bay from entering the work area via theFisherman's Channel during removal of contaminated sediment and of the intake structure.

Priorto dewatering, eelgrass will be collected and transplanted outside of the work area into suitablenearby 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 thework 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 waterthat may enter the work area from groundwater or stormwater during removal of sediment andinfrastructure 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 intakecanal approximately 500 feet downstream of the cofferdam near the King Salmon Road bridge.9 The contractor will mechanically remove up to approximately 1 ,OO0 yd3 of contaminated sediment from the northern corner of the canal, northeast of the pedestrian bridge and adjacent tothe intake structure (figure 4). The contractor will also demolish and remove the intakestructure, using heavy equipment and employ physical containment methods to prevent materialfrom falling into the dewatered intake canal.Direct disturbance area (approximate)

U Mudfiat ~ ~~INCoastal bluff scrub/Coastal Ursladm Open water .. l Eetgrass 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 yardsof 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 the10 60kV switchyard and associated structures, a physical shoring system may be necessary to safelyexcavate intake structures and protect existing infrastructure.

Direct disturb~ance area (approximate) rol Northern coastal salt marsh Ul Eelgrass benches O*t~t 2o22.3Alpha Road park~ing mitigation area 1 Mudilat U Deep water n.2 ,I.,, * .22SCoastal bluff scrub!Coastai grassland

"k , 0 3 *b 22 mn wnwI2,II..SterSC, ornFigure 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 thedewatered intake canal, the intake canal will be also expanded to create a 1.45 ac wetlandmitigation area that incorporates the adjacent Alpha Road parking area, and will create newdeepwater,

mudflat, intertidal

eelgrass, saltmarsh, and bluff scrub habitats (figure 5). Oncephysical construction of the mitigation area is completed, an estimated 2,000 yd3 of clean fill willbe 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 tothe unaffected portion of the intake canal and to the South Bay via Fisherman's Channel with fulltidal exchange (figure 2). Once the tidal circulation is restored, eelgrass from adjacent donorbeds 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 bereplanted to mitigate for the loss of 0.07 ac of eelgrass lost during dewatering of the intake canaland the 0.02 ac of eelgrass removed from the discharge canal (Stillwater Sciences 2013c).Management of Water from Dredged Sediment and CanalsContaminated sediment removed from the bottom of the intake and discharge canals will beplaced on settling pads or in containers located in one or more of the upland laydown areas onthe 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 methodsconsistent with characterization

results, If necessary, additional temporary water storage andtreatment, including tanks, clarifiers or filters will be installed to treat water removed from thecanals prior to treatment in the GWTS.Management of Waste from Intake and Discharge CanalsThe 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) toprevent soil and petroleum products from entering the bay. Construction activities on the sitehave the to generate pollutants (e.g., sediment,

concrete, petroleum products) that maybe 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 inthe 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 issubject to regulation and control by the NRC, Resource Conservation and Recovery Act, andCalifornia 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 wastecharacterization and shipping.

It is expected that little to none of the excavated soil and sedimenttaken from the canals would qualify for onsite reuse and that these materials will be shippedoffsite to a disposal facility;

however, if removed sediment and soil meet criteria for reuse, reuseon site will be considered.

If materials are not used onsite, they may be direct loaded or12 processed for shipment to a recycle facility, or disposed of at a Class II landfill.

Concrete wasteswould be tested to determine eligibility for onsite reuse; however, it is currently assumed thatsome demolition debris generated would also require packaging into intermodal containers forshipment to a radiological disposal facility offsite disposal due to contamination.

An Erosion,

Sediment, and Dust Control (ESDC) Plan will be prepared, which will conform tothe HBPP Stormwater Pollution and Prevention Plan (SWPPP);

and will include bestmanagement practices (BMPs) for controlling stormwater discharge to insure that runoff doesnot transport any sediment into Humboldt Bay. The ESDC plan will include BMPs for thehandling of contaminated sediment.

If dewatered sediment requires temporary stockpiling, pileswould be placed on and covered with plastic sheeting or tarps that are secured safely with sandbags and bermed with fiber rolls or silt fencing to prevent stormwater runoff from leaving thearea.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 contentand within secondary containment, and spill kits would be placed throughout the Project area forimmediate 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 inaccordance with the SWPPP.ACTION AREAUnder the ESA, the "action area" means all the areas to be affected directly or indirectly by theFederal action and not merely the immediate area involved in the action (50 CFR 402.02).

Theaction area in the intake canal remediation component of the Project includes an estimated 4.18acres (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 theFisherman's Channel below the bridge (figure 6). The action area for the intake canalcomponent of the Project includes the 380 ft of channel behind the water control structure, andextends to expected limits of the turbidity plume resulting from suspension of sediments duringinstallation 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 theintake structure, approximately 36 percent (0.07 ac) is located between the proposed location for thewater control structure and the intake structure (Stiliwater Sciences 20 14a). The substrate in the in theaction area is predominantly silt (GHD 2013). The most abundant benthic invertebrates in thesilty substrate of the intake canal are amphipods, (Corophium spp), which occur at densities ofapproximately 220 per ft2 (Adams 1975), and the non-native C. insidiosunm is the dominantspecies (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 theFields Landing Channel in South Bay (figure 2).13 The action area (figure 6) for the discharge canal remediation component of the Projectencompasses a 0.64 acre (27,878 ft-2) area in Entrance Bay, extending 225 ft along the HumboldtBay shoreline and approximately 124 ft perpendicular to the shoreline (Stiliwater Sciences2014b). The substrate is predominantly medium to fine sand, and benthic fauna consists ofprimarily 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 (0.17ac) as well as the area encompassed by the turbidity curtain (0.25 ac) and extends 30 ft beyondthe turbidity curtain to include the 10 outside lines and anchors.o 0 100 IM~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 Pointand Elk River, which includes a portion of the action area, flow parallel to the shore line; andcurrents 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 andtidal 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 wavesthat are focused on Entrance Bay and the shoreline of HBPP near the discharge canal (Costa andGlatzel 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 JettiesFigure 7. Entrance Bay and the mouth of Humboldt Bay (Costa and Glatzel 2002).Listed Species and Designated Critical Habitat in the Action AreaThe following threatened species and designated critical habitat may be affected by the proposedaction: (1) Southern Oregon/Northern California Coast (SONCC) coho salmon (Oncorhynchus kisutch)

Evolutionarily Significant Unit (ESU), listed on May 6, 1997 (62 FR 24588) and June28, 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 Americangreen sturgeon (A cipenser 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); andSouthern 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 SONCCcoho 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 apotential migratory

corridor, as well as habitat for feeding, for outmigrating SONCC cohosalmon 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 rearing15 and migratory corridor functions, namely areas free of obstruction and excessive predation withwater quality, water quantity and salinity conditions 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 theaction area provide the rearing and migratory corridor functions for CC Chinook salmon and NCsteelhead smolts, allowing for foraging and swimming through an area without expenditure ofadditional time and/for energy required.

The estuarine PCEs of green sturgeon critical habitat in Humboldt Bay that are essential to theirconservation include:

food resources; water flow; water quality; water depth; sediment quality;and migratory corridors to support feeding, migration, and aggregation and holding by greensturgeon 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 benthicinvertebrates, Dungeness crab, and a variety of clams. Ghost shrimp are the preferred prey itemfor 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 weremade in the North Bay. Based on the preponderance of detections in the North Bay it is likelythat green sturgeon utilize the deeper waters of the North Bay Federal Navigation Channel as amigratory corridor between the Pacific Ocean and North Bay.. Detections suggest that greensturgeon 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, CCChinook salmon, NC Steelhead, Southern DPS North American green sturgeon or theirdesignated critical habitats.

This determination was based on the spatial extent and temporalduration of the effects of the project and the likelihood of exposure of individuals to thoseeffects, and incorporated by reference the effects described in the iBA(Stillwater Sciences 2014a)and associated technical memorandum (Stillwater Sciences 20 14b). The Corps effects analysisthe removal of the discharge outfall pipes reasoned the turbidity curtain would minimize thespatial extent of the turbidity during sheet pile installation, and adverse effects of the anchors oncritical habitat were unlikely.

The Corps stated the temporary (six month) loss of 0.64 acres ofcritical 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 intakecanal during installation and removal of the water control structure will dissipate after 4 tidalcycles, the Corps reasoned there will be no meaningful effect to the rearing function of thecritical habitat in the action area in the intake canal. Although 0.90 ac of the intake canal wouldbe isolated and dewatered for a period of six months and result in a temporary loss of foodresources, the Corps did not expect the temporary loss to have a meaningful effect on the rearingfunction of the critical habitat in the intake canal. The Corps further reasoned that the habitat inthe 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 overallartificial construction.

Following removal of contaminated

sediment, the intake canal andadjacent Alpha Road parking area will be converted into a wetland mitigation area to create 1.45ac of new habitat including deepwater, intertidal

eelgrass, mudflat, salt marsh, and bluff scrub16 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 intakecanal or in the vicinity of the discharge pipes during Project implementation, and therefore arenot 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 becausethere will be a reduction in the quantity of eelgrass and intertidal habitat in the intake canal untilthe remediation of the contaminated soils and implementation of the habitat restoration andmitigation plan is complete.

There will be a reduction in EFH in the discharge canal duringdewatering and a loss of eelgrass from the discharge canal during sediment removal.

Loss ofeelgrass in both the intake and discharge canals will be compensated for by the restoration andcreation 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 duringinstallation 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 duringinstallation 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 daysin the fall and in the spring).

Installation of the turbidity curtain will reduce the spatial extent ofthe turbidity in Entrance Bay.ENDANGERED SPECIES ACTEffects of the .ActionUnder the ESA, "effects of the action" means the direct and indirect effects of an action on thelisted species or critical

habitat, together with the effects of other activities that are interrelated orinterdependent with that action (50 CFR 402.02).

The applicable standard to find that aproposed action is not likely to adversely affect listed species or critical habitat is that all of theeffects of the action are expected to be discountable, insignificant, or completely beneficial.

Beneficial effects are contemporaneous positive effects without any adverse effects to the speciesor critical habitat.

Insignificant effects relate to the size of the impact and should never r~each thescale 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 of20 Danforth anchors to affix the turbidity curtain to the substrate; increase in turbidity duringinstallation and removal of the sheet pile wall in Entrance Bay; temporary (21 days in fall andspring, 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 removalof outfall pipes; increase in turbidity from suspension of sediments during installation andremoval of the water control structure in the intake canal; temporary (six months) loss of 0.9 acof habitat (water column, subtidal, and intertidal mudflat and 0.07 ac eelgrass) in the upper 380 ftof the intake canal; restoration of 0.38 ac eelgrass habitat in the intake canal; and creation of 1.45ac of wetland habitats (e.g., deepwater,

mudflat, intertidal eelgrass salt marsh, and bluff scrubhabitats) adjacent to the intake canal. Although projects of this type have the potential to resultin 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 thelate summer and fall during migration to spawning tributaries in North Bay (e.g., Freshwater andJacoby Creeks),

Elk River (enters the North Bay Channel approximately 13, 225 ft to the northeast of the HBPP discharge canal); and in South Bay (Salmon Creek, approximately 18,000 ftfrom the mouth of Fisherman's Channel).

Because adult salmonids are likely to utilize thedeeper waters of the Entrance Bay approximately 5,000 ft from the action area to access eitherthe North Bay Channel or South Bay, adult salmonids are not likely to be exposed to anypotential effects of installation of the sheet pile wall. Because adults entering South Bay andutilizing the Fields Landing Channel to access Hookton Slough would be approximately 2,100feet from the action area in the intake canal, adult salmonids are not likely to be exposed to thepotential 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 onsurvey 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 movingthrough 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 lateMay 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 actionarea 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 thepotential effects of the installation of sheet piles and dewatering of the work area. Therefore, thepotential effects of the Project on individual salmon and steelhead smolts are expected to bediscountable in the action area present in the Entrance Bay.Based on surveys in Salmon Creek/Hookton Slough (Wallace 2006, 2008; Wallace and Allen2007), SONCC coho salmon smolts were collected from late March to early June, and juvenilesteelhead were collected from mid- February through August. Therefore, individual SONCCcoho salmon and NC steelhead smolts would likely be present in South Bay from mid- Februarythrough 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) ofentrainment 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 FieldsLanding Channel (figure 2), the Fields Landing Channel is approximately 2,100 feet from theaction area in the intake canal, and there is no evidence of juvenile salmonid presence in theaction 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 onsalmon 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 tothe 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 orsurvival of any life stages of salmon and steelhead.

E~ffects of the Action to Salmon and Steelhead Critical HabitatThe presence of the turbidity curtain in Entrance Bay may temporarily reduce the rearing andmigratory corridor function of the critical habitat for salmon and steelhead by preventing accessto and through the water column of the 0.44 ac of the action area for a maximum of 21 days frommid-September to October during installation of the sheet pile wall, and for 21 days duringremoval of the sheet pile wall in March; and by the presence of the sheet pile wall from Octoberthrough March, which will eliminate approximately 0.17 ac of water column and benthic habitatin 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 canalfor up to six months.Because the sheet pile wall is approximately 5,000 ft from the deeper water of Entrance Bay thatis the likely migration corridor for salmonid adults and juveniles, the effects of the presence ofthe turbidity curtain and the sheet pile wall on the migratory corridor function of critical habitatin the action area is expected to be insignificant.

Because the water control structure in theintake 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 themigratory 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 northernanchovy) are important salmonid prey items; and are seasonally abundant in Humboldt Bay andthe 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 toMarch, and larvae are present from January through May, and juveniles in spring, summer andfail (Barnhart et al. 1992, Ecological

Analysts, Inc. 1983). Northern anchovy larvae andjuveniles are present in Humboldt Bay throughout the year with peak larval abundance inJanuary (Bidridge 1970). Adult anchovies enter Humboldt Bay to feed and are present in thespring and summer (Barnhardt et al. 1992). Distribution of small forage fish is a function ofswimming ability as well as physical factors (e.g., tides, currents),

whereas planktonic prey aredistributed by the water currents.

Approximately 66 percent of the water column habitat of the action area will be unavailable for21 days in the fall and 21 days in March, and 26 percent of the available water column habitat inthe 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 suspendsediment, which may affect the rearing function of the action area as a result of the following:

anincrease in turbidity, reduction in water clarity, and subsequent reduction in prey visibility fortwo 21 day periods.

The substrate in Entrance Bay is primarily sand. At the Chevron TerminalDock to the north of the mouth of Elk River, sediment that is 70 percent sand settles out withinapproximately six minutes (Winzier

& Kelly 2009). Because there will be a distance of about 5019 feet between each pair of anchors, and the sediment is primarily sand and is expected to settle outquickly (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 ofthe sheet piles is expected to be localized in the vicinity of each pile, lasting for seven hours aday for a maximum of 21 days. Because the suspended sediment is sand and is likely to settle outin minutes (Winzler and Kelly 2009) and the turbidity curtain will limit the dispersion of anysuspended

sediment, the effects of increased turbidity and subsequent reduction in water clarityand visibility of prey in the action area outside the turbidity curtain are 1 expected to beinsignificant.

In addition, because of the timing of the proposed action (mid-September throughmid-March),

the abundance and distribution of pelagic and planktonic prey items in the actionarea, and availability of the majority of the approximately 1,800 ac of water column habitat inEntrance Bay immediately adjacent to the action area at MLLW (Barnhardt et al. 1992), thepotential effects of the turbidity curtain and the sheet pile wall on the rearing function of thecritical habitat in Entrance IBay are expected to be insignificant.

if the amount and duration of turbidity in estuarine habitats is significantly

elevated, in excess ofwhat normally occurs as a result of increased turbulence from seasonal and tidal changes inwater 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 willbe reduced (Berg and Northcote 1985). Installation of the sheet pile wall will suspend sedimentas 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 inminutes, 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 waterclarity.

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 forforaging 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 Mayand 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 exceed20 mg/i (Hailigan 2014, Stiliwater Sciences 2014b). Because the turbidity levels are low and ofshort duration, the availability of forage fish and planktonic prey in the water column of theremaining 3.28 ac of the action area -will likely remain unchanged, and suitable habitat isavailable in the adjacent Fisherman's Channel and is unaffected by the Project, the effects of theProject 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 termduration of turbidity, and the abundance and accessibility of pelagic and planktonic prey in andadjacent to the action area, the potential negative effects of the Project to the rearing andmigratory 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 aretemporary residents in Humboldt Bay from June through October, utilizing North Bay assummer-fall holding or feeding habitat, and the deeper waters of the North Bay Channel as amigratory corridor between the Pacific Ocean and Arcata Bay (Pinnix 2008). Green sturgeoncan move rapidly within an estuary (Lindley et al. 2011, Moser and Lindley 2007). In San20 Francisco Bay, tagged green sturgeon exhibit both directional and non-directional movements (Kelly et al. 2007). Directional movements are characterized by continuous and steadyswimming at a speed of approximately 1.8 ft per second, primarily within the top 6.5 ft of thewater column. During non-directional movements, green sturgeon are either stationary, or moveslowly near the bottom at an average speed of approximately 0.7 ft per second while makingfrequent 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 towater currents.

When near the surface, green sturgeon were swimming over deeper water inswift-flowing regions of the bay, and were oriented in the direction of the current.

The greensturgeon in Humboldt Bay will likely exhibit similar behavior, are expected to utilize the deeperwaters 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 EntranceBay 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 topotential effects of the project is highly unlikely.

Because exposure of individual green sturgeonis highly unlikely, the potential effects of the Project to individual green sturgeon are expected tobe discountable.

Therefore, the Project is not likely to reduce the growth or survival of greensturgeon.

Effects to North American Green Sturgeon Critical HabitatAn estimated 4.7 ft 2 o benthic habitat and associated benthic organisms in the action area couldbe temporarily disturbed, and sediment will be suspended during the installation and removal ofeach of the 20 Danforth-anchors that will anchor the turbidity curtain.

In addition, the benthicorganisms associated with 0.17 acre of substrate that will perish, as the site is dewatered withinthe sheet pile wall for six months. Mobile epibenthic invertebrates are likely to move away fromthe area during installation of the turbidity curtain.

Sandy substrates in Humboldt Bay aredominated primarily by mollusks (e.g., clams) and polychaetes (Barnhart et al. 1992); and peakrecolonization of invertebrates in disturbed areas has been observed in spring and summermonths. Because recolonization is affected by both sediment transport and densities of residentorganisms, recolonization of the disturbed areas in Entrance Bay by infaunal benthicinvertebrates 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 adjacenthabitats once the turbidity curtain and piles are removed.The sandy' substrate in the action area in Entrance Bay is normally subject to wave action anddisturbance during the winter months. Because Project-related impacts to the benthicinvertebrates would be highly localized in the immediate vicinity of each anchor (4.7 ft2), arelimited to a very small area of the total substrate under the turbidity

curtain, benthicinvertebrates 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 amaximum of 21 days during installation of the sheet pile wall in the fall. However, once thesheet 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 andundisturbed.

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 area21 represents a small portion of the approximately 1,803 and 1,952 ac of benthic habitat available atMLLW and Mean High Water, respectively (Baruhart et al. 1992); (3) benthic invertebrates areexpected to recolonize the disturbed areas in days to months; (4) the primary foraging area inHumboldt Bay is located in North Bay about six miles to the northeast, the potential effects ofthe 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 watercontrol structure for 6 months will result in the loss of all infaunal benthic organisms, this arearepresents approximately 22 percent of the 4.1i8 ac action area in the intake canal. The majorityof the benthic habitat and associated infaunal invertebrates are available and are not expected tobe affected by the installation or removal of the water control structure.

The amphipodCorophium 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 severalcohorts present in the population (Prato and IBiandolino 2006). Therefore, amphipods from theadjacent action area are likely to recolonize benthic substrate of the 0.9 ac within days ofremoval of the water control structure.

Because the majority (88 percent) of the benthic habitatin the action area is unaffected by the Project, the 12 percent of the affected habitat is expected torecolonize quickly following the removal of the water control structure and restoration of tidalcirculation.

The distance (greater than six miles) of the action area in the intake canal from theprimary sturgeon foraging area in North Bay, the potential effects of the Project on the rearingfunction of the critical habitat are expected to be insignificant.

Conclusion Based on this analysis, NMFS concurs with the Corps' determination that the proposed projectmay affect, but is not likely to adversely affect federally threatened SONCC coho salmon, CCChinook salmon, NC Steelhead, North American Green sturgeon, and SONCC coho salmon, CCChinook 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, wherediscretionary Federal involvement or control over the action has been retained or is authorized bylaw and (1) new information reveals effects of the action that may affect listed species or criticalhabitat in a manner or to an extent not previously considered; (2) the identified action issubsequently modified in a manner that causes an effect to the listed species or critical habitatthat was not considered in this concurrence letter; or if (3) a new species is listed or criticalhabitat 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 ACTUnder the MSA, this consultation is intended to promote the protection, conservation andenhancement 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 andsubstrate necessary to fish for spawning,

breeding, fee ding, or growth to maturity",

and includes theassociated

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 CFR22 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 thePacific 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 andremoval of the water control structure in the intake canal; (2) disturbance to 0.90 acres of benthichabitat 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 of2.7 ft2 of benthic habitat as a result of installation and removal of each of the 20 anchors of theturbidity curtain; and (4) disturbance to 0.17 acres during dewatering within the sheet pile wall inEntrance Bay.As described in the Proposed Action section, the potential adverse effects are minimized to theextent 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 theintake canal following removal of contaminated sediment; implementation of the eelgrassmitigation and monitoring plan (Stillwater Sciences 2013); and the rapid re-colonization of thebenthic habitat by invertebrates in the areas that were dewatered for six months in the intakecanal 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 theproposed 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 thepurposes of the ESA by carrying out conservation programs for the benefit of threatened andendangered species.

The Corps also has the same responsibilities, and informal consultation offers action agencies an opportunity to address their conservation responsibilities under section7(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, CAAR 15 1422S WR201 3AR00 14423 REFERENCES CITEDBarnhart, R.A. 1988. Species profiles:

life histories and environmental requirements of coastalfishes and invertebrates (Pacific Southwest):

Pacific herring.

U.S. Fish Wildl. Serv. Biol.Rep. 82(11.79).

U.S. Army Corps of Engineers, TR EL-82-4.

14 p.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 1.121 p.Berg L. and T.G. Northcote.

1985. Changes in territorial, gill-flaring, and feeding behavior injuvenile coho salmon (Oncorhynchus kisutch) following short-term pulses os suspended sediment.

Canadian Journal of Fisheries and Aquatic Sciences 42: 1410-1417.

California Stormwater Quality Association.

2009. California Stormwater Best Management Practices (BMP) Handbook.

http://www.cabmphandbooks.com/

Accessed July 7, 2014.Cole, M. E. 2004. Distribution of fish species in Humboldt Bay, Humboldt County, California, USA: a GIS perspective.

Master's Thesis. Humboldt State University, Arcata, California.

132 p.Corps of Engineers.

1987. Buhne Point shoreline erosion demonstration project.

Final.Appendices Volume III F-G. San Francisco and Los Angeles Districts.

August.Costa, S. L. and K. A. Glatzel.

2002. Humboldt Bay, California, Entrance Channel.

Report 1:Data Review. U.S. Army Corps of Engineers.

Coastal Inlets Research Program.ERDC/CHL CR-02-1.

124 p.Davy, Doug. 2014. Personal communication.

Program manager.

CH2M Hill, Sacramento, California.

Dumbauld, B.R., D.L. Holden, and O.P. Langness.

2008. Do sturgeon limit burrowing shrimppopulations in Pacific Northwest estuaries?

Environmental Biology of Fishes 83:283-296.Ecological

Analysts, Inc. 1983. Humboldt Bay Power Plant cooling water intake structures 3 16(b) demonstration.

Prepared for Pacific Gas and Electric Company.

200p. plusappendices.

Eldridge, M.B. 1970. Larval fish survey of Humboldt Bay. Masters Theis. Humboldt StateCollege.

52 p.GHD. 2012a. Workplan for sediment sampling and analysis prior to dredging.

Fisherman's Channel and Residential Channels.

King Salmon, California.

April. 20p. plus appendices GHD. 2013b. Report of findings-sediment sampling and analysis.

Fisherman's Channel andKing Salmon Residential Channels.

November.

22p plus appendices.

24

Halligan, D. 2014. Personal communication.

Senior fisheries biologist.

Stillwater Sciences.

Arcata, California.

Healey, M. C. 1991. Life history of Chinook salmon (Oncorhynchus tshawytscha).

In C. Grootand L. Margolis (Editors),

Pacific Salmon Life Histories,

p. 311-393.

UBC Press,Vancouver, British ColumbiaHumboldt Bay Harbor, Recreation, and Conservation District.

2004. Mitigated negativedeclaration for PG&E Humboldt Bay maintenance dredging of intake canal headworks.

35pKelly, J.T, Klimley, A.P., and C.E. Crocker.

2007. Movements of green sturgeon, Acipenser medirostris, in the San Francisco Bay estuary, California.

Environmental Biology ofFishes 79:28 1-295.Lindley, S.T., D.L. Ericson, M.L. Moser, G. Williams,

0. Langness, B. McCovey, Jr., M.Belchik, D. Vogel. W. Pinnix, J. Kelly, J. Heublein, and A.P. Klimley.

2011. Electronic tagging of green sturgeon reveals population structure and movement among estuaries.

Transactions of the American Fisheries Society 140:108-122.

MacFarlane, R. B. and E. C. Norton. 2002. Physiological ecology of juvenile Chinook salmon(Oncorhynchus tshawytscha) at the southern end of their distribution, the San Francisco estuary and Gulf of the Farallones, California.

Fishery Bulletin 100:244-257.

Morgan, R.P, and Stross, R.G. 1969. Destruction of phytoplankton in the cooling water supplyof a steam electric station.

Chesapeake Science 16(3&4):

165-171.Moser, M. L. and S.T. Lindley.

2007. Use of Washington estuaries by sub-adult and adult greensturgeon.

Environmental Biology of Fish 79:243-253.

North Coast Regional Water Quality Control Board. 2011. Water Quality Control Plan for theNorth Coast Region. Prepared by North Coast Regional Water Quality Control Board,Santa Rosa, California.

Northeast Region Essential Fish Habitat Steering Committee.

2002. Workshop on the effects offishing gear on marine habitats off Northeastern United States, October 23-25, 2001,Boston, Massachusetts.

Northeast Fisheries Science Center Reference Document 02-01.86p.Prato, E. and F. Biandolino.

2006. Life history of the amphipod Corophium insidiosum (crustacean:aAmphipoda) from Mar Piccolo (lonian Sea,. Italy). Scientia Marina70(3):355-362.

Pinnix, W. 2008. Unpublished document prepared for Julie Weeder of NMFS. Arcata, CA. 2 p.Pinnix, W. D., P.A. Nelson, G. Stutzer, and K. Wright. 2008. Residence time and habitat use of25 coho salmon in Humboldt Bay, California:

an acoustic telemetry study. U.S. Fish andWildlife

Service, Arcata Fish and Wildlife Office, Arcata, California.

21 p.Stillwater Sciences.

2012. Fisherman's Channel eelgrass survey. Final report. Technical memofrom Emily K. Teraoka to Robert Vogt, PG&E. February 17, 2012. l6p.Stiliwater Sciences.

2013a. Humboldt Bay Power Plant Intake and Discharge Canal Remediation Project Biological Assessment.

Draft report, July, 2013. Prepared by Stiliwater

Sciences, Arcata, California for Pacific Gas and Electric

Company, San Francisco, California.

65p.Stillwater Sciences.

2013b. Agency Review Draft. Biological Mitigation and Monitoring Planfor the Humboldt Bay Power Plant Canal Remediation Project.

Humboldt County,California.

November, 2013. Prepared by Stillwater

Sciences, Arcata, California forPacific Gas and Electric

Company, San Ramon, California.

58 p.Stilliwater Sciences.

2013c. Biological Mitigation and Monitoring Plan for the Humboldt BayPower Plant Canal Remediation Project.

Humboldt County, California.

December, 2013.Prepared by Stillwater

Sciences, Arcata, California for Pacific Gas and ElectricCompany, San Ramon, California.

58 p.Stillwater Sciences.

2014a. Humboldt Bay Power Plant Intake and Discharge Canal Remediation Project Biological Assessment.

Final report, May, 2014. Prepared by Stillwatcer

Sciences, Arcata, California for Pacific Gas and Electric

Company, San Francisco, California.

69 p.Stillwater Sciences.

2014b .Techical Memorandum.

NMFS additional information request forPG&E Humboldt Bay Power Plant Canal Remediation Prepared by Stiliwater

Sciences, Arcata, California for David Wickens ( Corps of Engineers) and Diane Ashton (NMFS)..June 3, 2014.5p.Teraoka, E.K. 2014. Personal communication.

Ecologist.

Stillwater Sciences.

Arcata,California.

Wallace, M. 2006. Humboldt Bay juvenile salmonid investigations, July 1, 2005 through June30, 2006. Annual project performance report. Grant F-51-R-16.

1lp.Wallace,.M.

2008. Humboldt Bay juvenile salmonid investigations, Julyl, 2007 through June30, 2008. Annual project performance report. 2lp.Wallace, M. and S. Allen. 2007. Juvenile salomonid ise the tidal portions of selectedtributaries to Humboldt Bay, California.

California Department of Fish and Game Finalreport for contract PO410504.

14p.Wilber, D. H. and D. G. Clarke. 2001. Biological effects of suspended sediments:

a review ofsuspended sediment impacts on fish and Shellfish with relation to dredging activities inestuaries.

North American Journal of Fisheries Management 21:855-875.

26 W~ilber, D. H., W. Brostoff, D. G. Clarke, and G. L. Ray. 2005. Sedimentation:

potential biological effects from dredging operations in estuarine and marine environments.

ERDC TN-DOER-E20.

U.S. Army Engineer Research and Development Center,Vicksburg, Mis~sissippi.

Winzler & Kelly. 2009. Initial study and environmental checklist 2010 maintenance dredgingChevron Eureka Terminal.

32p plus appendices Zajac, R.N. and R.B. Whitlach.

1982. _Responses of estuarine infauna to disturbance.

I. Spatialand temporal variation in initial recolonization.

Marine Ecology Progress Series 10:1-14.27 UNITED STATES DEPARTMENT OF COMMERCE,, National Oceanic and Atmospheric AdministrationNATIONAL MARINE FISHERIES SERVICE.West Coast Region 1655 Heindon RoadArcata, California 95521-4573 In response refer to:SWR-20 13-9644Ms. Jane HicksChief, Regulatory BranchU.S. Army Corps of Engineers 1455 Market Street, 16th FloorS 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 theIssuance of a U.S. Arxmy Corps of Engineers Permit Authorizing Pacific Gas and ElectricCompany to Implement the Humboldt Bay Power Plant Intake and Discharge CanalRemediation Project