# Siuslaw River, Oregon Ocean Dredged Material Disposal Sites Evaluation Studyand Environmental

Assessment

U.S. A rmyCorps of Engineers, Portland District U.S. Env ironmental Protection A gency , Region 10

Ap ril 2010

### Ab brevia tions and A crony ms

CFR Code of Federal Regulations cfs cubic feet per second cy cubic yard(s) CZMA Coastal Zone Management Act DMEF Dredged Material Evaluation Framework DPS Distinct Population Segment EA Environmental Assessment EFH essential fis h habitat EPA U.S. Environmental Protection Agency ESA Endangered Species Act ESU Evolutionarily Significant Unit km kilometers m3 cubic meter(s) mg/kg milligrams per kilogram mg/L milligrams per liter mm millimeter(s) MDL method detection limit M LLW mean lower low water MMPA Marine Mammal Protection Act MPRSA Marine Protection, Research and Sanctuaries Act MRL method reporting limit MSA Magnuson

- Stevens Fishery Conservation and Management Act NAD North American Datum NEPA National Environmental Policy Act NHPA National Historic Preservation Act NMFS National Marine Fisheries Service OC Oregon Coast (coho salmon) ODMDS ocean dredged material disposal site ODFW Oregon Department of Fish and Wildlife OHV off

- highway vehicle PAH polynuclear aromatic hydrocarbon(s) PCB polychlorinated biphenyl(s) ppb parts per billion ppm parts per million RM river mile(s) SEF Sediment Evaluation Framework SMMP Site Management and Monitoring Plan SONCC Southern Oregon/Northern California Coast (coho salmon) TOC total organic carbon TB T tributyltin ug/g microgram per gram ug/kg micrograms per kilogram ug/L micrograms per liter USACE U.S. Army Corps of Engineers U.S.C. United States Code ZSF Zone of Siting Feasibility

## Siuslaw River, Oregon

Ocean Dredged Material Disposal Sites Ev aluation Studyand Env ironmental As sessment

Report Preparers

Wendy K. Briner Biologist CENWP

- PM

- E Mark D. Siipola Civil Engineer CENWP

- EC

- HR Timothy J. Sherman Biologist CENWP

- EC

- HR Kim W. Larson Fishery Biologist CENWP

- PM

- E Bert Rader Archaeologist CENWP

- PM

- E Michael A. Martin Archaeologist CENWP

- PM

- E Jonathan Freedman Ocean Dumping Coordinator EPA, Region 10 Jessica Winkler Biologist EPA, Region 10 Justine Barton Ecologist EPA, Region 10 Karen Bahus Bi ologist/Writer ConsultantSiuslaw River ODMDS Environmental Assessment and MPRSA Criteria Evaluation page i 

## Siuslaw River, Oregon Ocean Dredged Material Disposal Sites Ev aluation Studyand Env ironmental As sessment



## Table of Contents

PURPOSE AND NEED

................................ ................................ ................................ .......... 1 Need for Disposal Site Designation

................................ ................................ .................... 1 Background

................................ ................................ ................................ ......................... 3 Offshore De signation and Disposal History

................................ ................................ ....... 4 AFFECTED ENVIRONMENT

................................ ................................ .............................. 7 Phy sical Resources

................................ ................................ ................................ .............. 7 General

................................ ................................ ................................ ........................... 7 Siuslaw River Sediments

................................ ................................ ................................ . 7 ODMDS Sediments

................................ ................................ ................................ ......... 9 Oceanographic Circulation

................................ ................................ .......................... 11 Surficial Geology

................................ ................................ ................................ .......... 11 Water Quality

................................ ................................ ................................ ................ 11 Biological Resources

................................ ................................ ................................ ........ 12 Plankton and Fish Larvae

................................ ................................ ............................. 12 Benthic Invertebrates

................................ ................................ ................................ .... 13 Fish and Epibenthic Species

................................ ................................ ......................... 14 Commercial and Recreational Fisheries

................................ ................................ ...... 14 Wildlife

................................ ................................ ................................ .......................... 15 Threatened and Endangered Species

................................ ................................ ............ 15 Socio

- Economic Resources

................................ ................................ .............................. 16 Cultural Resources

................................ ................................ ................................ ........ 16 Recreational Uses

................................ ................................ ................................ ......... 16 Commercial Uses

................................ ................................ ................................ .......... 17 ANALYSIS OF ALTERNATIVES

................................ ................................ ...................... 17 No Action Alternative

................................ ................................ ................................ ....... 18 Upland Disposal Alternative

................................ ................................ ............................. 18 Estuarine Disposal Alternative

................................ ................................ ......................... 18 Ocean Disposal Alternatives

................................ ................................ ............................. 19 Disposal Off the Continental Shelf

................................ ................................ ............... 19 Continued Use of Existing Sites

................................ ................................ .................... 20 Designation of New ODMDS

................................ ................................ ........................ 20 ANALYSIS OF OCEAN DUMPING SITE D ESIGNATION PROCESS AND ENVIRONMENTAL EFFECTS

................................ ................................ .......................... 21 Overview

................................ ................................ ................................ ........................... 21 Defining a Zone of Siting Feasibility

................................ ................................ ................ 21 Siuslaw River Zone of Siting Feasibility

................................ ................................ .......... 22Siuslaw River ODMDS Environmental Assessment and MPRSA Criteria Evaluation page ii

Regulatory

Criteria for Ocean Disposal Site Selection

................................ ..................... 23 Application of Four General Criteria (40 CFR 228.5)

................................ ................. 23 Application of Eleven Specific Factors (40 CFR 228.6)

................................ ............... 29 SUMMARY OF COORDINATION UNDER OTHER APPLICABLE FEDERAL STATUTES

................................ ................................ ................................ ........................... 37 Federal Action

................................ ................................ ................................ ................... 37 Public Comments

................................ ................................ ................................ .............. 37 Endangered Species Act

................................ ................................ ................................ ... 37 Magnuson

- Stevens Fishery Conservation and Management Act

................................ ..... 39 Marine M ammal Protection Act

................................ ................................ ....................... 39 Coastal Zone Management Act

................................ ................................ ......................... 40 National Historic Preservation Act

................................ ................................ ................... 40 Tribal Consultation

................................ ................................ ................................ ........... 40 SELECTION OF OCEAN DI SPOSAL SITES FOR FORMALDESIGNATION

............. 40 LITERATURE CITED

................................ ................................ ................................ ......... 41

List of Tables Table 1. Siuslaw River Project Dredging Volumes

................................ ............................... 5 Table 2. Proposed Siuslaw North and South ODMDS Conflict Matrix

.............................. 24
List of Figures Figure 1. Siuslaw River Proposed North ODMDS and South ODMDS

............................... 2 Figure 2. Historical Siuslaw River Ocean Disposal Sites

................................ ...................... 5 Figure 3. Siuslaw Ocean Disposal Sites Sampling L ocations, 2008

................................ ... 10 Figure 4. Overlay

Evaluation of Individual Resources

................................ ........................ 27

Technical A ppendices Appendix A

– Li ving Resources Appendix B

– Phy sical Processes and Geological Features Appendix C

– Sediment and Water Qualit y Appendix D

– Cultural Resources Appendix E

– Recreational Resources Appendix F

– Site Management/Monitoring PlanSiuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 1



## PURPOSE AN D NEED This Ocean Dredged Material Disposal Site (ODMDS) Evaluation and Environmental Assessment (EA) was jointly prepared b y the U.S. Army Corps of Engineers (USACE) and the U.S. Environmental Protection Agency (EPA). The purpose of this evaluation is to provide documentation in support of final EPA designation of two ODMDS (North and South) located offshore from the Siuslaw River, Oregon (Figure 1). These sites are needed for long

- term use b y the USACE for the federally authorized Siuslaw River navigation project and for use by others for disposal of dredged material meeting ocean disposal criteria. This evaluation will assess th e proposed final designation of the two Siuslaw sites against the statutory requirements set forth in the Marine Protection, Research and Sanctuaries Act, as amended (MPRSA), 33 U.S.C. 1401 to 1445, and the regulations found in Part 228 of Title 40 of the Code of Federal Regulations (CFR). These regulations were promulgated in accordance with criteria set out in Sections 102, 103 and 104 of the MPRSA. This evaluation also outlines EPA’s coordination under the National Environmental Policy Act of 1969 (NEP A), 42 U.S.C. Sections 4321 to 4370f; Endangered Species Act of 1973 (ESA), 16 U.S.C. Sections 1531 to 1599; Magnuson

- Stevens Fishery Conservation and Management Act (MSA), 16 U.S.C. Sections 1801 et seq .; Marine Mammal Protection Act of 1972 (MMPA), 16 U. S.C. Sections 1361 et seq .; National Historic Preservation Act of 1966 (NHPA), 16 U.S.C. Sections 470 et seq .; and the Coastal Zone Management Act of 1972 (CZMA), 16 U.S.C. Sections 1451 to 1466, all as amended. 

### Need for Disposal Site Designation The EPA undertook this evaluation to determine whether to designate any dredged material disposal site(s) near the mouth of the Siuslaw River pursuant to its authority under the MPRSA at Section 102(c) in response to several factors. These factors include:
1. The pr ohibition on further use of the existing Siuslaw Section 103 disposal sites following the close of the 2009 dredging season pursuant to USACE site selection authority under MPRSA Section 103(b), which allows the USACE to select a site under Section 103 for a period of 5 years with a maximum 5

- ye ar extension with EPA concurrence; 2. The understanding that in the absence of an EPA

- designated disposal site or sites, an y necessary open - water disposal would either be precluded or the USACE would have to undertake a dditional short

- term site selections, perhaps a number of them, in the future; 3. The clear Congressional preference expressed in MPRSA Section 103(b) that an y open water disposal of dredged material take place at EPA

- designated sites, if feasible; and 4. The st atutory

preference to concentrate, where feasible, any open - water disposal at sites that have been used historically , see 40 CFR 228.5(e).Siuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 2

Figure 1 . Siuslaw River Proposed North ODMDS and South ODMDSSiuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 3

The EPA’s evaluation cons idered whether there was a need for an y disposal site designations for long

- term dredged material disposal, including an assessment of whether other dredged material management methods and/or disposal options could reasonabl y be judged to obviate the need for such designations. Having concluded that there was a need for open

- water disposal sites, EPA then assessed whether there were sites that would satisfy the applicable environmental criteria to support a site designation under the MPRSA Section 102(c). 

### Background The MPRSA was passed by Congress in recognition of the fact that the disposal of material into ocean waters could potentially result in unacceptable adverse environmental effects. Under the MPRSA, the EPA and the USACE were assigned responsibil ity to regulate the dumping of dredged material into ocean waters and to prevent or strictly limit the dumping into ocean waters of an y material that would “unreasonabl y degrade or endanger human health, welfare, or amenities, or the marine environment, ec ological sy stems, or economic potentialities.” The EPA administers and enforces the overall permit program for ocean disposal of material other than dredged material and designates dredged material disposal sites. The USACE, with EPA’s concurrence, issue s permits for the disposal of dredged material for the purpose of ocean disposal where the USACE determines that dumping will not unreasonably degrade the environment or endanger human health, welfare, or amenities, or the marine environment, ecological s y stems, or economic potentialities. While the USACE does not administratively issue itself a permit, the requirements that must be met before dredged material derived from USACE projects can be disposed into ocean waters are the same as those where a permi t would be issued. The EPA must consider statutory criteria and evaluate the four general regulatory criteria codified at 40 CFR§ 228.5 and the eleven specific regulatory criteria at 40 CFR § 228.6. Pursuant to Section 102(c) of the MPRSA, the EPA is res ponsible for designating sites for the disposal of dredged material. The USACE is allowed, with EPA’s concurrence, to select a site for ocean disposal of dredged material pursuant to Section 103(b) and (c) of the MPRSA, when a feasible disposal site has n ot been designated b y EPA, or when the continued use of an alternative site is necessary to maintain navigation and facilitate interstate or international commerce, and EPA has determined that the alternative site does not pose an unacceptable risk to human health, aquatic resources, or the environment.
An EPA

- designated site requires a site management and monitoring plan (SMMP). Use of a designated site is subject to the restrictions included in the SMMP and EPA’s designation regulations. These restrict ions are based on an in

- depth evaluation of the site and potential disposal activity , as well as public review and comment. Designation of an ODMDS in itself does not result in disposal of dredged material. A separate evaluation of the suitability of dre dged material for ocean disposal must be undertaken for each proposed use of the site by either the USACE or non

- USACE permit applicant. Ty pically , this involves evaluation of the specific disposal activity under the criteria (which can include multiple years of use), circulation of a public notice, specific coordination with stakeholders, and concurrence b y the appropriate EPA region.Siuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 4

The EPA proposes to designate two ocean disposal sites, the North ODMDS and South ODMDS, which are located approximately 1 mile offshore of the entrance to the Siuslaw River (see Figure 1). The proposed North site is 4,800 feet by 2,000 feet, and, based on 2009 bathy metric data, ranges from 30 to 115 feet deep. The proposed South site is 3,000 feet by 2,000 feet and ranges in depth from 80 to 120 feet deep. 

### Offshore Designation and Disposal History An Interim ocean disposal site, or areas in the same vicinity , have been used by the USACE Portland District since 1929, when hopper dredges began to work the Siuslaw bar and entrance channel. The Interim ODMDS (Interim Site A on Figure 2) was designated an EPA Interim Site in 1977 (40 CFR 228.12) and was used from 1977 to 1996. It was suspected that ocean currents were transporting dredged material placed in the Interim site ba ck into the Siuslaw entrance channel. In 1986

- 1987, the USACE completed dye and seabed drifter studies (USACE 1988). Results demonstrated dredged material deposited south and/or east of the centroid of the interim site, with prevailing north to northwest winds, could possibly drift back across or into the Siuslaw entrance channel. The Interim site also experienced mounding to 14 feet relative to the 1981 bathy

metry due to its small size and the volume dredged. To address these issues, two adjusted and e xpanded ocean disposal sites, ODMDS B and C, were selected by the USACE under Section 103 of the MPRSA (Figure 2, Sites B and C). Site B includes a portion of Interim Site A. Material removed from the Siuslaw federal navigation project was first deposited at Site C in 1997, while Site B was first used in 1999. Since 1997, material removed from the Siuslaw federal navigation project has only been deposited into ODMDS B and C (see Table 1). Sites B and C experienced some mounding even though disposal restri ctions were used to enhance dispersal. The Interim Site A vicinity of Site B was avoided until previously placed materials could disperse. As a result of the larger sites, reduced overall volumes of dredging and disposal, and avoidance of the Interim Site A corner, all disposal restrictions were lifted in 2008. Pending final designation by EPA, in 2004 the USACE extended the selection of ODMDS B and C for a final 5

- ye ar period. Following expiration, the EPA must designate ocean disposal sites under Section 102 of the MPRSA in order for dredged material to be disposed offshore of the Suislaw River. Table 1 presents the volume of material placed offshore of the Siuslaw River. T he bulk of the material dredged has been placed in the larger Site B. Quantities of dredging overall have dropped and f

uture dredged material disposal volumes are not often expected to exceed 100,000 cubic yards (cy) annuall y (based on a 13

- ye ar average of about 60,000 cy and a range of 22,300

- 117,300 cy). Material is expected to be di sposed over a period of 20 day s of dredging and disposal (average is about 7 day s; range 3

- 23 day s). Generall y, dredging and disposal are expected to occur between June 1 and October 31 of each ye ar.Siuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 5

Figure 2 . Historical Siuslaw River Ocean Disposal SitesSiuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 6

Table 1 . Siuslaw River Project Dredging Volumes
Fiscal Year Dredging

Volumes (x 1,000 cy) 1929

- 1977 2,800.0* 1977 139.3* 1978 191.4* 1979 246.6* 1980 94.2* 1981 388.4* 1982 193.4* 1983 213.3* 1984 221.1* 1985 271.2* 1986 218.8* 1987 215.8* 1988 114.5* 1989 116.8* 1990 99.0* 1991 65.9* 1992 194.2* 1993 239.6* 1994 223.3* 1995 121.6* 1996 84.8* 1997 40.0 (Site C) 1998 69.6 (Site C) 1999 43.5 (Site B) 2000 55.1 (Site C) 2001 101 .2 (Site C) 2002 117.3 (Site B) 2003 55.0 (Site B) 2004 14.1 (Site B) & 9.0 (Site C) 2005 33.4 (Site B) 2006 22.3 (Site B) 2007 76.0 (Site B) 2008 69.9 (Site B) 2009 91.7 (Site B) * Dredged material from 1977 to 1996 was placed in the EPA

- designated Interim ODMDS (Site A). At other ocean disposal sites along the Oregon Coast, the EPA and the USACE have found that the strategy

of placing a site to the north and another to the south of the river mouth has worked well (Coos Bay , Umpqua, etc.), prim aril y because it allows for adaptive management of the sites given a dynamic current environment. Similarly, EPA is proposing two expanded ocean disposal sites located North and South of the mouth of the Siuslaw River. Generally, material placed deeper th an 60 feet is less mobile and less available to the active littoral system. To keep more material in the active littoral sy stem, EPA proposes a North site configuration that expands the existing Section 103 Site B to include the original 1977 Interim site (Site A), and a similarSiuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 7

relativel y “shallow” area to the north of Site A (see Figure 2). Based on likely northerl y movement of coastal littoral material over the course of the ye arl y dredging and disposal cycle, the EPA proposes to utilize the shallower portions of the North site to the maximum extent possible in order to disperse material into the active littoral zone, limit wave effects due to mounding, and keep material from reentering the navigation channel to the south. The proposed South site’s southern boundary was moved further south, doubling the size of the site, to allow for better dispersal should that site be needed. To support annual adaptive management of the sites, EPA anticipates annual bathy metric survey s and other management and monitoring at the proposed North and South sites in accordance with the Site Management and Monitoring Plan (SMMP) (see Appendix F). 

## AF FECTED ENVIRONMENT Physical Resources General This section provides a summary characterization of the phy sical resources in the Siuslaw River study area. Additional information is provided in Appendix B: Phy sical Processes and Geologic Features. The Siuslaw River estuary covers about 1,780 acres and opens into the Pacific Ocean about 160 miles south of the mouth of the Columbia River. It lies within the Heceta Head littoral cell, which extends for about 56 miles from Heceta Head south to Cape Arago. The estuary is fed mainly

by Siuslaw River, which is 108 miles from its mouth to headwaters and has a drainage basin of 773 square miles. The watershed encompasses part of the Coast Range, with the Siuslaw River extending inland to Cottage Grove. The coastal zone of the littoral cell consists of a wide plain that is 1

- to 2

- miles wide, covered b y active and stabilized sand dunes ba cked b y the mature upland topograph y of the Coast Range. The lower portion of the Siuslaw River is bordered b y broad alluvial flats. Between the Siuslaw River and Yaquina River estuaries, the continental shelf is at its widest along the Oregon Coast, ext ending over 44 miles offshore forming the Heceta Bank. Just south of the Siuslaw River, the shelf begins to narrow and is only

about 19 miles wide at the mouth of the Umpqua River. At the mouth of the Siuslaw River, the first 2 miles or so of the shelf i s covered with sand. From there a thin layer of mud (about 1

- inch thick) mantles the surface. The Heceta Head littoral cell is the largest on the Oregon Coast. Landward of the cell, the coast is primarily

beach

- fronting sand dunes. Headlands are locate d at the north and south landward ends of the cell. Three major river s ys tems enter the cell. From north to south, these are the Siuslaw River, the Umpqua River (largest of the three), and the Coos River. 

### Siuslaw River Sediments This section provides a s ummary characterization of the sediments to be dredged from the Siuslaw River. Additional information is provided in Appendix C. In 1991, the USACE collected 10 sediment samples from the Siuslaw River federal navigation channel for ph ys ical anal ys is; one sample from the turning basin at river mile (RM) 5.0 near Florence was subjected to chemical anal ys es (USACE 1991). Sediments were found to be 99.9% poorly graded sand with low volatile solids content (1.1%). The median grain size of 0.32 millimeters (mm) wasSiuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 8

that of medium sand. The results of the chemical anal ys is from the turning basin had metals concentrations below established levels of concern. No pesticides, polychlorinated biphenyls (PCBs), poly

nuclear aromatic hydrocarbons (PAHs), or phenols w ere detected. In 1996, 10 surface grab samples were collected from the entrance to RM 8 (USACE 1996). These samples were subjected to ph ys ical tests, with grain

- size ranging from 100% to 92.7% (mean 98.6%) poorl y graded sand with volatile solids content ranging from 1.4% to 0.3% (mean 0.8%). The mean grain

- size was that of medium sand (0.294 mm). In 2001, eight surface grab samples were collected from the entrance to RM 6 (USACE 2001). All samples were submitted for ph ys ical anal ys es, with grain

- size r anging from 100% to 97.9% (mean 99.2%) poorl y graded sand with volatile solids content ranging from 0.42% to 3.0% (mean 1.29%). The mean grain

- size was that of medium sand (0.29 mm). Two samples were selected for chemical analy ses to include metals, tota l organic carbon (TOC), PCBs, chlorinated hydrocarbons, phenols, phthalates, miscellaneous extractables, and PAHs; one sample was submitted for organotin (TBT

- pore water method) anal ys is. The samples submitted for chemical analy sis were taken from the f ederal channel near the outfall to the sewage treatment plant and near the boat dock. The one sample analy zed for TBT was collected near the boat dock. Sediment represented by these samples would meet the marine screening level guidelines established in the Sediment Evaluation Framework (SEF 2009) 1 for unconfined in

- water placement without further characterization. In August 2006 (Sherman 2007), seven samples were collected from the Siuslaw entrance to RM 5. All samples were submitted for phy sical anal y ses, with grain

- size ranging from 98.5% to 95.4% poorly

graded sand (mean 97.1%), with volatile solids content ranging from 0.69% to 2.24% (mean 1.14%). One sample was selected for chemical anal ys es to include metals, TOC, PCBs, chlorinated h ydrocarbons, phenols, phthalates, miscellaneous extractables, and PAHs. Two samples were submitted for TBT anal ys is, one from the turning basin adjacent to the marina and the second from the federal channel b y the fuel dock. Pore

- water TBT was not anal yz ed due to ins ufficient pore

- water volume in the samples, a result of the high sand content. The chemical anal ys es showed onl y low levels of contamination in any of the samples, with all levels well below their respective SEF screening levels. No pesticides, PCBs, PAH s, chlorinated hydrocarbons, or miscellaneous extractables were detected in any of the samples. Several metals, phthalates, phenol, and dibutyltin were detected, but at low levels and well below their respective screening levels. Detection levels were su fficiently low to evaluate material proposed for dredging. The anal yt ical results of this characterization are consistent with historical data.

1 Pursuant to the Ocean Dumping Regulations at 40 CFR § 227.13(b), dr edged material which meets the following criteria is environmentally acceptable for ocean dumping without further testing: (1) dredged material composed primarily of sand, gravel, rock, or any other naturally occurring bottom material with particle sizes larges than silt, and the material is found in areas of high current or wave energy such as streams with large bed loads, or coastal areas with shifting bars and channels; or (2) dredged material for beach nourishment or restoration and is composed primari ly of sand, gravel, or shell with particle sizes compatible with material on the receiving beaches; or (3) when the material is substantially the same as the substrate at the proposed disposal site and the site from which the material is taken is far remov ed from known existing and historical sources of pollution such that there is a reasonable assurance that the material has not been contaminated by such pollution. The use of the SEF screening levels provides an additional safeguard for material that woul d otherwise meet the regulatory criteria for environmentally acceptable material for ocean dumping without further testing.Siuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 9

Sediment represented b y these samples met the marine screening levels guidelines established in the SEF for un confined in

- water placement without further characterization. Sediments were collected in October 2006 from the Port of Siuslaw marina and from the upper river channel (RM 5 to 16.5). These samples are considered representative of the material from these areas, though dredging above RM 5 is very infrequent. Sediment from the Port’s marina ranged in grain

- size from 47.3% to 79.4% sand (mean 75.9%), while sediment from the upper river channel ranged from 93.6% to 97.0% sand (mean 95.4%). Sixteen samples were submitted for ph ys ical testing and eight samples (two upstream and six marina) were subjected to chemical anal ys is, including metals, PCB’s, pesticides, chlorinated hydrocarbons, miscellaneous extractables, phthalates, phenols, and low and high molecular weight PAH’s. The six marina samples were also tested for bulk and porewater TBT. Some samples contained low levels of several COC’s, however, none approached their DMEF/SEF screening levels, with all laboratory detection levels and quality controls at acc eptable levels.



### ODMDS Sediments This section provides a summary characterization of the sediments in the ocean environment offshore of the Siuslaw River. Additional information is provided in Appendix C. In August 2008, 10 surface

- grab sediment sample s were collected at ODMDS B and C (proposed North and South sites) with a 0.96 m 2 modified Gray

- O’Hara box core sampler (Figure 3). Three samples (01, 02 and 03) were collected from east to west on the centerline of Site B. Three samples (07, 08 and 09) were collected from east to west on the centerline of Site C. Four reference samples were collected north, south, and between Sites B and C (04, 05, 06, and 10). All samples were subjected to phy sical/chemical analy sis. Phy sical Analy sis and TOC . The m ean value for a grain

- size of sand or greater was 97.25% with a mean value of 3.71% fine

- grained material (less than 230 sieve); mean value for TOC was 0.107%. Metals . Sediments were anal yz ed for 10 metals. Of these, all but antimony (Sb), silver (Ag), and mercury

(Hg) were present in all of the samples. No detected metal values approached their respective SEF marine screening levels. Pesticides/PCBs . Chlordane was reported as technical chlordane in one sample (01), and alpha and gamma Chlordane in three samples (01, 02, 06). Detection levels for technical chlordane were problematic, with non

- detects reported at levels above the SEF marine screening levels. These values were not supported b y the values found for alpha and gamma chlordane where levels separatel y and additively were well below the SEF marine SL. In addition, the estimated and non

- detect values are all below the SLof 10 ug/kg currentl y used for decision

- making in Puget Sound (where total chlordane is defined as the sum of cis

- chlordane, trans

- chlordane, cis

nonachlor, trans

- nonachlor and ox ychlordane). Other than chlordane, all other pesticide values were below method reporting levels and well below SEF marine screening levels. No PCBs were detected.Siuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 10

Figure 3

. Siuslaw Ocean Disposal Sites Sampling Locations, 2008

Chlorinated Hydrocarbons, Phthalates, Phenols, and Miscellaneous Extractables . No chlorinated hydrocarbons were detected. Several phthalates, miscellaneous extractables, and phenols were detected at very

low levels; all were below their respective SEF marine screening levels.
PAHs . Various “low molecular weight” and “high molecular weight” PAHs were detected, but at very low levels and well below their respective SEF marine screening levels.Siuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 11



### Oc eanographic Circulation Coastal circulation offshore of the Siuslaw River is directly influenced by

large

- scale regional currents and weather patterns in the northwestern Pacific Ocean. During winter, strong low

pressure s ys tems with winds and waves predo minantly from the southwest, initiate strong northward currents. During summer, high

- pressure sy stems dominate and consequently , waves and wind are commonly

from the north. In both seasons, there are short

- term fluctuations related to local wind, tidal and bathy metric effects. Along the Oregon Coast, there is a southerl y wind in summer which creates a mass transport of water offshore resulting in upwelling of bottom water nearshore. In 1985 (see Appendix B), monitoring of currents in the Siuslaw nearsh ore area showed that summer currents were more frequentl y to the north and were generall y the stronger currents. There were onshore

- offshore currents during the summer with speeds equal to or greater than 1 foot/second. Bottom currents in the winter had a strong offshore component. The largest percentage of the winter currents was to the north with the majority of the speeds equal to or greater than 1 foot/second. Appendix B provides details of the sediment transport processes for the Siuslaw River and nearshore area. 

### Surficial Geology The geological data collected in 2008 for the ODMDS area showed the mean value for a grain

size of sand was 97.25% with a mean value of 3.71% fine

- grained material. Sediments dredged from the Siuslaw River entrance channe l are similar to the offshore sediments. Grain

- size anal ys es for these sediments in 2006 resulted in mean values of 0.2% gravel (shell hash, 0.0%

- 0.5% range), 97.1% sand (95.4%

- 98.5% range), and 2.7% silt/clay (1.5%

- 4.1% range). 

### Wa ter Quality Water quality

throughout the action area is expected to be ty pical for seawater of the Pacific Northwest. There is no reason to expect significant chemical contamination in either the water or sediments, as few industries are located along the estuary . A large data set regarding the impact of dredged material disposal on the water column was accumulated in the earl y 1980s, and focus has shifted away from the water column pathway to one having more direct contact with bulk or suspended sediment. Currently , wate r column tests are rarely performed unless there is a “reason to believe” a water column release may occur. In the summer of 2002, oxygen levels in the water near the Oregon coast plunged so low that fishes, crabs, and other marine organisms had to flee or die in the suffocating waters (PISCO 2009). These low ox yge n conditions, commonly called hy poxia, had never been documented in Oregon prior to 2002, but have recurred every summer since. The most severe event occurred in the summer of 2006 when ox ygen levels dropped to historic lows and hy poxic water could be found in large areas along the Washington and Oregon coasts. In 2006, the dead zone lasted 4 months and large areas of the coastal ocean were affected b y ox ygen levels that dropped as low as zero
. Itis normal to find naturally low

- oxygen conditions in deep, offshore waters, e.g., at the edge of the continental shelf and slope. However, the occurrence of low

- oxygen water close to shore (the inner shelf, less than 165’ of water) is highl y unusual and had not been reported prior to 2002, despite over 50 years of scientific observations along the Oregon coast. No evidence ofSiuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 12

impacts due to hy

poxia have been documented in over 34 years of studies at the various ODMDSs off the Oregon coast. 

### Biologica l Resources This section summarizes biological conditions in the ocean environment offshore of the Siuslaw River. Additional information is provided in Appendix A. 

### Plankton and Fish Larvae No specific data is available for zooplankton in the Siuslaw River nearshore area. However, Keister and Peterson (2003) provided a discussion of the zooplankton community found off the central Oregon Coast (along the Newport h ydrographic line). They indicated that the zooplankton community

is influenced strongl y b y sea sonal variations in wind and current patterns. During late spring and summer, northwesterly winds set up flow towards the equator and coastal upwelling. Northwesterl y winds dominate from April/May

- September; periodic relaxations or southwesterly storms r apidly

affect the hydrograph of nearshore areas. During this time period conditions about 30 kilometers (km) offshore are less variable. Boreal neritic copepods such as Pseudocalanus mimus , Calanus marshallae , Centropages abdominalis , Acartia longiremis , and Acartia hudsonica dominate the coastal plankton during summer (Peterson and Miller 1977). In early

fall, winds reverse and upwelling ceases; during autumn and winter, winds are predominantly

southwesterl y, the Davidson Current flows toward the pole, and offshore surface waters are transported onshore. In winter, the coastal zooplankton is populated by warm - water species such as Mesocalanus tenuicornis , Paracalanus parvus , Ctenocalanus vanus , Clausocalanus spp. , Acartia tonsa , and Corycaeus anglicus ( Peterson and Miller 1977). Auth and Brodeur (2006) examined ichthyoplankton off the central Oregon Coast (along the Newport h ydrographic line). The dominant taxa collected were northern anchovy ( Engraulis mordax ), slender sole (

Lyopsetta exilis ), rockfis hes ( Sebastes spp
. ), northern lampfish ( Stenobrachius leucopsarus ), and blue lanternfish ( Tarletonbeania crenularis ). Total larval concentration increased from 49.3 per 1,000 cubic meters (m 3 ) in 2000 to 72.0 per 1,000 m 3 in 2002, with seasonal concentrat ions highest in August 2000 (90.3 per 1000 m 3 ) and April 2002 (151.2 per 1,000 m 3 ). Relatively few larvae were found at depths greater than 100 meters, while highest larval concentrations generall y were observed from depths of 0 to 50 meters. Larval dive rsity and concentration were higher offshore (46

- 84 km off the coast) than in nearshore areas (9

- 28 km off the coast). Highest concentrations were normally found at an intermediate station, approximately

65 km off the coast. Species designated as either coastal or offshore species by previous studies were predominantly found in their respective shelf regions. Most larval concentrations were positively correlated with temperature and negativel y correlated with salinity

. Auth and others (2007) examined th e ichthyoplankton assemblages from a single station 69 km off Heceta Head on the central Oregon Coast. The authors noted that the species composition, assemblages, and dominant taxa were similar to those found in other studies conducted in this area durin g summer (Richardson 1973; Richardson and Pearcy 1977; Brodeur et al., 1985; Auth and Brodeur 2006). This similarity provided evidence to support the hy pothesis of Auth and Brodeur (2006) that past sampling along the Newport hydrographic line during summe r is representative of ichth yo plankton assemblages elsewhere along the Oregon Coast.Siuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 13



### Benthic Invertebrates Field sampling in October 1984 and January 1985 gathered information on benthic invertebrates at 14 stations off the mouth of the Siuslaw River (USAC E 1992). Another benthic study was conducted at 11 offshore stations in September 1988 (USACE 1992). During these studies, the Siuslaw offshore area exhibited diverse benthic invertebrate communities. A total of 135 taxa were collected in October 1984, 106 taxa in January 1985, and 163 taxa in 1988. Densities were very similar in 1984 and 1985, with approximately 2,200 individuals/m 2 collected. An average of 4,445 individuals/m 2 was collected in the 1988 survey . Polychaetes (annelid worms) were the numericall y dominate species collected during the 1984

- 1985 sampling periods . Scoloplos armiger , Chaetozone setosa , and Megelona sacculata were the dominant polychaete species, reaching densities of approximately 2,500/m 2 , 1,500/m 2 , and 1,400/m2 , respective ly . Other dominant species collected included the amphipods Eohaustorius sencillus , Mandibulophoxus gelesi , and E. sawyeri . The area also had a large number of sand dollars, Dendraster excentricus . In 1988, the dominant polychaete species was Owenia fus iformis , although the density of this polychaete was low to moderate when compared to other coastal areas. Another dominant polychaete collected was Spiophanes bombyx

. Field survey s were conducted in August and September 2008 by Marine Taxonomic Services (USACE 2009) to supplement earlier benthic invertebrate data and provide current information on fish and epibenthic species present in the area of the proposed Siuslaw ocean disposal sites. The benthic invertebrate fauna in the vicinity of the proposed s ites was found to be ty pical of the nearshore, high

- energy

environment found along the Oregon Coast. The density distribution data indicated large juvenile recruitment of most species from spring spawning. This recruitment includes both opportunistic sho rt

- lived species ( Spiophanes bombyx ) and longer

- lived species (razor clams, Siliqua sp. juv. and Dendraster excentricus ). The large recruitment of these longer

- lived species and the recruitment of some shorter

- lived species, mostly polychaeta and crustace a, indicate good ocean conditions in the spring and summer months in this area. The crustaceans showed some population spikes throughout the data; however, the same species were not alway s the driving factors. Gammarid amphipods were often present but al so present were Diastylopsis dawsoni (Cumacea) and barnacles (Cirripedia), which showed up on hard features such as snail shells and the occasional rock. The echinoderms were driven by Dendraster sp. juv/ Dendraster excentricus and the other miscellaneous groups were largely populated by Nemertinea and juvenile holothuroids. The benthos in the Siuslaw nearshore area is typical of the communities found near other ocean disposal sites along the Oregon Coast, such as Coos Bay sites E and F, Umpqua River, Rogu e River, and Chetco River (Hancock et. al., 1981; USACE 1985, 1988a, 1988b, 1990). This benthic community , largely dominated b y very m obile organisms, provides an important link in the marine food web. These organisms serve as a direct food source for other benthic organisms and demersal fishes. They also play an active role in the breakdown of organic debris and the tube

- building species that help stabilize the marine sediments. Man y of the benthic species in the area are able to survive in this dy nami c environment being either very mobile or being able to react both to natural or man

- made perturbations. The benthic community would be expected to re

- colonize within a period of a few weeks to months after disposal (USACE 1993).Siuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 14



### Fish and Epibenthic Species Commercially

and recreationally

important epibenthic species in the Siuslaw nearshore area are shellfish and Dungeness crab ( Cancer magister). Clam beds are located on the north side of the Siuslaw estuary

at RM 1. Gaper clams ( Tresus capex ) are the d ominant bivalves harvested in this area. Dungeness crab adults occur on sandflat habitat along the entire Oregon Coast. They spawn in offshore areas and occur in the estuary when conditions are favorable in late summer and fall. The nearshore area has b een known to be a squid spawning area with the location and size varying annuall y (USACE 1992). Although there have been incidental catches of squid within 1.5 nautical miles of the mouth of the Siuslaw, there has been no directed squid harvest within thi s area. There have been reports of egg capsules and adults caught in trawls, as well as the presence of egg capsules on crab gear. Outside of the 1.5 nautical mile radius from the mouth, there have been directed squid harvests south of Heceta Head to Cap e Perpetua. Squid spawn between water depths of 5 to 40 meters, with maximum spawning occurring at 15 meters. After hatching, they

school in the middle of the water column, moving toward the surface as they mature. Mature squid feed mostly at water depths of 20

- 50 meters (USACE 1992). The nearshore area off the Siuslaw River supports anadromous salmonids including coho salmon, winter steelhead, and spring and fall Chinook salmon, as well as a variety of other pelagic and demersal fish species. Other pe lagic species include the Pacific herring ( Clupea harengus pallasi ), northern anchov y ( Engraulis mordax ), and surf smelt ( Hypomesus pretiosus ). Demersal species present in the nearshore area are mostly residents and include a number of sculpins, sea perch , and rockfish species associated rocky habitats, as well as flatfish species occurring predominantly

over open sandflats. Flatfish include English sole ( Parophrys vetulus ), sanddab ( Citharichthys sp.), and starry flounder (Platichthys stellatus ). Englis h sole and starry flounder, along with the sand sole ( Psettichthys melanostictus ), spawn in the inshore area in the summer and juveniles of these, as well as other marine species, may rear in the Siuslaw estuary

. 

### Commercial and Recreational Fisheries Based on data from NMFS (2006) for commercial fishing, a total of 38 commercial vessels delivered landings to Florence in 2000. Landings were in the following West Coast fisheries (data shown represents landings in metric tons/value of landings/number of vesse ls landing): crab (112.8/$562,057/10), groundfish (124.3/$442,781/15), highl y migratory species (6.9/$11,712/5), salmon (29.7/$113,885/22), shrimp (35.7/$28,529/5), and other species (1.5/$6808/5). There were no fish processors operating in Florence in 2 000. A total of 41 commercial vessels were owned b y Florence residents in 2000, 19 of which participated in the federally managed groundfish fishery . Recreational fishing takes place in the same general areas as the commercial fishery but usuall y closer to shore. For the port complex around Florence, the 2000 recreational salmonid catch in the ocean boat fishery was 250 Chinook salmon and 472 coho salmon. The recreational non

- salmonid catch was a total of 213 fish. The top species landed, in order, inc luded greenstripe, canary , and yelloweye rockfish, and Pacific halibut.Siuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 15



### Wildlife Steller sea lions, harbor seals, and California sea lions are present most of the y ear in the Siuslaw nearshore area. Steller sea lions forage at river mouths and nearshore areas along the Oregon Coast. Harbor seals breed in the estuary and on nearshore rocks. The Siuslaw nearshore area and shoreline provides important habitat for shorebirds, waterfowl, herons, bald eagles, hawks, and man y other species of birds. Pelagic bi rds (e.g., murres, auklets, cormorants) are likel y to use the area near the proposed Siuslaw ocean disposal sites and adjacent waters for foraging. 

### Threatened and Endangered Species Oregon Coast (OC) coho salmon is a federally threatened species that may b e present in the vicinity of the proposed Siuslaw ocean disposal sites. The Siuslaw River and estuary are designated as critical habitat for this species, but the ocean area off the Siuslaw River is not designated critical habitat. Coho salmon are present in the vicinity of the proposed ocean disposal sites as both adults and juveniles. Adults hold in the offshore area prior to entering the estuary to migrate up river to spawn. Juveniles rear in the nearshore ocean area after migrating downstream and tr ansitioning to saltwater. Upstream migration of adult coho salmon generall y takes place from August through November. Juvenile outmigration extends from April through June, but peaks in May

. The Southern Oregon/Northern California Coast (SONCC) coho sal mon is also federally threatened and includes all naturally spawned populations of coho in coastal streams between Cape Blanco, Oregon, and Punta Gorda, California. The proposed Siuslaw ocean disposal sites are not located within designated critical habit at for SONCC coho. This coho species t ypicall y migrates north along the coast. While migrating individuals may utilize the coastal habitat off of the Siuslaw River for migratory purposes, they

are likely to be further offshore than the proposed ocean dis posal sites. The Southern Distinct Population Segment (DPS) of green sturgeon ( Acipenser medirostris ) is a federally threatened species. Critical habitat has been designated for the species (74 FR 52300, 9 October 2009). Green sturgeon that spawn to the north, primarily in the Klamath and Rogue rivers, constitute the Northern DPS, which is not federall y listed. These two DPSs for sturgeon were established because they were genetically

distinct. Southern DPS green sturgeon may be observed in the vicinit y of the proposed ocean disposal sites offshore of the Siuslaw River as they migrate to northern estuaries during summer and earl y fall. The Southern DPS of Pacific Eulachon was proposed threatened in March 2009. Eulachon (commonly

called smelt, candlefi sh, or hooligan) are a small, anadromous fish from the eastern Pacific Ocean. Eulachon ty picall y spend 3

- 5 years in saltwater before returning to freshwater to spawn from late winter through mid spring. Eulachon occur in nearshore ocean waters and to 1,0 00 feet in depth, except for the brief spawning runs into their natal (birth) streams. In the continental United States, most eulachon originate in the Columbia River Basin. Other areas where eulachon have been documented include the Sacramento River, Ru ssian River, Humboldt Ba y and several nearb y s maller coastal rivers, and the Klamath River in California; the Rogue and Umpqua rivers in Oregon; and infrequently in coastal rivers and tributaries to Puget Sound, Washington. The NMFS Status Review for Eula chon concluded that eulachon were thought toSiuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 16

occur in “rare” relative abundance in the Siuslaw River (NMFS 2008). Although eulachon migrate along the coast, little is known about eulachon use of the nearshore and marine habitat. Federall y listed avian sp ecies that may be present in the Siuslaw offshore area include the marbled murrelet, brown pelican, and short

- tailed albatross. Threatened marbled murrelets are observed in small flocks or as individuals in the ocean throughout the ye ar. Endangered brown pelicans are abundant from June to September along the coast and in the lower reach of the Siuslaw River estuary . The endangered short

- tailed albatross may forage in open ocean areas off the coast, however the normal range for this species is Alaska and sightings are rare along the Oregon coast. Two shoreline areas in Lane County support breeding and wintering western snowy plovers ( Charadrius alexandrinus nivosus ), a federall y threatened species (USFWS 2007). These shoreline areas are Heceta Head to th e Siuslaw River, and the Siuslaw River to the Siltcoos River. These shoreline areas fall outside the limits of the Siuslaw River project and would not be affected b y ocean disposal activities. The blue, fin , sei, sperm, humpback, and southern resident ki ller whales are all federally endangered and have been observed as migrants off the coast in waters typi cally farther from shore than within the proposed Siuslaw ocean disposal sites. Threatened Steller sea lions are ye ar - long residents and forage at the river mouth and nearshore areas along the coast. The proposed ocean disposal sites are not located in or near designated critical habitat for the Steller sea lion. 

### Socio - Economic Resources The City of Florence is bordered b y both the Pacific Ocean and Siu slaw River. The 2000 Census reported that Florence had a total population of 7,263 people, a 40.7% increase from the 1990 Census. Based on the 2000 Census, highest employ ment in Florence was in educational, health and social services (22.9%), followed b y accommodation and food services (16.6%), retail trade (16.1%), government (12.1%), and agriculture, forestry , fishing, and hunting (3.8%). 

### Cultural Resources Appendix D provides detailed information concerning cultural resources offshore of the mouth of the Siuslaw River. Prehistoric cultural resources are unlikel y to be found within the Siuslaw River offshore area. Shipwrecks are the most probable cultural resources to be expected within the offshore area. A review of the historical records indicates s everal recorded shipwrecks in the Siuslaw offshore area (see Appendix D). Side

- scan sonar survey s were conducted in the area, and no shipwrecks or other historic remnants were detected. Based on the studies and research in Appendix D, there are no known shipwrecks offshore of the mouth of the Siuslaw River. 

### Recreational Uses Recreational resources in the area of the proposed Siuslaw River ocean disposal sites are described in Appendix E. Although the Siuslaw River area receives recreational use year

- roun d, the most popular months are from May through October. Fishing in the area is particularl ySiuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 17

popular because of the excellent fishing opportunities in the Siuslaw River and nearb y freshwater lakes. Other recreational activities include camping, picnickin g, beachcombing, and sightseeing. The Siuslaw River marks the northern boundary of the Oregon Dunes National Recreation Area. This portion of the recreation area contains no developed facilities other than a paved road that parallels the shoreline and pr ovides access to the beach and South Jetty area. During the summer, beachcombing and sightseeing are the most popular activities. The Siuslaw jetty fishery is popular and accounts for a relativel y high number of angler use days. The jetties are among th e best in the state for catching surf perch. The most popular season is May through September. Scuba diving is another activity which occurs on the outside of both jetties. The main attraction for divers is the opportunity for spear fishing. A locally important salmon fishery exists offshore of the Siuslaw River. Even though the offshore salmon fishing can be productive, a rough bar has periodicall y limited this opportunity for most small pleasure craft. Salmon fishing is most popular from May through September when ocean conditions are more predictable and salmon are feeding in the nearshore area prior to the fall spawning runs. A smooth bottom offshore of the Siuslaw River has limited the establishment of any substantial bottom fish populations. On e exception is a small area located just off the mouth which has proven productive for flounder fishing. The lack of good bottom fishing opportunities and the relativel y short salmon fishing season have limited the number of charter boats in the area. 

### Com mercial Uses The Siuslaw River offshore area supports a moderate commercial fishery primarily for salmon, groundfish, and Dungeness crabs. Clams are commerciall y harvested in the estuary. The fishing and tourist industries are a primary source of income to the local econom y. No significant mineral or petroleum deposits are known to exist in the vicinity of the proposed Siuslaw ocean disposal sites.


## AN AL YSIS OF AL

TERNA TIVES A Section 102 site designation allows for long

- term sustainable use with no speci fied time limit on the life of the site. Specific regulatory criteria and factors per the MPRSA are analyzed later in this document. The EPA and the USACE considered several alternatives for disposal of dredged material generated from the Siuslaw River n avigation project and other projects with authorized users. Those alternatives included no action, upland disposal, and estuarine disposal. Alternatives considered for ocean disposal included disposal off the continental shelf, continued use of the exist ing ocean disposal sites, and/or designation of new sites. Although other users may require dredged material disposal options, the USACE navigation project is the largest and most regular source of dredged material in the vicinity . Since other potential, but smaller, users of the site would likely

face man y of the same constraints as the USACE in the disposal of dredged material, the discussion of alternatives focuses primarily on USACE navigational dredging.Siuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 18



### No A ction Al ternative Under the no action alt ernative, EPA would refrain from formal designation of any ODMDS for the placement of dredged material by the USACE or other authorized persons or entities. If EPA did not designate site(s), the USACE has the authority to select alternate sites under MPRS A Section 103. The substantive requirements for information and evaluation of a Section 103 site are similar to those of an EPA formal designation under Section 102, and site designation under Section 103 requires EPA concurrence. In addition, the use of a Section 103 site is limited to 5 ye ars with one possible 5

- ye ar extension. The present sites being used at Siuslaw River are Section 103 sites. At the end of the 2009 dredging season, both present sites will have reached the 10

- ye ar use restriction and will no longer be available for use. The no

- action alternative would not meet the project purpose, which is to provide dredged material disposal capacity for long

- term use by

the USACE for the federally authorized Siuslaw River navigation project and dis posal capacit y for other potential users. Therefore, the no action alternative was judged b y both the USACE and EPA to be unacceptable and was dropped from further consideration. 

### Upland Disposal A lternative Hopper dredges are self

- propelled, seagoing vess els and are the onl y equipment that can be used to dredge the navigation channel because they can move quickly

to minimize interference with navigation traffic and can adjust to rapidly changing weather and sea conditions. Because hopper dredges stockpile dredged material on

- board and are designed to bottom dump that material, they

are most efficiently

utilized in conjunction with an in

- water disposal area. Rehandling of material, moving it from the hopper dredge to another location for disposal, introduc es an additional cost and logistical component to the process. To dispose of material from a hopper dredge to a land

- based disposal site would necessitate dredging an in

- water sump in the estuary , bottom dumping the dredged material from the hopper dredge into the in

- water sump, and then pumping the material ashore with a pipeline suction dredge. Aside from increased costs, this approach would have additional adverse environmental impacts associated with the dredging of an in

- water estuarine site to be us ed as the sump. Estuarine sites are both highl y valued and limited (see below for additional discussion). In addition, a significant adverse impact of upland disposal is that naturally occurring sediments would be removed from the littoral sy stem. For the purposes of this analysis, regular upland disposal of Siuslaw River entrance material is not considered feasible due to the economic and environmental effects resulting from nearshore rehandling of dredged material. 

### Estuarine Disposal A lternative Estuarine habitat is limited and environmentally sensitive. Placement of dredged material in estuarine areas is generally onl y environmentall y acceptable for specific beneficial uses, such as in areas where substrate is eroding and the dredged material would be suitable (e.g., fine

- grained and clean) to supplement existing substrate. In general, disposal of dredged material in estuaries would result in greater adverse environmental impacts than disposal in the ocean due to both the limited abundance and high productivity of estuaries relative to nearshore oceanic habitats. Disposal of material into the estuary would also increase the risk of the material eroding and reshoaling in the channel, potentially increasing dredging frequency and/or volumes.Siuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 19

There are operational constraints to estuarine disposal as well. Due to the narrow and shallow confines of the Siuslaw River estuary , no suitable estuarine disposal areas were identified that could be accessed b y a hopper dredge and could accept the volume of material annuall y dredged from the Siuslaw River entrance channel. 

### Ocean Disposal A lternatives Ocean disposal alternatives include disposal of the material off the continental shelf, continued use, by designation, of the existing Section 103 ocean disposal site s, or designation of a new ocean disposal site(s). In addition to general criteria and specific factors required for anal ys is by MPRSA, at Siuslaw, EPA has site management criteria that will be applied when managing disposal at a designated site, and that help to inform the alternatives analy sis. These include maximizing site capacity and lifetime by maximizing the volume of material that moves from the site into the natural nearshore littoral sy stem; avoiding the potential for mounding and associated safet y concerns (e.g. encouraging rapid dispersal); supporting safe and efficient site use/management and site monitoring logistics; and avoiding adverse effects to unique resources. 

### Disposal Off the Continental Shelf The MPRSA directs EPA to utilize, whenever feasible, locations beyond the edge of the continental shelf (Section 102(a)(I), 33 U.S.C. § 1412(a)(I)). This same directive is found in the regulations in the general criteria at 40 CFR § 228.5(e). Transporting dredged material off the continental she lf presents potentially significant environmental concerns. Benthic and pelagic ecos ys tems near the shelf contain important fishery resources and the effects of disposal operations on them are not well understood. Fine

- grained sediment and rocky habitats would be directly impacted by

disposal. These deep

- water areas are stable and generally not disturbed by wave action or sediment movement. Consequently , the benthic invertebrate communities in these deep, offshore environments are adapted to very stable conditions and would likely be less able to survive disturbance from the immediate impact of disposal and the long

- term alteration of substrate ty

pe. Bottom gradients can be 5% to 25% on the continental slope, making accumulated unconsolidated sediments susceptible to slumping. Deposited sediments could be transported long distances both downslope, through turbidity currents, and offshore, by near bottom currents, potentially affecting organisms outside of any designated site. Disposal off the continent al shelf would remove natural sediments from the nearshore Hecata Head littoral transport s ystem, a system that functions with largely non

- renewable quantities of sand in Oregon. While the loss of the present volumes of Siuslaw River dredged material is unlikely to result in disruption of the mass balance of the littoral sy stem, the State of Oregon is already experiencing erosion/accretion patterns that are adversely impacting beaches, spits, wetlands, and other shoreline habitats. Consequently , keeping th is material in the littoral sy stem is perceived as a benefit and helps to sustain a dynamic equilibrium along the Oregon coast. An additional limiting factor in considering a location beyond the edge of the continental shelf is logistical feasibility . At and in the vicinity of the Siuslaw River, potential disposal areas located off the continental shelf would be at least 15 nautical miles offshore in water depths of 600 feet or greater. This distance is well beyond the reasonable haul distance of hopper dredges working the Siuslaw River project, which is discussed in greater detail in the discussion of the Zone of Siting Feasibility

(ZSF). In addition, the feasibility of monitoring a site located off theSiuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 20

continental shelf is questionable, based on safety, cost, and time constraints correlated with increased distance from shore. Given potential uncertain environmental concerns, coupled with the cost/logistical issues of both disposal and monitoring, disposal off the continental shelf is not a feasible al ternative. Substantial additional investigation would be required to determine the scope of the possible environmental impacts of this alternative. Such an investigation is not warranted unless there are no suitable sites closer to shore. 

### Continued Use o f Existing Sites The two existing 103

- selected Siuslaw ocean disposal sites (B and C) have been used for disposal of dredged material since 1997 (see Table 1 and Figure 2). Based on placement of dredged material between 1997 and 2009 at the sites prior to designation, approximately 800,000 cy total have been placed, for a 13

- ye ar average annual loading volume of about 60,000 cy /year. Annual bath ym etric survey s have shown the potential for mounding at the two previously utilized Section 103 Sites B and C. Disposal restrictions, until lifted in 2008, were placed on the southeast corner of Site B which overlapped the much smaller original 1977 Interim Site A. Since there has been a history of mounding at all of the previousl y utilized Siuslaw ocean disposal sites, continued use of existing sites is not considered a viable alternative. 

### Designation of New ODMDS New ODMDS could be evaluated for designation in location(s) that incorporate the existing historical disposal sites, or a new disposal site could be d esignated in an entirely new location. EPA and the USACE prefer to continue use of the two existing historical sites because there is a clear regulatory

preference for the designation of previously used sites (40 CFR 228.5(e)), and with expansion and adapt ive management, they are anticipated to meet the goals for designation. In addition, EPA can utilize past monitoring and surveillance information from these sites for designation, and maintain continuity of monitoring, while extending the monitoring program to expansion areas. The EPA is proposing to increase capacit y and minimize mounding by designating both a larger North and larger South ODMDS for the Siuslaw River. Generall y, material placed deeper than 60 feet disperses slowly , and is therefore rem oved from the active littoral s ystem. To keep more material in the nearshore active littoral sy stem, EPA proposes a North Site configuration that expands the existing 103 Site B to include the original 1977 Interim Site (Site A), and a similar “shallow” ( 30’ to 60’ deep) area to the north of Site A, away from the river mouth. EPA proposes to utilize the shallower portions of the North site to the maximum extent possible in order to keep material in the active littoral zone, and to promote dispersal of mate rial from the site. The EPA acknowledges that previous studies showed the potential for material disposed within the southeastern portions of Site A to re

- enter the channel. However, by allowing for adaptive management at an expanded North site, EPA and the USACE do not expect measurable volumes of dredged material to migrate back into the channel from the proposed North Site. In addition, the proposed South site’s southern boundary was moved to the south, away from the river mouth, doubling the size of the site. Continued management and monitoring of the new Section 102 North and South sites will take place in accordance with a Site Monitoring and Management Plan (see Appendix F).Siuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 21



## AN AL YSIS OF OCE AN DUMPING SITE DESIGNA TION PROCESS AN D ENVIRONMENT AL E FFEC TS Overview Formal designation of ocean dumping sites is the responsibility of EPA as stated in the MPRSA. The process for site designation is found in the ocean dumping regulations at 40 CFR Part 228. The process followed b y EPA, Region 10, and the USAC E for the proposed Siuslaw River ocean disposal sites generall y follows the site designation procedures developed by a joint task force of EPA and USACE personnel titled, General Approach to Designation Studies for Ocean Dredged Material Disposal Sites (EP A/USACE 1984). The procedures utilize a hierarchical framework that initially establishes the broadest economicall y and operationally feasible area of consideration for site location. A step

- by

- step sequence of activities is then conducted to eliminate c ritical and/or unsuitable subareas. Further evaluation of alternative sites (candidate sites) within this area entails various levels of assessment as suggested by the sensitivity

and value of critical resources or uses at risk, and potential for unreason able adverse impact presented by the dredged material to be disposed. The site designation criteria at 40 CFR §§ 228.5 to 228.6 are applied to the information assembled through this process, and a final site or sites are selected and proposed for formal d esignation. The MPRSA ( 33 U.S.C. 1401 to 1445 ) tasks EPA and the USACE with the joint obligation to ensure that ocean disposal will not “unreasonabl y degrade or endanger human health, welfare, or amenities, or the marine environment, ecological sy stems, o r economic potentialities.” The EPA’s site criteria and joint EPA/USACE guidance are intended to result in the designation of an environmentally

acceptable site, oriented toward avoidance of unreasonable degradation or endangerment of human health, welfar e, or amenities, or the marine environment, ecological sy stems, or economic potentialities, which is operationally efficient. 

### Defining a Zone of Siting Feasibility At the outset, and pursuant to jointly developed guidance titled General Approach to Desig nation Studies for Ocean Dredged Materials Disposal Sites (EPA/USACE 1984), a geographic area of consideration referred to as a Zone of Siting Feasibility (ZSF) is a first step towards designating a site. According to the guidance, a reasonable distance o f haul from the dredging site to the disposal site is the determining factor in establishing the ZSF, and will be affected b y available dredging equipment, energy use constraints, costs, and safet y considerations. The initial ZSF, once established, is eva luated according to the statutory and regulatory

criteria under the MPRSA. Each of the criteria is overlain on the preliminary Z SF in sequence to eliminate unsuitable areas and determine the location and overall suitability of remaining sites, if an y, within the ZSF that could be designated for the disposal of dredged material. If, based on that evaluation, a suitable site is not located within the initial ZSF, then the area of consideration must be expanded in order to ensure that a disposal site can be designated that will not unreasonably degrade or endanger human health, welfare, amenities, the marine environment, or ecological sy stems. Although an ODMDS may be proposed for use and potentially utilized by any

person or entity ,Siuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 22

the primary

anticipated user for the currently proposed Siuslaw ODMDS is the Corps, who is expected to use the site annually for disposal of dredged material from the Siuslaw River navigation project. No other potential users of the proposed Siuslaw ODMDS have been identified at this time. Therefore, the discussion of the ZSF below is based solely on the Corps’ anticipated disposal activities. On the West Coast, weather and ocean conditions are major considerations and act as significant limiting factors when assessing the reas onable distance of haul. Rough seas and adverse weather conditions are the norm from October through May on the West Coast. These conditions act to limit ocean disposal of dredged material to a narrow window where it is generall y safe to work from roughl y the end of May to no later than mid

- October, with a high probability of down time due to adverse weather at either end of that period. The availability

of dredging equipment is also a constraint that must be considered in the determination of a ZSF for a proposed ocean disposal site, but particularl y so for sites on the West Coast of the United States. For most of the designated sites in Oregon, the USACE is the primary user and must confront equipment availability issues. The USACE evaluates the avail ability

of Government or contract equipment annually and allocates the use of government dredges for the nation. Hopper dredges are mobile, can work in sea swell conditions up to 10 feet, and are self

- propelled. Therefore, they are generall y the onl y fea sible equipment for dredging most ocean entrance channel/bar situations. Hopper dredge availability on the West Coast has been limited. Many hopper dredges working in the U.S. are often committed to other work on the Atlantic and Gulf of Mexico coasts an d are not available to be used elsewhere, except perhaps on an emergency basis. As a result, there are ty picall y three hopper dredges working on the West Coast that can be used safel y at the Siuslaw River. These dredges must also maintain other projects i n Oregon, Washington, California, and occasionall y Hawaii and Alaska. 

### Siuslaw River Zone of Siting Feasibility The 8

- ye ar average (2002

- 2009) for dredging at the Corps’ Siuslaw River navigation project is 57,495 cy . The amount of time necessary to maintai n a coastal project (exclusive of weather downtime) is a function of dredging a hopper full of material (loading), then transporting that material to, and placing it at, the disposal site(s). This is called “cycle time” and the cycle time can be different for each dredge. Loading time is essentially fixed based on the characteristics of the sediments being dredged, the dredge itself (i.e., pumps, size of hopper, drag arms, etc) and the dredging site conditions. The time to discharge material also is basi cally fixed for a given dredge and the ty

pe of material, but may

vary slightly depending on the disposal methodology outlined in the Site Management and Monitoring Plan (SMMP). The SMMP will direct disposal activities in such a manner to minimize mounding or other environmental effects at the ODMDS. Transport time depends primarily on the haul distance to the disposal site as the speed of different hopper dredges, when full, are similar. Thus, the critical element for new construction or maintenance dred ging is the haul distance between the dredging site and the disposal site from both a time and cost perspective. A significant haul distance will affect the ability to construct or maintain the individual project and very probabl y would have repercussions on the Corps’ ability to maintain other West Coast projects.Siuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 23

Under current and foreseeable conditions at the project, the estimated volume of material to be removed annually

is expected to remain near the current average of 57,495 cy . Based on workload, available funding, and other constraints, the Government

- owned hopper dredge Yaquina is ty

picall y expected to be available 6.92 day s (according to latest 8

- ye ar average) at the Siuslaw River navigation project, or a contract dredge is expected to be availa ble for a similar length of time. This translates into an 8,309 cy per day average production requirement. The rated capacit y for the Ya quina is 1,042 cy and the average load for the Siuslaw project is 1,002 cy /load. Pump time ty

pically is around 65 minutes for the Siuslaw project. Depending on the SMMP, environmental conditions, and characteristics of the dredged material, dump time could vary from 2 to 6 minutes. The dredge ty picall y works 24 hours per day except for Tuesday s when the crew change occ urs. The ZSF can be calculated as follows: Assume 8.29 loads per day (8,309 cy/day  1,002 cy/load = 8.29 loads/day) Pump time (1.085 hr) + Dump time (0.095 hr) = 1.18 hr/load x 8.29 loads or 9.79 hr/day 24 hr/day

- 9.79 hr/day = 14.21 hr/day for transit to and from the disposal site 14.21 hr/day  8.29 loads/day = 1.71 hour transit time for one round trip 1.71  2 = 0.855 hr transit one way 0.855 x 6 kts (vessel speed) = 5.14 nautical miles Thus, the outer limit of the ZSF for the Siuslaw ODMDS, as limi ted by the capacity

of the available dredging plant, average annual dredging quantity , and limited dredging time period, is 5.14 nautical miles from the Siuslaw River navigation project. This is the area within which potential sites will initially be evaluated according to the MPRSA statutory and regulatory criteria. 

### Regulatory

Criteria for Ocean Disposal Site Selection The EPA evaluated the four general (40 CFR 228.5) and 11 specific (40 CFR 228.6) regulatory criteria for site designation in reviewing the currently proposed Siuslaw River North and South ODMDS. A conflict matrix format is utilized in Table 2 to simplify and consolidate scoring for the general and specific site criteria review process. Each area of consideration on the conflict matrix addr esses at least one general or specific criterion. A legend defining the matrix categories follows the table. 

### Application of Four General Criteria (40 CFR 228.5) Minimize Interference with Other Activities (a.) . The first of the four general criteria requ ires that a determination be made as to whether the proposed site or its use will minimize interference with other uses of the marine environment. This determination was made by overlaying individual uses with the resources presented in the Siuslaw Ocean Dredged Material Disposal Site Evaluation (USACE 1992) and the more recent appendices prepared for this evaluation. The report presented the overlay s on a base map giving bathy metry and location of the previous ocean disposal sites in the ZSF. The more i nteractions between various uses and limited resources exist, the more critical the area. The overlay process was used to minimize interference with other uses of the ocean. The selection of features to use for this determination was dependent on whether the resource was considered limited.Siuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 24

Table 2 . Proposed Siuslaw North and South ODMDS Conflict Matrix

AREA OF CONSIDERATION 1/CONFLICT2/POTENTIAL CONFLICTNO CONFLICTBENEFICIAL USE COMMENTS RELEVANT SPECIFIC FACTORS 11 Speci fic Factors 3/ (40 CFR 228.6) RELEVANT

GENERAL CRITERIA 4 General Criteria 4/ (40 CFR 228.5) 1. Unusual Topography/Unique Bottom Features X 1, 6, 8, 11 a 2. Physical Sediment Compatibility X 3, 4, 9 b, d 3. Chemical Sediment Compatibility X Periodic monitoring conducted 3, 4, 7, 9 a, b, d 4. Influence of Past Disposal X Mounding due to past disposal 5, 7, 9, 10 a, b, d 5. Living Resources of Limited Distribution X 2, 3, 6, 8, 11 a, b, d 6. Commercial Fisheries X Salmon, p elagic fish, crabs 2, 8 a, b 7. Recreational Fisheries X Salmon, pelagic fish 2, 8 a, b 8. Breeding/Spawning Areas X 2, 8 a, b 9. Nursery Areas X Juvenile flatfish and crabs. 2, 8 a, b 10. Feeding Areas X Juvenile/adult salmonids, mari ne mammals, pelagic birds 2, 8 a, b 11. Migration Routes X Marine mammals, salmonids, pelagic and shore birds 2, 8 a, b 12. Critical Habitat of Threatened or Endangered Species X No critical habitat present 2, 8 a, b 13. Spatial Distribution of Benthos X 2, 8, 10 a, b 14. Marine Mammals X Potential impact to resident and mi gratory species 2, 8 a, b 15. Mineral Deposits X 1, 8 a, b, 16. Navigation Hazard X Navigation of small boats around the dredge 1, 8 a, b, d 17. Other U ses of Ocean (cables, pipelines, etc) X 8 a, b, d 18. Degraded Areas X 4, 6, 7 a, b, d 19. Water Column Chemical/Physical Characteristics X 4, 6, 9 a, b, d
20. Recreational Uses X Inconvenience to recreational boats 2, 8, 11 a, b, d 2 1. Cultural/Historic Sites X No shipwrecks identified 11 b 22. Physical Oceanography

- Waves/Circulation X 1, 3, 6, 7 a, b, d 23. Direction of Transport/Potential for Settlement X 1, 3, 6, 7 a, b, d 24. Monitoring X 5 a, d 25. Shape /Size of Site X 1, 4, 7 d 26. Size of Buffer Zone X 2, 3, 4, 7, 11 b, d 27. Potential for Cumulative Effects X 4, 7 dSiuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 25

Conflict Matrix Tables Legend 1/ Definition of “Areas of Consideration” 1. Unusual Topography/Unique Bottom Features : Would placement of material in this candidate site affect physical bottom feature that is unique within the local or regional area? 2. Physical Sediment Compatibility : Does the candidate site have similar sediment characteristics to anticipated dredged material? 3. Chemical Sediment Compatibility : Does the candidate site have similar chemical characteristics to anticipated dredged material? 4. Influence of Past Disposal : Would placement of material in this candidate site be affected by previous disp osal of dredge material? 5. Living Resources of Limited Distribution : Would placement of material in this candidate site affect any living resources that do not have a coast

- wide distribution? 6. Commercial Fisheries : Would placement of material in thi s candidate site affect any commercial fishing activity (resource impacts are covered in 8

- 11)? 7. Recreational Fisheries : Would placement of material in this candidate site affect any recreational fishing activity (resource impacts are covered in 8

- 11)? 8. Breeding/Spawning Areas : Would placement of material in this candidate site affect breeding and spawning areas of any species? 9. Nursery Areas : Would placement of material in this candidate site affect nursery areas of any species? 10. Feeding Ar eas : Would placement of material in this candidate site affect feeding areas of any species? 11. Migration Routes : Would placement of material in this candidate site affect migration routes of species? 12. Critical Habitat of Threatened or Endangered S pecies : Would placement of material in this candidate site affect critical habitat of threatened or endangered species? 13. Spatial Distribution of Benthos : Would placement of material in this candidate site change the benthic invertebrate community str ucture (e.g., fine

- gain species to coarse

- grain species, etc)? 14 . Marine Mammals : Would placement of material in this candidate site affect marine mammals or their habitat (e.g., gray whale feeding areas etc)? 15. Mineral Deposits : Would any known min eral deposits be affected by the placement of material? 16. Navigation Hazard : Would the placement of material create a navigation hazard? 17. Other Uses of Ocean : Would placement of material impact other uses of the ocean not addressed elsewhere, such as cables, pipelines, tow boat lanes, and pilot transfer points? 18. Degraded Areas : Would disposal in this candidate site continue to affect or improve the degraded area? 19. Water Column Chemical/Physical Characteristics : Would placement of material in this candidate site affect water column chemical/physical characteristics? 20. Recreational Uses : Would placement of material affect recreational uses? 21. Cultural/Historic Sites : Would placement of material in this candidate site impact or protec t a cultural/historic site? 22. Phy sical Oceanography, Waves/Circulation : Would placement of material affect wave/circulation patterns? 23. Direction of Transport/Potential for Settlement : Would placement of material affect direction of sediment transp ort and/or potential for settlement? 24. Monitoring : Would use of this candidate site affect either on

- going monitoring or the ability to monitor using conventional methods? Monitoring typically would include periodic hydrographic surveys and could incl ude sediment sampling or biological data collection. 25. Shape/Size of Candidate Site : Is the candidate site suitable for the operation and maneuverability of a dredge? Is it oriented so the dredge can place material while heading into the waves? Is the depth of water sufficient to open the hopper doors/dump scow ? Can the dredge operate safely? Is the size of the candidate site large enough for long

- term use? 26. Size of Buffer Zone : Is the candidates site a sufficient distance from important resources or features to protect them from any affect of disposal? 27. Potential for Cumulative Effects : Would placement of material contribute to cumulative affects from other activities?Siuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 26

Conflict Matrix Tables Legend (continued)
2/ Definition of Degrees of C onflict Conflict : There will definitely be an adverse impact on the resource or the use. Potential Conflict : There is a possibility of an adverse impact; however, extent and significance are unknown. No Conflict : There will definitely not be an adverse im pact on the resource or the use. Beneficial Use : There will be a positive impact on the resource or the use. 3/ Eleven Specific Factors for Ocean Disposal Site Selection 1. Geographical position, depth of water, bottom topography, and distance from coast. 2. Location in relation to breeding, spawning, nursery, feeding, or passage areas of living resources in adult or juvenile phases. 3. Location in relation to beaches or other amenity areas. 4. Types and quantities of waste proposed to be dispose d and proposed methods of release, including methods of packaging the waste, if any. 5. Feasibility of surveillance and monitoring. 6. Dispersal, horizontal transport, and vertical mixing characteristics of the area, including prevailing current 1 veloci ty , if any. 7. Existence and effects of present or previous discharges and dumping in the area (including cumulative effects). 8. Interference with shipping, fishing, recreation, mineral extraction, desalination, shellfish culture, areas of special scientific importance and other legitimate uses of the ocean. 9. Existing water quality and ecology of the site, as determined by available data or by trend assessment or baseline surveys. 10. Potential for the development or recruitment of nuisance species w ithin the disposal site. 11. Existence at or in close proximity to the site of any significant natural or cultural features of historical im portance. 4/ Four General Criteria for the Selection of Ocean Disposal Sites a. The dumping of material into th e ocean will be permitted only at sites or in areas selected to minimize the interference of disposal activities with other activities in the marine environment, particularly avoiding areas of existing fisheries or shell fisheries, and regions of heavy commercial or recreational navigation. b. Locations and boundaries of disposal sites will be chosen so that temporary perturbations in water quality or other environmental conditions during initial mixing caused by disposal operations anywhere within the sit e can be expected to be reduced to normal ambient seawater levels or to undetectable contaminant concentrations or effects before reaching any beach, shoreline, marine sanctuary, or known geographically limited fishery or shell fishery. c. Effective January 1, 2009, this paragraph, 40 CFR 228.5(c) was removed and reserved, see 73 Fed. Reg. 74983 (December 10, 2008), and is therefore no longer a criterion in the regulations. d. The sizes of ocean disposal sites will be limited in order to localize, for id entification and control, any single immediate adverse impact and to permit the implementation of effective monitoring and surveillance programs to prevent adverse, long

- range impacts. The size, configuration, and location of any disposal site will be det ermined as a part of the disposal site evaluation or designation study. e. EPA will, whenever feasible, designate ocean dumping sites beyond the edge of the continental shelf and other such sites that have been historically used.Siuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 27

The following were sele cted for evaluation of resources of limited distribution: 1. Navigation Hazards Area/Other Recreation Areas 2. Shellfish Areas 3. Critical Aquatic Resources 4. Commercial and Sport Fishing Areas 5. Geological Features 6. Cultural, Historically

Signi ficant Areas Figure 4 is a composite of the above areas and shows high usage areas within the vicinity of the Siuslaw ocean disposal sites. The denser the pattern overlap, the more interactions between various limited resources exist, thus the more criti cal the overlap area. Figure 4 . Overlay Evaluation of Individual ResourcesSiuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 28

As Figure 4 shows, the adjusted sites are within minimal conflict areas in the ZSF. Disposal operations occur generally between June 1 and October 31 of each ye ar. While this represents a temporal overlap, communications with USACE personnel indicate no observable conflicts between the dredging activities and the fishery . Appendix A contains a discussion of all potential conflicts within the ZSF with living resources, and concludes that there are no major conflicts or predictable future conflicts. Minimizes Changes in Water Quality (b) . The second of the four general criteria requires changes to ambient seawater quality levels occurring outside the d isposal sites to be within water quality criteria, and that no detectable contaminants reach beaches, shoreline, sanctuaries, or geographically

limited fisheries or shellfisheries. No significant contaminant or suspended solids releases are expected with disposal of Siuslaw sandy material (about 97% of dredged material) or disposal of finer

- grained material (about 3% of dredged material) (see Appendix C). The proposed sites should not have an y long

- term impact on the water qualit y, with the primary impact of disposal activities on water quality expected to be the temporary turbidity caused by the phy sical movement of sediment through the water column. There should be no water quality perturbations moving toward a limited resource. Bottom movement of deposi ted material is discussed in Appendix B. Interim Sites Which Do Not Meet Criteria (c) . Effective as of January 1, 2009, this paragraph, 40 CFR 228.5(c) was removed and reserved. See 73 Fed. Reg. 74983 (December 10, 2008), and is therefore no longer a cri terion in the regulations. Size of Sites (d) . The third general criterion requires that the size, configuration, and location of the site(s) be evaluated as part of the study , and that the size be limited. Since 1977 specific dredged material disposal sites have been used off the mouth of the Siuslaw River. More than thirt y - years of monitoring at Siuslaw and other Oregon ODMDS have shown that original 1977 Interim Site configurations were too limited in size. Potential mounding limited long

- term site c apacity , and since there has been a history of mounding at the smaller previously

utilized sites, it is clear that new designated sites should be larger to increase capacity and enhance dispersal. The USACE 1992 Siuslaw Ocean Dredged Material Disposal S ite Evaluation report identified two ODMDSs north and south of the entrance. These sites have been used under the Corps Section 103 site selection authority since 1997. This tripled the area available for dredged material placement compared to the relative ly small 1977 Interim Site. Based upon annual bathy metric monitoring of the Section 103 sites from 1981 to 2009 (See Appendix B figures B

- 4 through B

- 8), EPA proposes to ensure long

- term disposal capacit y b y enlarging the designated sites

-- doubling the S outh Site and expanding the North Site into shallower water. Two sites are again being proposed, to ensure site managers can be responsive to the specifics of each dredging season based on dredge schedules and recorded seasonal sediment transport patterns north and south along the Oregon coast. The proposed sites are located within the generally homogeneous sandy

habitat off the mouth of the Siuslaw River, within a reasonable haul distance from dredging areas and generall y removedSiuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 29

from other use conflict s. They encompass previously

used and monitored sites, so past monitoring data may

be used to manage the sites. The proposed sites now incorporate shallow and deep water areas. Use of the shallower portion of the North Site will facilitate increased sedime nt transport thereby increasing long

- term site capacity . Preferential utilization of the shallow portions of the North Site also meets the management goal of keeping material in the littoral sy stem. However, as seen in the 1977 Interim Site, mounding could occur if too much material is placed too quickly in shallow water. The designation of multiple sites with deeper areas within the sites, allows site managers to be responsive to annual and long

- term sediment transport patterns. The proposed sites are or iented for safe and optimal on

- site dredge operations. Oriented with their long axis toward the west and northwest, the sites allow hopper dredges leaving the Siuslaw to head perpendicular to the dominant wave direction while disposing of dredged material. Finally , in addition to formal site selection criteria and factors, the size, configuration and locations of the proposed sites meet other selection and management considerations important to EPA, including maximized capacit y of the sites (since a Sect ion 102 site designation is not limited to a predetermined number of ye ars), minimized potential for mounding and associated safet y concerns, maximized volume of material remaining in the littoral system, and avoidance of effects to unique resources.
Si tes Off the Continental Shelf or Other Historically Used Sites (e) . Any potential disposal sites off the continental shelf in the area of the Siuslaw River would be at least 40 nautical miles offshore. By

contrast, the Siuslaw ZSF extends a maximum of on ly 5.14 nautical miles from shore. The Siuslaw navigation project could not be economically maintained using current dredging technology

and availability

if a site off the continental shelf was used. In addition, use of a site off the continental shelf w ould result in as loss of sediments from the nearshore littoral transport sy stem, which could cause detrimental bottom or shoreline changes in the ZSF. Further, very

little is known of the ecology of benthic communities on the continental slope, and dispo sal in this area could cause impacts of unknown severit y. Finally, relative monitoring and surveillance logistics would be more costl y and difficult at a site located off the continental shelf. For these reasons, designation of an ODMDS off the continental shelf is not recommended. The proposed sites encompass sites that have been historically used, meeting the second directive of this criterion. 

### Application of Eleven Specific Factors (40 CFR 228.6) Geographical Position, Depth of Water, Bottom Topography , and Distance from the Coast (1) . The proposed North and South ODMDS are approximately 1 mile offshore from the entrance to the Siuslaw River (see Figure 1). Appendix B contains a discussion of the bottom topograph y of the proposed sites. The two designated sites would be used for disposal of dredged material from the Siuslaw River navigation project and other permitted projects. The proposed North ODMDS is 4,800 feet by 2,000 feet with an average depth of 90 feet (depth ranges from approximately 30

- 11 5 feet), and has the following coordinates (NAD 83):Siuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 30

44 o 01’ 31.03”N, 124 o 10’ 12.92”W 44 o 01’ 49.39”N, 124 o 10’ 02.85”W 44 o 01’ 31.97”N, 124 o 09’ 01.86”W 44 o 01’ 13.45”N, 124 o 09’ 11.41”W The proposed South ODMDS is 3,000 feet by 2,000 feet with an aver age depth of 100 feet (depth ranges from approximately 80

- 125 feet), and has the following coordinates (NAD 83):
44 o 00’ 46.72”N, 124 o 10’ 26.55”W 44 o 01’ 06.41”N, 124 o 10’ 24.45”W 44 o 01’ 04.12”N, 124 o 09’ 43.52”W 44 o 00’ 44.45”N, 124 o 09’ 45.63”W Based upon consideration of the location, depth of water, bottom topography , and distance from the coast, the proposed Siuslaw ocean disposal sites are expected to be suitable for the disposal of dredged material when the material is placed in accordance with the SMMP. Location in Relation to Breeding, Spawning, Nursery, Feeding, or Passage Areas of Living Resources in Adult or Juvenile Phases (2) . Aquatic resources of the oceanic region off the mouth of the Siuslaw River are described in detail in Appendix A. Inaddition, EPA evaluated possible impacts to species and critical habitat listed under the Endangered Species Act in a Biological Assessment (EPA 2009). The proposed ocean disposal sites are located in the nearshore area and man y nearshore pelagic org anisms are found in the water column over the sites. These include zooplankton (copepods, euphausiids, pteropods, and chaetognaths) and meroplankton (fish, crab, and other invertebrate larvae). These organisms generall y display seasonal changes in abundance. Since they are present in the oceanic region off of most of the Pacific Coast, those populations directly off the Siuslaw River are small compared to the overall coastal populations. Based on evidence from previous zooplankton and larval fish studie s, it appears that there will be no impacts to organisms in the water column (Sullivan and Hancock 1977). Benthic samples are discussed in detail in Appendix A. Based on the anal ysis of benthic samples collected from the area of the proposed Siuslaw oce an disposal sites, the sites contain benthic fauna common to nearshore, sandy, wave - influenced regions that exist along much of the Pacific Coast in Oregon and Washington. Sediment in and near the proposed Siuslaw ocean disposal sites consists of well

- sorted, fine sands ty pical of Pacific Northwest coastal areas (Appendix C). The infaunal community of the Siuslaw study

area is dominated by

gammarid amphipods and polychaete worms. The benthos in the area is t ypical of the communities found near other ocean disposal sites along the Oregon Coast, such as Coos Bay

areas E and F, the Siuslaw River, and the Chetco River (Hancock et al., 1981; USACE 1985, 1988a, 1988b, 1990). This benthic community , largely dominated by

very mobile organisms, provides an import ant link in the marine food web. These organisms serve as a direct food source for other benthic organisms and demersal fish. They also play an active role in the breakdown of organic debris and the tube

- building species help stabilize the marine sediments. Many

of the benthic species in the area are able to survive in this dy namicSiuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 31

environment since they

are either very

mobile or are able to react both to natural or human perturbations. They

can readil y recolonize disturbed areas. The Siuslaw nearshore area supports a variet y of pelagic and demersal fish species and shellfish. Many of these species have a reproductive strategy that includes releasing a large quantity of eggs so that some individuals will survive the substantial mortality common to the species during the larval and juvenile stages. Crabs in particular release large number of eggs into the water column. The larvae that hatch are planktonic for several months before settling to the bottom of the estuary

and in the nearshore area as young crab. During this time, they are subjected to a variet y of environmental factors that affect their survival and have a direct affect on adult population numbers. Numerical modeling of the disposal process b y Pearson and others (2006) at the mouth of the Columbia River showed that predicted impact pressure, shear stress, and mound depth were greatl y reduced b y discharge in deep water (e.g., ocean disposal in 230 and 280 feet of water). The study found that vulnerability

of crabs to compression (vertical) forces was low and that crabs may

be vulnerable to injury

from surge currents. However, the surge currents from modeling the deep

- water scenarios were not strong enough to mobilize sediment greater than 1 millimeter or juvenile Dungeness crabs. Results also suggested that Dungeness crabs were vulnerable to injury

from burial through effects on crab respiration and survival (Pearson et al., 2006). Previous studies showed that under burial with 10 centimeters (about 4 inches) of material, crabs were unabl e to recover the respiratory pathway and switched to moving up through the sediment, a process that occurred over 24 hours. Vavrinec and others (2007) performed laboratory experiments to isolate the effects on Dungeness crabs from burial by dredged materi al, and crab response and injury caused b y tumbling in horizontal surge currents. The horizontal surge current experiments showed no damage, 100 percent survival, and the behavioral capability of crabs to recover their proper orientation after tumbling. The crabs either maintained their proper orientation on the bottom and in the water column, or righted themselves within 2 seconds after being moved by a 3.2 meter/second (about 10.5 feet/second) surge current. The crab burial experiments ( Vavrinec et al. , 2007) showed that survival from burial increased as burial depth decreased, and survival increased as crab size increased. Also, male crabs had a higher survival rate than female crabs. When restrained and not allowed an escape response, all the adult crabs suffocated and died within 24 hours when buried in 8 centimeters of dredged material. The observations clearl y show that maintaining the respiratory pathway is the key to surviving burial. For unrestrained crabs tested in large tanks with sufficient space for escape response, survival increased substantially . Escape response and other adaptive behavior clearl y enabled the subadult and adult crabs to achieve almost 100 percent survival under the same burial depth that allowed no survival at all for restrained crabs. For unrestrained age 2+ crabs, predicted survival begins to decrease at burial depths greater than 10 centimeters, and is less than 10 percent at burial depths greater than 16 centimeters. Behavioral observations and survival results sh owed that subadult and adult crabs have the capability to respond to surge currents and burial in way s that substantially reduce exposure to stress and allow high survival.Siuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 32

The nearshore area off the Siuslaw River supports anadromous salmonids including c oho salmon, summer and winter steelhead, and spring and fall Chinook salmon, as well as a variety of other pelagic and demersal fish species. Seals and sea lions inhabit the lower Siuslaw River and coastal area. The Siuslaw nearshore area and shoreline p rovides important habitat for shorebirds, waterfowl, herons, and man y other species of birds. Pelagic birds (e.g., murres, auklets, cormorants) likely use the area for foraging. Federall y listed species that may be present in the Siuslaw offshore area we re previousl y discussed in the Affected Environment, Biological Resources section of this report. In general, the locations of the proposed ocean disposal sites do not provide unique breeding, spawning, nursery , feeding, or passage habitat. It is unlikel y that any of the larger organisms (fish, marine mammals, etc.) would experience phy siological effects as a consequence of disposal because the resulting turbidity plume and phy sical disturbance to the water column would likely

cause them to avoid the area . Based on modeling completed by the USACE, water column turbidity

would be expected to dissipate within a few minutes to half hour. Any avoidance behavior would be limited to the duration of this phy sical disturbance. Indirect impacts could occur if di sposal operations changed the value of the habitat by burying the existing benthic community where dredged material is deposited. The benthic community would be expected to re

- colonize within a period of a few weeks to months after disposal, limiting any effects to forage fish (USACE 1993). Lastly , evaluation of past disposal activities has not indicated that an y long

- term adverse impacts to living resources have occurred. Location in Relation to Beaches and other Amenity Areas (3) . The proposed ocean d isposal sites are at least 2,000 feet from the end of the jetties and 3,000 feet from the nearest beach. There are no rocks or pinnacles in the vicinity of either site. The Siuslaw River marks the northern boundary

of the Oregon Dunes National Recreation Area. This portion of the recreation area contains no developed facilities other than a paved road that parallels the shoreline and provides access to the beach and South Jetty area. Two public recreation areas are located to the north of the Siuslaw Rive r. Heceta Beach Park is operated b y Lane Count y with beach access, picnic tables, and restrooms. Harbor Vista Park is also operated b y the county and offers 15 acres of tent and recreation vehicle camping on a ye ar - round basis. It is one of the few campgro unds on the Oregon Coast with an ocean view and has restrooms, showers, a playground and hiking trails. Beachcombing, sightseeing and clamming are popular activities along the entire coastline. The area within the Oregon Dunes National Recreation Area rece ives a greater amount of use because of availability

of public access. The proposed designation of the Siuslaw North and South ocean disposal sites is not expected to have any impact on the recreational uses of the adjacent uplands areas within these recre ation areas. Types and Quantity of Wastes Proposed to be Disposed of, and Proposed Methods of Release, including Methods of Packing the Waste, if any (4) . Dredged material subject to the MPRSA is not a waste. The sites that are designated will receive dredged materials transported by either government or private contractor hopper dredges or dump barges. Current hopper dredges or dump barges available for use have capacities ranging from 800 to 6,000 cy. This would be the likely

volume range of dredged material deposited in any one dredging placement cycle. The estimated volume to be removed annually from the Siuslaw River federal navigation project will range, but can be placed at the sites in one dredging season b y any combination ofSiuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 33

private and gove rnment dredges. For example, volumes from 1997 to 2009 ranged from 22,300 cy to 117,300 cy , giving a 13

- year average annual volume of about 60,000 cy. The dredges or barges would be under power and moving during disposal. The bulk of the dredged material to be disposed in the ocean comes from shoals in and near the Siuslaw River entrance channel. These shoals consist primarily of marine sand transported into the entrance as part of the Heceta Head littoral cell. The material meets marine sediment screen ing level guidelines for chemicals of concern per the Sediment Evaluation Framework (SEF 2009), is far removed from known sources of contaminants, and has been characterized under the SEF as suitable for unconfined open

- water disposal. The federall y mai ntained entrance channel into the Siuslaw River is authorized at 18 feet deep and 300 feet wide, and runs from deep water to river mile (RM) 0.2. From there upstream to the dock at Florence (RM 5.0), the channel is maintained to 16 feet deep and 200 feet w ide. A turning basin, currentl y maintained by the Corps at 16 feet deep, 400 feet wide and 600 feet long, is located opposite the dock at Florence. The channel from RM 5.0 upstream to RM 16.5 is an authorized (though not currentl y maintained) federal chann el, 12 feet deep and 150 feet wide. At RM 15.8 the channel widens into a turning basin 12 feet deep, 300 feet wide and 500 feet long, also part of the federally

authorized, but not currently maintained channel. The channel above RM 5.0 has required very infrequent maintenance. A pipeline dredge last cleared the shoals at RM 5.5 and 6.0 in 1982. No dredging has been performed above that point since 1976. Siuslaw River sediments (to RM 16.1) were last sampled in 2006. These ph ys ical and chemical anal ys es in dicate that the material is primarily sand, meets marine sediment screening level guidelines for chemicals of concern per the Sediment Evaluation Framework (SEF 2009), is far removed from known sources of contaminants, and would be characterized under the SEF as suitable for unconfined open

- water disposal Feasibility of Surveillance and Monitoring (5) . Monitoring and surveillance are both feasible within the ZSF and are included as requirements in the SMMP for these proposed sites (see Appendix F). At a minimum, annual bathy metric survey s will be conducted in areas that receive dredged material. More frequent survey s will be conducted when necessary to ensure unacceptable mounding is not occurring that could pose a threat to navigation safety. If actual field monitoring of the disposal activities is required because of a future concern for habitat changes or limited resources, several research groups are available in the area to perform any required work. The proposed Siuslaw ocean disposal sites are re adil y accessible. Most surveillance and monitoring work can be performed from small, surface research vessels at a reasonable cost, or from the disposal vessel. Dispersal, Horizontal Transport and Vertical Mixing Characteristics of the Area Including Pre vailing Current Direction and Velocity, if Any (6) . The sediments dredged from the Siuslaw River entrance are predominantl y marine sands and fluvial gravels. Although the Siuslaw River delivers a large sediment load, the bottom contours suggest a rapid d istribution away from the river mouth. The beaches seem to be in equilibrium, suggesting that littoral transport is in balance. From bottom current records, there appears to be a net annual transport of sediment to the north. There is some southward sediment transport during summer. DuringSiuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 34

summer, the current velocities are variable (see Appendix B). This is due to the constantly varying river outflow combined with tidal flows to produce a highl y variable influence on the nearshore circulation. Sedime nt movement in the littoral zone consists of two mechanisms depending upon the size of the sediment. Any

thing finer than sand

- size is carried in suspension in the water and is removed offshore relativel y quickly. The almost total lack of silts and clays within the Siuslaw ZSF attests to the efficiency

of this mechanism. Sediments sand

- size or coarser may be occasionally suspended b y wave action near the bottom, and are moved b y bottom currents or directly as bedload. Tidal, wind and wave forces contribute to generating bottom currents, which act in relation to the sediment grain size and water depth to produce sediment transport. Existence and Effects of Current and Previous Discharges and Dumping in the Area including Cumulative Effects (7) . No cumulative effects have been documented in the area aside from mounding, i.e. lack of material dispersal, within the sites as currently configured. The Siuslaw North and South ODMDS are being proposed because of mounding problems associated with disposal at the previous 1977 Interim and Section 103

- selected ocean disposal sites. The proposed North and South sites are located and sized to allow management of the sites

– a flexible disposal strategy implemented within larger sites to minimize mounding. Per the SMM P, annual bath ym etric monitoring will be used to track changes in site bathymetry and will be used to evaluate potential mounding. The preference for disposal of material in the shallow portions of the proposed North Site will provide the positive cumulat ive effect of returning natural material to the Heceta Head littoral cell. Interference with Shipping, Fishing, Recreation, Mining Extraction, Desalination, Fish and Shellfish Culture, Areas of Special Scientific Importance, and Other Legitimate Uses of the Ocean (8)

. Shipping . No conflicts with commercial navigation traffic have been recorded in the long history

of hopper dredging activity . The likely reason for this is the light commercial traffic in the Siuslaw River channel.
Commercial and Recre ational Fishing . Commercial and recreational fisheries occur in and around the proposed Siuslaw ocean disposal sites (see Appendix A). The Siuslaw ZSF area supports a moderate commercial fishery primaril y for salmon, groundfish, and Dungeness crabs. The c ommercial fishing season generall y begins in June and runs through October, subject to established catch quotas. During this period, the potential exists for conflicts between a dredge and fishing boats. Based on data from the National Marine Fisheries S ervice (NMFS 2006) for commercial fishing, a total of 38 vessels, all commerciall y registered, delivered landings to Florence in 2000, in the following West Coast fisheries: crab, groundfish, highl y migratory species, salmon, shrimp, and other species. Dun geness crab had the highest landing value at $562,057, while groundfish landings were the largest by weight at 124.3 metric tons. A total of 41 commercial vessels were owned b y Florence residents in 2000, 19 of which participated in the federally

- managed groundfish fishery

.Siuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 35

A locally important recreational salmon fishery exists offshore of the Siuslaw River. Based on data from NMFS (2006), there is at least one sport fishing charter business in Florence. There were seven sport fishing licensing agents in Florence in 2000, when 4,907 sport fishing licenses were sold at a value of $80,163. Even though the offshore salmon fishing can be productive, a rough bar periodicall y limits this opportunity for most small pleasure craft. Salmon fishing is most popular from May

through September when ocean conditions are more predictable and salmon are feeding in the nearshore area prior to the fall spawning runs. The y ear 2000 recreational salmonid catch in the ocean boat fishery was 250 Chinook salmon and 472 coho sal mon. The Siuslaw jetty

fishery is also popular and accounts for a relatively high number of angler use day s. The jetties are among the best in the state for catching surf perch. A smooth bottom offshore of the Siuslaw River has limited the establishment of substantial bottom fish populations, however the year 2000 non

- salmonid catch was a total of 213 fish including greenstripe, canary , and yelloweye rockfish, and Pacific halibut.
Mineral Extraction . There are no known metallic mineral deposits withi n the Siuslaw ZSF. No exploratory

oil/gas wells have been drilled offshore near the mouth of the Siuslaw River and no development is expected in the future.
Desalination . There are no desalination plants in the area of the Siuslaw River. Wave Energy

. With the increased interest in alternative energy sources, various wave energy projects have been proposed off the Oregon Coast. The Oregon State Governor, in a November 2007 news release to the Oregon Fishing Industry , stated that he was asking the Fed eral Energy

Regulation Commission to limit the permitting of wave energy to five to seven locations. Wave energy

projects at those locations will involve numerous generating buoy s moored offshore with transmission lines running to shore distribution facil ities. Currently , no wave energy

projects are proposed off the Siuslaw River.
Fish and Shellfish Culture . There are no fish or shellfish culture operations in the area of the proposed Siuslaw ocean disposal sites.
Marine Reserves . The State of Orego n has initiated efforts to establish a network of state marine reserves as part of an overall strategy to manage its marine waters and submerged lands. The overall purpose would be to protect, sustain, or restore the nearshore marine ecos ys tem, its habitats, and species. A state marine reserve, as defined by Oregon, is an area within Oregon’s state territorial sea or adjacent intertidal area that is protected from all extractive activities including the removal or disturbance of living and non

- living mari ne resources. Marine reserves are intended to provide lasting protection. Dredging and disposal are identified as disturbances and would be banned from areas designated as marine reserves. In 2009, Oregon authorized two marine reserves, one at Otter Roc k off Depoe Bay and one at Redfish Rocks off Port Orford. State agencies are to evaluate potential reserves at Cape Falcon south of Cannon Beach, Cascade Head near Lincoln City , and Cape Perpetua near Yachats. State agencies also have been directed to su

pport a reserve proposal for the Cape Arago

- Seven Devils area, south ofSiuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 36

Coos Bay . None of the sites currentl y identified are in or near the proposed Siuslaw OSMDS, and all coastal ocean disposal site designations will have to avoid marine reserve areas. Special Scientific Importance . There are no known transects or other scientific study locations that would be impacted b y disposal at the proposed Siuslaw ocean disposal sites. General Discussion of Other Legitimate Uses. There has not been a demonstrated conflict with an y of the above listed uses at the historically used ocean disposal sites and no use conflicts are expected at the two proposed sites. There is a low potential for future conflicts given that the area of the proposed sites has no unique value, is relatively small, and presents few potential conflicts with other uses in the vicinity . Since dredged material disposal sites in the vicinity have been in use for over 30 ye ars, EPA’s designation of the two proposed Siuslaw ocean disposal sites would not be expected to result in any change to the existing uses of the area, b y an y individuals or groups, or an y associated economic benefit of those uses. It should also be noted that EPA is proposing to designate these ODMDS primarily in support of the Corps’ operation and maintenance dredging in the Siuslaw River navigation channel. The need for that maintenance dredging was recentl y underscored by U.S. Coast Guard in a letter dated March 15, 2010 , which characterized the Siuslaw as the most restricted entrance bar on the coast of Oregon. The dredging of the entrance bar at Siuslaw is required annuall y in order to facilitate man y of the other uses of the area. The Existing Water Quality and Ecology of the Site as Determined by Available Data or b y Trend Assessment or Baseline Survey (9) . Water and sediment quality analy ses conducted in the study area and experience with past disposals in this region have not identified any adverse water qualit y impacts from ocean disposal of dredged material (see Appendix C). The ecology of the offshore area, based mainly on fisheries and benthic data, is that of a mobile sand community . Neither the pelagic or benthic communities should sustain any long

- term impacts due to their mobility

and widespread occurrenc e off the Oregon Coast (see Appendix A). Potentiality for the Development or Recruitment of Nuisance Species in the Disposal Site (10) . Nuisance species are an y undesirable organism(s) not previously found at a disposal site. They are transported to, or recruited to, a site because the disposal of dredged materials creates an environment where they can establish. Materials to be dredged and transported to the proposed Siuslaw ocean disposal sites historically have been classified as uncontaminated marin e sands similar to the sediment present at the sites. Potential material dredged from the upstream boat basin access channels may include fine

- grained material, however onl y limited quantities of fine

- grained material from the boat basin access channels h ave been placed in the ocean. An y m aterial proposed for ocean disposal would be subject to sediment quality evaluation. Therefore, it is highly unlikel y that nuisance species could be established at the disposal site since habitat or contaminant levels are unlikely to change over the long

- term. Existence at or in Close Proximity to the Site of any Significant Natural or Cultural Features of Historical Importance (11) . The cultural resources of the Siuslaw River study area is described in detail in Appen dix D. The cultural resource that has the greatest potential for impact by use of the proposed ocean disposal sites is shipwrecks. Potential shipwreck areas areSiuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 37

evaluated in Appendix D. Historical records show that there are not an y s hipwrecks within th e area of the proposed Siuslaw ocean disposal sites.


## SUMM ARY OF COORDINA TION UNDER OTHER AP PLIC AB LE FEDERA L ST

AT UTES Federal A ction The proposed federal action consists of designation of two ocean disposal sites at the mouth of the Siuslaw River. Site de signation does not create or confer rights on an y person to use a designated site upon the effective date of site designation. Persons or entities who seek to use a site must first obtain a federal permit, or in the case of the USACE, meet the substantive permit requirements, in order to actuall y use a designated ocean dredged material disposal site. This process would include meeting the requirements of applicable statutes and regulations. The EPA recognizes, however, that site designation is intended t o have a practical result. When sites are designated, it is expected that such sites will be used by persons or entities meeting the statutory and regulatory

criteria for ocean disposal of dredged material. Therefore, actual disposal is an indirect effec t of site designation and is included in the evaluation of effects under the below listed statutes.


### Public Comments EPA received three comments on the proposed rule. All three comments supported the Site designations. One commenter asked whether the Sit es could be extended to run parallel to the coastline in order to create a “speedbump” resulting in decreased wave energy and erosion on the beach. The final Sites include shallow areas (less than 50 ft), where more material is expected to remain the litt oral sy stem, thereby potentiall y decreasing potential beach erosion. The creation of a nearshore “speedbump” or berm would dissipate wave energy reaching the beach, but would increase the wave height at the berm, potentiall y creating an unacceptable safety risk. The same commenter asked whether the sandy dredged material could be used to restore an eroded beach rather than be disposed in the Sites. The sandy dredged material in the vicinity of these Sites is already found in abundance onshore in the near by Oregon Dunes Recreation Area and onshore dune fields. No eroded beaches in the immediate vicinity of the Sites for which this material is needed have been identified at this time. Other general questions included in this comment letter regarding timin g of dredging and disposal, sediment quality , alternatives, etc. are addressed elsewhere in this document. 

### Endangered Species Act In the Biological Assessment prepared for the proposed action (EPA 2009) and subsequent supporting documents, EPA concluded that the indirect effects of designation of the Siuslaw ocean disposal sites:Siuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 38

1. May affect, but is not likely

to adversel y affect OC coho salmon, SONCC coho salmon, and Lower Columbia River coho salmon; no effect to critical habitat for OC and SONCC coho sal mon. 2. May affect, but is not likely

to adversel y affect any

Chinook ESU; no effect to critical habitat. 3. May affect, but is not likely

to adversel y affect Southern DPS green sturgeon or designated critical habitat. 4. Is not likel y to jeopardize the continued e xistence of Southern DPS Pacific eulachon. 5. May affect, but is not likely

to adversel y affect Steller sea lion, blue whale, fin whale, humpback whale, southern resident killer whale; no effect to critical habitat. 6. May affect, but is not likely

to adversel y affect marbled murrelet, short

- tailed albatross, and brown pelican; no effect to critical habitat. 7. No effect on western snowy plover, northern spotted owl, Oregon silverspot butterfly , Fender’s blue butterfly , Kincaid’s lupine, Willamette daisy , and Bradsh aw’s desert parsley ; no effect to critical habitat. The EPA initiated consultation under Section 7 of the Endangered Species Act of 1973, as amended, 16 U.S.C. Sections 1531 to 1544, based on this documentation with both the U.S. Fish and Wildlife Service and National Marine Fisheries Service (NMFS) b y letter dated July 22, 2009. USFWS concurred with EPA’s “may affect, not likely

to adversely

affect determination for marbled murrelet, short

- tailed albatross, and brown pelican via letter dated August 24, 2 009. NMFS issued a Biological Opinion (BO) on April 21 , 2010. NMFS concluded that EPA’s action is not likely to jeopardize the continued existence of Oregon Coast (OC) coho salmon or southern green sturgeon (Acipenser medirostris), or to destro y or adversely modify critical habitat designated for green sturgeon. NMFS also concluded that EPA’s action would not likely adversel y affect southern green sturgeon, euchalon, eastern Stellar sea lions, blue whales, fin whales, humpback whales, Southern Resident Killer whales, marine turtle species, or critical habitat designated for southern green sturgeon or proposed for green leatherback turtles. NMFS concluded that dredging activities were not interrelated to EPA’s action. However, NMFS did make a finding that disposal of dredged material at the Sites by the Corps, the anticipated primary

user of the Sites, was interrelated to EPA’s action. NMFS then focused its effects anal ys is on the effects of disposal at the Sites. L ooking solely to the effects of disposal of dredged material at the Sites by the Corps from the Corps’ Siuslaw River Navigation project, NMFS estimated 19 juvenile OC coho salmon per year were likely to be injured or killed by Corps activities. NMFS acknowledged that EPA’s action does n ot authorize or compel site use and will not itself result in disposal of dredged material. NMFS found that all incidental take will occur at the project

- specific level. Based on this finding, NMFS did not find a basis to provide a take authorization in the current BO. NMFS stated that all take authorization will occur in subsequent site

- specific consultations. Finally NMFS included two discretionary conservation recommendations in the BO. The first recommendation suggested collaborating with NMFS a nd the Corps on a methodology to evaluate the effects of dredging and disposal on ESA

- listed species. The second recommendation suggested undertaking a study to determine seasonal distribution, abundance,Siuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 39

and habitat use of salmon, sturgeon, and marine turtles in the nearshore within and near the contour of designated ocean dredged material disposal sites. Such recommendations are purel y advisory in nature. EPA appreciates that collaboration on a methodology could be helpful and supports NMFS and Corps e fforts in such an endeavor. EPA also appreciates that the study recommended b y NMFS could contribute to the scientific knowledge base but believes that NMFS, the expert Federal agency on seasonal distribution, abundance and habitat use would be better sui ted than EPA to carry out such a study

. 

### Magnuson - Stevens Fishery Conservation and Management Act In the Essential Fish Habitat (EFH) assessment prepared for the proposed action (EPA 2009), it was concluded that the designation of the proposed Siuslaw ocean disposal sites may adversel y affect EFH for some flatfish species (arrowtooth and starry flounder; English, sand, butter, petrale, rock, and curlfin sole; and Pacific sanddab), big skate, spiny dogfish, soupfin shark, four c oastal pelagic fish species (no rthern anchov y, pacific sardine, pacific mackerel, and jack mackerel), and Chinook/coho salmon. However, any effects are expected to be minor and temporary

and are not expected to reduce the quality and/or quantit y in an y significant way for any EFH for these species. Additionally , the following measures were considered by EPA as a way to mitigate any

adverse impacts to designated EFH . The EPA expects to incorporate these measures into the SMMP for the proposed Siuslaw ocean disposal sites.
1. Dredged mate rial to be disposed at the Siuslaw North and South ocean disposal sites must determined to be suitable for unconfined, aquatic disposal. In the event that any dredged material is not suitable for unconfined, aquatic disposal, the dredged material found un suitable will not be disposed at the Siuslaw ocean disposal sites, but will be placed at acceptable upland disposal sites. 2. Bath ym etry

at the Siuslaw North and South ocean disposal sites will be monitored on a regular basis to ensure that mounding is not oc curring

. The EPA initiated consultation under the Magnuson

- Stevens Fishery Conservation and Management Act, 16 U.S.C. Section 1855(b), based on this documentation with NMFS by letter dated July

22, 2009. NMFS response, dated April 16, 2010, concluded th at the proposed action and the effect of disposal at the Sites would have adverse effects on designated EFH in the form of increased turbidity and decreases in prey

resources. NMFS provided two “conservation recommendations” seeking to implement the effec ts methodology and habitat usage studies included in the ESA section of the BO. EPA is responding to these recommendations separatel y, by letter as required under the Magnuson

- Stevens Fishery Conservation and Management Act. 

### Marine Mammal Protection Act The EPA determined that the proposed action to designate the proposed Siuslaw ocean disposal sites would not result in take or incidental take of any protected marine mammal under the Marine Mammal Protection Act of 1972, as amended, 16 U.S.C. Sections 13 61 to 1389. The Biological Assessment, which evaluated the possible effects on ESA listed marine mammals, including Steller sea lions and whales, was provided the NMFS Office of Protected ResourcesSiuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 40

for review on July

22, 2009. In their April 16, 2010 BO, NMFS found that all effects of the action are expected to be discountable or insignificant for ESA

- listed marine mammals. 

### Coastal Zone Management Act EPA submitted a consistency determination pursuant to the Coastal Zone Management Act, 16 U.S.C. Sections 1451 to 1465, to Oregon’s Department of Land Conservation and Development (DL CD) by

letter dated January

19, 2010. Via letter dated April 14, 2010, DL CD concurred with the EPA that the proposed project is consistent to the maximum extent practicable with the enforceable policies of the Oregon Coastal Management Program. 

### National Historic Preservation Act National Historic Preservation Act, as amended, 16 U.S.C. Sections 470 to 470a

- 2, which requires Federal agencies to take into account the effect of thei r actions on districts, sites, buildings, structures, or objects, included in, or eligible for inclusion in the National Register. The EPA determined that no historic properties would be affected by the proposed undertaking, the designation of the propose d Siuslaw ocean disposal sites. The EPA provided that determination and supporting evaluation to the State Historic Preservation Officer in the Oregon Parks and Recreation Department by letter dated November 24, 2009. The Tribal Governments, listed in th e next section, were copied on the historic property letter as consulting parties. By letter dated December 10, 2009, the State Archaeologist concurred that the project would have no affect on an y known cultural resources. 

### Tribal Consultation Government

- t o - government consultation letters, dated November 24, 2009, were sent to the Coquille Indian Tribe, the Cow Creek Band of Umpqua Tribe of Indians, the Confederated Tribes of the Grand Ronde Community , the Confederated Tribes of the Siletz Indians, and the Confederated Tribes of the Coos, L ower Umpqua and Siuslaw Indians. Tribal comments were also solicited during the NHPA process. Follow

- up phone calls were made to staff at each of the listed Tribes during January 2010. No Tribal comments were received.


## SELECTION OF OCE AN DISPOSA L SITES FOR FORM AL DESIGN AT ION Based on the evaluation of criteria contained in 40 CFR Part 228, the Corps and EPA have determined that the Siuslaw River North and South ocean disposal sites are suitable for designation. The des ignation of the ODMD Sites by EPA will be finalized through formal rulemaking adopting this Environmental Assessment/MPRSA Criteria Evaluation and the appendices to support this action.Siuslaw Riv er ODMDS Environmental Assessment and MPRSA Criteria Evaluation page 41



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