FINDING OF NO SIGNIFICANT IMPACT Mouth of the Columbia River Dredged Material Placement Sites Update Clatsop County, Oregon and Pacific County, Washington August 2018 FINDING OF NO SIGNIFICANT IMPACT Mouth ofth e.Collim bia Rive1· ·Drc~ged Ma t~rial J?fac~megl SitesUp.dat~ Clatsop County, Oregon and Pacific County, Washington Army Corps of Engineers, Portland Di~trict I find the Proposed A.ction, as described inthe environrne~talassessment (EJ\.)for ''Mouth ofthe Columbia RiverDredgedMaterial Placement Sites Update;. Clatsop Caunty, Oregon and Pacific Com:1ty, Washir]gton,i' will not significantly affect the quality of the human environment and that an envirornnental hnpactstatement is not tequh'ed. The EA was prepared by the Corps of Engin~ei·s, Port1and District. .PROJECTPb'R.POSE AND NEED The purpQse of the Proposed A.ctioni s toadd tw.o sites to the netWork oflong~tel'f11 dreclged ntateri~l placement sites, suppprtingqvery~Jl regional;sedi111entwam1gem9uta.nd increase the operational flexibility of dredging iti the Mouth of the Colum t5fa River (MCRYand Colt1mbia RiverFederal NavigationChannel (INC), Thetwoproposed ,Sitesa1:e a§;horelirre place111erit site atEast Sand Jslan<:l (ESI} and an it1-water placement Site off~shore ftom NorthHead (North Head .Near Shore~(NHNS)},along the Wlf&hington cq3:st '.µxpandingthenetwqtk ofplac~mefltsites retains a critical sand resource in the Columbia River littoral zone< that would otherwise be lostif materials were placed in offshore sites. 1 Furthehnon~, expand it1g the net¥)orkbf neatshote sites incre~ses the efficiency of dredging oper~tiorrs by util izin~ ~it~s closer to the i\1CR as opposed to sitesJocated further offshore, where :transittimes and placement costs arexincreased. The stmctural stability ofBSlplays>an integralrole+n stabilizing the.FNC andmaintaini~gsate navigation in the MGR and FNC.The need for addingESl to the.network of placement sites arises from an area of erosion on the south shoreline of ESI1 which:vvill ct.1ntit1ue fo faode and tiltimatelytesultirr .the island breachil)g withoufthe addition ofsup_plententalmaterfaL Without suppleintmlingJhe shoreli11ewithdrcqgcdmaterials1 an island breach wo~ldlikely alter sediment transpo1i and shoaling patterns in the MGR and est nary. Shoreline placernent atESlis needed in 2018 to prevent the island :fr01I1 breaching and periodic placement would be needed to maintain the shoreline and prevent an. island breachln the future. the need f6r addingthe filllis site to thenetwork ofplacementsites adses from limited opportunities to place qredged mate rim atexisting :>hes in the MCR. While the, existing sites red is tribute sediment back into the littoral zone, the srea is still experiencing a depletion of sediment and an.additional site i.s neededtqsuppdrLC§,ed~ent11umagemi;nteflorts. ;ilongtbe Wa~hfugton coast. An additional. nem·shore site would increase opportunities to retain dean, sandy matel'iaU11 the littoral zohewfthoutover··hurdening the eX.istil1g nearshore placementsites. 1 A l i~oral zope isanea~1Jore~9yiron1nent.'o/ith ;natur<!Ay oc¢Ul'ring 11rosi~and depositional(acc~tion ){1fucesses, A constant sediment somce is ne'eded in order to batance the 5cdi ment bud gel within a zone. .... PROPOSED.ACTION To'inci-easeoperationill tlexibUitg of tne Corps' dredglngmissiou" the Ptiipc,sedAction includes addingESiandthe NHNS'siteto thenetworkofplaceJ11ent sites fu. theMCR, and the associated cmlStru~til)n atESlto prepare the shoreline for placement. Ed-rt Sai1dlWm1d At EST, tlnfrc are t\vo phaRcs of the proposed action:· ihe first phas~ consisting of'construction and preparation ofthc'])lacement site, followed by operational use ofthe site t:hro'nghthe placement 'ofdredged materials. In COf:ljunctfon with,thfa action,Jbe Cotps is pr0posing 1o: 1. Remove selectpilings from. a derelict pier structure on the .southern shoreline of ESifu ,redµce,cQncen4-atel.1 wayc .c:ne1·gyfrom diffracting waves and river currents focusing em~1,gy along thtls11oreline;theProposed Action includes the removal of §elect pilings and the rocks supporting the pHings; 2. Placement ofapp1·oxilnntcly &0,000 cubic yards (cy) of dredged materialon.the sl10f('1ine ofPSI in 2018, COY"ering approximately 14.5 (ltres; 3. Co11dud periodic.sho~lin~ .. pla<:cmentto ··supplcmc~1ttl.1e shore Iinlj.with ·sandy material and stabilize the islandthroughthc benefidaluse of dredged materials: on an as•rweded basis, QS'determined bythe Corps . .. North HeadNear ShoreSft{ The NHNS site would'.he nsed as abencfioial i1se placement stte where materia 1would be placed ill t:ftin layers indifferent areaswithhrthe designated boun~fary. Following plf}cement,the 9edim~nt ·b e.xpect~g tpdlspersp .into· the Huor al cell and ·sµpplement nearqy beaches, and thus help protect tbe MCR coal'fal zonefrom increased ,stonn rind '>vav e event<>. Addingthc NIINS placement site to the rrehvtlrk of existing pla~eru.entsites wiUfncreasethe Corps' flexibility in managing sediment dtt;dgcdfr(1JU .the MCR. Th~total volume of rnateria.I dre?gcd pe1·season averages approximately 3.5--4;5 million cubic.yards;.thc addition ofNHNS sJtewould not increase the.volume or scope ofcu,rreut dredging actiyitie.s, A inaximum of50Q,000 cy ofdredged material wpµl\:Lbe place<l at tb~:.NHNSsi~ dt¢iug any givFn piaccm<mt eycnL Material would be placed ill a thin layer to reduce. potentially ad:vcnie impacts to species and Increase the rate of habitat recovery. · DETERMINATION Under ~E}:>A, the Corp& evaluates whether any effocts'(1ssociated with •the:a.ltematj vcs un~er cons idcration are si $fiifl ca1.~t. 40 C. F.R, .§ 1508 ,_27 lists crilcri<J.useful to assess whethe1· the proposed action·wi!I •;signfficantlyaffectthe humanenvironment't: l) ·lrnpacts thatmay be both benefic;iaLand adverse: ~or~liac placement.at ~St1J1ay he;ncfit· Juvenile salrrionids.f!y ipcreasirig sh'.tllo:wMwatel'habitat in the lower estuary (Section 5,6). Placement at the NHNS site will recharge thelittoralzone, bcnei1tit1g beach re~ nourishment efforts. Adverse cffectS ofp1aeement auhe NH.NS site would be minimized by· thin Jayli;l:.placemcnt.me~hods described in the· EA~ L.ocajized ·increased.turbidity due ·fo placemein and drndg)ngacti v!tics may ca11sc temporary~dv~rse impacts. on ~quutk species and habitat in the vicinfty. of the project H owcver, those impacts are 'like 1y to be :shrntw liy:ed .as the c-0nstttiction activityis temporal')' .in natul'e (Section.5 .3).. Neither the 2 beneficial, nor the adverse impacts;discussedin the EA areHkelyto be significant as described in the envitonmental effects sectiol'tof the EA. 2) The Degree towhichthe Action Affects Public T-I~~lth and Safety: Publichealthand >safety .would not be adversely .affected by these actions; Dredge material placement is perfor:tned by the coms and lt$ contractors who areJequitedto adhere to strict safety measures while wotking.(Section5.10). The general p11blic isnot allowed to enter .!.!btlStt·llctlon site.s \vJtlle dredge placementoperations are underway. 3) Vniqrie Charactel'isiics ofGeographical Ai'ea: As discussed in Chapter 4 ofthe'EA, the: projecLL1fea is Jocated ..within the Col~mbiaJliver. ESI, tho.ugh historically useda§a place.ment sit~. Is erddingandwiU likely breach inthe absence ofsupplementaLmaterial placed along the shoreline. The NHNS site is located on the Washington coast and placement of dredged materials is expectedto retainsedimeut in the littoral zone, suppm'ting regional sediment fllanagtmentefforts; 4) Highly Controvel'siaLE:ffects 01tthc Quality oftheJiumanEnvironment: The effects of the .proposed actions are not controversiaL.No.Congressional interest is associated wiili the ptoj~ct, nof:has th~e bee11sub~famial pµblic in.terest inthe prpjt~ct. 5) HighlyJJnccrtain, Unique, or Unkno\\11 Risli~: Adding t\vo sites to the dredge material placement network, as proposed in the EA,is considered roµtine a.ctivity ·tl1at has prediCtable. outcomes. No portion ofthe project is as5ociated with highly11rtcertain, uniqu~, 01' unknown risks. Shoreline placementat ~SI will rebuild the shoreline .to its !orrn~rJootpri~t, anqplacement at tht: NHl".('S site;will increase flexibilicyof dredging operations in the MCR and retain sediment in the Ji(toral wne. ·· 6) ~uturePrecedents: The actions and:associ~ted impacts d7scribedi11the EA are eonsidered minor modifications .to the placement network and are toutine in nature; Neitherplacem~ntatESI, nor placement at t4eNljN-S sit~ would set a p~·e:s.identfor future actions undertaken by the Corps. Both types of actions typicallytake place within the MGR on anannuaJ basis,. and nothing rela~cd ·t{) the tWq new actions would deviate from methods, timing, or impacts associatedwith prev ioits activities of a similm• nature . 7) . Significant C~ml.1lati~e Impacts: The impacts analysis for .the proposed l;l.Ctions presenteci in theJ3A did npt reve~l significantyuinulatiye. imps~ts {Section 6\3). Adding shoreline placement on ESl and in-waterplacemcnt at the NHNS site arc .not likely to result in significant cµm11lati\'eimpac~ when combined withJhe impa.ets ofother past, present, and future actions. Several bther. actions are fuking place. and/or scheduled to take place within the M(:R FN(;; however.none ofthem is associated.with individ~alimpacts that wouklresultjnsignificant cumulati:y.t;: impayts when c01nbi11ed with otheractioi:ii;;,. 8) ·Natiorral.RegisterofllistoricPlaces:(NRBPJandOtherHisforicalJmd··culturallx Significant Places: ESI is an lmportant component of the MCR navigation infrastructure iwedcdto maiJ1~ain