Draft Environmental Impact Statement for
Designation of an Ocean Dredged
Material Disposal Site
off Humboldt Bay, California
Prepared by:
U.S. Environmental Protection Agency
Region IX
San Francisco, California
Contact:
Allan Ota
In association with:
Jones & Stokes Associates, Inc.
Bellevue, Washington
March 1995
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Draft Environmental Impact Statement for
Designation of an Ocean Dredged
Material Disposal Site
off Humboldt Bay, California
Prepared by:
U.S. Environmental Protection Agency
Region IX
75 Hawthorne Street
San Francisco, California 94108
Contact:
Allan Ota
In association with:
Jones & Stokes Associates, Inc.
2820 Northup Way, Suite 100
Bellevue, Washington 98004-1419
(206) 822-1077
March 1995
-------
This document should be cited as:
U.S. Environmental Protection Agency, Region IX. 1995. Designation of an ocean dredged material disposal
site off Humboldt Bay, California. Draft environmental impact statement. March. San Francisco, CA.
Prepared in association with Jones & Stokes Associates, Inc. (JSA 93-197 and 94-253.) Bellevue, WA.
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DRAFT
ENVIRONMENTAL IMPACT STATEMENT
FOR DESIGNATION OF AN
OPEN OCEAN
DREDGED MATERIAL DISPOSAL
SITE OFF HUMBOLDT BAY, CALIFORNIA
U.S. Environmental Protection Agency
Region IX
San Francisco, California
Comments on this administrative action should be addressed to:
Alexis Strauss, Acting Director
Water Management Division
U.S. Environmental Protection Agency
75 Hawthorne Street
San Francisco, California 94105
Comments must be received no later than:
, 1995, 45 days after publication of the notice of availability in
the Federal Register for the DEIS.
Copies of this EIS may be viewed at the following locations:
EPA Public Information Reference U.S. Environmental Protection Agency
Unit (PIRU) Region IX
Room 2904 (rear) Library
401 M Street SW 75 Hawthorne Street, 13th Floor
Washington, DC San Francisco, CA
Humboldt Bay Harbor Humboldt County Library
Recreation and Conservation District 421 I Street
P.O. Box 1030 Eureka, CA
Eureka, CA
Arcata City Library Humboldt State University Library
500 - 7th Street Arcata, CA
Arcata, CA
in
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Copies of the DEIS may be obtained from:
Watershed Protection Branch (W-3)
U.S. Environmental Protection Agency
75 Hawthorne Street
San Francisco, CA 94105
For further information contact:
Allan Ota
Ocean Disposal Coordinator
U.S. Environmental Protection Agency
Region IX (W-3-3)
75 Hawthorne Street
San Francisco, CA 94105
(415) 744-1980
IV
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DRAFT
ENVIRONMENTAL IMPACT STATEMENT
FOR DESIGNATION OF AN
OPEN OCEAN
DREDGED MATERIAL DISPOSAL
SITE OFF HUMBOLDT BAY, CALIFORNIA
Reviewed by:
U.S. Environmental Protection Agency
Region IX
Water Management Division
75 Hawthorne Street
San Francisco, CA 98105
(415) 744-2125
Alexis Strauss
Acting Director, Water Management Division
Approved and Submitted by:
U.S. Environmental Protection Agency
Region IX
Office of the Regional Administrator
75 Hawthorne Street
San Francisco, CA 94105
(415) 744-1001
Felicia A. Marcus
Regional Administrator
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Table of Contents
Page
Section 1. Introduction 1-1
1.1 GENERAL INTRODUCTION 1-1
1.1.1 Background 1-3
1.1.2 Local Need 1-4
1.1.3 Federal Dredging Operations 1-5
1.1.4 Non-Federal Dredging Operations 1-6
1.2 PURPOSE OF AND NEED FOR ACTION 1-6
1.3 ALTERNATIVES CONSIDERED 1-6
1.4 REGULATORY FRAMEWORK 1-7
1.5 RELATIONSHIP TO PREVIOUS NEPA ACTIONS AND OTHER
MAJOR FACILITIES IN THE VICINITY OF THE PROPOSED SITE . . 1-12
Section 2. Alternatives 2-1
2.1 DESCRIPTION OF ALTERNATIVES 2-1
2.1.1 The No Action Alternative 2-1
2.1.2 Upland Disposal 2-1
2.1.3 Beach Nourishment 2-3
2.1.4 Disposal off the Continental Shelf 2-3
2.1.5 The Nearshore Disposal Site 2-4
2.1.6 Disposal Site SF-3 2-4
2.1.7 Preferred Alternative 2-4
2.2 DISCUSSION OF ALTERNATIVES 2-6
2.2.1 Alternatives Not Considered for Further Analysis 2-6
2.2.2 Compliance of the Three ODMDS Alternatives with the EPA's 5
General Criteria for Selection of Sites (40 CFR 228.5 [a]) 2-6
2.2.3 Compliance of the Three ODMDS Alternatives with the EPA's 11
Specific Criteria for Selection of Sites (40 CFR 228.6 [a]) 2-8
2.2.4 Selection of the Preferred Alternative 2-8
Section 3. Affected Environment 3-1
3.1 OCEAN DISPOSAL SITE CHARACTERISTICS 3-1
3.1.1 Historical Use of the Disposal Sites 3-1
3.1.2 Proposed Use of the Preferred Alternative Site 3-1
3.1.3 Quantities and Characteristics of Maintenance Dredging Sediments . 3-3
3.1.4 Existence and Effects of Current and Previous Discharges and
Dumping in the Area 3-4
3.1.4.1 The Simpson Paper Company 3-4
3.1.4.2 The Louisiana-Pacific Corporation 3-6
3.1.5 Feasibility of Surveillance and Monitoring 3-6
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3.2 PHYSICAL ENVIRONMENT 3-7
3.2.1 Meteorology 3-7
3.2.2 Air Quality 3-7
3.2.3 Physical Oceanography 3-7
3.2.3.1 Nearshore Circulation 3-8
3.2.3.2 Offshore Circulation 3-9
3.2.3.3 Waves 3-10
3.2.3.4 Tides 3-10
3.2.4 Water Quality 3-10
3.2.4.1 Dissolved Oxygen 3-14
3.2.4.2 Turbidity 3-16
3.2.5 Regional Geology 3-16
3.2.6 Sedimentation Patterns 3-17
3.3 BIOLOGICAL ENVIRONMENT 3-18
3.3.1 The Plankton Community 3-19
3.3.1.1 Phytoplankton 3-19
3.3.1.2 Zooplankton 3-20
3.3.2 The Benthic Algae Community 3-21
3.3.3 The Benthic Invertebrate Community 3-22
3.3.3.1 Benthic Infauna 3-22
3.3.3.2 Benthic Epifauna 3-25
3.3.3.3 Pelagic Macroinvertebrates 3-27
3.3.4 The Fish Community 3-27
3.3.4.1 Demersal Fish 3-27
3.3.4.2 Pelagic Fish 3-31
3.3.4.3 Occurrence of Pelagic and Demersal Fish at the Proposed
Disposal Sites 3-31
3.3.5 Coastal and Sea Birds 3-41
3.3.6 Marine Mammals 3-41
3.3.6.1 Pinnipeds 3-41
3.3.6.2 Cetaceans 3-43
3.3.7 Threatened and Endangered Species 3-44
3.3.8 Potential for Development of Nuisance Species 3-47
3.4 SOCIOECONOMIC ENVIRONMENT 3-48
3.4.1 Commercial Fishing 3-48
3.4.2 Commercial Shipping 3-48
3.4.3 Recreational Activities 3-49
3.4.4 Hunting 3-49
3.4.5 Sportfishing 349
3.4.6 Nature Study 3-51
3.4.7 Scientific and Educational Use 3-51
3.4.8 Cultural Resources 3-51
3.4.9 Public Health and Welfare 3-52
Section 4. Environmental Consequences 4-1
4.1 INTRODUCTION 4-1
4.2 THE HOODS - THE PREFERRED ALTERNATIVE 4-3
Vlll
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4.2.1 Physical Environment 4-3
4.2.1.1 Air Quality 4-3
4.2.1.2 Physical Oceanography 4-3
4.2.1.3 Water Quality 4-5
4.2.2 Biological Environment 4-6
4.2.2.1 Project Significance Criteria 4-6
4.2.2.2 Phytoplankton 4-6
4.2.2.3 Zooplankton 4-7
4.2.2.4 Benthic Algae 4-7
4.2.2.5 Benthic Infauna 4-7
4.2.2.6 Benthic Epifauna 4-8
4.2.2.7 Pelagic Invertebrates 4-9
4.2.2.8 Demersal Fishes 4-9
4.2.2.9 Pelagic Fishes 4-10
4.2.2.10 Coastal and Sea Birds 4-10
4.2.2.11 Marine Mammals 4-11
4.2.2.12 Threatened or Endangered Species 4-11
4.2.3 Socioeconomic Environment 4-12
4.2.3.1 Project Impacts 4-12
4.2.3.2 Mitigation 4-12
4.3 SF-3 4-12
4.3.1 Physical Environment 4-12
4.3.2 Biological Environment 4-13
4.3.2.1 Phytoplankton 4-13
4.3.2.2 Zooplankton 4-13
4.3.2.3 Benthic Algae 4-13
4.3.2.4 Benthic Infauna 4-13
4.3.2.5 Benthic Epifauna 4-14
4.3.2.6 Pelagic Invertebrates 4-14
4.3.2.7 Demersal Fishes 4-14
4.3.2.8 Pelagic Fishes 4-15
4.3.2.9 Coastal and Sea Birds 4-15
4.3.2.10 Marine Mammals 4-15
4.3.2.11 Threatened or Endangered Species 4-15
4.3.3 Socioeconomic Environment 4-16
4.3.3.1 Project Impacts 4-16
4.3.3.2 Mitigation 4-16
4.4 THE NDS 4-16
4.4.1 Physical Environment 4-16
4.4.2 Biological Environment 4-16
4.4.2.1 Phytoplankton 4-16
4.4.2.2 Zooplankton 4-16
4.4.2.3 Benthic Algae 4-17
4.4.2.4 Benthic Infauna 4-17
4.4.2.5 Benthic Epifauna 4-17
4.4.2.6 Pelagic Invertebrates 4-17
4.4.2.7 Demersal Fishes 4-18
IX
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4.4.2.8 Pelagic Fishes 4-18
4.4.2.9 Coastal and Sea Birds 4-18
4.4.2.10 Marine Mammals 4-18
4.4.2.11 Threatened or Endangered Species 4-19
4.4.3 Socioeconomic Environment 4-19
4.4.3.1 Project Impacts 4-19
4.4.3.2 Mitigation 4-19
4.5 LONG-TERM IMPACTS AS A RESULT OF THE PROJECT 4-19
4.6 RELATIONSHIP BETWEEN SHORT-TERM USE AND LONG-TERM
RESOURCE USES 4-20
4.7 IRREVERSIBLE OR IRRETRIEVABLE COMMITMENT OF
RESOURCES 4-20
Section 5. Coordination 5-1
Section 6. Preparers and Contributors 6-1
Section 7. Glossary 7-1
Section 8. References 8-1
Appendix A. Site Management and Monitoring Plan for HOODS ODMDS
Appendix B. Common and Scientific Names of Species Mentioned in Text
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List of Tables
Table Page
2-1 List of EPA's Five General and Eleven Specific Site Selection
Criteria 2-2
2-2 Comparison of Alternative Ocean Disposal Sites Based on EPA's
Eleven Specific Site Designation Criteria 2-9
3-1 Volumes of Dredged Material Disposed at the HOODS, the NDS,
and Site SF-3 by the Corps (1982-1994) 3-2
3-2 Current Speed and Direction from Current Meter Mooring
Stations E60 and E90 3-13
3-3 List of the Dominant Benthic Macrofaunal Invertebrates Reported
near Humboldt Bay 3-23
3-4 Demersal Fish Known to Occur near Humboldt Bay 3-28
3-5 Summary of Critical Stages of Commercially Important Nearshore
Demersal Fish Found near Humboldt Bay 3-30
3-6 Summary of Critical Stages of Commercially Important Deep-
Water Demersal Fish Found near Humboldt Bay 3-32
3-7 Pelagic Fish Known to Occur near Humboldt Bay 3-34
3-8 Summary of Critical Stages of Commercially Important Pelagic
Fish Found near Humboldt Bay 3-36
3-9 Breeding Seabirds Found in Humboldt and Del Norte Counties 3-42
3-10 Federally Listed Threatened or Endangered Marine Species
Occurring in the Project Region 3-45
XI
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List of Figures
Figure Page
1-1 Location of Past and Present Ocean and Land Dredged Material
Disposal Sites near Humboldt Bay, California 1-2
2-1 Humboldt Open Ocean Disposal Site 2-5
3-1 Approximate Locations of Louisiana-Pacific Corporation and
Simpson Paper Company Ocean Outfalls 3-5
3-2 Approximate Location of Current Meter Stations E60 and E90 3-11
3-3 Records for Four Periods of Current Meter Deployment at Sites
E60 and E90 3-12
3-4 Location of Offshore and Nearshore Field Surveys for Water
Column Characteristics 3-15
Xlll
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Abbreviations and Acronyms
CAA Clean Air Act
CEQA California Environmental Quality Act
CO carbon monoxide
Corps U.S. Army Corps of Engineers
CWA Clean Water Act
CZM coastal zone management
CZMA Coastal Zone Management Act
CZMP California Coastal Zone Management Plan
DDLS Dredge Data Logging System
DEIS draft environmental impact statement
DO dissolved oxygen
EIR environmental impact report
EIS environmental impact statement
EPA U.S. Environmental Protection Agency
ESA Endangered Species Act
FWCA Fish and Wildlife Coordination Act
HC hydrocarbons
HOODS Humboldt Open Ocean Disposal Site
L-P Louisiana-Pacific Corporation
LC London Convention
MHHW mean higher high water
MLLW mean lower low water
MMS Mineral Management Service
MPRSA Marine Protection, Research and Sanctuaries Act
NCUAQMD .... North Coast Unified Air Quality Management District
NDS Nearshore Disposal Site
NEPA National Environmental Policy Act
NHPA National Historic Preservation Act
NMFS National Marine Fisheries Service
NOX nitrogen oxides
NPDES National Pollutant Discharge Elimination System
ODMDS ocean dredged material disposal site
PM particulate matter
PM10 particulate matter smaller than or equal to 10 microns in diameter
ROG reactive organic gases
SBDs seabed drifters
SHPO State Historic Preservation Officer
SMMP site management and monitoring plan
SO2 sulfur dioxide
USCG United States Coast Guard
USFWS U.S. Fish and Wildlife Service
xv
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WRDA Water Resources Development Act
ZSF Zone of Siting Feasibility
xva
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Units of Measure and Conversions
cm/s centimeters per second
ft feet
gm2 grams per square meter
g/C/m2/day grams of carbon per square meter per day
m meters
mg/1 milligrams per liter
mg/m2 milligrams per square meter
mm millimeters
nmi nautical miles
ppt parts per thousand
yd3 cubic yards
Mg/g microgram per gram
Mg/kg microgram per kilogram
jug/1 microgram per liter
micro meters
To Convert From To Multiply By
cubic yards cubic meters 0.7646
nautical miles miles 1.1508
miles kilometers 1.6093
short tons pounds 2,000
meters feet 3.2808
centimeters inches 0.3937
feet fathoms 0.1667
xvn
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Executive Summary
The proposed action is the designation of an ocean disposal site for dredged material
from Humboldt Bay, California. The site is located in the Pacific Ocean at a depth of 49 to
55 meters (160 to 180 feet) approximately 3 to 4 nautical miles northwest of the mouth of
Humboldt Bay. The site would be used for disposal of dredged material from federal
projects permitted under Section 103 of the Marine Protection, Research, and Sanctuaries
Act (MPRSA) of 1972, as amended. This site, known as the Humboldt Open Ocean
Disposal Site (HOODS), has been used on an interim basis for disposal of material dredged
from the navigation channels in Humboldt Bay since September 1990.
Continued use of the proposed site is not expected to cause significant long-term
adverse environmental effects. The sediments and the benthic community have been altered
by previous disposal operations at the proposed site. The smothering effect on the benthos
caused by sediment inundation is expected to continue, but impacts would be localized and
are not considered significant. No significant environmental impacts are expected to occur
outside of the HOODS. Impacts on water quality, which would be temporarily experienced
during disposal operations, are expected to be minimal. Short-term effects on organisms in
the water column would be negligible.
Few of the potentially adverse environmental effects of dredged material disposal at
the proposed site are likely to be irreversible or to involve any irretrievable commitment of
resources. A site management and monitoring plan (SMMP) is incorporated into this draft
environmental impact statement (DEIS). Implementation of the SMMP will be a
requirement of site use.
The seven alternatives considered for dredged material disposal are No Action,
disposal off the continental shelf, upland disposal, beach nourishment, the SF-3 site, the
nearshore disposal site (NDS), and the HOODS. After detailed field investigations and
analysis of each alternative, EPA Region IX determined that ocean disposal at a designated
dredged material disposal site was the only viable alternative for the proposed action. The
preferred alternative identified in this DEIS is the HOODS. This decision is based on the
potential for disposal activities to adversely affect the alternative sites, the demonstrated
need for an ocean disposal site for dredged material, and the insignificance of the long-term
environmental impacts at the HOODS.
xix
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Section 1
Introduction
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Section 1. Introduction
1.1 GENERAL INTRODUCTION
This draft environmental impact statement (DEIS) evaluates the proposed
designation of an ocean dredged material disposal site (ODMDS) northwest of the mouth
of Humboldt Bay, California. The purpose of this action is to provide an environmentally
acceptable site for disposal of materials dredged from Humboldt Bay by the U.S. Army
Corps of Engineers (Corps). The preferred site for final designation is the Humboldt Open
Ocean Disposal Site (HOODS) (Figure 1-1).
The U.S. Environmental Protection Agency (EPA) has the authority to designate
ODMDSs under Section 102 of the Marine Protection, Research and Sanctuaries Act
(MPRSA) of 1972 (33 USC 1401 et seq.). The Act established a permitting program for
ocean disposal of dredged material. The permitting program requires the determination of
environmental impacts, designation of sites, enforcement of permit conditions, and
management of disposal sites. It is the EPA's policy to publish an environmental impact
statement (EIS) for all ODMDS designations (39 FR 37119, October 21, 1974).
The EPA promulgated final Ocean Dumping Regulations to implement the MPRSA
in 40 CFR 220-229 (January 11,1977). The regulations set forth criteria and procedures for
the selection and designation of ocean disposal sites. In addition, the regulations designated
interim ocean sites for the disposal of dredged material to allow the necessary time for site
designation studies as required by EPA regulations. Use of the interim designated sites was
dependent on compliance with the requirements and criteria contained in the EPA's Ocean
Dumping Regulations (40 CFR 220-229).
The Corps, in close cooperation with the EPA, with federal and state resource
agencies, and with members of the concerned public, has conducted studies of the ocean
area offshore of Humboldt Bay for the purpose of characterizing the physical, chemical, and
biological environment of these ocean waters. The EPA requested the Corps San Francisco
District to assist with the preparation of the ODMDS designation EIS because the Corps
will use the site for disposal of sediments dredged from Humboldt Bay. The EPA retains
responsibility for selection of the preferred alternative, for authorizing the site, and for
publication of the EIS and related public coordination.
The final designation process is being conducted in accordance with the requirements
of the MPRSA, as amended (33 USC 1401 et seq.); the EPA's Ocean Dumping Regulations
(40 CFR 220-229); and other applicable regulations.
1-1
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PACtP1C
0 C£AN
Figure 1 -1. Location of Past and Present Ocean and Land Dredged Material Disposal Sites
Near Humboldt Bay, California
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1.1.1 Background
Humboldt Bay is a deep-draft harbor located near Eureka, California. The natural
transport of sediment in the area results in shoaling at the Harbor entrance and within
Humboldt Bay. To provide for safe navigation into and through the Harbor, the Corps has
conducted annual maintenance dredging of the Harbor and entrance channels since 1931.
The Corps currently has two dredging cycles each year, one in the fall and one in the
spring. During the fall, the Corps dredges the Bar and Entrance and North Bay Channels,
removing 145,000 to 1,400,000 cubic yards (yd3) of sediment. During the spring, a smaller
quantity of material (1,900 to 192,000 yd3) is dredged from the Eureka, Samoa, and Field's
Landing Channels, as well as the North Bay Channel. (Corps 1994a, 1994b.)
Several ocean sites have been used to dispose of the dredged materials from
Humboldt Bay; however, there is currently no permanently designated ODMDS. Interim
disposal sites were selected, based on historical use, by the EPA in consultation with the
Corps. The three ocean sites that have been used are the SF-3 disposal site, the Nearshore
Disposal Site (NDS), and the HOODS (Figure 1-1).
The SF-3 site has been used for dredged material disposal since the 1940s. Interim
designation of the SF-3 site was originally issued for a 3-year period between 1977 and 1980
but was later extended by the EPA to February 1, 1983. An additional extension until
December 31, 1988, was granted to allow completion of field studies, environmental
evaluation, and preparation of an EIS for designation of SF-3 as an ODMDS.
In the mid-1980s it was discovered that dredged materials placed at the SF-3 disposal
site were not dispersing as had been anticipated. The mounding at the SF-3 site caused
adverse surface wave conditions and resulted in navigation hazards to commercial fishing
and recreational boats traversing the site. The commercial fishing community expressed
concern to the Corps. In light of mounting concern, the site was closed in 1988.
Because of the problems associated with disposal at the SF-3 site, the Corps decided
that an investigation of other potential sites near Humboldt Bay should be undertaken to
select a permanent disposal site that would not interfere with navigation and that would
minimize impacts on the ocean environment.
In 1988 and 1989, the Corps disposed of sand dredged from the Bar and Entrance
Channel and the North Bay Channel at the NDS. The material was disposed at the NDS
because of the impacts on navigation associated with disposal at the SF-3 site and to keep
the material within the littoral cell. Concerns have also been raised about the use of the
NDS, including the effect of the disposal on navigational safety and commercial fisheries
resources, and dispersion of disposed sediments toward the Harbor mouth.
The Corps was authorized by EPA to use the SF-3 site to dispose of dredged
materials from Humboldt Bay on one occasion in 1990.
1-3
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The Corps has used the HOODS for disposing of dredged material from Humboldt
Bay since fall 1990. The HOODS was sized to provide the capacity for 50,000,000 yd3 of
dredged material (Corps/HBHRCD 1994). Between 1990 and 1994, the HOODS has been
used on 10 occasions for dredged material disposal. Approximately 2,860,000 yd3 have been
disposed of at this site.
1.1.2 Local Need
Humboldt Bay is the second largest coastal estuary in California. The Bay consists
of two shallow basins, South Bay and Arcata Bay, which are connected by a narrow channel
(Figure 1-1). The Bay is the only naturally enclosed, deep-draft harbor for major
commercial shipping between San Francisco, California, and Coos Bay, Oregon. The
Harbor provides berthing for deep-draft vessels serving the forest products industries,
shallow-draft vessels serving the petroleum and chemical industries, and a large commercial
fishing fleet. In 1993, 154 deep-draft vessels called on Humboldt Bay, representing the
shipment of 1,125,544 short tons of cargo (Corps/HBHRCD 1994). This accounted for
approximately 70% of the total tonnage shipped through the Harbor. The fishing industry
is the third largest economy in Humboldt Bay, supporting approximately 500 vessels and
delivering catches with an average annual dockside value of $10-20 million
(Corps/HBHRCD 1994). Other beneficial uses of the Bay include hunting, sport fishing,
and educational and recreational use.
Natural sediment transport processes result in the shoaling of the Harbor and
entrance channels and thereby create hazards to vessel navigation into and within the
Harbor. Shoaling occurs rapidly in the Bar and Entrance Channel as a result of the large
volume of littoral material that is transported by ocean currents along the northern
California coast. The Bar and Entrance Channel requires annual dredging to maintain safe
depths for deep-draft vessels. To provide safe passage for deep-draft vessels into and
through the Harbor, it is necessary to dredge the Harbor entrance and inner Harbor
channels on an annual basis. The other in-bay channels, taken individually, require less
frequent dredging; however, each year there is a need to dredge specific in-bay channels.
Between 1982 and 1994 (excluding 1989), an average of 802,000 yd3 of material was
dredged annually by the Corps to maintain sufficient operating depths (Corps 1994a, 1994b,
1995). No upland disposal sites that have the capacity to contain the volume of material
generated during maintenance dredging have been identified. The Corps has disposed of
this material at the HOODS since 1990. The Corps has asked the EPA to propose the
HOODS as a designated ODMDS for disposal of dredged materials from Humboldt Bay.
1-4
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1.1.3 Federal Dredging Operations
The only federal dredging operation presently occurring in the Humboldt Bay region
is the annual maintenance dredging of the Bay and Harbor by the Corps. The Corps uses
a self-propelled hopper dredge for dredging the Harbor. As noted earlier, the Corps
performs maintenance dredging in two phases each year. During the spring, the Corps
dredges the Bar and Entrance Channel and portions of the North Bay Channel. During the
fall, the Corps dredges the interior channels (i.e., the Samoa, Eureka, Field's Landing
Channels and portions of the North Bay Channel) as needed. The Corps splits the
maintenance dredging operations into two phases to take advantage of periods of relatively
calm weather and ocean conditions. The average volume of material dredged annually
during these operations is 802,000 yd3.
The Bar and Entrance Channel and the southern portion of the North Bay Channel
lie within an exposed ocean environment subject to large swells, breaking seas, and strong
currents. This area contributes 84% of the total annual dredge volume (687,400 yd3) of the
project. The remaining average annual volume dredged from the interior channels (Samoa,
Eureka, Field's Landing, and North Bay Channels) during fall is 106,100 yd3.
The Corps has utilized three ocean disposal sites for placement of sediments dredged
from Humboldt Bay navigation channels. These include the SF-3 disposal site, the NDS,
and the HOODS. The SF-3 site has been used since the 1940s, most recently in April 1990.
The NDS has been used twice, once in 1988 and again in 1989. Only sand is suitable for
disposal at the NDS, because the purpose of disposal at the NDS is to maintain the disposed
sand in the littoral zone and nourish the south spit of Humboldt Bay. The HOODS has
been used on 10 occasions for dredged material disposal since the fall of 1990. It is
anticipated that the HOODS will be used for all future maintenance dredge disposal under
Section 103 permitting authority until a permanent EPA designation is complete.
In addition to the discharge of materials from the annual maintenance dredging
operations, the Corps is also proposing to dispose of dredged material generated from the
proposed Humboldt Harbor and Bay Deepening Project at the HOODS. The proposed
Harbor and Bay Deepening Project is scheduled to occur in 1997. The proposed project
would generate 5,600,000 yd3 of spoils. The Corps is proposing to dispose of all of this
dredged material at the HOODS, except for 26,000 yd3 which would be disposed at the
Louisiana-Pacific upland disposal site (Corps/HBHRCD 1994). The Corps has recently
published its Draft Feasibility Report and EIS/EIR for the proposed deepening project
(Corps/HBHRCD 1994).
The Corps does not issue permits for its own projects. However, each Corps project
is subject to the same suitability determination as nonfederal projects requiring permits,
including the EPA Ocean Dumping Criteria at 40 CFR 227 and sediment testing
requirements in accordance with EPA/Corps 1991 Evaluation of Dredged Material
Proposed for Ocean Disposal - Testing Manual (the Green Book).
1-5
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1.1.4 Non-Federal Dredging Operations
To date, non-federal dredging and disposal operations at Humboldt Bay have not
utilized ocean disposal. For dredging work at Humboldt Bay for the years 1977 through
1988, the Corps issued 16 permits for non-federal projects, authorizing the dredging and
disposal of approximately 350,000 yd3 of sediment. These projects typically involved
dredging of local public marinas and forest product berthing facilities. Disposal was usually
at upland locations, with at least one occurrence of disposal in the surf zone along the North
Spit (the beach disposal site shown in Figure 1-1).
Should there be a future need for non-federal dredging operations to utilize an EPA-
authorized ocean disposal site, those projects would be assessed on an individual project
basis in accordance with the provisions of EPA/Corps 1991 Green Book testing
requirements; EPA's Ocean Dumping Regulations; 40 CFR 220-225,227-228; and the Corps
dredged material disposal permitting procedure under Section 103 of the MPRSA.
12 PURPOSE OF AND NEED FOR ACTION
The Corps considers maintenance dredging of Humboldt Bay essential to the
continued safe navigation of vessels into and within the Bay. Upland disposal sites do not
have the capacity to receive dredged materials from annual dredging operations. At present,
there is also no permanently designated open ocean disposal site for dredged materials from
the Bay.
Since expiration of the interim designation of the SF-3 site in 1988, ocean disposal
has been authorized by the EPA on a case-by-case basis under Section 103 of the MPRSA
at the SF-3 site, NDS, and the HOODS. However, use of interim sites would be terminated
under provisions of the Water Resources Development Act (WRDA), which would not allow
disposal of dredged material at interim ocean sites under Section 103 of the MPRSA after
January 1,1997, unless the site has received final designation. The purpose of the proposed
action is to respond to the need for a permanently designated ODMDS to receive dredged
materials from Humboldt Bay.
1.3 ALTERNATIVES CONSIDERED
The proposed action is the designation of an ODMDS for disposal of dredged
materials from Humboldt Bay. A number of alternatives were considered to identify the
most suitable and least environmentally damaging site: No Action, upland disposal, disposal
off the continental shelf, beach nourishment, disposal at site SF-3, disposal at the NDS, and
disposal at the HOODS.
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If the No Action alternative were implemented, there would be no regionally
designated ocean disposal site. The HOODS could continue to be used under MPRSA
Section 103 permit authority. In the short term, the EPA and the Corps would continue to
evaluate ocean disposal sites on a case-by-case basis; however, use of interim sites would be
terminated on January 1, 1997, under provisions of WRDA, which specifies using only
permanently designated ocean disposal sites for disposal of dredged materials.
Upland disposal alternatives are not practicable due to the limited availability and
capacity of upland disposal areas, increased costs, and vessel safety.
The Corps conducted a Zone of Siting Feasibility (ZSF) analysis for the proposed
Humboldt Bay ODMDS (Corps 1989). Disposal off the continental shelf was not considered
feasible due to operational constraints on the Corps' maintenance dredging for the
Humboldt Bay region. U.S. law defines the continental shelf as the seaward extension of
the coast to a depth of 183 meters (m) (600 feet [ft]). Seaward of Humboldt Bay, the
continental shelf break (the 600 ft contour line) occurs at an approximate distance of
10 nautical miles (nmi) from shore.
The ZSF analysis defined an area within which disposal of dredged material would
be feasible based on operational and economic criteria. Candidate disposal sites within this
zone were then evaluated according to environmental and important resources criteria. The
analysis concluded that the ZSF boundary for an ODMDS located outside Humboldt Bay
should be set at a radius of 4 nmi from the end of the Humboldt Harbor jetty heads. The
600 ft line is not encountered within the 4 nmi operational radius outside Humboldt Bay as
set by the ZSF. Therefore, for Humboldt Bay, it is not feasible to designate an ocean
disposal site beyond the continental shelf.
The HOODS, SF-3, and the NDS are all historical sites located within the ZSF.
These three potential sites were evaluated according to criteria established in the EPA's
Ocean Dumping Regulations. The HOODS is the preferred alternative for designation.
1.4 REGULATORY FRAMEWORK
An international treaty as well as federal and state laws and regulations apply to the
designation of an ODMDS. The relevance of these statutes to the proposed action and
related compliance requirements for the proposed site are described below.
1. Convention on the Prevention of Marine Pollution by Dumping of Wastes
and Other Matter (26 US Treaties and Other International Agreements
2403: Treaties and Other International Acts Series 8165)
The principal international agreement governing ocean dumping is the Convention
on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, also known
as the London Convention (LC). This agreement became effective August 30, 1975, after
ratification by 15 contracting countries, including the United States. Ocean dumping
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criteria, incorporated into MPRSA permits for ocean dumping, have been adapted from the
provisions of the LC. Thus, when material is found to be acceptable for ocean disposal
under MPRSA, it is also acceptable under the LC.
2. The Marine Protection, Research and Sanctuaries Act of 1972, as
amended (33 USC 1401 et seq.)
The MPRSA regulates the transportation and disposal of materials in the ocean and
prohibits ocean disposal of certain wastes. Section 102 of the MPRSA gives the EPA
designating authority for multiple-user, long-term, dredged material disposal sites. Section
102 of the MPRSA also allows the EPA to promulgate environmental evaluation criteria for
all dumping permit actions and to retain review authority over Corps MPRSA 103 permits.
The EPA's regulations for ocean dumping are published as 40 CFR 220-229. This DEIS is
for designation of an ocean disposal site rather than permitting of dredged material disposal;
therefore, it only relates to the criteria of 40 CFR 228.
Section 103 of the MPRSA sets forth requirements for obtaining Corps permits to
transport dredged material for the purpose of ocean disposal. Under Section 103, those
using ocean disposal must comply with both EPA and Corps requirements for transportation
and disposal of dredged material in the ocean. The permitting regulations promulgated by
the Corps under the MPRSA appear in 33 CFR 320-330 and 335-338. Based on an
evaluation of compliance with the regulatory criteria of 40 CFR 227, both the EPA and the
Corps may prohibit or restrict disposal of material that does not meet the criteria. The EPA
and the Corps also may determine that ocean disposal is inappropriate because of ODMDS
management restrictions or because options for beneficial use exist (i.e., using spoils
beneficially).
3. Water Resources Development Act of 1992 (PL 102-580)
Section 506 of the WRDA amends Section 102(c) of the MPRSA. These
amendments require, in part, that a site management plan be developed for each designated
ocean disposal site. This site management plan is required to include:
a baseline assessment of conditions at the site;
a program for monitoring the site;
special management practices necessary for protection of the site;
consideration of the quantity and contaminant levels of the material to be
disposed at the site;
consideration of the active life of the site and management requirements after
site closure; and
a schedule for review and revision of the site management plan.
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Section 506 of the WRDA further requires that after January 1, 1995, a site
management plan must be developed and approved before final designation is issued. After
January 1,1997, no permit for dumping may be issued under Section 103 of the MPRSA for
a site unless the site has received final designation.
In the case of this proposed action, the final designation is scheduled for fall 1995.
Thus, a site management plan is required to be developed and approved, pursuant to the
WRDA, before the final designation may be issued. A site management and monitoring
plan has been developed and incorporated into this DEIS (Appendix A).
4. The National Environmental Policy Act of 1969 (42 USC 4341 et seq., as
amended)
The National Environmental Policy Act (NEPA) requires that environmental
consequences and alternatives be considered before a decision is made to implement a
federal project. It also establishes requirements for preparation of an EIS for major federal
projects having potentially significant environmental impacts, including opportunities for
public review and comment. NEPA regulations specifically require integration with
requirements of the Fish and Wildlife Coordination Act (FWCA), the National Historic
Preservation Act, the Endangered Species Act, and other applicable laws and executive
orders. This DEIS has been prepared to fulfill NEPA requirements and to satisfy EPA
policy.
The President's Council on Environmental Quality has published regulations for
implementing NEPA in 40 CFR 1500-1508. EPA NEPA regulations are published in 40
CFR 6, and Corps regulations for implementing NEPA are published in 33 CFR 220.
5. The Clean Water Act of 1977 (33 USC 1251 et seq., as amended)
The Clean Water Act (CWA) was passed to restore and maintain the chemical,
physical, and biological integrity of the nation's waters. Specific sections of the CWA
control the discharge of pollutants and wastes into aquatic and marine environments.
Section 404 established a program to regulate the discharge of dredged material into waters
of the United States inside the boundary drawn to differentiate coastal waters from oceanic
waters.
The preferred site for designation (HOODS) lies outside of state territorial waters.
Both alternative sites (SF-3 and NDS) lie within state waters. Section 401 of the CWA
applies to ocean disposal of dredged material within state waters. This section requires the
State of California, prior to any discharge, to certify that the permitted action complies with
all effluent limitations and state water quality standards. The Section 401 water quality
certification by the state would not be applicable if the HOODS is selected for designation.
However, if either of the two alternative ocean sites is selected, state certification would be
required.
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6. The Clean Air Act of 1990 (42 USC 7401 et seq., as amended)
The Clean Air Act (CAA) is intended to protect and enhance the nation's air quality
by regulating the emission of air pollutants through the development and execution of air
pollution prevention and control programs. The CAA is applicable to permits and planning
procedures related to disposal within the 2.6 nmi territorial sea limit (3 statute miles). The
HOODS is not within state territorial waters. The SF-3 site and the NDS are located within
the state territorial sea, and are within the North Coast Air Basin. Air quality issues related
to permitting and planning procedures for the alternative disposal sites would fall under the
jurisdiction of the North Coast Unified Air Quality Management District. Air quality issues
associated with the transport of dredged material to the HOODS have been evaluated as
part of the Corps EIS/EIR for the proposed Harbor deepening project (Corps/HBHRCD
1994).
7. The Fish and Wildlife Coordination Act of 1958 (16 USC 661 et seq.)
The FWCA is intended to protect aquatic resources. The FWCA requires that water
resource development programs consider fish and wildlife conservation. The FWCA also
requires that the lead agency consult with both state and federal fish and game agencies and
fully consider their recommendations in decision-making. Section 106 (e) of the MPRSA
requires compliance with the FWCA.
8. The Coastal Zone Management Act of 1972 (16 USC 1456 et seq.)
The Coastal Zone Management Act (CZMA) regulates development and use of the
coastal zone and encourages states to develop and implement coastal zone management
(CZM) programs. Federally permitted projects occurring within state territorial waters must
be certified as consistent with approved state CZM programs under Section 307(c) of the
CZMA. The Coastal Zone Reauthorization Amendments of 1990 (Section 6208) require
that any federal agency conducting or supporting activities which affect the coastal zone
prepare a determination of consistency with the state's coastal management program. No
federal agency activities are categorically exempt from this requirement. Although the
preferred site for designation lies beyond state territorial waters, the EPA has a policy of
preparing a coastal consistency determination for all site designations even if they are
beyond state territorial limits, because dredged materials are transported through state
waters. Transport of dredged materials through state waters to the HOODS has been
evaluated as part of the Corps EIS/EIR for the proposed Harbor deepening project
(Corps/HBHRCD 1994).
9. The Endangered Species Act of 1973 and Amendments (16 USC 1531 et
seq., as amended)
The Endangered Species Act (ESA) was enacted to protect threatened and
endangered species. Section 7 of the ESA requires that lead federal agencies consult with
the U.S. Fish and Wildlife Service (USFWS) and/or the National Marine Fisheries Service
(NMFS) regarding any federal project which could jeopardize the continued existence of
federally listed threatened or endangered species, or destroy or adversely modify any
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designated critical habitat of such species. During the site designation process, the USFWS
and NMFS evaluate potential impacts of ocean disposal on threatened or endangered
species. These agencies are asked to certify, or concur with the sponsoring agency's findings,
that the proposed activity will not adversely affect the endangered or threatened species.
Documentation of the Section 7 consultation is presented in Section 5 of this DEIS.
10. The National Historic Preservation Act of 1966 (16 USC 470 et seq.)
The National Historic Preservation Act (NHPA) is intended to preserve and protect
historic and prehistoric resources. Federal agencies are required to identify cultural
resources that might be damaged, destroyed, or otherwise made inaccessible by a project,
and to coordinate project activities with the State Historic Preservation Officer (SHPO).
This consultation process is documented in Section 5 of this DEIS.
11. Executive Order 11514, Protection and Enhancement of Environmental
Quality (May 1977), as amended by Executive Order 11991
Executive Order 11514 requires the Corps to prepare NEPA documents that are
concise, clear, and supported by evidence that the necessary analyses have been made. It
also establishes a NEPA and CAA dispute resolution procedure.
12. Executive Order 11593, Protection and Enhancement of the Cultural
Environment (36 FR 8921, May 15, 1971)
Executive Order 11593 requires federal agencies to initiate measures necessary to
direct their policies, plans, and programs in such a way so that federally owned sites,
structures, and objects of historical, architectural, or archaeological significance are
preserved, restored, and maintained for the inspiration and benefit of the people.
Compliance with this order was coordinated with the California SHPO and is documented
in Section 5 of this DEIS.
13. Executive Order 12372, Intergovernmental Review of Major Federal
Programs (47 FR 3959, July 16, 1982)
Executive Order 12372 requires federal agencies, to the extent permitted by law, to
utilize the state process to determine official views of state and local elected officials and
communicate with state and local officials as early in the program planning cycle as is
reasonably feasible to explain specific plans of action. The Resources Agency of California
was contacted to notify appropriate state agencies.
14. The California Coastal Act of 1976 (PRC Section 3000 et seq.)
The California Coastal Act establishes the California Coastal Zone Management Plan
(CZMP), which has been approved under the federal CZMA. All federal actions that affect
the CZMP must be certified as consistent with this state program (see "Coastal Zone
Management Act of 1972," above).
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15. The California Environmental Quality Act of 1986 (PRC Section 21001)
The California Environmental Quality Act (CEQA) establishes requirements similar
to those of NEPA for consideration of environmental impacts and alternatives and for
preparation of an environmental impact report (EIR) prior to implementation of applicable
projects. This proposed action is a federal action involving site designation outside state
boundaries and therefore does not fall under the purview of CEQA. However, if either of
the alternative sites is selected for designation, CEQA would apply. Actions requiring state
approval are subject to CEQA.
1.5 RELATIONSHIP TO PREVIOUS NEPA ACTIONS AND OTHER MAJOR
FACILITIES IN THE VICINITY OF THE PROPOSED SITE
The only known NEPA actions or facilities in the project area that could possibly be
affected by or affect the designation of an ODMDS for the Humboldt Bay region are the
annual maintenance dredging operations in Humboldt Bay and the Corps' proposed
Humboldt Harbor and Bay Deepening Project. Discharge of dredged material from the
annual maintenance dredging program has been permitted on a case-by-case basis under
Section 103 of the MPRSA. However, use of interim sites will be terminated under
provisions of the WRDA, which would not allow disposal of dredged material at interim
ocean disposal sites under Section 103 after January 1, 1997, unless the site has been
permanently designated. If an ocean disposal site is not designated, the Corps would not
have the option of ocean disposal after 1997, and would have to utilize other disposal
options (i.e., upland disposal) which could adversely affect the maintenance dredging
program and the economies related to navigation into and within the Harbor.
The Harbor and Bay Deepening Project proposed by the Corps will generate
approximately 5,600,000 yd3 of dredged material. If no permanently designated ODMDS
is available for the project, the EPA can permit the Corps to dispose of the material at the
HOODS or another interim site under Section 103 of the MPRSA until January 1, 1997.
However, there are no other upland or ocean disposal sites other than the HOODS which
could contain the volume of dredged material generated from the proposed project, and the
lack of a designated ODMDS after January 1997 would adversely affect the project.
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Section 2
Alternatives
-------
Section 2. Alternatives
This section describes each disposal alternative considered and selection of the
preferred alternative. Evaluation of a reasonable range of alternatives is required by NEPA
as part of 40 CFR 1502.14. Once the need for an ODMDS is established, potential sites are
screened for feasibility through the ZSF process. The feasible alternative sites are evaluated
according to the EPA's 5 general disposal site selection criteria and 11 specific disposal site
selection criteria (40 CFR 228.5-228.6 [a]) (Table 2-1). The detailed discussion of each
specific criterion can be found in Sections 3 and 4.
2.1 DESCRIPTION OF ALTERNATIVES
2.1.1 The No Action Alternative
The EPA has the authority under MPRSA Section 102 (c) to designate a
recommended site for disposal of dredged material. Selection of the No Action alternative
would mean that there would not be an EPA-designated ocean disposal site for material
dredged from Humboldt Bay. The Corps would either continue requesting approval from
the EPA under the MPRSA Section 103 for disposal of sediment at the HOODS or other
ocean disposal sites on a case-by-case basis until January 1, 1997, or it would cancel
dredging operations in Humboldt Bay because upland disposal would not provide the
capacity needed to contain the average annual quantities of sediment dredged from
Humboldt Bay's federal navigation channels.
2.12 Upland Disposal
Several upland disposal sites were considered for disposal of dredged materials from
Humboldt Bay. The "Superbowl" site (Figure 1-1), a 60-acre site on the North Spit, was
originally designed to contain 1,000,000 yd3. This site was used once in 1979. Presently the
site has capacity for approximately 400,000 yd3 of dredge material. The Superbowl site was
eliminated from further consideration because it does not have the capacity to serve as the
permanently designated site. However, this site could be used for future smaller dredging
projects requiring upland disposal if sensitive areas (wetlands and endangered plant species)
are avoided.
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Table 2-1. List of EPA's Five General and Eleven Specific Site Selection Criteria
General Site Selection Criteria - 40 CFR 2285
(a) The dumping of materials into the 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 shellfisheries, and regions of heavy commercial or
recreational navigation.
(b) Locations and boundaries of disposal sites will be so chosen that temporary perturbances in water
quality or other environmental conditions during initial mixing caused by disposal operations
anywhere within the site 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 shellfishery.
(c) If at any time during or after disposal site evaluation studies, it is determined that existing disposal
sites presently approved on an interim basis for ocean dumping do not meet the criteria for site
selection set forth in Sections 228.5 through 228.6, the use of such sites will be terminated as soon as
suitable alternate disposal sites can be designated.
(d) The sizes of the ocean disposal sites will be limited in order to localize for identification and control
any immediate adverse impacts and 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 determined as a part of the disposal site evaluation or designation study.
(e) EPA will, wherever feasible, designate ocean dumping sites beyond the edge of the continental shelf
and other such sites that have been historically used.
Specific Site Selection Criteria - 40 CFR 228.6(a)
(1) Geographical position, depth of water, bottom topography, and distance from the coast;
(2) Location in relation to breeding, spawning, nursery, feeding, or passage areas of living resources hi
adult or juvenile phases;
(3) Location in relation to beaches and other amenity areas;
(4) Types and quantities of wastes proposed to be disposed of, 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 direction and velocity, if any;
(7) Existence and effects of current and previous discharges and dumping in the area (including
cumulative effects);
(8) Interference with shipping, fishing, recreation, mineral extraction, desalination, fish and 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) Potentiality for the development or recruitment of nuisance species in the disposal site; and
(11) Existence at, or in close proximity to, the site of any significant natural or cultural features of
historical importance.
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The Louisiana-Pacific site, also on the North Spit, was also excluded from
consideration as the designated site because of its small capacity. However, the Corps is
proposing to use this site during the Harbor and Bay Deepening Project for the disposal of
26,000 yd3 of dredged material considered to be unsuitable for ocean disposal.
Several other land disposal sites were originally considered for permanent
designation, but they were not investigated further because of the potential for adverse
effects on wetlands, prohibitive costs, inadequate capacity, or conflicts with other land uses.
2.1.3 Beach Nourishment
Much of the material dredged from Humboldt Bay consists of sand; therefore, beach
nourishment warrants consideration as a disposal alternative. Sediment dredged from the
Bar and Entrance and North Bay Channels and the Field's Landing Channel in the area
north of Buhne Point is predominantly medium- to fine-grained sand. Sediments in the
southern reach of the Field's Landing Channel and the Samoa and Eureka Channels have
historically been silty sand (much finer grained than the native material on the beach) that
would not be suitable for beach nourishment.
At this time, disposal of the Bar and Entrance and North Bay Channels' dredged
material onto the beach face of the spits is not considered practicable. The bulk of the
sediment suitable for beach nourishment is located in areas that are exposed to rough sea
conditions where stationary dredging plants are not suitable. Use of a hopper dredge would
require that the material be deposited in a sheltered area in the back bay adjacent to one
of the spits, thereby producing adverse effects on in-bay biota near the disposal site. A
stationary hydraulic dredge would then slurry it across the spit to the beach for final
disposal, causing further localized adverse effects. This approach to beach nourishment
would increase the cost of dredging, increase adverse impacts on the Bay, and increase
operational time.
2.1.4 Disposal off the Continental Shelf
The EPA Ocean Dumping Regulations state in Section 228.5(e) that the "EPA will,
whenever feasible, designate ocean dumping sites beyond the edge of the continental shelf
and other such sites that have been historically used." As described in the ZSF (Corps
1989), the Corps must site the ODMDS within a 4 nmi radius from the center point at the
end of the Humboldt Bay jetties. This limitation reflects the constraints on dredging and
disposal operations for the Humboldt Bay area. Disposal off the continental shelf would
require use of a site located 10 nmi or farther from Humboldt Bay, a distance beyond the
point at which dredged material disposal is considered feasible. Because historical sites
(NDS, SF-3, and the HOODS) exist on the continental shelf within the ZSF, this alternative
will not be considered in this DEIS.
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2.1.5 The Nearshore Disposal Site
Another approach to beach nourishment would be nearshore disposal within the
longshore current system. The Corps has used a nearshore disposal area known as the NDS
for this purpose. The site is located 2 nmi southwest of the Harbor mouth. Two disposal
episodes were conducted at this site and were considered test disposals to investigate
whether material placed at the NDS remained in the littoral zone and promoted beach
nourishment. The NDS has been monitored by periodic bathymetric surveys to determine
sediment movement.
The Humboldt Fishermen's Marketing Association and the Commercial Fishermen's
Wives of Humboldt have objected to disposal at this site (Corps/HBHRCD 1994). Their
concerns relate to potential adverse impacts on navigational safety in the vicinity of the
southern approach, and commercial fishery resources in the nearshore area. Egg-brooding
Dungeness crab females, juvenile Dungeness crab, and juvenile English sole are of primary
concern.
2.1.6 Disposal Site SF-3
This disposal site has been used by the Corps since the 1940s for disposal of sediment
dredged from Humboldt Bay. This former EPA interim disposal site lost its interim status
on December 31,1988. The Corps has used the SF-3 site for disposal of dredged material
on several occasions since the site lost its interim status. Approval for this disposal was
granted under Section 103 of the MPRSA. The most recent use occurred in April 1990.
The SF-3 site is located approximately 1.1 nmi southwest of the Harbor mouth (Figure 1-1).
The SF-3 site is 457 m (1,500 ft) in diameter.
2.1.7 Preferred Alternative
The preferred alternative for designation of a site for disposal of dredged material
from Humboldt Bay is the HOODS, which has been used for disposal of dredged material
since autumn 1990. The HOODS is 1 square nmi in size (Figure 2-1) and is located
between the 49 m and 55 m (160 ft and 180 ft) depth contours.1 It is positioned within the
coordinates 40° 48'25"N, 124°16'22"W;40°49'3"N, 124°17'22"W;40°47'38N, 124°17'22"W;
40°48'17"N, 124°18'12"W (Figure 2-1). The site lies approximately 3 to 4 nmi from the
mouth of Humboldt Bay.
The HOODS has been identified as the preferred alternative for the following
reasons: the site is located within a distance that is economically and operationally feasible
1 All ocean depths reported in this DEIS are relative to mean lower low water (mllw).
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STATION
CG55C
40°48'17'N>
124° 18' 139-W
544.432.319N
1,3627346.191E
A2
A3
A4
A5
STATION
CG49C
40" 47' 38'N
124°17'13'W
540.3A3.699N
1,366,858.852E
Source: Corps 1994b
B
Bl
B2
B3
B4
B5
Cl
C2
C3
C4
C5
C6
D1
D2
D3
D4
D5
El
E2
E3
E4
E5
E6
1 NAUTICAL Mll£
Fl
F2
F3
F4
F5
STATION
CG55N
40° 49' 3'N
124°17'22iW
54S.944.9SON
1,366,414.8E
STATION
CG49N
40° 48' 24"N
124°16'22iW
544,876.360N
1,370,927.472E
Figure 2-1. Humboldt Open Ocean Disposal Site
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(Corps 1989); the site reflects the preference of the local boating and fishing community;
use of the site will minimize unavoidable adverse ecological effects; and the site complies
with the EPA's siting criteria (40 CFR 228.5-228.6 [a]).
22 DISCUSSION OF ALTERNATIVES
2.2.1 Alternatives Not Considered for Further Analysis
The No Action, upland disposal, beach nourishment, and disposal off the continental
shelf alternatives were eliminated from further consideration. These alternatives are not
cost effective and/or would increase navigational and operational hazards. The No Action
alternative would result in evaluation of disposal on a case-by-case basis until 1997. After
1997, dredged material disposal would not be permitted at undesignated sites.
Upland disposal is not a viable option for the large quantities of suitable dredged
material removed annually as part of the Corps' maintenance dredging at Humboldt Bay.
Although this alternative has been eliminated from further evaluation as a designated site
in this DEIS because of excessive cost and the present lack of land availability, it remains
an option for disposal of smaller quantities of unsuitable material.
2.2.2 Compliance of the Three ODMDS Alternatives with the EPA's 5
General Criteria for Selection of Sites (40 CFR 228.5 [a])
a. "The dumping of materials into the 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 shellfisheries, and regions of heavy commercial or
recreational navigation."
As part of the site selection process, the Corps conducted several information surveys
of the local fishing and other maritime operators active in the Humboldt Bay area. The
Corps requested information on navigation routes into and out of Humboldt Bay, as well
as preferred areas for dredged material disposal and nondisposal within the ZSF. The
selection of the HOODS as the preferred alternative was in part based upon the information
gathered from these surveys, and it is believed that disposal at the HOODS has not
interfered with commercial fishing, sport fishing, recreational activities, or navigation in the
Humboldt Bay area.
In contrast, the SF-3 site and the NDS are both objected to by local members of the
commercial and recreational fishing community because of their perceived negative impacts
on safe navigation.
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b. "Locations and boundaries of disposal sites will be so chosen that
temporary perturbations in water quality or other environmental
conditions during initial mixing caused by disposal operations anywhere
within the site can be expected to be reduced to normal ambient seawater
levels or to undetectable concentrations or effects before reaching any
beach, shoreline, marine sanctuary, or known geographically limited
fishery or shellfishery."
None of the alternative ODMDS sites are located near or within any sanctuary
boundaries. The dredged material is composed primarily of coarse- and fine-grained sand
and some clay/silt. Results of dispersion modeling indicate that dredge materials settle to
the bottom rapidly and are initially contained within the disposal sites (0.26 nmi) (Borgheld
and Pequegnat 1983, Scheffner 1990). The shoreward edge of the HOODS is 3 nmi
offshore, and disposal at this preferred site would minimize any potential for water quality
impacts to beaches, shorelines, sanctuaries, or limited fisheries or shellfisheries.
c. "If at any time during or after disposal site evaluation studies, it is
determined that existing disposal sites presently approved on an interim
basis for ocean dumping do not meet the criteria for site selection set
forth in Sections 228.5 through 228.6, the use of such sites will be
terminated as soon as suitable alternate disposal sites can be designated."
The MPRSA site selection process is designed to identify a preferred alternative that
minimizes or avoids unacceptable impacts to the physical, biological, and socioeconomic
environment. The continued use of any site designated as an ODMDS will be evaluated as
part of the site management and monitoring program established for the site. The
management and monitoring program will be administered jointly by the EPA and the
Corps.
d. "The sizes of ocean disposal sites will be limited in order to localize for
identification and control any immediate adverse impacts and 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 determined as part of the disposal site
evaluation of designation study."
The specific locations and sizes of the ocean disposal sites have been defined in order
to minimize the area affected by the disposal of dredge materials and to facilitate
monitoring of the sites. Evaluation of the continued acceptability of the designated
ODMDS will be accomplished through the implementation of the site management and
monitoring program.
e. "EPA will, where feasible, designate ocean dumping sites beyond the edge
of the continental shelf and other such sites that have been historically
used."
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None of the ODMDS site alternatives lies beyond the edge of the continental shelf.
The existing historical sites are all located on the continental shelf. Furthermore, based on
the ZSF conducted by the Corps, disposal of dredged materials from Humboldt Bay off the
continental shelf is not considered to be feasible.
22.3 Compliance of the Three ODMDS Alternatives with the EPA's 11
Specific Criteria for Selection of Sites (40 CFR 228.6 [a])
Detailed discussions of the 11 general criteria are contained in Section 3, "Affected
Environment" and Section 4, "Environmental Consequences". A summary table of these
comparisons (Table 2-2) is presented here to support the decision-making process in
selecting the preferred alternative over the other viable alternatives.
22.4 Selection of the Preferred Alternative
The EPA and the Corps have determined that a site must be designated for disposal
of materials dredged from Humboldt Bay. The HOODS was selected as the preferred site
alternative for the following reasons:
The HOODS is a historical site which lies within the ZSF.
The HOODS has the capacity necessary to sustain the maintenance dredging
program for Humboldt Bay.
Use of the HOODS would comply with EPA's 5 general and 11 specific site
selection criteria.
Use of the HOODS would comply with all international, federal, state, and local
regulations.
Use of the HOODS would result in minimal environmental impact.
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Table 2-2. Comparison of Alternative Ocean Disposal Sites Based on
EPA's Eleven Specific Site Designation Criteria
40 CFR 228.6(a) Criteria
Site SF-3
NDS
HOODS
1. Geographical position, depth of water,
bottom topography and distance from
coast.
located 1.1 nmi WSW of harbor
entrance
site depth 12 m (40 ft)
relatively flat bottom topography with
mostly sandy substrates
located 1.2 nmi from coast
located 2 nmi SSW of harbor entrance
site depth 15-18 m (50-60 ft)
relatively flat bottom topography with
mostly sandy substrates
located 0.6 nmi from coast
located 3-4 nmi W of harbor entrance
site depth 49-55 m (160-180 ft)
relatively flat bottom topography with
substrates ranging from sandy to silty
located 3-4 nmi from coast
2. Location in relation to breeding,
spawning, feeding or passage areas of
living resources in adult or juvenile
stages.
typical demersal fish community but
lower abundance and diversity than
nearshore reference site
general commercially important fish
species spawn in waters of this depth
lower Dungeness crab abundance than
at NDS
minimal use by marine mammals and
birds
typical demersal fish community but
lower abundance and diversity than
nearshore reference site
general commercially important fish
species spawn in waters of this depth
greater Dungeness crab abundance
than other sites considered
minimal use by marine mammals and
birds
typical demersal fish community but
lower abundance and diversity than
SF-3
fewer commercially important fish
species spawn at this depth
lower Dungeness crab abundance than
NDS
minimal use by marine mammals and
birds
3. Location in relation to beaches and
other amenity areas.
located 1.2 nmi from public beaches
located 0.6 nmi from public beaches
located 3 nmi from public beaches
Types and quantities of wastes
proposed to be disposed of, and
proposed methods of release,
including methods of packing the
waste, if any.
sediment composition approximately
85% sandy-silt, 15% silt and silty-sand
the site will be used over a 50-year
period
dredge material disposal for the
annual maintenance dredging of
Humboldt Bay with average disposal
volumes of 106,089 cubic yards in
spring and 687,401 cubic yards in fall
self propelled hopper dredges will be
used to dredge and dispose of the
material
sediment composition approximately
85% sandy-silt, 15% silt and silty-sand
the site will be used over a 50-year
period
dredge material disposal for the
annual maintenance dredging of
Humboldt Bay with average disposal
volumes of 106,089 cubic yards in
spring and 687,401 cubic yards in fall
self propelled hopper dredges will be
used to dredge and dispose of the
material
sediment composition approximately
85% sandy-silt, 15% silt and silty-sand
the site will be used over a 50-year
period
dredge material disposal for the
annual maintenance dredging of
Humboldt Bay with average disposal
volumes of 106,089 cubic yards in
spring and 687,401 cubic yards in fall
self propelled hopper dredges will be
used to dredge and dispose of the
material
5. Feasibility of surveillance and
monitoring.
U.S. Coast Guard has surveillance
responsibility
monitoring is feasible at the site
dredge data logging system used for
surveillance
U.S. Coast Guard has surveillance
responsibility
monitoring is feasible at the site
dredge data logging system used for
surveillance
U.S. Coast Guard has surveillance
responsibility
monitoring is feasible at the site
dredge data logging system used for
surveillance
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Table 2-2. Continued
40 CFR 228.6{a) Criteria
Site SF-3
NDS
HOODS
Dispersal, horizontal transport and
vertical mixing characteristics of the
area, including prevailing current
direction and velocity, if any.
currents predominantly NW in winter
and offshore and SW in summer, but
relatively non-dispersive
currents predominantly shoreward but
relatively non-dispersive
currents relatively non-dispersive
7. Existence and effects of current and
previous discharges and dumping in
the area (including cumulative effects).
site used as an interim disposal site
since the 1940s
last disposal event occurred in fall
1990
sediments did not disperse from the
site as anticipated
site was closed due to navigational
safety concerns by interaction of waves
with accumulated dredge material
site has been used for disposal of
dredged material from Humboldt Bay
on two occasions in 1988 and 1989
site has not been used since 1989 due
to navigational safety concents like
those at SF-3 site
site has been used for disposal of
dredged material from Humboldt Bay
on 10 occasions between fall 1990 and
fall 1994
8. Interference with shipping, fishing,
recreation, mineral extraction,
desalination, Fish and shellfish culture,
areas of special scientific significance
and other legitimate uses of the ocean.
navigational safety concerns
no other activities in area
navigational safety concerns
no other activities in area
fewer navigational safety concerns
than SF-3 or NDS site
no other activities in area
9. Existing water quality and ecology of
the site as determined by available
data or by trend assessment or
baseline surveys.
water quality good
lower density and diversity of demersal
fish than nearshore reference site
possible spawning area for
commercially important fish species
lower abundance of Dungeness crab
than at other sites
water quality good
lower density and diversity of demersal
fish than nearshore reference site
possible spawning area for
commercially important fish species
greater Dungeness crab abundance
than at other sites considered
water quality good
lower density and diversity of
demersal fish than SF-3 site
10. Potentiality for the development or
recruitment of nuisance species in the
disposal site.
unlikely to recruit nuisance species
unlikely to recruit nuisance species
unlikely to recruit nuisance species
11. Existence at, or in close proximity to,
the site of any significant natural or
cultural features of historical
significance.
no known significant natural or
cultural features
no known significant natural or
cultural resources
three potential shipwreck sites are
located in HOODS
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Section 3
Affected Environment
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Section 3. Affected Environment
3.1 OCEAN DISPOSAL SITE CHARACTERISTICS
3.1.1 Historical Use of the Disposal Sites
The SF-3 disposal site has been used by the Corps to dispose of maintenance dredge
material since the 1940s. The most recent use of SF-3 was in the spring of 1990. It is
estimated that a total of 20 to 25 million yd3 of material dredged from Humboldt Bay
federal navigation channels has been disposed of at SF-3.
The NDS has been used for two fall disposal episodes. In September 1988 and
September 1989, approximately 837,000 yd3 and 585,000 yd3 of sand were deposited at the
NDS respectively. Material deposited at the NDS was dredged from the Bar and Entrance
and North Bay Channels.
The HOODS has been used for disposal of sediments dredged from Humboldt Bay
by the Corps on an interim basis since the fall of 1990. As of autumn 1994, the site will
have been used on 10 occasions (Table 3-1). A total of approximately 2,861,289 yd3 of
dredged material has been disposed of at the site (Corps 1994a, 1994b).
The HOODS lies in the mud-sand transition zone. The site has been divided into
four quadrants (Quads 1 through 4), each containing nine cells (Figure 2-1). The site has
been divided to facilitate the disposal of dredged materials into areas of the site containing
substrates similar in character to the dredged material. Quads 2 and 3 contain sandier
substrates, while Quads 1 and 4 contain finer substrates.
In the fall of 1990,683,000 yd3 of dredge materials were dumped into Quad 2 Cell E5
to monitor the long-term fate of dredged materials at the site.
3.1.2 Proposed Use of the Preferred Alternative Site
The preferred alternative ODMDS will be used for the disposal of all suitable
materials dredged by the Corps for new work in, and maintenance dredging of, the
Humboldt Bay federal navigation channels. In addition to annual maintenance dredging,
the Corps is currently proposing to deepen and widen the navigation channels and dispose
of that portion of the dredged materials suitable for unconfined open ocean disposal at the
ODMDS (Corps/HBHRCD 1994). All permit applications and Corps civil works projects
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Table 3-1. Volumes (cubic yards) of Dredged Material Disposed at the HOODS,
the NDS, and Site SF-3 by the Corps (1982-1994)
Year
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
Annual Average
Fall
490,447
1,010,676
494,000
1,414,156
1,119,776
698,431
836,966
585,000
414,208
682,000
145,000
536,350
509,200
687,401
Spring
98,000
1,900
12,830
163,500
64,250
93,605
130,254
123,203
192,224
152,912
150,395
90,000
106,089
Total
588,447
1,012,576
506,830
1,577,656
1,184,026
792,036
967,220
537,411
874,224
297,912
686,745
599,200
802,024
Location of Dredged
Material Disposal
Site SF-3 only
Site SF-3 only
Site SF-3 only
Site SF-3 only
Site SF-3 only
Site SF-3 only
Site SF-3 in Spring,
NDS in Fall
NDS in Fall, no
disposal in Spring
Site SF-3 in Fall,
HOODS in Spring
HOODS
HOODS
HOODS
HOODS
Source: Corps 1994a, 1994b, 1995
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will be evaluated for suitability for ocean disposal at the site in accordance with the EPA
Ocean Dumping Regulations (40 CFR 220-227).
3.1.3 Quantities and Characteristics of
Maintenance Dredging Sediments
Between 1982 and 1994 (1989 excluded), the Corps has dredged an annual average
of 802,000 yd3 of sediment from Humboldt Bay (Table 3-1). Dredging operations typically
occur twice yearly for maintenance of federal navigation channels at Humboldt Bay.
Dredging of the Samoa, Eureka, and Field's Landing Channels occurs in the spring
(March-April). Depending upon need, portions of the North Bay Channel may also be
dredged in the spring. The average annual volume of material dredged in the spring is
106,089 yd3. Larger average annual quantities of materials are dredged in the fall (687,401
yd3) when the Corps performs maintenance dredging of the Bar and Entrance Channel and
portions of the North Bay Channel.
In September 1992, the EPA, the Corps, and the Northern Coast Regional Water
Quality Control Board developed testing requirements for sediments dredged annually from
the Humboldt Bay channels (Corps 1994b). To better define contaminants of concern and
to determine how frequently the sediments should be tested, the agencies agreed to conduct
baseline studies of existing sediment quality in the harbor channels. The baseline studies
include three sediment evaluations. Two evaluations have already been conducted (October
1993, March 1994) and are summarized below. The third evaluation will occur in 1995.
Based on analyses of dredged sediment composition, sand will usually account for
80% to 90% of the total material dredged from Humboldt Bay (Corps/HBHRCD 1994).
Sediments dredged from the Bar and Entrance and North Bay Channels and the Field's
Landing Channel north of Buhne Point have historically been composed of sand (grain size
> 0.075 mm). Sediments dredged from these channels may be determined to be acceptable
for ocean disposal without further testing. This determination would be based on acceptable
existing information including grain size, sediment chemistry, bioassays, and reports oif spills
and other contaminants.
Sediments dredged from the Eureka and Samoa Channels and the Field's Landing
Channel south of Buhne Point have been composed of predominately (more than 50%) silt
and clay (grain size < 0.075 mm) with some (less than 50%) fine sand. Sediment chemistry
and toxicity testing were conducted on samples from these channels. The samples contained
relatively few detectable organic contaminants, and the concentration of detected
contaminants was not significant. Toxicity tests of sediments from these channels also did
not indicate significant levels of toxicity compared to reference samples. (Corps/HBHRCD
1994.) Thus far, all sediments that would be dredged during maintenance dredging activities
have been considered environmentally acceptable for ocean disposal.
The Corps is proposing to deepen and widen the navigation channels in Humboldt
Bay. Physical and chemical sediment sampling for the proposed Humboldt Bay channel
3-3
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deepening project was conducted in December 1991 (EVS Consultants 1993) to determine
the suitability of dredged materials from the channel deepening project for disposal at the
ODMDS, in compliance with MPRSA Section 103. The proposed project would generate
approximately 5,600,000 yd3 of dredged material to be disposed at an ODMDS and
approximately 26,000 yd3 of material, unsuitable for unconfined aquatic disposal, which
would be disposed at an upland disposal site. (Corps/HBHRCD 1994.)
3.1.4 Existence and Effects of Current and Previous
Discharges and Dumping in the Area
This section describes significant discharges into the ocean in the vicinity of the
ODMDS alternatives where potential cumulative or synergistic impacts are possible. There
are two significant discharges into the marine environment offshore of Humboldt Bay
(Figure 3-1). The Simpson Paper Company and the Louisiana-Pacific Corporation both
operate pulp mills on the Samoa Peninsula and discharge wastewaters outside of Humboldt
Bay.
3.1.4.1 The Simpson Paper Company
The Simpson Paper Company owns a pulp mill located near the community of
Fairhaven on the Samoa Peninsula in Humboldt County, California (Figure 3-1). The
company discharges through an outfall into ocean waters adjacent to the Samoa Peninsula.
The Simpson plant is not operating currently, but it is discharging fresh water through its
outfall. Historically, the discharge consisted of:
process wastewater from kraft pulping, pulp bleaching, and pulp drying;
solids from its water treatment plant;
power boiler effluent;
sawmill effluent;
treated sanitary sewage; and
stormwater.
Effluents are discharged from an 866 m (2,840 ft) outfall through a 58 m (189 ft)
multiple-port diffuser at an average depth of 10.6 m (35 ft).
As authorized under its National Pollutant Discharge Elimination System (NPDES)
Permit, the Simpson Paper Company is prohibited from discharging wastewater in violation
of effluent standards or prohibitions established under Section 307(a) of the Clean Water
Act, and it is prohibited from discharging sewage sludge.
The outfall is approximately 3 nmi east of the HOODS, 3 nmi north of the SF-3 site,
and 3.5 nmi north of the NDS. It is not expected that there would be either a cumulative
or synergistic effect from the disposal of dredged material and wastewater effluent
discharged by the Simpson Paper Company at any of the ODMDS alternatives considered
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PA Off 1C
0 C B A
Oi
Figure 3-1. Approximate Locations of Louisiana-Pacific Corporation and
9 Paper Company Ocean Outfalls
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in this DEIS. Prevailing currents would direct discharge plumes up or down the coast,
depending upon the seasonal current regime, not offshore toward the HOODS. Based upon
past receiving water monitoring and marine biological monitoring in the vicinity of the
outfall, impacts from effluent pollutants would be expected to occur in close proximity to
the point of effluent discharge. Combined impacts from dredged material disposal in the
nearshore area at either SF-3 or the NDS with effluent disposal from the Simpson Paper
Company would not result in a significant cumulative effect on the nearshore aquatic
environment.
3.1.4.2 The Louisiana-Pacific Corporation
The Louisiana Pacific Corporation (L-P) owns and operates a market bleached kraft
pulp mill located near the community of Samoa, California, on the Samoa Peninsula hi
Humboldt County (Figure 3-1). Under its NPDES Permit, L-P is prohibited from
discharging wastewater in violation of effluent standards or prohibitions established under
Section 307(a) of the Clean Water Act, and it is prohibited from discharging sewage sludge.
The L-P Corporation discharges effluents similar to those discharged historically by the
Simpson Paper Company into the Pacific Ocean through a 975 m (3,200 ft) outfall with a
152 m (498 ft) multiple-port diffuser at an average depth of 12.6 m (41.5 ft).
The discharge outfall is approximately 3.5 nmi east of the HOODS, 3.5 nmi north of
the SF-3 site, and 4 nmi north of the NDS. As previously stated for the Simpson Paper
Company outfall, it is not anticipated that the use of any of the alternative sites would result
hi any adverse cumulative or synergistic impacts.
3.1.5 Feasibility of Surveillance and Monitoring
Surveillance and site management are conducted by the United States Coast Guard
(USCG), the EPA, and the Corps. Under Section 107(c) of the MPRSA, the USCG
conducts surveillance to discourage unauthorized disposal (33 USC 1417). Additional
surveillance, site management, and enforcement responsibilities are delegated to the EPA
(40 CFR 22.36) and the Corps (33 CFR 226). The Corps utilizes a Dredge Data Logging
System (DDLS) as a surveillance tool on contract hopper dredging at Humboldt Bay. The
DDLS is installed on the hopper dredge and provides full-time, hard-disk records of all
pertinent dredge performance data (position, draft, date and time, work and disposal area,
etc.).
Monitoring is practicable at all three alternative sites. The accessibility of the SF-3
site and the NDS may at times be more restricted than at the HOODS because SF-3 and
the NDS are located in shallower water (14 to 17 m [45 to 56 ft] deep) and are subject to
a more rigorous wave climate than the HOODS (49 to 55 m [160 to 180 ft] deep).
However, these conditions have not interfered with the collection of bathymetric and
biological data at SF-3 and the NDS in the past.
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32 PHYSICAL ENVIRONMENT
3.2.1 Meteorology
The northern California coast has a moderate climate. Average minimum and
maximum temperatures for Eureka are 5°C (41°F) (January) and 17°C (62°F) (August).
Temperatures of 0°C (32°F) or lower can occur nearly every year along the coast.
Maximum temperatures seldom exceed 27 °C (80 °F). Fog is common in the coastal region
from late spring until early fall. It usually remains until late morning and returns again in
the early evening. Winds generally blow from the south and southwest in the winter, and
from the north and northwest in the summer.
The Humboldt Bay area is noted for its high precipitation (97 centimeters [cm]
[38 inches] of rainfall annually) and associated episodic storms. Most of the rainfall occurs
between mid-October and mid-May. During the winter, storms are most severe, with high
wind and squall conditions occurring frequently.
322 Air Quality
The study area lies within the North Coast Air Basin, which includes Del Norte,
Humboldt, and Trinity Counties. Onshore air pollution sources in Humboldt County are
regulated by the North Coast Unified Air Quality Management District (NCUAQMD).
Primary sources of air pollution are forest products industries and agricultural operations
(Corps/HBHRCD 1994). The NCUAQMD presently is in compliance with all state and
federal air quality standards except the state's 24-hour standard for PM10, which has been
violated several times between 1985 and the present (Herr pers. comm. in Corps/HBHRCD
1994).
The Corps' existing maintenance dredging program involves ships dredging and
hauling dredged material for ocean disposal. Exhaust emissions from these ships contain
reactive organic gases (ROG), nitrogen oxides (NOX), carbon monoxide (CO), paniculate
matter (PM), sulfur dioxide (SO2), and hydrocarbons (HC), all of which are released to the
atmosphere during operations. The proposed designation and the disposal at an ODMDS
of material from the maintenance dredging would not increase the loading of these
pollutants above the present level. However, dredge operation during the proposed harbor
deepening project may have a short-term significant impact on air quality (Corps/HBHRCD
1994).
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3.2.3 Physical Oceanography
The dominant circulation influence offshore of Humboldt Bay is the California
Current. The California Current system is a broad (540 nmi), sluggish current flowing
southward off the Oregon and California coasts. It is the eastern boundary current of the
large clockwise current circulation pattern that occupies most of the North Pacific Ocean.
The California Current is largely wind-driven, affected to a lesser degree by tides and
coastal topography.
The California Current system along the northern California coast undergoes
seasonal fluctuation. Three basic oceanographic regimes that influence the waters and
hydrographic conditions within the nearshore environments of northern California have been
described: the upwelling, Davidson Current, and oceanic regimes (Pine and Steller 1987,
Pequegnat et al. 1990). Each of these regimes is dominant during specific times of the year;
however, current conditions are influenced by wind events such that it is possible for the
regimes to occur any time of the year. Pequegnat and Mondeel-Jarvis (1991) describe the
three regimes as follows:
The upwelling regime. This regime occurs most commonly in the spring and
early summer months and is characterized by strong winds from the north and
northwest and a southerly current on the shelf of 26 to greater than 100 cm/sec
(0.5 to greater than 2.0 knots). Nearshore waters associated with this regime
have low temperatures, high nutrient concentrations, and moderately high
salinities (at least for the North Pacific Ocean).
The Davidson Current regime. This regime is associated with the storms
common in the late fall and winter and is characterized by strong south and
southwest winds, large waves, and a northerly current of up to 50 cm/sec (1
knot). During these periods, nearshore waters have low salinities, high
concentrations of suspended sediment, moderate nutrient concentrations, and
saturated dissolved oxygen concentrations.
The oceanic regime. This regime is common in late summer and early fall, when
winds are light and from no predominant direction. During these periods, the
California Current, normally offshore, moves closer to shore and causes low
nutrient concentrations, high temperature, and moderate salinities in the
nearshore environment.
3.2.3.1 Nearshore Circulation
Nearshore currents in the northern California region are determined by the alignment
of the coast, the width of the continental shelf, oceanic currents, topography, bathymetry,
winds, tides, density structure of the water, waves, and river discharge. At any location or
time, one or more of these forces can be the predominant influence on local currents.
3-8
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Some limited data have been collected on current systems in the vicinity of the two
nearshore disposal sites (SF-3 and the NDS). In a report on sediment transport at the SF-3
disposal site, Borgheld and Pequegnat (1986) state that existing current data for the shelf
area near the SF-3 disposal site are generally inadequate to permit precise estimation of
sediment transport. Borgheld and Pequegnat (1986) utilized a nearshore current data set
collected by Winzler and Kelly Consulting Engineers (1984) along the north spit of
Humboldt Bay in their description of dredged material transport at the SF-3 site. The time
periods summarized by Winzler and Kelly Consulting Engineers have been used to produce
a year-long summary of the currents in the vicinity of these stations. Winzler and Kelly
Consulting Engineers (1984) noted that the major current signal was best correlated with
local winds, and that tidally produced currents were of secondary importance. Borgheld and
Pequegnat (1986) believe that the proximity of the SF-3 site to the mouth of Humboldt Bay
increases the importance of surface tidal currents in the formation of nearshore currents and
the bottom currents as well. Borgheld and Pequegnat (1986) describe currents in the
nearshore area as unidirectional, with the predominant winter movement offshore and to
the northwest; less vigorous transport is characteristic of the summer conditions, with current
motion generally offshore and to the southwest.
In November 1988, the Corps San Francisco District, in cooperation with the Corps
Waterways Experiment Station - Coastal Engineering Research Center, released 475 seabed
drifters (SBDs) at SF-3 and the NDS to investigate current direction at both disposal sites.
The SBDs were released at five sites. One was released at the center of SF-3, and the other
four were released at the edges of the NDS.
The total SBD recovery was extremely high (67%) compared to similar studies at
other sites. Recovery of drifters released from the SF-3 site and the offshore edge of the
NDS was noticeably lower than from the northern and southern boundaries and the inshore
boundary of the NDS. There was an even stronger distinction in direction of flow from SF-3
as compared to direction of flow from the NDS. No NDS seabed drifters were found north
of the entrance channel to Humboldt Bay, whereas all but one of the SF-3 recoveries
indicated northward transport of the SBDs, either across or around the entrance channel.
Although this SBD study was short and indicative only of bottom current trajectories
(not of sediment transport specifically), the results do support the hypothesis that sediment
from the NDS was more likely to disperse shoreward and away from the entrance channel
than sediment from the SF-3 site under the conditions existing at the time of the study.
Offshore Circulation
Offshore current data are available for several sites near the HOODS. Long-term
current measurements were collected for the U.S. Department of the Interior's Mineral
Management Service (MMS) as a component of the Northern California Coastal Circulation
Study (MMS 1989). These data were made available to the Corps for subsequent analysis
for the site designation process. The current data were collected at two mooring sites:
Mooring E60 at a depth of 60 m (197 ft) supported a 1 current meter array at depths of
10 m (33 ft) and 15 m (49 ft), and mooring E90 at a depth of 90 m (295 ft) supported a
3-9
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3 current meter array with meters at depths of 15, 45, and 75 m (49, 148, and 246 ft)
(Figure 3-2). The current meters were deployed during four time periods between 1987 and
1989. Summary plots of the four recorded periods are shown in Figure 3-3. The current
vectors (representing current velocity in different directions) shown in the figure indicate
current direction upcoast (positive vector value) and downcoast (negative vector value).
Summary computations in the form of northerly (+U) and easterly (+V) component
averages, velocity magnitudes, standard deviation, and percent magnitudes above 50 cm/sec
are shown in Table 3-2.
In general, these data indicate 10 m to 15 m deep current velocities on the order of
25 cm/sec (0.5 knot); 45 m deep current velocities of 20 cm/sec (0.4 knot); and bottom
current velocities of 15 cm/sec (0.3 knot).
3.2.3.3 Waves
Low-pressure storms are the most important source of storm waves reaching the
California coast during winter months. These storms originate near Japan and proceed
eastward across the Pacific, with the intensity of the waves decreasing southward along the
California coast. The summer months are dominated by the high-pressure storms, with
predominant wave action generated by the prevailing west/northwest winds along the coast.
Borgheld and Pequegnat (1986) utilized wave data from two wave rider buoys
offshore of Humboldt Bay and described a seasonal wave spectra pattern. During the winter
months, the wave spectra are dominated by longer period swells (periods greater than 12
seconds between waves). During the rest of the year, the spectra demonstrate a greater
predominance of waves with shorter periods (i.e., less than 12 seconds between waves).
3.2J.4 Tides
The Humboldt area experiences mixed tides. Mixed tides refer to two sets of tides
each day (two high and two low tides). The sets of tides are not equal in amplitude. The
tidal range between mean lower low water (MLLW) and mean higher high water (MHHW)
is 1.95 m (6.4 ft) at the south entrance jetty to Humboldt Bay. Extreme low tides have been
observed, as low as 0.6 m (2 ft).
32.4 Water Quality
Ocean water temperatures along the California coast respond to seasonal current
changes, wind direction, insolation, and upwelling. The temperature of the nearshore waters
of northern California normally ranges from 9°C to 14°C (48°F to 57°F). The salinities
of the nearshore environment range from less than 25 parts per thousand (ppt) during
periods of high runoff to greater than 34 ppt when deeper water is advected to the surface
during periods of intense upwelling (Pequegnat and Mondeel-Jarvis 1990).
3-10
-------
Figure 3-2. Approximate Location of Current Meter Stations E60 and E90
-------
50
C*irr«nl <.tn/\
-50
50
C-90/IS
Current cm/i
-18
C-90/4J
Current cm/i
-18
C-SO/7S
Co'rtnl cm/i
-50
50
Currt.il cm/i )
-50
50
t-'JO/K)
Currcit cm/i
-18
C-00/4S
Current cn\/i
-B
C-00//S
C**rrt nl cn^s .
-50
i
Source: MMS 191
Period 1 Period 2
: ' 60
P" jk ' ' Cumnl cm/«
IV -50
Y i i i i t i i i i i i i i i i i i n i i
_ 50
Al' jllL-Jl ,h_)".j,l'N r» C-90/iO
"WHPff ' ^ «-.n,W.
0 c-to/u
° Cumnl em/i
l-l ' ~5fi
ik. 1 . JJ» , irj*i Ml1 l» f'»u >*»! .1 ... . a C-90/75
T\ JP^riJ4r-i4i_jTjLa .mi Iii '«.. " "i J^i'n'*t 0
IF^ flr^HflfliV */ *^
i i i|| i i i i 1 i i i i i i i i i i i i i i r i i
A. .Ltu , ^^, .Mo
' ]H']rV|plTp»Vr^ ^-*
0* *" -_*.- fc-
^
U22»S UltJIJtOPlOlT M JI2I3 U If 31 2 t UMJO
MAR APR MAY JUN JUL AUG
1988
Period A
i 1 50
^rv^ffr^^wpnTrrr^^^jp^f^ir'^^ cu'-'i^
.^, .... ,'f /'/,,,, , v . i i^r -50
i i i i i i i i i i i i 1 i 1 i i i i i i i i i i i 5jJ
l^tf/ iH^f'^ .uAl 0 E-40/4S
'" jlf "^ Jf ^ " Curr«nl em/i
0 r-WK
Curr«nl cm/'
T-r-r-r-,-.-.... ... . . .-.-.- -50
0 ( 1)1017 4 II III} 1 t 15111* t 1)1017 1 10 f7 14)1 7 M 1111 7
SEP OCT NOV DEC JAN FED
1988 1989
19
Jlj »r . . M
P lVjHn ' '^ ^'r ^1 ^ ' ' ' ^' D
1^1 i i i i i i i i i i r i r i i i i r i i i II i i i'i i i i i ;-
~^»T Ml1 1|"np''^>r* *^ff "jrr1^* ' '* l"fcrf"-"*>'-s.-'»-JIi Q
\Ls, i 'j^.'^1. ' ' a 'A ' 'ilu ' ' ' 'j 'a ' V '. ' ' ' V
~^^V*>npo <-'V^<~'^ * t *"' i «...'»..» i*.».ii,*A^«tuJu^ o
1 Ulll»» 01* 11 ) 101714)17 M 1I11S UN Ml l«l))0i I) JO 17 4 It 111} I
MAR APR MAY JUN JUL AUG SEP OCT
1989
Figure 3-3. Record of Four Periods of Current Meter Deployment at Sites E60 (15 m)
and E90 (15 m, 45 m, 75 m)
-------
Table 3-2. Current Speed and Direction from Current
Meter Mooring Stations E60 and E90
Mooring Number/
Depth (m)
Period 1
E-60/15
E-90/15
E-90/45
E-90/75
Period 2
E-60/10
E-90/10
E-90/45
E-90/75
Period 3
E-60/10
E-90/10
E-90/45
E-90/75
Period 4
E-60/10
E-90/10
E-90/45
E-90/75
Average
U1
(cm/sec)
-1.90
-5.37
2.46
-6.70
-2.88
0.41
-4.49
1.89
-7.82
-3.74
2.47
1.11
Average
V2
(cm/sec)
-4.36
14.08
3.52
-8.40
-6.81
4.06
-5.48
-0.44
-12.23
-3.68
1.91
3.93
Average
Velocity
(cm/sec)
30.51
27.12
15.54
17.82
17.63
14.90
22.12
16.65
24.79
20.60
14.80
15.79
Standard
Deviation
(cm/sec)
17.63
17.03
8.28
14.45
13.51
8.06
12.71
10.23
13.96
13.12
9.46
8.79
% of Time
Exceeding 50
cm/sec
1529
11.08
0.00
3.79
3.24
0.10
3.25
0.45
4.42
3.26
0.58
0.17
1 U - Positive values indicate current flow to the north; negative values indicate current flows to the
south.
2 V - Positive values indicate current flow to the east; negative values indicate current flows to the
west.
3-13
-------
Pequegnat and Mondeel-Jarvis (1990) describe temperature and salinity changes in
nearshore waters adjacent to Humboldt Bay in relation to the hydrographic regimes as
follows:
The upwelling regime. During upwelling periods, the nearshore water
temperature drops to below 10 °C (50 °F) and the salinity rises to over 33.6 ppt.
During intense upwelling periods, the sea surface temperature may drop to less
than 8°C (46 °F), with salinities greater than 34 ppt. The water column is not
stratified shoreward of the upwelling front. The distance offshore at which the
upwelling front is found depends on both the wind velocity and the wind
duration but is typically more than 4 nmi offshore during periods of moderate
upwelling.
The Davidson Current regime. Because the northerly flowing Davidson Current
is associated with winter storms, the nearshore surface waters tend to be cool
(less than 11 °C [52°F]) and of low salinity (less than 32 ppt) because of high
runoff. The nearshore waters also tend to be highly stratified, primarily due to
the vertical salinity gradient.
The oceanic regime. During periods of light and variable winds, the warm
surface water offshore tends to move onshore. Consequently, the sea surface
temperature typically rises to greater than 13 °C (55 °F) and the salinity is usually
less than 33.5 ppt. The waters are usually vertically stratified with respect to
temperature and, to a lesser extent, salinity.
As part of this designation effort and an earlier effort to designate the SF-3 site,
water column characteristic studies were performed at the preferred site (the HOODS), the
SF-3 site, and a nearshore reference site (Figure 3-4). The studies were conducted at the
HOODS in September 1990 and April 1991, and at SF-3 in May 1983 and July 1983. They
included the evaluation of temperature, salinity, and density (SIGMA-t) profiles at two
stations located at the shoreward and seaward boundaries of the HOODS (in 49 m [160 ft]
and 55 m [180 ft] of water respectively). These same profiles were also collected at SF-3 and
at a reference station (both in approximately 21 m [70 ft] of water). (Pequegnat and
Mondeel-Jarvis 1991, Winzler and Kelly Consulting Engineers 1984.)
3.2.4.1 Dissolved Oxygen
The surface layers of the ocean are usually saturated with dissolved oxygen (DO), and
DO concentration generally decreases with depth. During upwelling conditions, the oxygen
concentration in the surface waters may be less than 50% of the saturation concentration;
this low oxygen concentration is associated with the deeper, low-oxygen water that is
advected to the surface.
During nearshore field surveys conducted in May 1983 at the SF-3 disposal site and
at a reference site, DO levels ranged from a high of 8.2 milligrams per liter (mg/1) (98%
saturation) to a low of 6.4 mg/1 (70% saturation) near the bottom. During the July 1983
3-14
-------
I SOmtmCOHIOOKUHKAHUffKOXIIilAH |
Sources: Pequegnat and Mandeel-Jarvis 1991, Winzler and Kelly 1984
Figure 3-4. Location of Offshore and Nearshore Field Surveys for Water Column Characteristics
-------
survey of these sites, DO levels were higher. Supersaturated water (9.7 mg/1 [117%
saturation]) was present near the surface. The lowest level detected was 6.8 mg/1 (77%
saturation) near the bottom (Winzler and Kelly Consulting Engineers 1984).
In offshore field surveys conducted in September 1990 at the HOODS, DO levels
ranged from 6.2 mg/1 (105% saturation) to 3.5 mg/1 (55% saturation) at the 49 m (160 ft)
station; DO values at the 55 m (180 ft) station ranged from 5.9 mg/1 (100% saturation) to
2.2 mg/1 (35% saturation).
In April 1991, DO concentrations at the 49 m (160 ft) and the 55 m (180 ft) stations
were supersaturated (115% and 123% respectively). Oxygen concentration in near-bottom
samples were lower (66% and 62% of saturation respectively).
3.2.4.2 Turbidity
Coastal waters generally have higher turbidities than open ocean waters because
coastal waters are more subject to paniculate inputs from land. Wastewater dischargers,
river runoff, and resuspension of small particles by waves and currents are the major
contributors to nearshore turbidity. Nearshore turbidity values will increase during the
spring runoff season due to increased sediment loading from river waters. This has a direct
effect on primary production because the amount of sunlight available to phytoplankton
directly affects primary algal productivity and biomass.
Within the study areas, suspended sediments and phytoplankton are the main factors
affecting water clarity. Changes in light transmittance with depth are a reflection of these
two factors. Occurrences of high concentrations of phytoplankton are typical of the upwelling
regime. Periods of high concentrations of sediment load occur during the Davidson Current
regime. It is expected that transmittance would decrease in surface waters during these
periods. During oceanic regime conditions, when surface waters containing low
phytoplankton and low sediment concentrations move into the study areas, transmittance
would be high. Below the surface layer, phytoplankton would tend to increase in
concentration, resulting in lower transmittance. (Pequegnat and Mondeel-Jarvis 1990.)
Results of field studies at the HOODS indicated that water was clearer at mid-depth
than at the surface but decreased in transmissivity near the bottom. It is suspected that this
decrease in transmissivity near the bottom could be caused by either suspended sediment,
sinking phytoplankton, or detritus.
3.2.5 Regional Geology
The northern California continental shelf has a complex morphology that has
developed because of active tectonic movements in the area. The study area lies in close
proximity to the Gorda-Pacific-North American triple junction, which is usually defined as
the juncture of the San Andreas fault and the Mendocino Escarpment. North of the
3-16
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Mendocino Escarpment, the coastline can be divided into two major sections based on the
coastal morphology and underlying geologic structure.
The coast north of Trinidad Head is generally steep and rugged; offshore islands and
seastacks are common. Beneath this section of the coast lies the Franciscan Formation.
The beaches are generally steep, coarse-grained, and limited in lateral extent (the only
major exception is Gold Bluffs Beach, just south of the Klamath River).
The study areas lie within the second major morphologic area, the area between
Cape Mendocino and Trinidad Head. The coast in this area has been formed over
underlying Tertiary marine deposits and features a coastal plain dissected by meandering
rivers and streams. The shore consists of relatively broad, flat beaches. The only major bay
along the coast, Humboldt Bay, is found in this area.
The continental shelf north of Cape Mendocino is relatively narrow, ranging from 5.2
to 19 nmi in width. The surface of the shelf shows little relief except in areas near the
major headlands where seastacks and underwater promontories are common. The lack of
shelf relief, which is surprising considering the active tectonism, is due to the rapid
sedimentation in the area. The shelf area has been called the Eel River Shelf by Borgheld
(1985) because the modern sedimentation is dominated by material supplied by the Eel
River. Sedimentation rates vary but apparently range from 0.5 to 2.0 cm (0.8 inch) per year
(Borgheld 1985, 1986). This rate is rapid for shelf areas supplied by all but the world's
largest rivers. The rate is high because sediment yield from the local rivers is higher than
that of any watershed of comparable size in the United States.
32.6 Sedimentation Patterns
Sedimentation patterns on the Eel River Shelf are produced by a number of
processes acting together. Sediments are supplied to the shelf in a series of short-term
deposition events. The pulsed nature of the sediment supply system is extremely important
in the production of the sediment stratification on the shelf.
Numerous rivers and streams empty directly onto the coast in this area. Of these,
two deliver the majority of the sediment to the coast. The major supplier is the Eel River,
which delivers an average of 27,282,000 tons of suspended sediment per year to the
continental shelf (Borgheld 1985). The Mad River supplies approximately one tenth of this
amount to the shelf, an average of 2,774,000 tons of suspended sediment per year. The
rivers along the northern California coastline have short drainage basins and highly variable
stream flows. These rivers characteristically carry the majority of their sediment load during
two or three flood events per year. (Borgheld 1985.)
Borgheld (1988) has documented a secondary sediment supply system in the study
area that is produced by the ebb-tidal plume exiting Humboldt Bay. This plume acts like
an additional river sediment plume by supplying sediment to the shelf. It delivers less
3-17
-------
sediment than the Eel River but delivers the majority of its sediment during spring tides
rather than during river flooding.
Each major sediment supply event (i.e., major flood or major spring tide) deposits
a layer of sediment on the shelf. The layer is generally thickest near the sediment source
and decreases in thickness with distance from the source. Therefore, floods tend to produce
layers that are thickest near river mouths, and the layers produced by the ebb-tidal plume
from Humboldt Bay tend to be thickest near the bay mouth.
Once deposited, a layer is mixed physically by waves and currents, and biologically
by benthic organisms (bioturbation). The amount of physical mixing is primarily controlled
by the size of incoming waves and the water depth; wave mixing is more intense in shallower
water. Borgheld (1986) collected box cores near the mouth of the Eel River and noted that
the flood history of the river has been preserved in the sediments near the river mouth.
Thick layers (up to 10 to 12 cm [4 to 5 inches] thick) have been deposited during past floods
of the river. In shallower water, generally less than 40 m (131 ft) deep, these layers were
subsequently destroyed by sediment remobilization and mixing caused by incoming waves.
In water depths greater than 40 m (131 ft), many of the sediment layers were preserved,
since presumably the water depths were too great for the incoming waves to significantly
remix the bottom sediments. Instead, the mixing that occurred was generally limited to
bioturbation.
Biological mixing occurs during the day-to-day activities of organisms that live in the
bottom (infauna) or near the bottom (epifauna). It is unlikely that biologically produced
mixing is uniform on the continental shelf, but no detailed study of this mixing in the study
area has been conducted. Borgheld (1985) noted that the biological mixing history of a
layer was apparently related to the layer thickness; thick layers had little if any biological
mixing, while thin layers were commonly intensely mixed.
Wave mixing has an additional effect on the shelf s sediment distribution: areas
where the bottom sediments are continually resuspended by wave action tend to have
coarser sediments than deeper areas less influenced by waves. Fine-grained sediments (silts
and clays) settle slowly compared to larger particles, and their continual resuspension
effectively prevents them from accumulating in an area influenced by wave activity.
3.3 BIOLOGICAL ENVIRONMENT
The area of study described herein encompasses the region identified by the Corps
in 1989 as the Zone of Siting Feasibility (ZSF). Within ZSF boundaries, three candidate
sites have been chosen for disposal of material dredged from Humboldt Bay. These sites
are the HOODS, SF-3, and the NDS.
Commercially important biological resources include groundfish (e.g., English sole,
Dover sole, Pacific sanddab, rockfish), Dungeness crab, and salmon, all of which seasonally
occur in the region, including the sites proposed for dredged material disposal. A variety
3-18
-------
of seabirds and marine mammals also occur in the region, including the disposal sites. Of
lesser importance commercially, but of great importance ecologically, are the planktonic
communities (phytoplankton and zooplankton) and benthic communities (polychaete worms
and clams) that provide food for higher trophic level organisms (fish, marine mammals, and
birds).
3.3.1 The Plankton Community
The open waters off Humboldt Bay are part of the California Current region, where
biological components from a variety of marine biotic provinces mix. Few endemic (native)
species or distinct neritic assemblages (organisms that occur on the coastal shelf) are found
in this pelagic environment, but warm-water species from the central Pacific province and
warmer-water cosmopolitan species occasionally occur. (Jones & Stokes Associates 1981.)
Plankton biomass and species composition in this region are influenced by the
southern-flowing California Current and the Davidson Current that flows sporadically
northward in winter. In addition, the upwelling of cold, nutrient-rich deep water during late
spring and summer fertilizes surface waters, promoting phytoplankton production.
33.1.1 Phytoplankton
Phytoplankton are chlorophyll-bearing microscopic algae that passively drift or have
limited means of locomotion and are, therefore, carried by waves and currents.
Phytoplankton form the basis of marine food chains by using solar energy to convert
inorganic nutrients into organic matter through photosynthesis. The distribution and
abundance of phytoplankton depend on light intensity, nutrient concentrations, intensity of
grazing, turbulence, turbidity, upwelling, and circulation. The abundance and variety of
phytoplankton in surface waters, in turn, influence the subsequent production of zooplankton
and other organisms.
Phytoplankton concentrate in surface waters where light is available, but vertical
distribution is mainly affected by turbulence, stratification, and limited mobility (i.e.,
dinoflagellates). Phytoplankton biomass (as indicated by chlorophyll a concentration) is
usually lower offshore (15 to 20 milligrams of chlorophyll a per square meter [mg
chlorophyll a/m2] in the upper 150 m [500 ft]) than nearshore (approximately 300 mg
chlorophyll a/m2 in the upper 150 m [500 ft]) (Owen 1974).
Phytoplankton populations in the coastal waters of northern California are generally
composed of diatoms, dinoflagellates, coccolithophores, and flagellates (Hood et al. 1990).
Primary production and phytoplankton biomass increase after persistent upwelling periods
during the late spring and summer when cold, nutrient-rich waters induce intense blooms
of diatoms. Photosynthetic carbon production rates can be 2 to 10 times higher in areas of
pronounced upwelling than in open ocean waters. The rate of primary production in
northern California coastal waters is about 150 grams of carbon per square meter per year
3-19
-------
(g/C/m2/year) but may reach 300 g/C/m2/year in upwelling regions (Jones & Stokes
Associates 1981). Following blooms, phytoplankton biomass declines as nutrients become
limiting and phytoplankton is eaten by zooplankton or other grazers.
The warmer, nutrient-poor oceanic water of the California Current supports less
biomass and smaller phytoplankton species than those present during upwelling (Hood et
al. 1990). During the stormy fall and winter season, primary production rates are low due
to reduced solar radiation, reduced upwelling, increased mixing of surface waters below the
euphotic (light-penetration) zone, and increased turbidity due to wave action and increased
flow of sediment-laden river water. The northern-flowing Davidson Current occasionally
influences phytoplankton composition offshore of Humboldt Bay during winter months by
bringing warm-water phytoplankton species from central Pacific waters.
2 Zooplankton
Zooplankton are aquatic invertebrates that have limited mobility or passively drift
with water currents. Zooplankton transfer some of the energy of primary producers
(phytoplankton) to larger invertebrates, fish, birds, and marine mammals. Zooplankton are
divided into two main groups: (1) holoplankton, which spend their entire life cycle in the
water column; and (2) meroplankton, which consist mostly of the larvae of benthic
macroinvertebrates that are temporary members of the pelagic zooplankton community.
The larvae of polychaetes, bivalves, gastropods, and crustaceans are typical meroplanktonic
organisms, while holoplanktonic organisms include copepods, opossum shrimp (Mysidacea),
krill (Euphausiaced), and arrow worms (Chaetognatha).
Zooplankton populations are regulated by water temperature, food availability, and
predation. Zooplankton are most abundant within the top 20 to 30 m (66 to 100 ft) of the
water column (Peterson and Miller 1977) and closer to the shore over the continental shelf
(Pearcy 1972, Colebrook 1977, Peterson and Miller 1977).
Zooplankton distribution tends to be extremely patchy, largely as a result of ocean
currents (Wickett 1967). The vertical distribution of zooplankton is determined by light,
phytoplankton density, food, and the biology of each species. Zooplanktonic species from
the Subarctic, Transition, and Central Pacific faunal groups have been identified in the
coastal upwelling regions offshore of Oregon (Peterson and Miller 1977). The oceanic
currents that influence the zooplankton composition in the coastal waters of Oregon are
similar to those that influence the area offshore of Humboldt Bay (Hickey 1979); therefore,
the species composition of zooplankton found offshore of Humboldt Bay is comparable to
that reported for the coast of Oregon.
Peak zooplankton abundance in the coastal waters of northern California occurs from
May through July in response to increased food availability following upwelling.
Zooplankton species characteristic of northern faunal groups dominate in the summer when
the California Current flows to the south. The copepod Pseudocalanus spp. is an abundant
component of the California Current zooplankton, with highest densities occurring within
the nearshore zone (2.6 nmi off the coast). In general, the nearshore zone is an important
3-20
-------
habitat for many other species of zooplankton. Acartia spp. and Centropages abdominalis
are restricted to this zone, while other important zooplankton, Pseudocalanus spp. and
Calanus marshallae, move into the nearshore zone to reproduce. Many higher trophic level
organisms (i.e., pelagic fishes, marine birds, and mammals) occur seasonally in the area in
an apparent response to the increased abundance of zooplankton and other prey. During
the winter, however, warm-water species are transported northward by the Davidson
Current, and zooplankton species abundance is generally lower (Peterson and Miller 1977).
The predominant holoplanktonic organisms in the coastal waters of northern
California are copepods such as Calanus pacificus, Acartia spp., and Pseudocalanus sp.;
mysids such as Neomysis kadiakensis and N. rayi; and euphausiids, including Thysanoessa
spinifera (Peterson and Miller 1977, Lockheed Center 1979, Pequegnat et al. 1990).
Of the meroplankton, the pelagic larval stages of many shallow-shelf benthic
invertebrates (such as the Dungeness crab1) are an important seasonal component (Jones &
Stokes Associates 1981). Following hatching, zoea stages of Dungeness crab larvae remain
in the plankton off central California from mid-December to mid-March (Reilly 1983a).
Considerable offshore movement of this larvae occurs during this time, and these larvae can
be found at depths greater than 30 m (100 ft) (Reilly 1985). After upwelling begins in April
and May, megalopae, the final pelagic stage of the Dungeness crab, appear near shore in
large concentrations. The mechanism by which they move inshore is unclear (Pauley et al.
1989). Megalopae occur off Humboldt Bay from April to June, concentrating at the surface,
especially at dawn and dusk (Toole 1989). They are frequently associated with floating
materials, slicks, and upwelling fronts (Toole 1989). Dungeness crab larvae feed on
zooplankton and are important prey items for plankton-feeding fish such as salmon (Reilly
1983b) and rockfish (Prince and Gotshall 1976).
No data are available describing the seasonal abundance and distribution of other
meroplanktonic invertebrate larvae in the area offshore of Humboldt Bay. Oliver and
Slattery (1976) reported that the reproductive patterns of the benthic invertebrate fauna
correlated well with day length and phytoplankton blooms in the spring and fall in a study
of a similar environment in Monterey Bay.
The zooplankton species that accompany the current regimes occurring offshore of
Humboldt Bay are an essential link in the food web of the waters of the area but are not
of direct economical or commercial importance.
3.3.2 The Benthic Algae Community
Attached plants are uncommon in open coastal waters with sandy bottoms because
of a lack of nutrients, few attachment sites, and inhibition by waves and longshore currents.
Some seaweed, mostly Fucus distichus and Ulva sp., is found along the intertidal and subtidal
1 Scientific names for all species mentioned in text are presented in Appendix B.
3-21
-------
portions of the north and south jetties. The lack of suitable substrate and the intensity of
wave action prohibit the development of large kelp beds in the subtidal area off of
Humboldt Bay.
3.3.3 The Benthic Invertebrate Community
Benthic macrofaunal invertebrates are those organisms (generally > 1 mm
[0.04 inches]) that occur in bottom sediments. Several detailed studies of the benthic
invertebrate communities offshore of Humboldt Bay have been performed (ERC 1976,
Lockheed Center 1979, IEC 1981, Winzler and Kelly Consulting Engineers 1984, Pequegnat
and Mondeel-Jarvis 1990, Pequegnat et al. 1990). However, only one study sampled the
benthic macrofauna in water deeper than 30 m (100 ft) (Pequegnat et al. 1990). Benthic
invertebrate communities have been surveyed more thoroughly at the shallower ocean
alternative sites (the NDS and SF-3) than at the HOODS, which ranges in depth from 49
to 55 m (160 to 180 ft). A summary of the dominant benthic macrofaunal invertebrates
reported near Humboldt Bay is provided in Table 3-3.
3.3.3.1 Benthic Infauna
Benthic infauna are invertebrates that burrow into the bottom sediments. The
distribution, abundance, and species composition of benthic infauna communities in
nearshore continental shelf sediments are related to sediment grain sizes (Gray 1974),
organic content of sediments, production of organic matter in overlying waters, interactions
among organisms, and environmental disturbances (such as storm waves and high sediment
loads associated with episodic floods and drag fishing) (Pequegnat et al. 1990).
Pequegnat et al. (1990) conducted a study of benthic fauna in the area of study from
1989 to 1990. Polychaetes, mollusks, and crustaceans account for over 90% of the species
and numbers of individuals of the benthic infauna in the area. The polychaete biomass is
also greater in the finer sediments within the region. In general, the number of species and
the abundance of benthic infaunal invertebrates increased with increasing depth in the
benthic environment offshore of Humboldt Bay.
A total of 295 species of benthic invertebrates were identified by Pequegnat et al.
(1990). Annelids, primarily polychaete worms, are the most abundant species group found
in the benthic environment, accounting for over 70% of the individuals. The abundance of
polychaetes, in general, increased with increasing depth. Mollusks, primarily gastropods and
bivalves, were the next most abundant species group of the benthic infauna. The most
abundant gastropod snail, Olivella pycna, occurred primarily in the shallower depths, while
the most abundant bivalve was found in highest densities in the deeper areas. Crustaceans,
especially amphipods, were the third largest species group contributing to benthic infaunal
abundance.
3-22
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Table 3-3. List of the Dominant Benthic Macrofaunal Invertebrates
Reported near Humboldt Bay
Annelida
Polychaeta
Chaetazone setosa pugettensis
Decamastus gracilis
Gfycera oxcephala
Heteromastus filobranchus
Lumbrineris luti
Mediomastus califomiensis
Scoloplos armiger
Spiophanes bombyx
Tharyx spp.
Arthropoda
Crustacea
Malacostracans
Cumacea
Diastylopsis dawsoni
Amphipoda
Ampelisca careyi
Anisogammarus pugettensis
Atylus tridens
Monoculodes spinipes
Protomedia prudens
Isopoda
Synidotea bicuspida
Mollusca
Gastropoda
Olivella pycna
Mitrella spp.
Bivalvia
Axinopsida sericata
Siliqua patula
Source: Pequegnat et al. 1990.
3-23
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Overall, the abundance of benthic infaunal invertebrates declines during the winter
in the region. Total benthic infaunal abundances range from 2,400 organisms/m2 in March
1990 to 3,450 organisms/m2 in August 1989. Polychaetes are the most abundant infaunal
species group in both summer and winter. Mollusks account for a greater percentage of the
total number of individuals in the region during the winter than during the summer
(Pequegnat et al. 1990).
Three zones of benthic infauna have been identified (Pequegnat et al. 1990): (1) the
nearshore zone (< 35 m [115 ft] in depth), (2) the mid-depth zone (> 35 m [115 ft] but
< 55 m [180 ft] in depth), and (3) the offshore zone (> 75 m [250 ft] in depth).
The nearshore benthic zone contains clean sand with little organic debris and is swept
by waves. The infaunal diversity in the nearshore is low, and there are more suspension-
feeders and fewer burrowing deposit-feeders than are found farther offshore. Small
polychaetes, amphipods, cumaceans, and mollusks are the principal infauna in the nearshore
zone (Lockheed Center 1979, IEC 1981, Winzler and Kelly Consulting Engineers 1984,
Pequegnat et al. 1990). The abundance and diversity of infauna in the nearshore zone vary
seasonally (Pequegnat et al. 1990, Winzler and Kelly Consulting Engineers 1984), probably
because of seasonal wave action in the relatively shallow depths.
Two alternative ocean disposal sites, the NDS and SF-3, are located within this
nearshore zone. Following disposal of dredged material, the abundance and numbers of
infaunal species were lower than offshore and at nearby reference stations (Lockheed
Center 1979, IEC 1981, Winzler and Kelly Consulting Engineers 1984, Pequegnat et al.
1990). The dredged material disposed at the sites was coarser than that of the adjacent
habitat at similar depths, and the frequency of dumping inhibited benthic succession.
Therefore, the benthic fauna at the site was characterized by opportunistic, small, mobile,
surface-dwelling invertebrates. There has been no disposal at SF-3 since April 1990, or at
the NDS since fall 1989. This period of respite from disposal disturbance is reportedly long
enough to allow the benthic communities at these disposal sites to recolonize to an
assemblage more similar to the adjacent benthic habitats (Bott and Diebel 1982, Tatem
1984).
The sandy sediments of the mid-depth zone contain more organic debris and so
support a more diverse and abundant infauna than is found in the nearshore zone. The
mid-depth zone also supports more burrowing deposit feeders, which have limited mobility
and feed from burrows within the sediments. Sediments with high organic content provide
better habitat for non-motile deposit-feeders than is found in the nearshore zone.
The break between the mid-depth and the offshore zones does not occur at a fixed
depth but ranges from a depth of 55 to 75 m (180 to 250 ft) in response to wave energy and
sediment supply. At water depths greater than 55 m (180 ft), the percentage of silt in the
sediment increases, as does the amount of organic material. The boundary between the
sands found in the nearshore and mid-depth zones and the muds found farther offshore (in
waters greater than 75 m [250 ft] in depth) lies in this area. This transition area between
the mid-depth and offshore zones is called the "mud-sand transition zone." The HOODS
3-24
-------
is located within the outer limit of the mid-depth zone and the inner limit of the mud-sand
transition zone.
Higher diversity and greater abundances of infaunal species, including burrowing,
deposit-feeding polychaetes and mollusks, are found in this transition zone than nearer to
shore. The sediments in this zone are finer and contain more organic material, and so
provide a more suitable habitat for burrowing infaunal organisms than the sand substrates
characteristic of the nearshore and mid-depth zones. For example, the bivalve Axinopsida
serricata has been found only in water > 49 m (161 ft) deep, probably because the finer-
grained sediments found in deeper water are better for burrowing (Pequegnat et al. 1990).
The stability of this environment is partly responsible for its relatively higher diversity and
the increase in sedentary burrowing and tube-dwelling infauna (Oliver et al. 1980).
The offshore zone (> 75 m [250 ft] in depth) contains fine sands with silty clays and
terrestrial organic debris. The area of study extends only a short distance into the offshore
zone, so the offshore muds were not sampled. It is likely that even higher numbers of
species and individuals would be found in samples from deeper locations.
The benthic invertebrate infauna of the region may be an important link in the food
web supporting higher trophic level species, some of which are of commercial significance.
Although the feeding preferences of demersal fish species and of Dungeness crab include
benthic infaunal invertebrates, specific areas important for feeding have not been identified.
These feeding habitats are likely to be widespread within similar depth zones and sediment
types in the region.
33.3.2 Benthic Epifauna
Epifauna refers to animals that are associated with the surface of the sea floor rather
than those that burrow into sediments. Most of the epibenthic species captured in trawls
offshore of Humboldt Bay are carnivorous or omnivorous. These species affect the
distribution and abundance of their infaunal prey (Woodin 1974, Virnstein 1977).
Decapods, particularly Dungeness crabs, and three species of shrimp (bay shrimp,
sand shrimp, and coon-stripe shrimp), are numerically dominant organisms in the region.
Pequegnat et al. (1990) report that these species are generally more abundant and found
at greater depths in March than in August. Common echinoderms include sea stars, the
short-spined star, the brown mud star, and the Pacific sand dollar. Large numbers of sand
dollars are found in the nearshore and mid-depth zones.
The most economically important epifaunal invertebrate reported in this region is the
Dungeness crab, which is fished commercially along the northern California coast. Most of
these crabs are taken from water less than 55 m (180 ft) deep; however, this may be partly
due to the depths to which fisherman are willing to lower their crabpots (Pequegnat et al.
1990). Adult crabs are found living over several substrate types, but they prefer sandy mud
bottoms (Karpov 1983, Lawton and Elner 1985). Dungeness crabs are highly mobile and
change depths in response to local conditions such as turbulence due to storms.
3-25
-------
Adult male and female Dungeness crabs move into shallow sandy areas to mate
between March and July; between September and November, egg-brooding females partially
bury themselves in the sand in shallow subtidal and intertidal areas until their eggs hatch.
The distribution of the planktonic life stages of the crab is discussed in Section 3.3.1.2.
Juvenile Dungeness crabs remain at the bottom of estuaries or shallow nearshore areas for
11 to 15 months before moving offshore. Researchers are currently debating whether
juvenile crabs need specific areas such as estuaries for nursery grounds for rearing (Toole
1989, Pauley et al. 1989, Pequegnat et al. 1990).
Dungeness crabs occupy successive trophic levels as they develop. Larvae eat
zooplankton and are, in turn, preyed upon by fish. Adult Dungeness crabs are opportunistic
feeders that eat mollusks, crustaceans, and fish, as well as serving as prey to numerous
predators. According to Stevens et al. (1982), crabs eat bivalves during their first year,
shrimp (Crangon spp.) in their second year, and juvenile fish in their third year.
Cannibalism is common among these crabs and probably influences juvenile and adult
abundance. Crabs move into shallower water at night and deeper water in the day; this
response has been correlated with food availability (Stevens et al. 1984).
The field data obtained by Pequegnat et al. (1990) indicate that Dungeness crabs in
the region are more abundant and found at greater depths in March in comparison to
August. The greatest abundance of Dungeness crab has been found at and adjacent to the
NDS (Lockheed Center 1979, IEC 1981, Winzler and Kelly Consulting Engineers 1984,
Pequegnat et al. 1990), with the highest abundances in November at that site (Pequegnat
et al. 1990).
Few or no crabs were reported from trawls made at the SF-3 site in April (IEC
1981), May (Winzler and Kelly Consulting Engineers 1984), or July (Winzler and Kelly
Consulting Engineers 1984); or in the vicinity of the HOODS in April (IEC 1981) or August
(Pequegnat et al. 1990). However, an increased abundance of Dungeness crabs was found
at SF-3 in February (Lockheed Center 1979) and at the HOODS in March (Pequegnat et
al. 1990). Lockheed Center (1979) found a greater abundance of Dungeness crabs in
February in the areas adjacent to SF-3 compared to the trawls performed within the disposal
site boundaries.
Caridean shrimp (bay and sand shrimp) found offshore of Humboldt Bay are
important food items for demersal fish and crabs. The commercially fished pink ocean
shrimp was not found in any of the trawl samples collected by Pequegnat et al. (1990). Pink
shrimp are reportedly commercially fished in depths of over 70 m (230 ft) approximately
26.9 nmi north of the study areas at Patrick's Point.
The sea stars Pisaster brevispinus and Luidia foliolata are important predators of the
benthic invertebrate community. They have been reported to prey heavily upon juvenile
Dungeness crabs, olive snails, and clams. Sand dollars are found in extensive, densely-
packed beds at depths of 0 to 100 m (0 to 330 ft) (Pearse 1975). Sand dollars migrate in
response to sea conditions, moving into shallow water when seas are calm and moving
offshore during storms. Sand dollars are found in narrow bands along the shore off of
3-26
-------
Humboldt Bay throughout the year and are common at 12 m (40 ft) in September
(Pequegnat and Mondeel-Jarvis 1990). They have been reported in large numbers at the
NDS (Pequegnat et al. 1990).
33.3.3 Pelagic Macroinvertebrates
A few squid (Loligo sp.) were captured in trawls made by Pequegnat et al. (1990)
offshore of Humboldt Bay at depths of 31 to 55 m (102 to 180 ft) in August and March.
However, squid have not been reported in previous trawl samples from this vicinity
(Lockheed Center 1979, ffiC 1981, Winzler and Kelly Consulting Engineers 1984). The
distribution of market squid is unclear, and environmental influences are largely unknown
(Kaskiwada and Reckseik 1978). Squid egg sacks are occasionally found on crab pots off
the Humboldt County coast and are an incidental catch by trawling shrimp fisherman in
water 72 to 182 m (240 to 600 ft) deep. However, they apparently do not occur in adequate
numbers to support a commercial fishery in this area.
3.3.4 The Fish Community
A total of 562 species of fish have been identified in California's coastal waters. In
discussing the ecology of fishes, species are commonly grouped into assemblages based on
broad similarities in biology or habitat (Miller and Lee 1972). Nearshore bottomfish, deep-
water benthic fish, schooling marine fish, and anadromous fish are examples of major fish
assemblages. Nearshore bottomfish and deep-water benthic fish are called demersal
because they are associated with the sea floor, whereas schooling and anadromous fish are
called pelagic because they live in open water. The following sections discuss the demersal
and pelagic fish found within the region, as well as the occurrence of these fish in the
vicinity of the alternative disposal sites.
33.4.1 Demersal Fish
Demersal fish are characterized as either nearshore species living at depths of 11 to
100 m (36 to 330 ft) or deep-water species occurring in shelf habitats at depths of 100 to
550 m (330 to 1,800 ft). Common demersal fish found near shore in the waters off of
Humboldt Bay are English sole, Pacific sanddab, starry flounder, butter sole, sand sole,
speckled sanddab, curlfin turbot, pricklebreast poacher, tubenose poacher, warty poacher,
plainfin midshipman, staghorn sculpin, and showy snailfish (Table 3-4) (Winzler and Kelly
Consulting Engineers 1984, Pequegnat et al. 1990). In addition, lingcod may occur near
rocks off the Harbor entrance jetties, and California halibut may occur in nearshore waters
outside the Bay (Monroe 1973). Of these species, the commercially important fish are
English sole, Pacific sanddab, starry flounder, California halibut, and lingcod. Critical life
history stages of these species are summarized in Table 3-5.
3-27
-------
Table 3-4. Demersal Fish Known to Occur near Humboldt Bay
Common Name
Scientific Name
Class: Osteichthyes (Bony Fishes)
Righteye flounders: Pleuronectidae
English sole
starry flounder
butter sole
sand sole
curlfin turbot
Dover sole
petrale sole
rex sole
Lefteye flounders: Bothidae
Pacific sanddab
California halibut
speckled sanddab
Poachers: Agonidae
pricklebreast poacher
tubenose poacher
warty poacher
Sculpins: Cottidae
staghorn sculpin
Toadfishes: Batrachoididae
plainfin midshipman
Snailfishes: Cyclopteridae
showy snailfish
blacktail snailfish
Greenlings: Hexagrammidae
lingcod
Rattails: Macrouridae
roughscale rattail
black rattail
giant rattail
Parophrys vetulus
Platichthys stellus
Isopsetta isolepsis
Psettichthys melanostictus
Pleuronichthys decurrenss
Microstomus pacificus
Eopsetta jordani
Gfyptocephalus zachirus
Citharichthys sordidus
Paralichthys califomicus
Citharichthys stigmaeus
Stellerina xyostema
Pallasina barbata
Occella verrucosa
Leptocottus armatus
Porichthys notatus
Liparis pulchellus
Careproctus melanurus
Ophiodon elongates
Coryphaenoides acrolepis
C. acrolepis
C. pectoralis
3-28
-------
Table 3-4. Continued
Common Name
Scientific Name
Eelpouts: Zoarcidae
twoline eelpout
Sablefishes: Anoplopomatidae
sablefish
Scorpionfishes: Scorpaenidae
widow rockfish
canary rockfish
bocaccio
darkblotched rockfish
chilipepper rockfish
Class: Chondrichthyes (Cartilaginous Fishes)
Ratfishes: Chimaeridae
ratfish
Skates: Rajidae
longnose skate
Dogfish sharks: Squalidae
spiny dogfish
Bothrocara brunneum
Anoplopoma ftmbria
Sebastes entomelas
S. pinniger
S. paucispinis
S. crameri
S. goodei
Hydrolagus colliei
Raja stellulata
Squalus acanthias
Sources: Pequegnat et al. 1990, Winder and Kelly Consulting Engineers 1977,
Lockheed Center 1979.
3-29
-------
Table 3-5. Summary of Critical Stages of Commercially Important
Nearshore Demersal Fish Found near Humboldt Bay
Species
English sole1**"-'
Parophrys vetulus
Pacific sanddabw
Citharichttys sordidus
Starry flounder"
Platichthys Stellas
Lingcod"*-"*
Ophiocon elongatus
California halibut*-"-"
ParalictuJtys
californicus
Spawning
Habitat/Season
spawn in sand and
sand/mud bottoms at
depths of 60 to 110 m;
most abundant from
December to February,
but occur year-round
spawn in 30 to 90 m,
sandy bottoms; July to
September, with peak
activity in August
spawn in shallow,
coastal and bay areas,
December to January
spawn in rocky
bottoms, from
intertidal to 19 m;
November to April
with peak activity in
late December to early
February
spawn at depths of 6
to 20 m over sandy
bottoms; February to
August, peak in May
Egg
Habitat
pelagic, November
to March
pelagic
pelagic
demersal, rocks in
tidepools from
lower intertidal to
19 m depth
pelagic,
concentrated in
areas with depths
of 6 to 20 m
Larval
Habitat
pelagic; most larvae
within 2 km of shore;
December to May
pelagic; inshore to
724 km offshore; July
to August peak
abundance in October
to November
pelagic
demersal, January to
July; rocks and
vegetation in lower
intertidal, but older
larvae are pelagic, near
surface
pelagic, usually found
between 12 and 45 m
isobaths
Juvenile Habitat/
Seasonal Feeding
larval juveniles settle to bottom from
November to May into open coastal
areas, mainly <16 m deep; nursery areas
are mainly estuaries but also open
coastline, April to October; juveniles
emigrate to deeper waters, August to
November
Diet: ampbipods, cumaceans,
polychaetes, benthic invertebrates
most occur in 66 to 92 m, spring to fall
Diet: amphipods, copepods, cumaceans,
mysids
juveniles settle to bottom, probably in
shallow waters
pelagic, January to July; 1-yr juveniles
may recruit to sandy, shallow bottoms,
down to 60 m but usually in bays,
estuaries
March to May move to deeper, offshore
waters with growth; juveniles recruit to
sand and mud bottoms off coastal
embayments/
estuaries in June
Diet: copepods, mysids, cumaceans,
amphipods
Adult Seasonal
Distribution/Habitat,
Range, Feeding
summer depths of 20 to 70 m, winter
depths of 40 to 130 m; offshore sand,
sand/mud substrate; Baja, California to
Bering Sea
Diet: epifaunal, infaunal prey, including
polychaetes, bivalves, small crustaceans,
brittle stars
commonly occur at depths of 35 to 90 m;
deep sand to sand/mud areas; Baja,
California to Bering Sea
Diet: euphausiids and mysid crustaceans
most abundant over soft sand, mainly in
shallow water; Santa Barbara, California
to Arctic Alaska
Diet: crabs, shrimp, worms, clams
rocky habitat, mainly in waters less than
100 m deep; Baja, California to Shumagin
Islands, Alaska
adults most common from surf (S3 m)
zone to 60 m; Baja, California to
Quillayute River, Washington
Diet: anchovies, croakers, flatfish, squid
Sources:
* MCP Applied Environmental Sciences 1987 c Took et al. 1987 e Lassuy 1989 8 Shaw and Hussler 1989
b Took 1989 d Hart 1973 ' Rflckowsld and Rikitch 1989 h Kucas and Hussler 1986
-------
The most abundant demersal fish living in the deeper shelf environments are
chimaeras, sharks, skates, flatfishes, and rockfishes (Winzler and Kelly Consulting Engineers
1977). The commercially important fish species in the deeper shelf areas are Dover sole,
petrale sole, rex sole, black rattail, widow rockfish, canary rockfish, bocaccio rockfish,
darkblotched rockfish, and chilipepper rockfish. Other fish species common to the deeper
shelf areas include ratfish, roughscale rattail, giant rattail, blacktail snailfish, twoline eelpout,
longnose skate, and spiny dogfish.
Many deepwater flatfishes and rockfishes move between deep and shallow water
during their development (Pequegnat et al. 1990). Adult bottomfishes tend to move from
deep to shallow water to aggregate and spawn; their eggs and larvae are pelagic and move
with the currents. Juveniles settle to the bottom and move into nursery grounds in estuaries
or shallow coastal areas. The juvenile stages of deepwater fish, in particular, are sensitive
to conditions in nearshore habitats. The juvenile stages of many commercial deep-water
bottomfish, including Dover sole, petrale sole, widow rockfish, canary rockfish, bocaccio
rockfish, darkblotched rockfish, and chilipepper rockfish, occur in nearshore areas (Toole
1989). Critical life history stages of these species are summarized in Table 3-6.
3.3.4.2 Pelagic Fish
Pelagic fish are found in the epipelagic zone, which roughly encompasses the upper
200 m (660 ft) of the water column. The epipelagic zone extends over the continental shelf
where upwelling occurs. The abundant phytoplankton and zooplankton in this area support
vast schools of pelagic fish. Pelagic fish offshore of Humboldt Bay include anadromous fish
and schooling marine species (Table 3-7).
Adult anadromous fish migrate through Humboldt Bay on their way to freshwater
spawning grounds, and juveniles pass through the nearshore environment during their
seaward migration. Anadromous fish species in Humboldt Bay include chinook salmon,
coho salmon, steelhead trout, and coastal cutthroat trout (Monroe 1973).
Other species known to occur commonly in this open coastal area (the study area)
include schooling fish such as blue rockfish, black rockfish, Pacific tomcod, Pacific herring,
northern anchovy, night smelt, whitebait smelt, eulachon, shiner surfperch, spotfin surfperch,
silver surfperch, walleye surfperch, white seaperch, and bay pipefish (Toole 1989, Pequegnat
et al. 1990). Pacific cod, a year-round commercial and sport species, may also be found in
this area (Dames and Moore 1981). The brown smoothhound shark also occurs in this area;
it is a member of the family Triakididae, a group of schooling shark species (Eschmeyer et
al. 1983). Critical life history stages of pelagic fishes found near Humboldt Bay are
summarized in Table 3-8.
33.4.3 Occurrence of Pelagic and Demersal Fish at the Proposed Disposal Sites
The HOODS. Trawl surveys were conducted by Humboldt State University in August
1989 and March 1990 at depths of 49 and 55 m (160 and 180 ft) just south of the HOODS
3-31
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Table 3-6. Summary of Critical Stages of Commercially Important
Deep-Water Demersal Fish Found near Humboldt Bay
Species
Dover sote****
Microstomus
pacificus
Petrale sole***
Eopsetta jordani
Rex sole"
Gfyptocephalus
zachims
Sablefish"**
Anoplopoma fimbria
Rockfish spp.
Widow rockfish**'4
Sebastes entomelas
Canary rockfishb>e
Sebastes pinniger
Boccaccio
rockfish***
Sebastes paucispinis
Spawning
Habitat/Season
spawning aggregations
in 80 to 732 m,
November to March
major spawning
aggregations in 274 to
450 m, November to
March; move offshore
in winter and inshore
in summer
spawn at 100 to 300 m
deep water, January to
February
mid-November to mid-
March
little known; spawning
may be confined to
restricted areas,
January to March
spawning may be
confined to specific
areas, mid-winter
two broods; spawning
in mid-November and
March
Egg
Habitat
pelagic eggs
primarily in upper
SO m, from
November to
March
pelagic eggs, float
with current, sink
before reaching
nearshore areas
pelagic
pelagic
ovoviviparous
ovoviviparous
ovoviviparous
ovoviviparous
Larval
Habitat
pelagic, primarily in
upper 50 m
pelagic, in shallow
waters
pelagic
pelagic, upper 1 m, 5.6
to 370 km from shore,
March to July
pelagic, found year-
round, commonly at
depths >100m
pelagic, March
not in epipelagic, or
shallow waters
occur often far
offshore in the upper
100 m, mid-December
and April
Juvenile Habitat/
Seasonal Feeding
mud bottom, on shelf; February, 130 to
183 m depth, may move into shallows (10
to 183 m) in summer
Diet: same as adults
benthic in fall of first year (64 to 82 m
depths), May to August found 18 to 90 m
Diet: mysids, sculpins, juvenile flatfishes
become benthic in winter, 150 to 200 m,
use this depth as nursery
shallow waters; occur at depths of 100 to
200 m, occasionaly 30 m deep
Diet: euphausiids, copepods, amphipods,
larvaceans
become benthic, small juveniles occur
from surface to depths of 20 m; older
juveniles at depths of 9 to 37 m, mainly
June to August
Diet: euphausiids, salps
become benthic, occur at depths less than
22 m; mainly May to August
some benthic juveniles occur in less than
22 m, but not common
Diet: perches, jack mackerel, juvenile
rockfishes
Adult Seasonal
Distribution/Habitat,
Range, Feeding
mud bottoms, 18 to 915 m; Baja,
California to Bering Sea
Diet: polychaetes, bivalves, benthic
crustaceans, brittle stars
sandy bottom; 18 to 547 m; Baja,
California to Gulf of Alaska
Diet: euphausiids, shrimp, pelagic fish,
juvenile flatfish
sand or mud bottom; 18 to 614 m depth,
but mainly below 61 m; San Diego to
Bering Sea
mud/clay bottoms; bottoms at 305 to
1,829 m; Baja, California to Bering Sea
Diet: squid, octopus, euphausiids, shrimp
rocky banks; 34 to 366 m; Baja,
California to Kodiak, Alaska
Diet: amphipods, euphausiids, shrimp,
salps
rocky bottom; 91 to 274 m; Baja,
California to Southeastern Alaska
rocky reefs and open bottom; 27 to
320 m; Baja, California to Gulf of Alaska
Diet Pacific hake, northern anchovy
-------
Table 3-6. Continued
Species
Thorn/head
rockfish"*
(shoitspine and
longspine)
Sebastolobus
alascanus and
5. alavelis
Darkblotched
rockfish"*
Sebastes crameri
Chilipepper
rockfish1^
Sebasates goodei
Spawning
Habitat/Season
little known
little known; spawning
may be confined to
restricted areas,
February
spawn in mid-
November to mid-
March
Egg
Habitat
pelagic; eggs float
at surface in
gelatinous masses,
January to May
ovovrviparous
ovovtviparous
Larval
Habitat
pelagic
pelagic, March
pelagic, occur near
surface; December to
April
Juvenile Habitat/
Seasonal Feeding
not restricted to shallow, nursery areas
not restricted to shallow, nursery areas;
0-yr old found at 73 to 130 m
age 0 found at surface to 8 m, around
rocky reefs during summer, subadults and
adults occur at depths of SO to 350 m
Diet: planktonic crustaceans
Adult Seasonal
Distribution/Habitat,
Range, Feeding
soft bottom, 29 to 549 m; southern
California to Bering Sea
sand and mud bottom; 61 to 329 m; Baja,
California to British Columbia
Diet: euphausiids, anchovies, laternfish
References:
MFC Applied Environmental Sciences 1987 c Morton 1989 ' Hart 1973
b Toole 1989 d Miller and Lee 1972
-------
Table 3-7. Pelagic Fish Known to Occur near Humboldt Bay
Common Name
Scientific Name
Class: Osteichthyes (Bony Fishes)
Trouts: Salmonidae
chinook salmon
coho salmon
steelhead trout
coastal cutthroat trout
Scorpionfishes: Scorpaenidae
blue rockfish
black rockfish
Codfishes: Gadidae
Pacific tomcod
Pacific cod
Herrings: Culpeidae
Pacific herring
Anchovies: Engraulidae
northern anchovy
Smelts: Osmeridae
night smelt
whitebait smelt
eulachon
Surfperches: Embiotocidae
shiner surfperch
spotfin surfperch
silver surfperch
walleye surfperch
white surfperch
Pipefishes: Syngnathidae
bay pipefish
Oncorhynchus tshawytscha
O. Jdsutch
O. mykiss
O. clarki clarki
Sebasates tnystinus
S. paucispinis
Microgaddus proximus
Gadus macrocephakis
Culpea harengus pallasi
Engraulis mordax
Spirinchus starlds
Allotments elongates
Thaleichthys pacificus
Cymatogaster aggregata
Hyperprosopon anale
H. ellipticum
H. argenteum
Phanerodon furcatus
Syngnathus leptorhynchus
3-34
-------
Table 3-7. Continued
Common Name Scientific Name
Class: Chondrichthyes (Cartilaginous Fishes)
Requiem sharks: Carcharhinidae
brown smoothhound Mustelus henlei
Source: Pequegnat et al. 1990, Winzler and Kelly Consulting Engineers 1977,
Lockheed Center 1979.
3-35
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Table 3-8. Summary of Critical Stages of Commercially Important
Pelagic Fish Found near Humboldt Bay
Species
Spawning
Habitat/Season
Egg
Habitat
Larval
Habitat
Juvenile Habitat/
Seasonal Feeding
Adult Seasonal
Distribution/Habitat,
Range, Feeding
Anadromous Fish
Chinook salmon**
Oncorhynchus
tshawytscha
Coho salmon**
Oncorhynchus Idsutch
Steelhead trout"-0-"
Oncorhynchus myldss
Summer run
Winter run
Coastal cutthroat
trout
Oncorhynchus clarki
clarki
fish return to
Humboldt County
rivers and must hold in
estuaries and
nearshore areas until
rains provide sufficient
flows to move
upstream; September
to February
fish return to
Humboldt County
rivers and must hold in
estuaries and
nearshore areas until
rains provide sufficient
flows to move
upstream; September
to February
return to Middle Fork
Eel River; May to
October
return to Humboldt
County rivers;
November to April
spend summer in
ocean and estuaries;
spawn in January and
February
freshwater
freshwater
freshwater
freshwater
freshwater
freshwater
freshwater
freshwater
freshwater
freshwater
juveniles in nearshore waters, but little
information on nearshore distribution
in ocean; concentrate near canyon
heads; May to October in some
locations
juveniles in nearshore waters, in ocean
off Oregon, most juveniles found within
4 m of surface; concentrate near canyon
heads; March to June
juveniles (1 to 4 yr olds) move through
nearshore waters; March to April
juveniles (1 to 4 yr olds) move through
nearshore waters; March to April
seaward smolt migration peaks in May,
fish remain close inshore
ocean; San Diego to Bering Sea
ocean; Baja, California to Arctic Alaska
ocean; Baja, California to Bering Sea
ocean; Baja, California to Bering Sea
ocean; Eel River to southeast Alaska
-------
Table 3-8. Continued
Species
Spawning
Habitat/Season
Egg
Habitat
Rockfish
Blue rockfishb
Sebastes mystinus
Black rockfish'
Sebastes melanops
Yellowtail rockfish"
Sebastes flavidus
spawn in
mid-November to
mid-April
spawning area
unknown; maybe
offshore; January to
April
spawn in
mid-November to
mid-March
pelagic
pelagic
not applicable
Larval
Habitat
Juvenile Habitat/
Seasonal Feeding
Adult Seasonal
Distribution/Habitat,
Range, Feeding
pelagic
pelagic; April to June
pelagic
become benthic in <2S m; late May to
June
restricted to benthic; 40 to 50 m depth;
mainly in June; range is from April to
October
juveniles have been found in bay,
nursery areas
schooling rockfish; off bottom near
reefs and pinnacles; surface to 550 m;
Baja, California to Bering Sea
primarily found in areas with depths of
54 m or less; mainly found in mid-
waters; southern California to Aleutian
Islands
mostly pelagic, 24 to 46 m; San Diego
to Kodiak Island
Beach and Bay Fish
Herring*-'
Clupea harengus
paliasi
Surf, night smelt,
whitebait smelt4*
Hypomesus preaosus,
Spainchus starksi,
AUosmerus elongatus
surfperches11*
Cymatogaster
aggregata, Amphistus
rhodotenu,
Hyperprosopon
ellipticum,
H. argenteum,
Phanerodon fuKonu
spawn in protected
embayments, especially
Humboldt Bay,
December to March
restricted to spawning
in surf zone of sandy
beaches; March to
August; surf smelt
spawns at day; night
smelt spawn at night
spawn in protected
embayments and
shallow coastal waters;
spring and early
summer
eggs restricted to
embayments, especially
Humboldt Bay,
December to March
eggs attached to sand
grains in surf zone of
sandy beaches; March
to August
viviparous
restricted to bays and
shallow coastal areas
near shore; spring and
early summer
little known
viviparous
not restricted to shallow water nursery
areas
little known
restricted to bays and shallow areas,
especially Humboldt Bay, summer and
fall
when not spawning, typically offshore;
Baja, California to Arctic Alaska
little known; generally, southern
California to British Columbia or
Alaska
shallow surf, sheltered bays; generally,
southern California to British
Columbia or Alaska
References:
* Toole 1989 c Pauley et al. 1986 c Stein and Hussler 1989
b Hart 1973 d Pauley et al. 1989 ' Lassuy 1989
-------
(Pequegnat et al. 1990). In August 1989, the trawl catch in the HOODS was composed
primarily of whitebait smelt and, in order of decreasing abundance, Pacific sanddab, rex
sole, Dover sole, Pacific tomcod, and juvenile sanddab. More species were found during the
March 1990 surveys; in order of decreasing abundance these were night smelt, whitebait
smelt, Pacific tomcod, Pacific sanddab, shiner surfperch, black rockfish, English sole,
speckled sanddab, Pacific sand sole, showy snailfish, curlfin turbot, eulachon, Pacific herring,
juvenile sanddab, and larval smelt. Most of the catch (by weight) was made up of black
rockfish, night smelt, English sole, Pacific sanddab, and Pacific tomcod.
These trawl surveys also showed that fish assemblages change with distance offshore.
At the HOODS, two fish assemblages are likely to occur: an assemblage at mid-depth waters
(40 to 49 m [130 to 160 ft] deep) composed mainly of Pacific sanddab, rex sole, and Dover
sole; and another deep-water assemblage (greater than 55 m [180 ft] deep) with a species
composition that is not clearly understood (Pequegnat et al. 1990). In comparison, fish
communities captured in shallow waters at a depth similar to that of SF-3 (18 to 40 m [59
to 130 ft]) consisted mainly of smelt.
Commercially important bottomfish species occurring within the HOODS are English
sole, Pacific sanddab, and probably lingcod and California halibut (Table 3-5 summarizes
the life histories of these species). The English sole that use the HOODS are primarily
adults and older juveniles. Adults live at depths of 20 to 70 m (66 to 230 ft) in the summer
and 40 to 130 m (130 to 426 ft) in the winter; larger juveniles move from nearshore to
deeper waters and may be found within the HOODS. Adult Pacific sanddab spawn at
depths of 35 to 90 m (115 to 295 ft) between July and September, with most spawning
activity in August. Juvenile lingcod could potentially use the HOODS since they are found
in sandy bottoms from the intertidal zone to depths of 200 m (656 ft). Also, adult California
halibut are found in waters as shallow as 55 m (180 ft), and older juvenile California halibut
move from shallow bays to deeper offshore water such as the HOODS.
Of the deep-water bottomfish, Dover sole, petrale sole, and juvenile stages of widow
rockfish, canary rockfish, bocaccio rockfish, and chilipepper rockfish are likely to occur in
the vicinity of the HOODS (Table 3-6 summarizes the life stages of these bottomfish in
relation to the importance of nearshore habitats). Juvenile Dover sole and petrale sole are
likely to occur within the HOODS during the summer; adults may also occur in this area
during their nonspawning period (April to October). Juvenile rockfish are commonly found
in shallow waters (less than 37 m [121 ft] deep) in late spring and summer, but older
juveniles gradually move offshore as they grow and may occur within the HOODS.
Many commercially important pelagic fish, including anadromous and schooling
marine species, may occur in the HOODS (Table 3-7). Adult anadromous fish may pass
through the HOODS as they migrate toward Humboldt Bay to spawn, and juveniles may
pass through in their seaward migration. Of the schooling marine species, juvenile black
rockfish, adult yellowtail rockfish, and juvenile and adult stages of whitebait smelt and night
smelt may all occur in the vicinity of the HOODS (Pequegnat et al. 1990).
Results from Humboldt State University's trawl surveys showed a general tendency
toward decreased fish abundance and total biomass in the deeper, offshore areas (Pequegnat
3-38
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et al. 1990). The number of fish caught at the HOODS in August (32) was lower than the
number of fish caught at the SF-3 site (1,150) during the same survey period. There was
also a correspondingly lower total biomass (weight) of fish caught at the HOODS (1,102
grams) compared to the shallower SF-3 site (3,503 grams) (Pequegnat et al. 1990). Similar
trends were apparent during the surveys conducted in March.
Species diversity, however, did not decrease in all cases toward offshore sites. In
August, the number of species appeared reduced at depths of 55 m (180 ft) and deeper, but
in March surveys, species diversity seemed similar at most depths.
The SF-3 Site. SF-3 was surveyed by otter trawls on several occasions in the late
1970s and early 1980s (Lockheed Center 1979). The diversity of fish caught at SF-3 was
characteristic of the fishes in the surrounding area. In February 1979, the trawl catches
were dominated by Pacific tomcod, pricklebreast poacher, and showy snailfish. Trawl
catches were composed primarily of night smelt in May 1983 and speckled sanddab in July
1983. These differences in catch were probably a function of season. In another survey,
comparison of the SF-3 catches to catches at a nearby control site at similar depths
indicated that fish species diversity and fish abundance were lower at SF-3 than at the
control site. In February 1979, 55 individuals of 8 species were collected within the SF-3
site. Just outside SF-3, 178 individuals representing 18 different taxa were found. In the
1983 surveys, the assemblage of fish species was not significantly different between SF-3 and
a nearby control site (outside the SF-3 disposal area). However, several species were more
abundant at the control site, with a greater biomass than at SF-3. In May, Pacific tomcod
were much more abundant at the control site than at SF-3; in July, English sole juveniles
were the second most abundant species at the control site while only a few were found at
SF-3. As with the benthic communities, differences in fish diversity and abundance were
probably the result of the deposition of dredged material. (Winzler and Kelly Consulting
Engineers 1984.)
Many nearshore bottomfish found at the SF-3 site are important to commercial and
recreational fisheries. Pacific sanddab, English sole, starry flounder, lingcod, and California
halibut are found year round (Table 3-5). During the summer, adult English sole are found
at depths similar to that of the SF-3 site (average depth of 20 m [66 ft]). Juvenile English
sole use shallow (16 m [52 ft] and shallower) sandy bottoms from November to May and
may use the SF-3 site as a nursery. Several life stages of Pacific sanddab may use the SF-3
site: adults spawn in shallow (35 to 90 m [115 to 295 ft]) waters from July to September.
Juvenile Pacific sanddab reside in the nearshore zone, and adults live in sandy to sand/mud
shallow habitats. Adult starry flounder live and spawn in shallow, sandy areas, and juveniles
probably reside in the nearshore habitat. The juvenile stages of lingcod and California
halibut also may occur in the SF-3 site. Year-old lingcod move into sandy bottom habitats
from the intertidal zone to 200 m deep, and juvenile California halibut use shallow, sandy
bottoms as they gradually move to more offshore waters.
Commercially important deepwater bottomfish may use the SF-3 site as juveniles
(Table 3-6). Dover sole, petrale sole, widow rockfish, canary rockfish, and bocaccio rockfish
species all occur in waters with depths similar to those at the SF-3 site.
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Commercially important anadromous fish, rockfish, and bay and beach fish may be
found at the SF-3 site during all seasons. Adult and juvenile stages of anadromous fish
species (chinook salmon, coho salmon, winter-run and summer-run steelhead trout, and
coastal cutthroat trout) are found within the SF-3 site year round. Juvenile blue rockfish
move to benthic habitats in waters less than 25 m (82 ft) deep from late May to June.
Surfperches are also restricted to shallow coastal waters during spawning in spring and early
summer. Juvenile surfperch use shallow waters in summer and fall. Night and surf smelt
(adults and juveniles) are also common to this area.
Fish populations appeared to be higher at the SF-3 site than at other alternative
disposal sites (Pequegnat et al. 1990). Trawl surveys conducted by Humboldt State
University showed that fish abundance and biomass were generally higher in nearshore
areas; in August samplings, abundance and biomass seemed to be higher in an area near
the SF-3 disposal site than at the HOODS or the NDS.
The NDS. Otter trawl surveys were conducted at the NDS in August and November
1989 and March 1990 (Pequegnat et al. 1990). The most common fishes collected were
night smelt, larval smelt, and whitebait smelt (93.9% total). Other species collected, in
order of declining abundance, were Pacific sanddab, butter sole, Pacific tomcod, spotfin and
shiner perch, Pacific sand sole, bay pipefish, larval flatfish, English sole, pricklebreast
poacher, juvenile poacher, speckled sanddab, plainfin midshipman, and brown smoothhound.
Surveys showed that species diversity and biomass increased by more than 60% between
summer and late fall. The highest number of species and greatest biomass occurred in
November, and the lowest occurred in August. Also notable was the presence of larval
flatfish hi the November trawl catch, suggesting that flatfishes use the nearshore zone as a
nursery. The fish biomass at the NDS was low as compared to a nearby control site
(Pequegnat and Mondeel-Jarvis 1990). An average of 740 grams per trawl was collected at
this site, compared to catches in nearby control waters (adjacent to the Samoa Peninsula)
of 6,100 grams per trawl and 1,500 grams per trawl in September 1988 and September 1989,
respectively.
Since the NDS is similar in depth to SF-3, and because fish assemblages have been
shown to vary with depth, the commercially and recreationally valuable fish using this site
are probably very similar to those at the SF-3 site. Nearshore bottomfish include English
sole, Pacific sanddab, starry flounder, lingcod, and California halibut. Adult English sole
may reside within the NDS, and it is likely that juvenile English sole use the site since they
are found in sandy, shallow bottoms in less than 16 m (52 ft) of water from November to
May. Juvenile and adult stages of Pacific sanddab and starry flounder species prefer sandy,
shallow areas nearshore and are also likely to use the NDS. Juveniles of both lingcod and
California halibut occur in shallow bottoms and may occur at the NDS. Commercially
important demersal fish living in deeper waters that may use this nearshore habitat include
Dover sole, petrale sole, widow rockfish, canary rockfish, and bocaccio rockfish (Table 3-6).
Juveniles of all of these species settle to the bottom in shallow nearshore waters during late
spring and summer.
Pelagic species of commercial importance occurring in the NDS are anadromous
species (chinook salmon, coho salmon, winter-run and summer-run steelhead trout, coastal
3-40
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cutthroat trout), blue rockfish, night and surf smelt, and surfperches. Anadromous fish may
pass through the NDS throughout the year as adults and juveniles. Juvenile blue rockfish
occur in shallow waters less than 25 m (82 ft) deep in late May and June. Smelt spawn in
sandy areas near the surf zone; surveys off the Samoa Peninsula found adult smelt in
nearshore waters (ERC 1976). Adult surfperches also are restricted to shallow surf areas
and spawn in coastal waters; juveniles are found in shallow waters as well.
In August 1989, Humboldt State University's trawl surveys showed that fish
abundance and biomass may be lower at the NDS than at the HOODS. However, in March
1990, fish abundance was higher at the NDS, with fish biomass similar to that of the
HOODS.
3.3.5 Coastal and Sea Birds
The Humboldt Bay area provides habitat for a large number of migrant and resident
bird species. The Bay and coastal area serve as both a stopover point in migration and as
an over-wintering area for migratory shorebirds and waterfowl. Shorebirds and wading birds
such as turnstones, plovers, and sandpipers are found only near shore and can occur along
the shoreline within and outside of Humboldt Bay (see Table 3-9 for scientific names).
Coastal species of seabirds and waterfowl such as alcids, loons, cormorants, California brown
pelican, gulls, terns, and scoters and other sea ducks also occur throughout the Bay and
nearshore waters of the area. Humboldt Bay is an important California breeding site for
double-crested cormorants. Small numbers of western gulls breed within the Bay, and snowy
plovers nest on the south spit of the Bay. The coastline of the region, including northern
Humboldt and Del Norte Counties, provides critical habitat for 41% (13 species) of the
state's breeding seabirds (Table 3-9) (Sowles et al. 1980).
The offshore waters of the Humboldt continental shelf provide habitat for seabirds
that feed on fish and marine invertebrates at the surface or in the water column. The
species likely to use the area for feeding and resting will be those regularly found in
continental shelf waters. Common species include those listed above as well as phalaropes,
shearwaters, and jaegers (ECI 1988).
Species of concern occurring in the region include the California brown pelican, the
short-tailed albatross, the marbled murrelet, and the Aleutian Canada goose (discussed in
Section 3.3.7).
3.3.6 Marine Mammals
33.6.1 Pinnipeds
Five species of pinnipeds (seals) occur in the Humboldt area. The northern (Steller)
sea lion (see Section 3.3.7) and harbor seal breed in the area, and the California sea lion,
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Table 3-9. Breeding Seabirds Found in Humboldt
and Del Norte Counties
Common Name
Scientific Name
Fork-tailed storm petrel
Leach's storm petrel
Double-crested cormorant
Brandt's comorant
Pelagic comorant
Black oystercatcher
Western gull
Common murre
Pigeon guillemot
Marbled murrelet
Cassin's auklet
Rhinoceros auklet
Tufted piffin
Snowy plover
Source: Sowles et al. 1980.
Oceanodroma furcata
O. leucorhoa
Phalacrocorax auritus
P. penidllatus
P. pelagicus
Haematopus bachmani
LOTUS occidentalis
Una aalge
Cepphus colwnba
Brachyramphus marmoratus
Ptychoramphus aleuticus
Cerorhinca monocerata
Fratercula cirrhata
Charadrins alexandriniis
3-42
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northern elephant seal, and northern fur seal use the area for feeding and during migration
(ECI 1988).
Humboldt Bay is one of California's most important pupping grounds for harbor
seals. Peak numbers (on land) occur in May during the spring breeding season and in June
when adults are on land to molt (ECI 1988). Harbor seals are usually found within 10.8 nmi
from shore in waters less than 200 m (656 ft) deep (Bonnell et al. 1983).
The California sea lion is the most frequently sighted pinniped in the area. Sea lions
migrate to and from breeding grounds in southern California and the Baja Peninsula. Major
haul-out sites in the Humboldt region are to the north of Humboldt Bay at St. George Reef
and Castle Rock (ECI 1988). The number of sea lions in the area peaks in September and
October during the northward migration and again in May during their southward migration
(ECI 1988).
Northern elephant seals occur regularly off Humboldt County in spring and summer
after the winter breeding season (December-March) as pelagic, widely dispersed, solitary
feeders. Northern fur seals occur seasonally in the region from December to June, mostly
offshore along the continental shelf and shelf break. (ECI 1988.)
33.6.2 Cetaceans
At least 20 species of cetaceans (whales and dolphins) have been recorded in waters
off of Humboldt Bay, and about half of these can be considered relatively common. The
most common continental shelf species in the area are the harbor porpoise and the gray
whale. Harbor porpoises are present throughout the year but are seen more frequently
during fall, usually within 0.5 nmi of shore (ECI 1988) in waters 30 to 80 m (98 to 262 ft)
deep.
The gray whale is the most common cetacean in the nearshore coastal waters and has
recently been removed from the federal list of threatened or endangered species. Gray
whales migrate south in December and January and north from March through May, usually
passing within 0.8 to 4.3 nmi of the shore (ECI 1988). Gray whales pass closest to shore
during spring migration when cows with calves stay close to the shoreline. Gray whales may
feed during migration, particularly during the northward migration when females are with
young. Their diet consists of soft-bottom benthic invertebrates found at depths of 9 to 40 m
(30 to 131 ft) as well as dense swarms of shrimp and spawning squid (Jones et al. 1984).
Dohl et al. (1983) noted that gray whales avoid very turbid water and change direction when
approaching large river plumes such as the ones off the Klamath and Eel Rivers and San
Francisco Bay during periods of heavy runoff.
Humpback whales are found in nearshore waters during their annual migrations
between the southern winter breeding grounds and the feeding areas in Alaska. Minke
whales also occur in nearshore waters. Other less common large migrant cetaceans in the
area include the blue whale, finback whale, and sperm whale. These species generally occur
in deeper waters, offshore from the HOODS.
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Other common smaller cetaceans in waters off of Humboldt Bay are the Pacific
white-sided dolphin, northern right-whale, Dall's porpoise, and Risso's dolphin. These
species also occur primarily in deeper waters offshore from the HOODS. All but the
northern right-whale also occur in smaller numbers in shelf waters (ECI 1988).
33.7 Threatened and Endangered Species
Four birds, four cetaceans, a pinniped, a marine turtle, and a fish that are federally
and/or state listed as threatened or endangered may occur in the region: the California
brown pelican, the marbled murrelet, the short-tailed albatross, and the Aleutian Canada
goose; the humpback, blue, finback, and sperm whales; the northern (Steller) sea lion; the
leatherback turtle; and the winter-run chinook salmon (Table 3-10).
The brown pelican is found in estuarine, coastal, and oceanic waters along the
California coast. In northern California, pelicans are common from June through November
and rare to uncommon from December to May (ECI 1988). In other areas of California,
they breed from March to July on the Channel Islands at Anacapa Island and near Santa
Barbara Island. Breeding also occurs on islands off the Pacific Baja California coast of
Mexico and in the Gulf of California (Sowles et al. 1980). Pelicans feed during daylight
hours, mostly on small schooling fish. They are plunge divers and prefer clear waters for
easy prey detection. Because their feathers are wettable, pelicans usually forage within
8 nmi of shore and return to specific coastal roosts for the evening, usually arriving by late
afternoon (Schrieber and Clapp 1987). Within the area of study, pelicans use the south spit
of Humboldt Bay for roosting.
Marbled murrelet populations have been reduced by logging of old-growth forests
where these birds nest. In California, the marbled murrelet is found from the Oregon
border south to Santa Cruz. During the summer breeding season, murrelets concentrate
nearshore closer to their nests. Marbled murrelets feed on fish they catch by surface diving
within 1 nmi of shore in depths of 30 m (98 ft) (Ehrlich et al. 1988).
The short-tailed albatross was once abundant in the northwest Pacific and off
northern California but was thought to be extinct by the late 1940s. By 1954, a few birds
had returned to nest on Torishima, an island south of Japan. The present worldwide
population is estimated at 250. North American sightings in recent years have been mainly
from Alaska, although two have been recorded in California. Prior to their population
decline, short-tailed albatrosses flew in large flocks offshore (Harrison 1983, Stallcup 1990).
Their diet consists of fish, shrimp, and squid.
The Aleutian Canada goose is a subspecies of the Canada goose and prefers
lacustrine, fresh emergent wetlands, moist grasslands, croplands, pastures, and meadow
habitats. It feeds on green shoots, seeds, wild grasses, forbs, and aquatic plants. In
northeastern California, it nests mainly from March to June and prefers to nest near water
on a dry, slightly elevated site, with good visibility from the nest. It will also use man-made
structures such as platforms, baskets, and artificial rock islands. Approximately 12,000 geese
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Table 3-10. Federally Listed Threatened or Endangered Marine Species
Occurring in the Project Region
Common Name
Cetaceans
Blue whale
Fin whale
Humpback whale
Sperm whale
Scientific Name
Balenoptera musculus
B. physalus
Megaptera novengliae
Physter catodon
Status
Endangered
Endangered
Endangered
Endangered
Pennipeds
Northern (Steller) sea lion
Ewnetopias jubatus
Endangered
Sea Turtles
Leatherback sea turtle
Dermochefys coriacea
Endangered
Sea Birds
California brown pelican
Short-tailed albatross
Marbled murrelet
Aleutian Canada goose
Pelicanus occidentalis
Diomedea albatrus
Brachyramphus
marmoratus
Branta canadensis
leucopareia
Endangered
Endangered
Endangered
Endangered
Fish
Winter-run chinook salmon
Onchorhynchus
tshawytscha
Endangered
345
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were counted in a 1993 USFWS survey in Crescent City (Shoulak and Kay 1994).
Historically, Humboldt County has been used as an important staging area during spring and
fall migration; however, since their population levels are low, use of the project area by the
Aleutian Canada goose is unpredictable (USFWS 1994).
The humpback whale has a worldwide range. The summer feeding grounds range
from the coasts of Japan and southern California north to the Chukchi Sea. Humpback
whales typically can be found off the California coastline from approximately March through
January, with the greatest concentrations occurring from mid-August through October (Dohl
et al. 1983). According to recent National Marine Fisheries Service (NMFS) surveys
conducted in 1991 and 1993, approximately 600 humpbacks were counted off the California
coast (Shoulak and Kay 1994).
Summer feeding occurs from the Aleutian Islands to the Farallon Islands off central
California. Humpback whales feed on baitfish, euphausiids, pelagic crabs, and a variety of
other prey in the summer and early fall.
Similar to humpback whales, blue whales are pelagic and may occur offshore from
Humboldt Bay in summer and early fall. Blue whales are usually found in continental slope
and deeper waters. Because their primary food is euphausiids, they almost always occur
within 200 nmi of the continental shelf. Off northern and central California, Dohl et al.
(1983) noted blue whales in waters from 80 to 3,600 m (262 to 11,800 ft) deep, and recent
NMFS surveys have counted approximately 2,200 blue whales off the California coast
(Shoulak and Kay 1994).
The finback whale ranges in the Pacific from the Bering Sea to Cabo San Lucas, Baja
California. They are most abundant off northern and central California during summer and
autumn; approximately 985 were recorded in recent NMFS surveys. The finback whale
feeds on small fish, pelagic crustaceans, and squid.
The sperm whale occurs in deep oceanic waters and is rarely reported over the shelf.
Sperm whales range in the Pacific from the Bering Sea to the equator. They are deep
divers and prey mostly upon large squid, skate, and bottomfish.
The northern (Steller) sea lion was recently listed as threatened because of a
worldwide decline in populations. The cause for their decline in California is unclear;
several factors may be acting synergistically, including infertility due to pollutants and
disease, interspecific competition with California sea lions, and a depleted food source.
Northern sea lion populations have been declining throughout their range over the past two
decades. Recent counts in Alaska indicate that northern sea lion populations have declined
by 70% since 1979 (Sease et al. 1993). Waters off Humboldt Bay are not identified as
critical habitat for this species.
The endangered leatherback turtle is the only marine turtle that commonly occurs
in the offshore waters of northern California; however, it is unlikely to occur in nearshore
waters in this region due to its pelagic habits (Dames and Moore 1981).
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Winter-run chinook salmon, an anadromous species, reside as adults off the Pacific
coast, including areas off Humboldt Bay (USFWS 1994). Adult chinook salmon tend to be
opportunistic feeders, their diet consisting primarily of krill, larval crabs, and fish. Waters
off Humboldt Bay have not been identified as critical habitat for this species.
The NMFS is reviewing petitions to list coastwide populations of coho salmon and
steelhead trout. The NMFS is expecting to publish their determination for listing
(warranted, not warranted, or warranted but precluded from listing actions for other higher
priority species) soon (previous deadlines have expired). Like chinook salmon, coho salmon
and steelhead trout may reside as adults off the Pacific coast, including areas off Humboldt
County.
3.3.8 Potential for Development of Nuisance Species
Dredged material that is high in organic content or contaminants may promote
conditions favorable to the growth of nuisance species. Opportunistic or pollution-tolerant
species can dominate disturbed or contaminated substrates and prevent recolonization by
the surrounding benthic fauna (SAIC 1986). Examples of nuisance species previously
reported in organically enriched contaminated sediments include the polychaetes Capitella
capitata and Streblospio benedicti (Pearson and Rosenberg 1978).
Opportunistic and generalist species commonly occur in the benthic fauna offshore
of Humboldt Bay, especially in the nearshore zone. These species respond to the
availability of uncolonized substrate and not to the presence of organically enriched or
contaminated sediments. Winzler and Kelly Consulting Engineers (1984) observed the
changes in benthic fauna following the disposal of dredged material offshore of Humboldt
Bay and found that opportunistic fauna were composed of small, surface-dwelling
crustaceans, gastropods, and polychaetes.
Pequegnat et al. (1990) reported the polychaete Ophelia assimilis in the sediments at
the NDS following disposal of dredged material. This organism has been reported in high
densities in the channels in Humboldt Bay and is a generalist with regard to substrate.
Pequegnat et al. (1990) did not find O. assimilis at sufficient densities to consider it a
nuisance species.
Since the sediment dredged from Humboldt Bay has a high sand content and is low
in organics and contaminants, disposal of the material at any of the alternative sites should
not promote the development of nuisance species over the long term. Previous
examinations of the benthic fauna present at the SF-3 site and at the NDS support this
prediction (Winzler and Kelly Consulting Engineers 1984, Pequegnat et al. 1990).
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3.4 SOCIOECONOMIC ENVIRONMENT
3.4.1 Commercial Fishing
Humboldt County has a long history of commercial fishing and ranks as one of the
most productive areas on the west coast. A variety of fish and shellfish are caught year
round in waters adjacent to the County. About 500 vessels fish primarily out of Eureka,
Field's Landing, Trinidad, King Salmon, and Shelter Cove, and land seafood with a dockside
value of $10 to 20 million annually (Corps/HBHRCD 1994). Seafood processors in Eureka
and Field's Landing fillet, pack seafood, and ship Humboldt County products throughout the
United States and overseas.
There are 45 marine species that contribute to the commercial fishing effort. Oyster
culture is the largest commercial fishing activity within Humboldt Bay itself and is limited
to the North Bay, where a small amount of sea perch and clam are also taken. In other
areas, the primary fishes caught commercially are groundfish (flatfish and rockfish), albacore
tuna, Dungeness crab, and salmon. Flatfishes averaged 31% to 42% of the total annual
landings for Humboldt Bay region from 1981 to 1985 (Barnhart et al. 1989), with Dover sole
and English sole being the most important of these. Rockfish are caught by commercial
fishermen outside the Bay and comprised 25% to 31% of the commercial landings from
1981 to 1985. Salmon is the most valuable finfish on a per pound basis, but landings in
recent years have been greatly reduced due to declines in salmon runs and a restricted
commercial season.
During the 1981 to 1985 period, commercial fishermen annually landed an average
of nearly 1.6 million pounds of Dungeness crab, worth over $1.4 million, at Eureka
(Corps/HBHRCD 1994). The Bay supports a minor commercial fishery for sevengill and
leopard sharks, which are caught by hook and line and drift gill nets. There is a commercial
gill net fishery each winter in Arcata Bay for adult herring, primarily to obtain herring roe,
which is exported to Japan, and there is a live anchovy bait fishery by albacore fishermen
in the fall. A minor commercial fishery for surfperch exists, primarily for redtail, which are
captured by beach seine and hook and line.
3.4.2 Commercial Shipping
Humboldt Bay is the only harbor between San Francisco, California, and Coos Bay,
Oregon, with channels deep enough to permit passage of large, commercial ocean-going
vessels. In 1988, 120 deep-draft vessel trips accounted for 1,145,922 tons of commerce,
consisting of woodchips, pulp, logs, lumber, petroleum, and particle and fiber board.
Historically, annual deep-draft tonnage accounts for approximately 70% of the total annual
tonnage passing through the Harbor, with all but petroleum representing exports
(Corps/HBHRCD 1994).
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3.4.3 Recreational Activities
Humboldt Bay provides a multitude of outdoor recreational opportunities associated
with its biological resources. The unique combination of redwood forests, rocky headlands,
sandy beaches, and estuaries makes the Humboldt County coastline particularly attractive.
The number of visitors to the area is increasing, and their importance to the local economy
is high. Cold air and water temperatures limit the use of the area for swimming,
waterskiing, and other such water contact sports. The greatest use is, therefore, closely tied
to fish, wildlife, and aesthetic values. Use of these resources can be divided into two types:
appropriative and nonappropriative uses. Appropriative uses involve the actual removal of
individual units such as fish or game. Nonappropriative uses involve the same resources but
without any removal - activities such as nature study, photography, or wildlife observations.
Both of these are important and each has its place in the overall recreational picture.
3.4.4 Hunting
The most significant appropriative use in the immediate area of the Bay is waterfowl
hunting, which is estimated to supply over 25,000 hunter-days of recreation annually
(Monroe 1973). Most hunting is done from temporary or permanent blinds along the
shorelines of the Bay, marshes, sloughs, and agricultural lands. Another popular waterfowl
hunting style here, which is rarely seen in other parts of the state, is known as sculling. This
is accomplished by approaching rafted birds on open water in a uniquely designed low-
profile boat. These vessels are highly efficient when in the hands of a skilled operator.
The regular waterfowl season usually opens in October and extends into January.
The black brant season opens in November and ends in late February. Humboldt Bay is
the most important brant hunting area in California, contributing up to 75% of the total
state kill. Wilson's snipe is a bird found in salt marshes, freshwater marshes, and wet
pasturelands adjacent to the Bay, and these are also hunted on a limited scale over a season
that coincides with the waterfowl season. There are many private hunting clubs in
operation, and many private landowners permit hunting on their farmlands. Upland game
hunting species include pheasant, quail, dove, bandtailed pigeon, grouse, squirrel, and rabbit.
Deer hunting is the major appropriative use of big game. (Corps/HBHRCD 1994.)
3.4.5 Sportfishing
Humboldt Bay is one of the primary sportfishing areas in California. Anglers fishing
in the Bay catch at least 41 species of fish as well as collecting oysters, 10 species of clams,
and 3 species of crabs. Animals such as shore crabs and ghost shrimp are collected by
fishermen for bait, thereby indirectly contributing to sport fishing activities. Seven of
California's 12 shellfish reserves are within Humboldt Bay. These areas are state lands that
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have been set aside for clam digging and native oyster taking by the public, as authorized
by the State Fish and Game Code.
Sport clam diggers operate mostly in the South Bay due to the easier access to and
greater abundance of the more desirable clams. The most popular areas are the northern
end of Clam Island and Buhne Point. The clamming that takes place in Arcata Bay is
focused on Indian Island, Bird Island, San Island, and along the Mad River Channel. Of
the 25 species of clam found, only 10 are harvested to any extent. These include two species
of gaper clams, two species of Washington clams, the littleneck clam, basket cockle, softshell
clam, bentnose clam, geoduck, and rough piddock. Mussels and native oysters are also
taken in Arcata Bay, the greatest abundance of these being north of Woodley Island and
within the Arcata Channel. Sport crabbers usually operate in the winter months and catch
market, red, and rock crabs.
The fishing effort can be separated into shore, pier, skiff, and skindiving categories.
Shore fishing is the most popular type of sport fishing effort and takes the form of surf-
casting, surf-netting, and rocky shore fishing. Shore anglers operate predominantly on the
South Jetty and Buhne Point Jetty and catch the widest variety of species, approximately 27
different kinds. These include surfperches, night and surf smelt, blennies, greenlings,
rockfish, flatfish, and salmon. Salmonids are caught during the summer at the entrance,
particularly from the jetties or in a boat between the jetties, but most are caught in the
nearshore waters outside the Bay.
Some 10,000 to 15,000 anglers operate from 500 boats out of Humboldt Bay annually.
The Pacific Fishery Management Council reported that for the years from 1971 to 1975,
recreational salmon anglers fished an average of 40,000 angler days out of the Bay and
averaged about 10,000 chinook salmon. Salmon anglers took 26,000 chinook in 1985 from
ports on the Bay. Several licensed party boats operate from Humboldt Bay, predominantly
from June through September. Salmon and crabs have been the target species.
Pier anglers catch the most sport-caught fish in terms of tonnage. Given the general
area in which these structures are located, this type of fishing is limited to surf-frequenting
species, bottom-dwellers, and surface-feeders. Smelt dipping is popular and makes up a
large portion of the angling catch taken from piers. Greenling and lingcod are usually taken
from the jetties and other rocky areas but also occur in waters of mud flats and channels.
Rockfish as well as surfperch are commonly caught by anglers fishing from the jetties.
Humboldt Bay supports a very active marine skiff fishing center and is the most
important area in Northern California for this effort. Most skiff fishing occurs during the
summer and fall, and the fishery is showing a growing trend. Harvest by skindivers is
increasing in popularity, and target species include lingcod, seaperch, rockfish, kelp
greenling, and cabezon. Divers are also in search of abalone, sea urchins, shells, coral, and
clams.
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3.4.6 Nature Study
Nonappropriative uses of the Bay constitute by far the heaviest recreational use.
These include nature study, wildlife observation, and photography, and are enjoyed by
residents and visitors in excess of 135,000 user days annually. The Humboidt Bay National
Wildlife Refuge is a location for many of these uses, and the number of people engaging
in these activities is increasing. The Audubon Society and the Sierra Club are among the
environmental organizations with local chapters in the Humboidt area.
3.4.7 Scientific and Educational Use
Humboidt Bay, with its wealth of natural resources and physical features, is highly
attractive for educational and scientific purposes. It offers almost unlimited possibilities for
the study of natural history, ecology, and marine sciences. The College of the Redwoods
and Humboidt State University are located close to the Bay, and these institutions provide
research results on the many facets of the Bay environment. High school and grammar
school classes also use the Bay and its resources for field trips and classroom work, both of
which have become a regular part of many school conservation programs. Scientific use of
the Bay is also made by many governmental agencies, independent foundations, and private
industry, as is evidenced by the hundreds of publications on record concerning the Bay and
its resources. These uses are expected to increase.
3.4.8 Cultural Resources
The ocean waters in the vicinity of Humboidt Bay have been the site of numerous
vessel accidents and sinkings. Coordination with the California Office of Historic
Preservation and the State Lands Commission has indicated that several ships have been
reported as sinking in the vicinity of the HOODS. No shipwrecks are recorded as situated
within the disposal site.
To assist in identifying the possible presence of marine archaeological properties at
the HOODS, an archaeological survey (magnetometer and side-scan sonar) was completed
in 1990, under contract to the Corps. A report entitled Historic Shipwreck Survey of the
Humboidt Bay Dredged Material Disposal Site (Land and Sea Surveys/BioSystems - copy
available from the Corps) was issued in 1991. This project was coordinated with the State
Historic Preservation Officer and the National Park Service, including submittal of review
copies of the report. Numerous magnetic and sonar anomalies were identified within the
HOODS. Three of the identified seafloor features were interpreted as potential shipwreck
locations. No further investigation of the suspected wrecks was conducted, but such study
was recommended should disposal possibly affect these locations. Subsequent to the marine
survey, these potential locations were avoided during disposal of dredged materials from
maintenance dredging projects.
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3.4.9 Public Health and Welfare
Ensuring that public health and welfare are not adversely affected by ocean disposal
of dredged materials is a primary concern. Here only two issues, health and safety, are
discussed.
Health hazards may arise if the chemical nature of the dredged materials has the
potential to cause bioaccumulation of toxic substances in organisms. Potential impacts on
human health can be inferred from bioassay and bioaccumulation tests performed on marine
mammals. Since marine waters, including those at the HOODS and at other alternative
sites, provide a large amount of fish and invertebrates for human consumption, the public
health issue gains added importance. Green Book testing requirements for proposed
dredged materials are intended to minimize these risks.
The disposal of dredged material could present safety hazards to navigation either
as a result of mounding within the disposal site or as a result of the disposal barges
interfering with shipping traffic. Mounding effects on wave height which would affect
navigation would only occur if sediments accumulating at the disposal site were shallow
enough to interact with waves. This has occurred at the NDS and the SF-3 site. Potential
mounding effects on waves at the HOODS site are discussed under Section 4.2.1.2.
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Section 4
Environmental Consequences
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Section 4. Environmental Consequences
4.1 INTRODUCTION
The purpose of this section is to provide a detailed discussion of the potential
impacts of the proposed and alternative actions on the physical, biological, and
socioeconomic environment. This DEIS has been prepared in accordance with the National
Environmental Policy Act (NEPA) guidelines. Potential impacts identified in this section
are classified according to the following scheme (modeled after EPA 1988):
Significant adverse impacts that cannot be mitigated to insignificance. No
measures can be taken to avoid or reduce the adverse impacts to insignificant or
negligible levels.
Significant adverse impacts that can be mitigated to insignificance. These
impacts potentially are similar in magnitude to nonmitigatable impacts, but the
severity can be reduced or avoided by implementation of specific mitigation
measures.
Adverse but insignificant impacts or no effects anticipated. No mitigation
measures are necessary to reduce the magnitude or severity of these impacts.
Beneficial effects. These effects could improve conditions relative to existing or
preproject conditions. These can be classified further as significant or
insignificant beneficial effects.
The definition of "significant" under the NEPA guidelines (40 CFR 1508.27) requires
the consideration of both the context and intensity of the impact. The context of an impact
refers to analyzing the impact in relation to society (human, national), the affected region
(localized or regional), the affected interests, and the locality. Both short-term and long-term
effects are relevant.
Intensity of an impact refers to the severity of the impact. The following factors need
to be considered in the evaluation of the intensity of an impact:
Impacts may be either beneficial or adverse. A significant effect may exist even
if the federal agency believes that on balance the effect will be beneficial.
The degree to which the proposed action affects public health or safety.
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Unique characteristics of the geographical area such as proximity to historic or
cultural resources, park lands, prime farmlands, wetlands, wild and scenic rivers,
or ecologically critical areas.
The degree to which the effects on the quality of the human or ecological
environment are likely to be highly controversial.
The degree to which the possible effects on the human or ecological
environment are highly uncertain or involve unique or unknown risks.
The degree to which the action may establish a precedent for future actions with
significant effects or represents a decision in principle about a future
consideration.
Whether the action is related to other actions with individually insignificant but
cumulatively significant impacts. Significance exists if it is reasonable to
anticipate a cumulatively significant impact on the environment. Significance
cannot be avoided by terming an action temporary or by breaking it down into
small component parts.
The degree to which the action may adversely affect districts, sites, highways,
structures, or objects listed in or eligible for listing in the National Register of
Historic Places or may cause loss or destruction of significant scientific, cultural,
or historical resources.
The degree to which the action may adversely affect an endangered or
threatened species or its habitat that has been determined to be critical under
the Endangered Species Act of 1973.
Whether the action threatens a violation of federal, state, or local law or
requirements imposed for the protection of the environment.
Based on these broad definitions, significance criteria were developed and applied
to the environmental impact assessment for each of the resource areas evaluated in this
DEIS. Specific significance criteria for physical, biological, and socioeconomic resources are
presented at the beginning of each section.
The following sections identify potential impacts associated with the designation of
the HOODS or the alternative sites. Additional mitigation sections are included where
significant impacts are identified.
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42 THE HOODS - THE PREFERRED ALTERNATIVE
42.1 Physical Environment
42.1.1 Air Quality
Project Significance Criteria. Significance criteria for air quality impacts are based
on federal, state, and local air pollution standards and regulations. An impact was
considered significant if project emissions are projected to:
increase ambient pollutant levels from below to above federal or state air
quality standards; or
substantially contribute to an existing or projected air quality standard
violation.
Project Impacts. No significant impacts to regional air quality are expected as a
result of the proposed designation of the HOODS as the regional ODMDS
(Corps/HBHRCD 1994). Although combined regional emissions sometimes result in
exceedance of regional air quality criteria (PM10), exhaust emissions from annual
maintenance dredging and disposal operations are not expected to increase from present
levels. Emissions associated with the transport and disposal of dredged materials at the
HOODS are not expected to adversely impact any sensitive receptors.
Potential air quality impacts associated with the proposed Harbor and Bay Deepening
Project are discussed in the draft EIR/EIS for that project, and will not be discussed in
detail in this DEIS. Briefly, as a worst case, the deepening project is expected to result in
exceedance of NCUAQMD criteria for NOX and PM10. However, disposal of dredged
materials at the HOODS would not cause emissions significantly different than those
generated by disposal at any of the alternative sites.
Mitigation. The Corps will operate equipment in a manner which minimizes
emissions, including avoidance of unnecessarily idling construction equipment. Additional
mitigation measures that would reduce potential air quality problems include obtaining and
complying with all required AQMD and NCUAQMD permits and applicable rules and
regulations.
42.12 Physical Oceanography
Project Significance Criteria. Impacts of the proposed and alternative actions on
physical oceanography were considered significant if the project would:
produce any measurable effect on regional or site-specific physical
oceanographic conditions (i.e., waves or currents); or
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substantially change the character of sediments at the disposal site.
Project Impacts. Disposal of dredged material at the HOODS is expected to result
in accumulation of dredged material over the seafloor, changes in the bathymetry, and slight
changes in sediment characteristics within the site. Over the 50-year life of the site (a site
capacity of 50,000,000 yd3), accumulations of material and changes in bathymetry could be
substantial. Assuming the dredged material is distributed evenly across the site and there
is no transport of material outside of the site, the depth of the site would be reduced by 11
m (36 ft) over the 50-year life of the site.
Numerical modeling of sediment dispersion indicated that, due to the relatively weak
bottom currents, the HOODS is a non-dispersive site (Scheffner 1990). Accumulations at
other sites (site SF-3 and the NDS) have resulted in the creation of adverse sea surface
conditions by waves shoaling on the accumulated mounds of dredged material. The
HOODS site is located in much deeper water (49 to 55 m [160 to 180 ft]) than the SF-3 site
and the NDS (less than 18 m [60 ft]). Therefore, the potential for adverse sea surface
conditions or wave refraction caused by mounding of sediments at the HOODS is much
lower than at the shallower sites.
Disposal of dredged material which is dissimilar in character to bottom sediments can
potentially adversely affect the recolonization of the site by benthic fauna. The HOODS
is located between the 49 and 55 m (160 to 180 ft) depth contours, which is generally
described as the mud-sand transition zone. General physical impacts to the character of the
seafloor within the site can be minimized by disposing of sandy materials at sandy areas
within the HOODS, and disposing of finer materials at locations within the HOODS with
sillier bottom conditions.
Mitigation. Although significant impacts to sediment characteristics are not
anticipated under the proposed action, accumulations of dredged material are unavoidable.
To minimize the significance of disposal impacts on the site, several mitigation measures
have been included in the site management and monitoring plan including:
Periodic surveys of the entire site will be conducted to determine changes in
bathymetry.
Accurate positioning of the hopper dredge will used to ensure that dredged
material is deposited over seafloor areas within the site with similar sediment
character.
A Dredge Data Logging System (DDLS) will be used as a monitoring and
surveillance tool on contract hopper dredges. Disposal logs will be maintained
and spot inspection will be performed during disposal operations.
Hopper dredges will not be overloaded to minimize the potential for accidental
spillage of materials outside the HOODS.
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4.2.13 Water Quality
Project Significance Criteria. Significance criteria for water quality impacts are
based on federal, state, and local water quality criteria and regulations, and the potential
for long-term degradation or endangerment to the environment.
Project Impacts. No significant, long-term water quality impacts are anticipated to
occur as a result of designation of the HOODS as the regional ODMDS. Dredged material
disposal typically has a short-term (several hours to days) localized impact on the water
column. Water quality variables which could be temporarily affected by disposal of dredged
material from Humboldt Bay include: total suspended solids, light transmittance through the
water column, dissolved oxygen, and nutrients. Materials dredged from Humboldt Bay
during routine dredging operations have not been found to contain significant concentrations
of potentially toxic substances. Any materials proposed for disposal at the site will be tested
and approved in accordance with EPA Ocean Dumping Regulations (40 CFR 227) and
EPA/Corps testing guidelines (EPA/Corps 1991 "Greenbook") prior to disposal at the
HOODS.
The disposal of dredged material in the marine environment occurs through three
major phases (convective descent, dynamic collapse, and passive dispersion) which affect the
behavior of the material in the water column and the nature of the deposit on the bottom.
The convective descent phase occurs as the majority of the dredged material falls to the
bottom as a concentrated cloud under the influence of gravity. Dynamic collapse occurs as
the downward momentum of the cloud is converted to horizontal dispersion of the material
as it contacts the bottom. Passive diffusion occurs following the loss of momentum when
ambient currents and turbulence act as the major forces of dispersion.
Dredged materials to be disposed of at the HOODS during maintenance dredging
operations are primarily coarse sand, with a smaller volume of sediment characterized as
sand/silt. Coarser materials fall relatively rapidly to the bottom. Finer materials can
remain in the water column for longer periods of time. Numerical models can provide
reasonable estimates of the transport and fate of coarser materials (Koh and Chang 1973).
The fate and transport of finer material are difficult to model because some fraction of the
finer material descends as relatively large aggregates. However, some fraction of the finer
materials remains in suspension in the water column following disposal operations. The
ultimate fate of this suspended material depends primarily on its settling rate and the
ambient currents and water column conditions at the disposal site at the time of disposal.
Mitigation. Short-term water quality (primarily turbidity) impacts during disposal
operations are unavoidable. To minimize potentially significant impacts to water quality,
sediments will be chemically analyzed in order to determine suitability for disposal at the
HOODS. A chemical characterization study of sediments dredged during annual
maintenance dredging of federal channels in Humboldt Bay is currently being performed.
Based on the results of this study, a schedule of sediment quality studies for these channels
will be established and become a part of the site management and monitoring program.
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Sediments dredged as part of the proposed Harbor and Bay Deepening Project have
been tested (Corps/HBHRCD 1994). The Corps proposes to dispose of the materials
acceptable for unconfined ocean disposal at the HOODS. The Corps proposes to dispose
of unacceptable materials at a confined upland site.
Any dredged materials from non-federal projects would also require testing in order
to determine suitability for ocean disposal at the HOODS.
422 Biological Environment
422.1 Project Significance Criteria
A biological impact was considered significant if it:
is expected to affect the population status of a state or federally listed, proposed,
or candidate threatened or endangered species or is expected to affect the
breeding or foraging habitat of such species so as to result in increased mortality
or reduced reproductive success;
causes the loss or long-term degradation of any environmentally sensitive species;
interferes substantially with the movement of any resident or migratory fish or
wildlife species; or
causes a measurable change in species composition or abundance of a sensitive
community or causes a substantial, long-term change to marine habitats.
4222 Phytoplankton
Project Impacts. The disposal of dredged material at the preferred site may cause
mortality to phytoplankton due to entrainment in the sediment plume and may temporarily
reduce phytoplankton production by increasing turbidity, consequently reducing light
available to algae. However, the increased turbidity produced during disposal of dredge
spoils is localized and temporary, and the impacts are expected to be insignificant compared
to natural fluctuations in primary production (Copeland and Dickens 1974, Hirsch et al.
1978). The pelagic environment offshore of Humboldt Bay is seasonally subjected to large
amounts of suspended sediments discharging from the Eel River and Humboldt Bay. The
impact from the disposal of the projected amounts of maintenance dredged materials at the
HOODS is not expected to have any significant long-term adverse effects on the
phytoplankton offshore of Humboldt Bay.
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Zooplankton
Project Impacts. Impacts on zooplankton, including planktonic larvae of fish and
invertebrates, as a result of dredged material disposal may include mortality due to
entrainment in the sediment plume and interference with filter feeding caused by a
temporary increase in suspended sediments. These impacts are expected to be short-term
and localized and not significantly affect planktonic conditions over the nearshore waters
in the region.
4.2.2.4 Benthic Algae
Project Impacts. Disposal of dredged material at the preferred site would not have
any significant short-term or long-term effects on the benthic algae communities in the area.
The only significant benthic algae communities in the study area are along the intertidal and
subtidal portions of the jetties. Disposal operations are not expected to affect the limited
algal communities along the jetties because those communities are about 3 nmi from the
HOODS.
422.5 Benthic Infauna
Project Impacts. Survival of organisms varies according to species and their ability
to burrow through the sediments; it also depends on the thickness of disposed materials
(Hirsch et al. 1978). Direct mortality due to burial of organisms and reductions in the
number of species and the abundance of infaunal organisms is expected to be restricted to
the immediate disposal area (Oliver and Slattery 1976, Scott et al. 1987, Hirsch et al. 1978).
Recolonization by opportunistic species occurs within 3 to 6 months (Bingham 1977, Scott
et al. 1987).
The most permanent impact of dredged material disposal is a change in substrate
(Tatem 1984). Although the grain size of the substrate at the HOODS ranges from
approximately 50% sand in the easterly cells to approximately 10% sand in the westerly cells
(Pequegnat et al. 1990), the sediments dredged from Humboldt Bay are predominantly sand
(approximately 85% to 90%). Many benthic invertebrates will be unable to move through
the spoils, and the lateral migration of adults from the adjacent benthic community will be
hindered because those individuals are adapted to finer-grained sediments (Hirsch et
al. 1978). In addition, the planktonic larvae of many benthic invertebrates respond to
specific cues, including grain size of the substrate, for settlement and metamorphosis
(Meadows and Campbell 1972). Dexter et al. (1984) found that although the sediments at
a dredged material disposal site in Elliott Bay, Washington, were sandier than ambient
sediments, 3 years after disposal there was a greater abundance and biomass of benthic
invertebrates in the dredged spoils mound than in the surrounding area. However, this may
have been the result of organisms introduced by currents around the mound (Tatem 1984).
From previous observations of macrobenthic recolonization at dredged material
disposal sites, it is expected that after the dredged material is deposited, the initial
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recolonization will be by motile, short-lived, shallow-burrowing, opportunistic species,
probably small crustaceans (e.g., amphipods and cumaceans) and polychaetes (Oliver and
Slattery 1976, Winzler and Kelly Consulting Engineers 1984). Deposit-feeding fauna will
have a more difficult time recolonizing because the low organic content and coarseness of
the dredged spoils are not conducive to burrowing infauna. The rate at which the benthic
community at the HOODS recovers will depend on the length of time between disposal
operations. Recolonization of a diverse and stable benthic assemblage at the HOODS
would probably be complete for 1 to 3 years after the cessation of all disposal operations
(Dillon 1984, Scott et al. 1987). Hence, impacts of dredged material disposal on the benthic
infauna community within the disposal area are expected to be significant but localized.
Mitigation. Several operational procedures are designed to minimize potential
impacts to benthic infauna. The selection of the HOODS was based in part on the sediment
characteristics of the site. The HOODS lies within a mud-sand transition zone with fine
sand to sandy silt substrates in the eastern portion of the site, and silty sands and clay in the
western portion of the site. The variability in substrate composition allows the disposal of
dredged materials on bottom substrates of similar character.
Significant accumulations of dredged materials and associated burial of infaunal
organisms is an unavoidable significant impact within the site. Numerical modeling
conducted by the Corps and a sediment dispersion analysis performed by Scheffner (1990)
for the HOODS concluded that the site is non-dispersive. To ensure that impacts to
benthos are isolated to the site, the Corps is conducting post-disposal bathymetric surveys
to verify the non-dispersive nature of the site. The Corps requires that accurate positioning
is used during disposal events and that performance data (position, time, draft, disposal
area) be collected via DDLS to verify dredged material disposal within the site. The Corps
will also be required by EPA to conduct periodic monitoring to verify the nontoxic nature
of disposed sediments, and that significant quantities of sediments have not been transported
out of the HOODS.
422.6 Benthic Epifauna
Project Impacts. Of particular concern is the potential impact of disposal operations
on Dungeness crab. The impacts on planktonic larval stages (zooplankton) were discussed
above. Dredged material disposal operations offshore of Humboldt Bay generally occur
during April and May, when Dungeness crabs are mating in shallow, sandy areas; and in
September and October, when egg-brooding females partially bury themselves in the sand
in the shallow subtidal areas. Juvenile Dungeness crabs settle in shallow offshore areas
from April to July. During these critical life stages, Dungeness crabs caught beneath the
disposal plume would be smothered. With regard to the alteration in sediment type
following disposal, however, Dungeness crabs are found in association with a range of
substrates, so this change should not have a detrimental effect on colonization of the site
by crabs.
Because the HOODS is located in waters deeper than those usually associated with
Dungeness crabs at their critical life stages, few Dungeness crabs are expected to be
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affected. The HOODS has not been identified as a critical habitat for any life stages of
Dungeness crab or any other epifaunal species reported in this area. Since the impacts will
be short-term and restricted to the area within the disposal site boundaries, significant long-
term impacts on Dungeness crabs and other epifauna populations in the study area are not
expected.
422.7 Pelagic Invertebrates
Project Impacts. The HOODS is not known to provide critical spawning habitat for
the market squid Loligo opalescens. In addition, this species is highly mobile and would be
able to avoid the disposal plume. Although this species has been reported to be a
component of the biological community offshore of Humboldt Bay, there is no evidence that
this species would be adversely affected by dredged material disposal at the preferred site.
4223 Demersal Fishes
Project Impacts. Disposal of dredged material at the HOODS is likely to adversely
affect the demersal fishes. The immediate local effect of dredged material disposal would
be the burial of adult and juvenile bottornfish as well as their epifaunal and infaunal food
resources. After dredged material is dumped, much of the fine-grained sediment would
remain suspended near the ocean floor (Hirsch et al. 1978). This may physically stress fish
by clogging their gills and reducing the absorption of dissolved oxygen. Adults can avoid
suspended material by moving out of the area, but juvenile fish may be more vulnerable and
susceptible to stress (SAIC 1986). Sediments can remain suspended for weeks or months,
and areas outside of the immediate disposal area might be affected if bottom currents
transport suspended sediments. The HOODS, however, is far enough offshore (3 to 4 nmi)
that, except during storms, bottom current velocities are small, and suspended sediments are
not expected to move beyond the disposal area (Scheffner 1990).
Over the long term, dredged material disposal at the HOODS may result in a
localized decrease in species diversity and abundance. Previous studies at the NDS and
SF-3 indicate that past disposal actions have adversely affected demersal fish fauna (ERC
1976, Lockheed Center 1979, Winzler and Kelly Consulting Engineers 1984, Pequegnat et
al. 1990). These reductions could be caused, in part, by reduced food availability. Benthic
infauna and epifauna populations, which are the main food source for demersal fish, decline
when disposal occurs frequently because the benthic fauna are unable to reestablish
themselves (SAIC 1986). Some recovery of the benthic community occurs within months,
but complete recovery of the original benthic communities requires about 1 to 3 years
(Dillon 1984, Scott et al. 1987). When dumping occurs more than once a year, it is likely
that the benthic community will be reduced and so support a more limited demersal fish
community. However, dredged material disposed at the HOODS might have a smaller
effect on fish populations than would disposal at nearshore areas (such as SF-3 and the
NDS) since, in general, fish abundance and biomass decrease toward offshore areas.
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To reduce the effects of suspended sediments on fish, very fine-grained sediments
should be deposited in the smallest area possible so that the least amount of benthic habitat
is affected (Hirsch et al. 1978). However, sandy sediment deposited in an area with similar
indigenous sediments should be dispersed over a large area. The similar-grained sediment
should minimally modify the disposal area, and a thin layer of sediment would allow
bottomfish a better chance of surviving burial (Hirsch et al. 1978).
Mitigation. Mitigation for potential impacts to demersal fish communities is the
same as that discussed for benthic infauna (Section 4.2.2.5). The effects of disposal could
be further minimized by scheduling activities during seasons that would least affect fish
reproduction. Recovery from physical impacts is most rapid when disposal operations are
completed shortly before seasonal peaks in spawning or larval abundance (Hirsch et al.
1978). Peak spawning activity of many benthic fish occurs from December to February, and
usually eggs and larvae are pelagic by spring. Disposal of dredged material in November,
just before the peak in spawning activity, might allow a rapid recovery. Preservation of
nursery areas is also critical. Juveniles of many species usually occur in the shallow, sandy
bottoms from May through August. Older juvenile English sole might use the area from
August to November as they move from protected areas to deeper waters off the open coast
(Lassuy and Moran 1989).
422.9 Pelagic Fishes
Project Impacts. Disposal activities at the HOODS are expected to minimally affect
pelagic marine and anadromous fishes. Pelagic fish passing through the immediate area
might be forced to change their route during discharge operations. Adult fish within and
immediately adjacent to the disposal area may experience short-term clogging of then- gills
by suspended materials, as well as a slight decrease in available oxygen due to the biological
oxygen demand of the dredged material. Adult fish may also experience stress from
avoidance reactions. However, these impacts are expected to be short-term and localized,
and the effects on pelagic adults in the water column are not expected to be significant.
Juveniles may be more susceptible to the effects of released dredged material.
Juveniles passing through a turbidity plume may be subject to gill clogging, interference with
oxygen exchange, and slightly lowered oxygen availability due to the biological oxygen
demand of the suspended sediments. Juvenile anadromous fish generally move seaward
between March and October, and juvenile black rockfish usually move to benthic habitats
in June. Release of dredged material is expected to be least likely to affect juvenile
anadromous and marine fish during the late fall and winter.
4.2.2.10 Coastal and Sea Birds
Project Impacts. Disposal of dredged material at the HOODS would have little
direct effect on seabird breeding colonies in the area because the site is located offshore,
away from known colonies. Indirect impacts on seabirds from dredged material disposal at
the HOODS could result from temporary turbidity, which would displace and obscure prey
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items in the water column. This would affect surface-diving seabirds (such as alcids) and
lunge divers (such as brown pelicans) that feed in clear water. Turbidity from disposal
would be both localized and temporary; consequently, birds that feed in clear water and in
the mid-water column will likely avoid plumes and feed elsewhere. Benthic fish and
invertebrates at the preferred site are not generally used as food by seabirds. Only a few
deep-diving species (e.g., common murres, cormorants, and loons) dive to depths of more
than 35 m (115 ft), and studies indicate that bottomfish compose only a small portion of
their diet (Ainley and Boekelheide 1990). Disposal of dredged material might actually
provide a brief supply of food for surface-feeding seabirds such as shearwaters, storm
petrels, fulmars, and gulls, depending on the abundance of marine organisms present within
the spoils. This food source, however, would be temporary and incidental to the total diet
of these birds.
Use of the HOODS would have no direct effect on the marbled murrelet, snowy
plover, or double-crested cormorant breeding populations because these species usually
occur closer to the coastline.
4.2.2.11 Marine Mammals
Project Impacts. Use of the HOODS will have no direct impact on populations of
marine mammals in the Humboldt Bay area. Many marine mammals occur in offshore
waters deeper than those found at the preferred site. It is possible that the plume or
disposal ship traffic would cause gray and humpback whales to slightly alter migratory
routes. Gray whales might move offshore to avoid ship traffic and turbid water (Dohl et al.
1983). Disposal at this site would probably have little direct effect on marine mammal
foraging, since most marine mammals in the area forage on mobile organisms that would
likely avoid the disposal area during disposal operations.
Use of the HOODS will have no direct effect on pinniped breeding or haul-out sites
because the site is located offshore of known breeding colonies and haul-out sites.
422.12 Threatened or Endangered Species
Project Impacts. No significant impacts to threatened or endangered species are
expected to occur as a result of the proposed designation of the HOODS as the regional
ODMDS. Potential impacts are expected to be temporary in nature, and confined to the
disposal site. Therefore, no loss of critical foraging habitat, increases in mortality, or
reductions in reproductive success for these species are expected to occur relative to the
entire region as a result of the proposed action.
Brown pelicans are plunge divers and thus require relatively clear waters in which
to feed (Ashmore 1971). Therefore, depending on the amount and duration of disposal,
dumping at the HOODS would temporarily exclude brown pelicans from foraging in the
local area. Pelicans may be indirectly affected if reproduction and abundance of favored
prey are reduced by dumping activities. However, as noted above, pelagic fish species
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(pelican prey) are expected to be only minimally affected by disposal operations at the
HOODS. There would be no direct effects on the brown pelican roosts on the south spit
of Humboldt Bay.
The short-tailed albatross is rarely sighted in California (Stallcup 1990). Therefore,
it is highly unlikely that dredged material disposal at the HOODS would affect this species.
The marbled murrelet nest in the coastal forests of the Humboldt Bay area and can
be observed feeding in waters near the Bay entrance. Because murrelets generally feed in
waters closer to shore, this species is not expected to be affected by disposal operations at
the HOODS.
Winter-run chinook salmon may occasionally pass through the site during disposal
operations. However, any impact of turbidity to this species would be short-term and
localized. No significant impact to this stock of chinook salmon is anticipated.
4.2.3 Socioeconomic Environment
4.2.3.1 Project Impacts
Impacts to commercial fishing and shipping, recreation, hunting, sport fishing, nature
study, or science and education are not anticipated as a result of designation of the HOODS
site. The site is situated 3 to 4 nmi offshore and does not lie within any established shipping
routes or at a commercially important fishing ground.
Several magnetic and sonar anomalies were identified within the HOODS. Three
of these anomalies were identified as potential shipwreck locations; however, no positive
identification of these sites has been made.
4232 Mitigation
The Corps will avoid disposal of dredged materials at potential shipwreck sites within
the HOODS to protect their cultural value.
4.3 SF-3
43.1 Physical Environment
Disposal of dredged material at the SF-3 site has resulted in significant impacts to
the oceanic conditions near the Bay entrance. Waves shoaling on the accumulated mound
of previously disposed dredged materials are reported to have resulted in breaking waves
within the site. This condition affects safe navigation when entering the Bay from the south.
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If SF-3 is designated as the regional ODMDS, continued disposal of materials would result
in continuation and magnification of navigation hazards. No mitigation has been identified
which would reduce this significantly adverse impact to less than significant levels.
Potential impacts to water quality would be similar to those discussed for the
HOODS. However, higher current and more intense wave action at the SF-3 site would
likely resuspend and disperse suspended sediment over a greater area.
4.32 Biological Environment
4.3.2.1 Phytoplankton
The impacts of dredged material disposal on phytoplankton at SF-3 are expected to
be similar to those discussed for the preferred alternative.
Zooplankton
The impacts of dredged material disposal on zooplankton at SF-3 are expected to be
similar to those discussed for the preferred alternative.
4.3.2.3 Benthic Algae
Although SF-3 is closer than the other sites to the intertidal and subtidal algal
communities on the jetties, dredged material disposed at this site is not expected to be
transported from SF-3 to the jetties in significant quantities. No significant adverse effects
on the benthic algae are anticipated.
432.4 Benthic Infauna
The benthic communities in the shallow nearshore zone are better adapted for
surviving physical disturbances than the more stable offshore communities. Initially, dredged
material disposal would smother the resident infauna. Although the grain size of dredged
spoils from Humboldt Bay is more like that of the nearshore zone sediments than that of
the mid-depth and offshore zones, previous studies have shown that disposal at SF-3 clearly
affected the infaunal community (Winzler and Kelly Consulting Engineers 1984). Coarse-
grained sediments do not provide a suitable habitat for most infaunal burrowing species.
Species diversity at the SF-3 disposal site was low while the site was active; the benthic
community consisted mainly of small surface-dwelling, surface-deposit feeders. This
indicates that disposal disrupted the ecology of the area and provided newly deposited
sediments for recolonization by generalist and opportunistic species. Because of substrate
type, wave action, and the annual disturbance resulting from disposal activities, the benthic
community observed at SF-3 remained unstable during its use as a disposal site. Long-term
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use of SF-3 for dredged material disposal would cause biological impacts on the benthic
infauna that would be significant and would adversely affect this community. Oliver and
Slattery (1976) reported that 1 to 3 undisturbed years would have to pass before the benthic
communities recovered to a state similar to the unaffected adjacent areas.
No mitigation has been identified which would reduce this significantly adverse
impact to less than significant levels.
432.5 Benthic Epifauna
The dredged material disposal operations offshore of Humboldt Bay generally occur
during periods of Dungeness crab breeding and spawning. The SF-3 site is located within
the shallow subtidal area that serves as habitat for critical life stages of Dungeness crabs.
Brooding females partially bury themselves in shallow subtidal areas from September to
November offshore of Humboldt Bay. Dungeness crabs mate in shallow, sandy areas from
March to July; the process can take up to 9 days as the male waits for the female to molt.
During these critical life stages, individuals in the immediate disposal area would be
adversely affected by burial under dredged material. These impacts would be limited to the
boundaries of the disposal site and are not expected to have significant long-term adverse
impacts on Dungeness crab populations offshore of Humboldt Bay. If the disposal of
dredged material offshore of Humboldt Bay became more frequent, as might occur if a
channel widening and deepening project in Humboldt Bay were undertaken, the magnitude
of these impacts would increase.
43.2.6 Pelagic Invertebrates
The impacts of dredged material disposal on the market squid Loligo opalescens at
SF-3 are expected to be similar to those discussed for the preferred alternative.
4.32.7 Demersal Fishes
Disposal of material at the SF-3 site is expected to adversely affect resident demersal
species at the site. The immediate effects of dredged material disposal are similar to those
discussed for the HOODS. Disposal at SF-3 has already modified the fish community and
lowered the density of fish species (Lockheed Center 1979, Winzler and Kelly Consulting
Engineers 1984). Resumption of disposal at this site would reduce the epifaunal and
infaunal food resources, as in the past, limiting the number of fish that the area can support.
Species diversity would also continue to be depressed. However, previous studies at SF-3
did not definitively determine that certain species previously occurring in the area became
excluded as a result of disposal activities. Also, nuisance fish species did not become
established.
No mitigation has been identified which would reduce this significantly adverse
impact to less than significant levels.
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43.2.8 Pelagic Fishes
Disposal operations are expected to minimally affect pelagic species. Migrating
fishes might temporarily avoid SF-3 during disposal activities but would not be blocked from
the entrance channel to Humboldt Bay and could pass around the disposal site. Pelagic
fishes present inside or immediately adjacent to the disposal site during operations might
experience physiological stresses similar to those discussed for the preferred alternative.
432.9 Coastal and Sea Birds
Selection of SF-3 as a disposal area is expected to have little direct effect on breeding
colonies of seabirds because the site is located approximately 16.5 nmi from the nearest
coastal seabird colonies. The only impacts would be the short-term loss of prey and foraging
habitat that would result from increased turbidity. This would apply especially to diving
seabirds such as common murres, rhinoceros auklets, and cormorants. The degree of
seabird displacement from foraging areas depends upon the duration and size of sediment
plumes and the volume of dredge spoils. The effect on seabirds could be significant if the
reproduction and abundance of favored prey are affected in nearshore waters. The loss of
the benthic community at SF-3 would result in a loss of localized feeding habitat for
seabirds that feed on benthic organisms; however, seabirds would likely find food elsewhere
in the area. Disposal at this site might briefly provide food for seabirds such as gulls,
depending on the number of marine organisms in the dredged sediments. This food source,
though, would be temporary and incidental to the main diet of these birds.
4.3.2.10 Marine Mammals
The impacts of dredged material disposal on marine mammals at the SF-3 site would
be similar to those discussed for the preferred alternative. Pinniped breeding and haul-out
sites are not expected to be affected by the use of SF-3. All breeding and haul-out sites,
except for harbor seal rookeries, are located more than 8 nmi from the SF-3 disposal site,
and the nearest harbor seal rookery is located approximately 0.9 nmi away, inside Humboldt
Bay.
The SF-3 site may provide some foraging habitat for marine mammals because of its
relatively shallower depths and proximity to shore. However, loss of this habitat in relation
to the foraging range of marine mammals would be less than significant.
43J2.ll Threatened or Endangered Species
The impacts of dredged material disposal at SF-3 on threatened or endangered
species would be similar to those discussed for the preferred alternative site, but with the
exceptions discussed below.
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The SF-3 site lies within potential foraging range of both marbled murrelets and
Steller sea lions. However, the foraging habitat at the SF-3 site is small in relation to the
foraging range of these species, and use of the site is not expected to cause significant
impacts to threatened and endangered species.
4.3.3 Socioeconomic Environment
4.33.1 Project Impacts
Designation and dredged material disposal will result in accumulations of sediments
at the SF-3 site. These accumulations will likely intensify the present navigation hazards at
the site. Additionally, the site is not large enough to adequately contain disposed dredge
materials, given the anticipated quantity of 50,000,000 yd3 over the 50-year life of the site.
4.33.2 Mitigation
Enlargement of the SF-3 site is the only potential mitigation to reduce impacts to
navigation. However, the environmental impacts associated with enlarging the site enough
to contain 50,000,000 yd3 without impacts to surface navigation would likely preclude this
mitigation alternative.
4.4 THENDS
4.4.1 Physical Environment
Potential impacts of designating the NDS as the regional ODMDS are similar to
those discussed for the SF-3 site.
4.4.2 Biological Environment
4.42.1 Phytoplankton
The impacts of dredged material disposal on phytoplankton at the NDS are expected
to be similar to those discussed for the preferred alternative.
4.4.2.2 Zooplankton
The impacts of dredged material disposal on zooplankton at the NDS are expected
to be similar to those discussed for the preferred alternative.
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4.423 Benthic Algae
Although the NDS disposal site would be closer to benthic algal communities than
the HOODS or SF-3, these communities are still located at a safe distance from the site.
Dredged material disposal at the NDS is not expected to have any significant adverse effects
on the benthic algae in the study area.
4.4.2.4 Benthic Infauna
A month after the disposal of dredged material at the NDS, benthic invertebrate
species diversity and abundance were observed to be reduced (Pequegnat et al. 1990).
However, benthic communities tend to be unstable in shallow water due to wave action.
Since the NDS has not been used for dredged material disposal since the fall of 1989, the
benthic community has most likely recolonized, with the fauna more like that of the adjacent
environment.
The impacts of dredged material disposal on the benthic infauna at the NDS are
expected to be similar to those discussed for the SF-3 site alternative. The number of
species and individuals decreased by more than 60% between the August and November
1989 samplings conducted by Pequegnat et al. (1990). Although this might have been
related to the disposal of dredged material at this site prior to the November sampling, it
is also probable that this is a seasonal trend (Pequegnat et al. 1990).
No mitigation has been identified which would reduce this significantly adverse
impact to less than significant levels.
4.4.2.5 Benthic Epifauna
The potential impacts of dredged material disposal on the benthic epifauna at the
NDS might be greater than at either of the other two alternative disposal sites because of
the relatively high seasonal abundance of Dungeness crab reported there. The highest
abundances of Dungeness crab were recorded in the vicinity of the NDS, with the greatest
numbers observed in November following the disposal of dredged material in the fall. Both
the April-May and September-October disposal periods offshore of Humboldt Bay occur
when Dungeness crabs can be found at the shallow depths.
4.42.6 Pelagic Invertebrates
The impacts of dredged material disposal on the pelagic invertebrates at the NDS
are expected to be similar to those discussed for the SF-3 site alternative.
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4.42.7 Demersal Fishes
Project Impacts. Dredged material disposal activities are expected to adversely affect
bottomfish species at the NDS and in areas adjacent to the site. Such disposal operations
have only occurred twice at this site, but trawl catches indicated that species diversity and
biomass were reduced as compared to catches in control areas. The immediate effect of
disposal is expected to be similar to that described for the SF-3 site alternative. The long-
term effects of disposal would include reduced food resources and modified sedimentation
patterns. Disposal material would be composed of fine-grained sediment (fine sand to silt
and clay) in the spring and of coarse-grained materials in the fall (Scheffner 1990). Fine-
grained material differs from the indigenous sediment at the NDS and is not suitable for
nearshore disposal. When disposed sediments differ from bottom sediments, recolonization
of dredged material by epifauna and infauna might be slow, and food resources for fish
might be limited (Hirsch et al. 1978).
Mitigation. The effects of dredged material disposal could be reduced by conducting
disposal operations before peak spawning periods and when juveniles are unlikely to use the
area, and by using material with similar grain size. Recovery from physical impacts is most
rapid when dredged material disposal occurs just prior to peak spawning periods, which for
bottomfish are typically from December to February. Also, juveniles are most likely to be
in nearshore areas such as the NDS from April to August, except for juvenile English sole,
which might be found as late as November.
4.42.8 Pelagic Fishes
The impacts of dredged material disposal on pelagic species at the NDS are expected
to be similar to those discussed for the preferred alternative.
4.42.9 Coastal and Sea Birds
The impacts of dredged material disposal on coastal and sea birds at the NDS are
expected to be similar to those discussed for the SF-3 alternative.
4.42.10 Marine Mammals
The impacts of dredged material disposal on marine mammals at the NDS are
expected to be similar to those discussed for the preferred and SF-3 alternatives. Pinniped
rookeries and haul-out sites would probably not be affected by disposal at the NDS because
all rookery and haul-out sites, except for harbor seal rookeries, are located more than 8 nmi
from this alternative site. Harbor seal haul-out sites are about 0.65 nmi away, inside
Humboldt Bay.
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4.4.2.11 Threatened or Endangered Species
The impacts of dredged material disposal on threatened or endangered species at the
NDS are expected to be similar to those discussed for the SF-3 site alternative.
4.4.3 Socioeconomic Environment
4.4.3.1 Project Impacts
Designation and dredged material disposal will result in accumulations of sediments
at the NDS. These accumulations will likely intensify the present navigation hazards at the
site. Additionally, the NDS is not large enough to contain disposed dredged materials, given
the anticipated quantity of 50,000,000 yd3 over the 50-year life of the site.
4.4.3.2 Mitigation
Enlargement of the NDS is the only potential mitigation to reduce impacts to
navigation. However, the environmental impacts associated with enlarging the site enough
to contain 50,000,000 yd3 without impacts to surface navigation would likely preclude this
mitigation alternative.
4.5 LONG-TERM IMPACTS AS A RESULT OF THE PROJECT
Long-term significant impacts on the biological community are expected to be
localized within the boundaries of the preferred alternative site. Impacts may include a
decrease in benthic infaunal and epifaunal populations and lowered fish diversity. Benthic
infaunal communities at the preferred alternative site are expected to be affected as long
as disposal is taking place. Benthic infauna would be buried during disposal and, depending
on the volumes dumped, the thickness of deposited material on the bottom, and the length
of time between disposal operations, might not have sufficient time to recolonize. Benthic
epifauna, including Dungeness crabs, might also be affected to some extent; however, few,
if any, of the critical life stages of this crab species are found at the HOODS.
The long-term effect of dredged material disposal on demersal fish at the preferred
site may be a decrease in species diversity and abundance. This effect has been documented
offshore of Humboldt Bay at the NDS and at SF-3 (ERC 1976, Lockheed Center 1979,
Winzler and Kelly Consulting Engineers 1984, Pequegnat et al. 1990) and at other coastal
disposal sites (EPA 1987). These reductions are partially caused by reduced populations of
benthic infauna and epifauna populations, a main food source for fish.
Overall, disposal of dredged material at the preferred alternative site is not expected
to affect any geographically limited species or affect any unique habitats, breeding areas, or
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critical areas that are essential to commercially important species and to rare or endangered
species.
4.6 RELATIONSHIP BETWEEN SHORT-TERM USE AND
LONG-TERM RESOURCE USES
The proposed designation of any of the alternative sites as an ODMDS is not
expected to produce significant, long-term, adverse impacts to resources, including the
physical, biological, and socioeconomic environments, within the Humboldt Bay region.
Impacts to benthic invertebrates within the site are expected to persist as long as the site
is used for disposal. However, cessation of disposal should result in gradual recovery over
time. Recolonization of a diverse and stable benthic community would probably be
complete 1 to 3 years after cessation of disposal operations (Dillon 1984, Scott et al. 1987).
Use of the proposed ODMDS is not expected to interfere with uses of resources
outside of the boundaries of the alternative sites. These resources include commercial and
sport fishing, marine bird and mammal observation, and use of the regional by commercial
and recreational vessels. No significant mineral or oil and gas resources occur within any
of the alternative sites. Therefore, use of the ODMDS does not represent a potential
conflict with the long-term use of resources.
Any impacts or restricted uses of resources within the site boundaries would
represent a very small percentage of these resources within the Humboldt Bay study region.
This marginal loss of some resources is balanced by the significant benefit that would be
derived from the proposed action. In contrast, lack of a designated ocean disposal site
capable of receiving large quantities of dredged material could have a significant adverse
effect on the economic productivity associated with Humboldt Bay.
4.7 IRREVERSIBLE OR IRRETRIEVABLE COMMITMENT OF RESOURCES
Irreversible or irretrievable resources that would be committed if an ocean disposal
site is designated will include:
energy resources used as fuel for dredges, pumps, and disposal vessels, and for
research vessels involved in monitoring studies;
economic resources associated with ocean disposal including monitoring and
surveillance;
unavailability of sediments disposed at the ODMDS for potential beach
restoration or other beneficial use projects; and
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some loss or degradation of the benthic habitat and associated benthic
communities at the site for at least the duration of site use.
The commitment of energy and economic resources will increase with increased
distance of a site from dredging areas. However, the three alternative sites are similar
distances from Humboldt Bay, and no significant differences in the resources contained
within the alternative sites are evident. Therefore, the magnitude of any long-term
commitment of irreversible or irretrievable resources that can be determined from the
existing information is essentially the same for each of the three alternative sites.
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Section 5
Coordination
-------
Section 5. Coordination
This section contains information on public involvement and interagency activities
related to the DEIS for designation of the ODMDS off Humboldt Bay, California. Several
scoping meetings occurred between January 1989 and January 1991. Initial field studies
were conducted by the Corps in 1990. During preparation of the DEIS, EPA initiated
coordination with agencies regarding the potential impacts of the proposed site designation
to threatened or endangered species that may occur in the area of the alternative sites.
Although some of these agencies have responded with lists of these species, they have
reserved formal determination until after the release of the DEIS (see following letters).
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UNITED STATES DEPARTMENT OF COMMERCE
t*S» a National Oceanic and Atmospheric Administration
\ ^pJ / NATIONAL MARINE FISHERIES SERVICE
''«<** Southwest Region
501 West Ocean Boulevard, Suite 4200
Long Beach, California 90802-4213
TEL (310) 980-4000; FAX (310) 980-4018
JAN I 7 I995 F/SW03:SHK
Mr. Jeff Rosenbloom
Chief, Wetlands and Sediment Section
U.S. Environmental Protection Agency
Region IX
75 Hawthorne Street
San Francisco, California 94105-3901
Dear Mr. Rosenbloom:
Thank you for requesting information regarding the presence of
Federally listed threatened or endangered species or critical
habitat that may be affected by the designation of an ocean
dredged material disposal site off Humboldt Bay, California.
Available information indicates that the endangered Sacramento
River winter-run Chinook salmon and the threatened Steller sea
lion may occur at the proposed project site. No critical habitat
occurs for either species at the proposed project site. The
National Marine Fisheries Service is also conducting status
reviews of coho salmon and steelhead trout on the west coast, and
these reviews may result in proposals to list either or both
species. Both of these species may also occur in the area of
your proposed project.
The U.S. Fish and Wildlife Service (USFWS) may also have listed
species or critical habitat under its jurisdiction in the project
area. Please contact Mr. Joel Medlin, Field Supervisor, USFWS,
at 2800 Cottage Way, Room E-1803, Sacramento, California 95925,
or (916) 978-4613, regarding the presence of listed species or
critical habitat under USFWS jurisdiction that may be affected by
your project.
If you have questions concerning these comments, please contact
Mr. Gary Stern at (707) 578-7513.
Sincerely,
^ -'
^jAHiM
Hilda Diaz-Solterd
Regional Director
5-3
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United States Department of the Interior
FISH AND WILDLIFE SERVICE
Ecological Services
Sacramento Field Office
2800 Cottage Way, Room E-1803
Sacramento, California 95825-1846
In Reply Refer To:
1-1-95-SP-277 January 18, 1995
Mr. Jeff Rosenblum
Chief, Wetlands and Sediment Management
U.S. Environmental Protection Agency
Region IX
75 Hawthorne Street
San Francisco, California 94105-3901
Subject: Species List for Proposed Ocean Dredged Material Disposal
Site Off Humboldt Bay, Humboldt County, California
Dear Mr. Rosenblum:
As requested by letter from your agency dated December 12, 1994, you will find
enclosed a list of listed, proposed and candidate species that may be present
in the subject project area (see Enclosure A). This list fulfills the
requirement of the Fish and Wildlife Service to provide a species list
pursuant to Section 7(c) of the Endangered Species Act, as amended, (Act).
Pertinent information concerning the distribution, life history, habitat
requirements, and published references for the listed species is available
upon request. This information may be helpful in preparing the biological
assessment for this project, if one is required. Please see Enclosure B for a
discussion of the responsibilities Federal agencies have under Section 7(c) of
the Act and the conditions under which a biological assessment must be
prepared by the lead Federal agency or its designated non-Federal
representative.
Formal consultation, pursuant to 50 CFR § 402.14, should be initiated if you
determine that a listed species may be affected by the proposed project. If
you determine that a proposed species may be adversely affected, you should
consider requesting a conference with our office pursuant to 50 CFR § 402.10.
Informal consultation may be utilized prior to a written request for formal
consultation to exchange information and resolve conflicts with respect to a
listed species. If a biological assessment is required, and it is not
initiated within 90 days of your receipt of this letter, you should informally
verify the accuracy of this list with our office.
We have included the candidate species that may be present in the project area
(see Enclosure A). These species are currently being reviewed by our service
and are under consideration for possible listing as endangered or threatened.
Candidate species have no protection under the Endangered Species Act, but are
included for your consideration as it is possible that one or more of these
candidates could be proposed and listed before the subject project is
completed. Should the biological assessment reveal that candidate species may
be adversely affected, you may wish to contact our office for technical
assistance. One of the potential benefits from such technical assistance is
that by exploring alternatives early in the planning process, it may be
possible to avoid conflicts that could otherwise develop, should a candidate
species become listed before the project is completed.
5-5
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Mr. Jeff Rosenblum
We appreciate your concern for endangered species. If you have further
questions, please call Laurie Stuart Simons of this office at (916) 979-2725
If you have any questions regarding wetlands, contact Mark Littlefield at
(916) 979-2113.
Sincerely,
A. Medlin I
Field Supervisor
Enclosures
5-6
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ENCLOSURE A
LISTED AND PROPOSED ENDANGERED AND THREATENED SPECIES AND CANDIDATE
SPECIES THAT MAY OCCUR IN THE AREA OR MAY BE AFFECTED BY THE PROPOSED
OCEAN DREDGED MATERIAL DISPOSAL SITE OFF HUMBOLDT BAY
HUMBOLDT COUNTY, CALIFORNIA
(1-1-95-SP-277, JANUARY 18, 1995)
Listed Species
Fish
tidewater goby, EucyclogobLus newberryi (E)
Birds
marbled murrelet, Brachyramphus marmoratus (T)
Proposed Species
None
Candidate Species
Fish
green sturgeon, Acipenser medirostris (2R)
(E)--Endangered (T)--Threatened (P)--Proposed (CH)--Critical Habitat
(1)--Category 1: Taxa for which the Fish and Wildlife Service has sufficient
biological information to support a proposal to list as endangered or
threatened.
(2)--Category 2: Taxa for which existing information indicated may warrant
listing, but for which substantial biological information to support a
proposed rule is lacking.
(1R)-Recommended for Category 1 status.
(2R)-Recommended for Category 2 status.
()--Listing petitioned.
(*)--Possibly extinct:.
5-7
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ENCLOSURE B
FEDERAL AGENCIES' RESPONSIBILITIES UNDER
SECTIONS 7(a) and (c) OF THE ENDANGERED SPECIES ACT
SECTION 7 (a) Consultation/Conference
Requires: 1) Federal agencies to utilize their authorities'to carry out
programs to conserve endangered and threatened species; 2) Consultation with
FWS when a Federal action may affect a listed endangered or threatened species
to insure that any action authorized, funded or carried out by a Federal
agency is not likely to jeopardize the continued existence.of listed species
or result in the destruction or adverse modification of critical habitat. The
process is initiated by the Federal agency after determining the action may
affect a listed species; and 3) Conference with FWS when a Federal action is
likely to Jeopardize the continued existence of a proposed species or result
in destruction or adverse modification of proposed critical habitat.
SECTION 7(c) Biological AssessmentMajor Construction Activity
Requires Federal agencies or their designees to prepare a Biological
Assessment (BA) for major construction activities. The BA analyzes the
effects of the action^ on listed and proposed species. The process begins
with a Federal agency requesting from FWS a list of proposed and listed
threatened and endangered species. The BA should be completed within 180 days
after its initiation (or within such a time period as is mutually agreeable).
If the BA is not initiated within 90 days of receipt of the list, the accuracy
of the species list should be informally verified with our Service. No
irreversible commitment of resources is to be made during the BA process which
would foreclose reasonable and prudent alternatives to protect endangered
species. Planning, design, and administrative actions may proceed; however,
no construction may begin.
We recommend the following for inclusion in the BA: an on-site inspection of
the area affected by the proposal which may include a detailed survey of the
area to determine if the species or suitable habitat are present; a review of
literature and scientific data to determine species' distribution, habitat
needs, and other biological requirements; interviews with experts, including
those within FWS, State conservation departments, universities and others who
may have data not yet published in scientific literature; an analysis of the.
effects of the proposal on the species in terms of individuals and
populations, including consideration of indirect effects of the proposal on
the species and its habitat; an analysis of alternative actions considered.
The BA should document the results, including a discussion of study methods
used, any problems encountered, and other relevant information. The BA should
conclude whether or not a listed or proposed species will be affected. Upon
completion, the BA should be forwarded to our office.
1A construction project (or other undertaking having similar physical
impacts) which is a major Federal action significantly affecting the quality
of the human environment as referred to in NEPA (42 U.S.C. 4332(2)C).
2"Effects of the action" refers to the direct and indirect effects on an
action on the species or critical habitat, together with the effects of
other activities that are interrelated or interdependent with that action.
5-8
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Section 6
Preparers and Contributors
-------
Section 6. Preparers and Contributors
Agency and Name
Expertise
Experience
Responsibility
EPA
Allan Ota/M.S.
Corps
Dave Hodgcs/B.S.
Jones & Stokes Associates
Richard Oestman/M.S.
Jones & Stokes Associates
Grant Bailey/B.S.
Jones & Stokes Associates
Larry Larscn/Ph.D.
Jones & Stokes Associates
Andrew Wones/M.S.
Jones & Stokes Associates
Sara Noland/B.S.
Biological Oceanography
Geology
Fisheries, Marine Biology,
Dredged Material Disposal
Analysis, NEPA Document
Preparation
Marine Biology, Regulatory
Compliance, NEPA BIS
Preparation
Physical Oceanography,
Numerical Modeling
Marine Biology
Technical Editing
13 years conducting research
and preparation and review of
technical reports.
4 years experience in
preparation and review of
dredging projects.
Over 8 years experience in
managing and conducting
environmental studies and
impact assessments in the
marine environment, and EIS
management and preparation.
Over 20 years experience in
managing and conducting
environmental studies and
impact assessments in marine
environment, and EIS
management and preparation.
Over 25 years experience in
conducting research in physical
oceanography and pollutant
transport.
Over 5 years experience in
conducting research and
preparing technical reports and
EIS sections.
Over 3 years experience in
performing editing and
production of NEPA
documents and technical
reports.
Work Assignment Manager
and EIS review
Project Manager
Project Manager,
preparation of EIS, EIS
review
EIS review
Preparation of EIS
sections: Affected
Environment and
Environmental
Consequences
Preparation of EIS
sections: Affected
Environment and
Environmental
Consequences
Editing and production of
EIS
6-1
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Section 7
Glossary
-------
Section 7. Glossary
adverted - horizontally or vertically transported, as by a current
ambient - the existing level of air pollutants or other environmental factors
amphipods - an order of crustaceans with laterally compressed bodies, including sand fleas
and beach fleas
amplitude - for a wave, the vertical distance from sea level to crest, or sea level to trough,
or one-half the wave height
anadromous - migrating from the sea up rivers to breed in fresh water; salmon are
anadromous
annelids - members of the phylum annelidea; includes segmented worms such as polychaetes
bathymetric - pertaining to seafloor elevations and variations of water depth
benthic - of the seafloor, or pertaining to organisms living on or in the seafloor
bioaccumulation - the uptake of substances, such as heavy metals, leading to elevated
concentrations of those substances within plant or animal tissues
biomass - the weight of living organisms in a given area or volume at a given time
biota - the plants and animals living in a given area
bivalves - marine shellfish with two shells, such as oysters and clams
bloom - an explosive growth of algae that can contribute to reduced clarity of the water
box core - a device used to collect sediment samples from the ocean floor
carbon monoxide (CO) - a colorless, odorless gas resulting from incomplete combustion;
high concentrations can cause sickness and death in humans
carnivorous - having a diet consisting of the flesh of other animals
chlorophyll - a pigment found in plants that converts sunlight, water, and carbon dioxide into
sugars needed for plant growth; gives green plants their color
7-1
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chlorophyll a. - a specific chlorophyll pigment characteristic of higher plants and algae,
frequently used as a measure of phytoplankton biomass
copepods - a large diverse group of small planktonic crustaceans representing an important
link in oceanic food chains
cosmopolitan species - species with world-wide distribution
crustaceans - a class of animals with jointed legs and hard external skeletons; includes crabs,
barnacles, shrimp, and lobsters
decapods - crustaceans such as crabs, lobsters, and shrimp having 10 legs
demersal - living at or near the bottom of the sea
deposit-feeder - an animal which feeds on organic material in and on the seafloor
diatoms - microscopic phytoplankton with a cell wall made of overlapping silica plates
dinoflagellates - a large, diverse group of phytoplankton with flagella (whip-like appendages
used for locomotion); some dinoflagellates are responsible for toxic red tides
dissolved oxygen (DO) - the quantity of oxygen dissolved in a unit volume of water
diversity - a statistical measurement which generally combines a measure of the total
number of species in a given environment with the number of individuals of each species;
species diversity is high when there are many species with a similar number of individuals,
and low when there are fewer species and when one or two species dominate
echinoderms - a group of marine invertebrates that includes sea urchins, sea cucumbers, sea
stars, and sand dollars
epifauna - animals that live on bottom sediments or hard surfaces
epipelagic zone - the upper portion of the pelagic zone, including surface waters
estuary - a partially enclosed coastal body of water where fresh water (such as a river) and
salt water mix
euphasiids - planktonic, shrimp-like crustaceans
faunal group - a group of biologically or ecologically related animals
flagellates - one-celled animals with flagella (whip-like appendages used for locomotion)
7-2
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food web - the complex of feeding relationships within a community of organisms including
production, consumption, decomposition, and the flow of energy within the community and
the environment
gastropods - mollusks that have a distinct head, a flat foot, and usually a spiral shell, such
as snails
hopper dredge - a self-propelled vessel with capabilities to dredge, store, transport, and
dispose of dredged materials
hydrocarbons (HC) - organic compounds containing only hydrogen and carbon, occurring
in petroleum, natural gas, and coal
hydrographic - related to the physical conditions of waters
infauna - animals that live in the bottom sediment
insolation - exposure to sunlight
invertebrates - a group of animals lacking backbones; includes many marine species such as
worms, jellyfish, snails, and clams
jetty - a structure located to influence currents or protect the entrance to a harbor or river
from waves
littoral - of or pertaining to the seashore, especially the area between tide lines
macrofaunal - pertaining to animals large enough to see with the unaided eye
macroinvertebrates - animals lacking backbones (invertebrates) that are large enough to be
visible to the unaided eye
mollusk - a group of animals lacking body segments and usually having a shell made of
calcium; examples are snails, clams, and octopus
multiple-port diffuser - the terminus of an outfall pipe fitted with several holes or ports to
enhance the mixing of effluent in receiving waters
nitrogen oxides (NOX) - a group of compounds containing varying proportions of nitrogen
and oxygen; one of these, nitrogen dioxide, is a primary component of smog
omnivorous - having a diet consisting of both plants and animals
otter trawl - a large conical net dragged along the seafloor to catch fish and other marine
life
pelagic - pertaining to near surface waters of the ocean
7-3
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phytoplankton - that portion of the plankton that consists of microscopic plants
plankton - the passively floating or weakly swimming, usually microscopic plant and animal
life in a body of water
paniculate matter (PM) - particulates suspended in the air that contribute to air pollution
PM10 - particulate matter smaller than or equal to 10 microns in diameter; PM10 is of health
concern because particles this size are small enough to reach the lungs when inhaled
polychaetes - a type of marine worms
primary production - the amount of organic matter (such as starches) produced by plants
from inorganic substances per unit time and volume of water
reactive organic gases (ROG) - the components of organic gases which react with nitrogen
oxides to form ozone
salinity - a measure of the salt content of water
seabed drifter (SBD) - an umbrella-shaped device which is used to determine the direction
of transport along the seafloor
sulfur dioxide (SO2) - an air pollutant that reacts with sunlight and other pollutants to
contribute to atmospheric haze
suspension-feeder - an animal that feeds on nutrients and other animals suspended in the
water column
synergistic effect - an effect caused by two or more interacting factors
tectonic - relating to the movement of the earth's crust and production of earthquakes
Tertiary - a geologic period of time between 65 and 2 million years ago
topography - the description of the physical features of a place or region
transmittance - a measure of light passing through a specific distance in water, used as a
measure of light penetration or water clarity
trophic level - the position of an organism in a food chain or food web such as primary
producers, secondary producers, consumers, and detritivores
turbidity - the measure of sediment suspended in a volume of water
upwelling - the rising of nutrient-rich bottom waters to the surface; usually the result of
divergent surface currents
7-4
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wave period - time required for two successive wave crests or troughs to pass a fixed point
zoea stage - a stage in the development of certain crustaceans such as crabs
zooplankton - that portion of the plankton that consists of microscopic animals
7-5
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Section 8
References
-------
Section 8. References
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Appendix A
Site Management and Monitoring Plan
for HOODS ODMDS
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APPENDIX A
SITE MANAGEMENT AND MONITORING PLAN (SMMP) FOR
HUMBOLDT BAY (HOODS) OCEAN DREDGED
MATERIAL DISPOSAL SITE
I. INTRODUCTION
The Marine Protection, Research and Sanctuaries Act (MPRSA) of 1972 (33 USC
Section 1401 el seq.) is the primary legislative authority regulating the disposal of dredged
material into ocean waters. The MPRSA prohibits disposal activities that would
unreasonably degrade or endanger human health or the marine environment. Under the
act, the U.S. Environmental Protection Agency (EPA) and the U.S. Army Corps of
Engineers (Corps) have joint authority for regulating ocean disposal of dredged material and
for managing ocean disposal sites. Management of an ocean disposal site consists of:
(a) regulating the quantities, types of material, times, rates, and methods of disposing
dredged material at an ocean disposal site; (b) development and maintenance of an effective
monitoring program for the site; (c) recommending changes to site use, disposal amounts,
or designation for a limited time based on periodic evaluation of site monitoring results; and
(d) enforcement of permit conditions.
Section 506 of the Water Resources Development Act (WRDA) amends
Section 102(c) of the MPRSA. These amendments require, in part, that a site management
plan be developed for each designated ocean disposal site. This site management plan is
required to include:
a baseline assessment of conditions at the site;
a program for monitoring the site;
special management practices necessary for protection of the site;
consideration of the quantity and contaminant levels of material to be disposed
at the site;
consideration of the active life of the site and management requirements after
site closure; and
a schedule for review and revision of the site management plan.
Section 506 of the WRDA further requires that, after January 1, 1995, a site
management plan must be developed and approved before final designation is issued. After
January 1,1997, no permit for dumping may be issued under Section 103 of the MPRSA for
a site unless the site has received final designation.
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In the case of this proposed action, the final designation is scheduled for fall 1995.
Thus, a site management plan is required to be developed and approved, pursuant to the
WRDA, before the final designation may be issued.
Two key parts of an effective management plan are the flexibility to accommodate
unforeseen needs, and the ability to revise the plan as changes are identified. The primary
goal of site management is to ensure adequate environmental protection and regulatory
compliance. To this end, the SMMP (see Exhibit A) for the ocean dredged material
disposal site (ODMDS) off Humboldt Bay (HOODS) will be reviewed periodically by EPA
Region IX and the Corps' San Francisco District. Agency representatives will meet to
review site operations, to discuss potential problems with the condition at the HOODS or
monitoring activities, and to address public concerns about disposal at the HOODS. Any
changes must meet the approval of both agencies. Resolution of management and
monitoring issues and public concerns will be worked out cooperatively.
A. Purpose of the SMMP
The SMMP for the HOODS has been developed jointly by EPA Region DC and the
Corps' San Francisco District. It is designed to identify possible unacceptable adverse
environmental impacts that may occur beyond the site boundary, and to ensure that disposal
operations comply with established permit conditions. This document provides guidance to
EPA Region IX and the Corps' San Francisco District staff on available management
options and the proper times when management decisions may be required.
The HOODS is located in water depths between 49 and 55 meters (160 and 180 feet)
and is positioned within the coordinates 40° 48 25N, 124° 16 22W; 40°49'3"N, 124°17'22"W;
40°4T38"N, 124°17'22"W; 40°48'17" N, 124°18'12"W (Figure 1). The site is one square
nautical mile (run2; 850 acres) in area and is divided into 4 quadrants (1-4), each containing
9 cells (Figure 2). Management decisions must reflect local characteristics of the disposal
site such as: (1) geographic location; (b) oceanographic conditions; (c) physical, chemical,
and biological characteristics and composition of the proposed dredged material; and (d)
adjacent amenities and resources that might be adversely affected by disposal operations.
As an integral part of the SMMP, a site monitoring program has been designed for
the HOODS to provide necessary data for site management. These data will address
potential and actual impacts to the marine environment and biological resources at the
HOODS or in areas adjacent to the site boundaries. The program design facilitates
monitoring of both short-term and long-term impacts, enabling EPA Region IX and the
Corps' San Francisco District to make management decisions in a timely manner should
potential or actual unacceptable adverse impacts be detected. Specific portions of the
SMMP will also help EPA Region IX and Corps' San Francisco District staff to verify
whether disposal operations are carried out in compliance with permitting requirements and
other environmental laws.
The SMMP addresses the options available to the federal agencies for modification
of activities at the site to avoid significant environmental impacts, or options to mitigate
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PAClFtC
/I 0 CBA
Figure 1. Location of Past and Present Ocean and Land Dredged Material Disposal Sites
Near Humboldt Bay, California
-------
STATION
CG55C
40°48'171N1
124°18'139'W
544.432.319N
1,36^346.191E
Al
A2
A3
A4
A5
A6
STATION
CG49C,
40° 47' 38'N
124°17'131W
540.363.699N
1,36
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The SMMP addresses the options available to the federal agencies for modification
of activities at the site to avoid significant environmental impacts, or options to mitigate
potentially adverse impacts. Management actions may include: (a) adjustment of permitting
and monitoring procedures, (b) adequate enforcement of permit conditions, or
(c) modification of disposal activities, either temporarily or permanently. Specific
considerations may include a change in dredging or disposal practices, restrictions on
amounts of dredged material disposal, revision of site size, use of the site for a limited time,
or designation of a new site.
B. SMMP Objectives
1. The following specific objectives are included in the SMMP to ensure acceptable
long-term use of the HOODS as the designated site. These objectives may be
used to revise the configuration or location of the disposal site, and will
accommodate disposal of acceptable dredged material without causing adverse
impacts outside site boundaries:
a. Define the overall strategy and rules for site use.
b. Establish specific site use requirements to ensure compliance with the EPA's
Ocean Dumping Regulations.
c. Publish sediment testing and reporting requirements jointly agreed to by
EPA Region IX and the Corps' San Francisco District to complement
national guidance on sediment testing. This will be accomplished by
publishing a San Francisco District Public Notice defining the proposed
testing and reporting procedures to obtain comments from other agencies,
prospective permit applicants, and contractors.
d. Identify biological resources of concern based on the HOODS Final
Environmental Impact Statement (U.S. Environmental Protection Agency,
Region IX, 1995).
e. Facilitate assessment of any potential problems which may be identified as
a result of routine site monitoring, and implement changes to avoid such
problems.
f. Provide an instrument of agreement for site management between the EPA
Region IX, the Corps' San Francisco District, the U.S. Coast Guard, and
other concerned regulatory and resource agencies responsible for successful
site operation or enforcement.
2. The suitability of any dredged material proposed for disposal will be determined
before disposal at the HOODS. This involves appropriate physical, chemical and
biological testing of the proposed dredged sediments based on requirements and
procedures defined in EPA's Ocean Dumping Regulations at 40 CFR Parts 220,
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225, 227 and 228. The following information will be supplied by the permit
applicant to EPA Region IX and the Corps' San Francisco District as part of the
permit application process (33 CFR Parts 335 to 338):
a. Written documentation of the need to dispose the dredged material in the
ocean, including a disposal alternatives analysis. This will be used to decide
the proper disposal alternative for the sediments proposed for dredging.
b. A description of historical dredging and activities at or adjacent to the
proposed dredging site that may have contaminated the sediments. The
historical analysis will give the federal agencies information on potential
sources of contamination at the site. Additional chemicals of concern may
be identified by this report.
c. The quantity of dredged material proposed for disposal, including
overdredge (tolerance) material. EPA Region IX and the Corps' San
Francisco District will use this information to determine whether the
HOODS can accommodate the amount of sediment proposed for disposal.
d. A recent condition survey of the proposed dredging area showing present
hydrographic data at the proposed dredging site, including proposed
dredging depths, overdredge depths, side slopes, and depths adjacent to the
boundary of the proposed dredging area. This survey is required before field
sampling occurs to locate the sampling stations at the proposed dredging
site.
e. Characteristics and composition of the proposed dredged material, including
physical, chemical, and biological tests. These data will be used by the
federal agencies to determine whether the proposed dredged materials are
suitable for disposal at the HOODS.
f. An estimate of the starting and ending dates for the dredging project. This
information will be used to plan inspections at the dredging site or during
disposal operations at the HOODS.
g. A debris management plan and the most likely types of equipment to be
used in the project. This plan will address the disposal of materials other
than approved sediment (such as piling, tires, metal debris, etc.) to assure
that these other materials are not disposed of at the HOODS.
II. SITE MANAGEMENT
Site management consists of three major activities jointly administered by EPA
Region IX and the Corps' San Francisco District. These activities are:
ocean dumping permit requirements,
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site monitoring program requirements, and
evaluation of permit compliance and monitoring results.
A. MPRSA Section 103 Permitting
Management decisions about the suitability of dredged material for ocean disposal
will be guided by criteria set out in MPRSA and EPA's Ocean Dumping Regulations.
MPRSA Section 103 authorizes the Corps to administer the permit program. This section
provides for EPA review of Corps' Public Notices and permits. Initial opportunities for
management decisions begin with the MPRSA Section 103 permitting process. Guidance
on specific aspects of these regulations is provided in the Evaluation of Dredged Material
Proposed for Ocean Disposal (the Green Book, U.S. Environmental Protection Agency and
U.S. Army Corps of Engineers 1991). EPA Region IX and the Corps are developing
regional guidance for sediment testing which should be used in addition to the 1991 Green
Book. The current regional guidance is EPA (1991).
An adequate sampling plan must be developed by the permittee to characterize
sediment quality. The sampling plan should address information listed in EPA Region IX's
1991 sediment testing requirements. This plan and the information listed in Section I.B.2.
above are submitted to the Corps' San Francisco District and interested federal and state
regulatory agencies. Early consultation with concerned federal and state regulatory and
resource agencies is highly recommended to prevent delays in sampling, sediment testing
and agency review. This consultation is normally conducted with the Corps' San Francisco
District Permit and Regulatory Branch; however, it is advisable that the permit applicant
or the Corps' Civil Works planner coordinate with EPA Region IX on the sampling before
any sampling is conducted.
A reference site will be identified prior to the designation of the HOODS. Proposed
dredging site sediment characterization test results are compared to similar information
from the HOODS reference site to determine whether the sediment is suitable for ocean
disposal. Management decisions related to the proposed dredged material and the disposal
operations at the HOODS will be based on:
1. compliance with applicable criteria defined in the EPA's Ocean Dumping
Regulations at 40 CFR Part 227,
2. the requirements imposed on the permittee under the Corps' Permitting
Regulations at 33 CFR Parts 320-330 and 335-338, and
3. the potential for significant adverse environmental impacts at the HOODS from
the disposal of the proposed dredged material.
For any environmental impact to be considered significant and, therefore, a basis for
a management decision at the permitting stage, such an impact or change must be shown
to be statistically significant and to pose an unacceptable risk to the marine environment or
human health. These determinations will be based on appropriate statistical methods to
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evaluate differences between the proposed dredged material and reference site conditions
for the chemicals of concern, acute toxicity of the proposed dredged material, the magnitude
of bioaccumulation, and potential ecological impacts. The main concerns are: (1) disposal
of sediments that may cause significant mortality or bioaccumulation of contaminants at the
disposal site or adjacent to the site boundaries, and (2) adverse ecological changes to the
HOODS and the surrounding ocean floor. Changes in the benthic community inside the
HOODS site could occur because coarser or finer grain sizes in dredged material are
expected to allow different benthic species to colonize the site. If material is found moving
off the disposal site, benthic community changes adjacent to the site may be evaluated to
determine whether these changes are acceptable.
Management decisions will be implemented to reduce or mitigate any significant
adverse environmental impacts. Management options for the permitting process may
include: full or partial approval of dredged material proposed for ocean disposal,
prohibition of sediments proposed for ocean disposal, or special management restrictions
for ocean disposal of the proposed material such as limits on disposal quantities or disposal
at specific areas within the HOODS site.
Existing regulatory information, such as the Federal Water Quality Criteria and the
State of California Water Quality Objectives, may also be management decision triggers in
some cases. Such mathematically precise tests cannot be applied to all proposed dredged
material disposal projects. Most permit reviews will require the agencies' best professional
judgment to manage the MPRSA Section 103 permitting process properly. The Corps' San
Francisco District staff will prepare the Public Notice and EPA Region IX will participate
in its review. EPA Region IX will only approve, disapprove, or propose conditions on the
draft of the MPRSA Section 103 permit, because EPA must review the MPRSA Section 103
permit as specified in 40 CFR Section 220.4(c). The possible management options for the
draft permit will be concurrence or denial.
B. Conditions at the HOODS
Conditions at the HOODS were documented in EPA Region IX's Draft EIS for the
proposed designation action (U.S. Environmental Protection Agency, Region IX, 1995).
These two documents will be used, with reference site data, to evaluate future changes at
the site. As part of the three-tiered site monitoring program, EPA Region IX and the
Corps' San Francisco District can evaluate the physical, chemical, and biological parameters:
1. inside the HOODS site boundaries,
2. over an area adjacent to the HOODS site boundaries that may be found to be
affected by dredged material disposal, and/or
3. at the reference site.
Both agencies are particularly concerned with effects at the HOODS site boundary
and the adjacent area. When evaluations of biological resources of concern are made, the
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reference site will be used as the point of comparison for data obtained from the areas
adjacent to the HOODS and stations within the HOODS.
C. Surveillance and Enforcement of Permits
Once dredging and disposal activities have begun, management responsibilities,
including surveillance and inspection of dredging and disposal operations, will be initiated
to ensure compliance with permit conditions. Surveillance of the disposal operations will
be carried out by the U.S. Coast Guard with the assistance of EPA Region IX and the
Corps' San Francisco District. EPA Region IX has the authority to enforce against illegal
dumping activities, including non-compliance with permit conditions. Section 105 of
MPRSA defines EPA's enforcement authority over these permits. Management options by
the Corps' San Francisco District could involve the temporary or permanent withdrawal of
a permit by the Corps' San Francisco District.
Surveillance and inspection may consist of one or more of the following activities:
1. On-board inspection by EPA Region IX or the Corps' San Francisco District
staff to ensure that transportation and disposal of the sediment occur within the
designated dump zone, and that the permittee complies with all the permit terms
and special conditions.
2. On-board inspection by a certified inspector hired by the permittee or a
regulatory agency to ensure that transportation and disposal of the sediment
occur within the designated dump zone, and that the permittee complies with all
the permit terms and special conditions.
3. Plots of barge navigation course while inside the confines of the disposal site.
Permittees may be required to provide a record of the barge navigation course,
annotated with the coordinates at the beginning and end of the disposal
operation. For example, dumping contractors will be required to navigate using
an electronic positioning system or other approved navigation system with
sufficient accuracy to dispose of dredged material at specific locations within the
disposal site.
4. The permittee will be required to prepare a detailed postdredging hydrographic
survey of the dredging site to determine the quantity of dredged material
disposed at the HOODS and to confirm that only permitted dredged material
was disposed at the site. This survey will be compared to the predredging
survey. An estimate of the total amount of dredged material disposed at the
HOODS site should be provided based on pay yardage and any non-pay
overdredged sediment.
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III. SITE MONITORING
A. Overview
The site monitoring activities were designed specifically for the HOODS. They are
an integral part of the SMMP framework. The major concerns and hypotheses are
explained in Exhibit A. Implementation of site monitoring is a shared responsibility of EPA
Region IX and the Corps' San Francisco District. The primary purpose of the site
monitoring activities is to evaluate the impact of the disposal on the marine environment
at the HOODS.
Monitoring activities will ensure that the area of acceptable impact is primarily
restricted to the disposal site and that unacceptable environmental impacts do not occur
beyond the site boundaries. To accomplish this, the site monitoring activities have been
designed to:
Identify the physical extent of dredged material disposal at the HOODS and to
see whether material is moving outside the site boundaries.
Identify what effects sediment moving outside the disposal site are having on
sensitive benthic resources identified by EPA Region IX and the Corps' San.
Francisco District compared to similar benthic resources at a reference site.
Determine whether body burdens of chemicals of concern exist in benthic
resources that show significant adverse impacts at the HOODS compared to the
reference site, and determine whether any potentially adverse impacts on
resident fisheries resources or other amenities are possible, if significant body
burden impacts are found.
The site monitoring activities are designed as a three-tiered hypothesis testing
framework. Management decisions at each tier are defined for sediment fate and effects,
body burdens of chemicals of concern or benthic biological community effects. Each tier
will require a management decision based on the information gathered. If the null
hypothesis for a particular tier is rejected, then a more complex set of tests are invoked at
the next higher tier to determine the extent of impacts. Sequential-tiered testing is used to
facilitate rapid, accurate and economical collection of information for use by the EPA
Region IX and the Corps' San Francisco District in the management process. If monitoring
results show that significantly adverse environmental impacts are predicted to occur or have
occurred, then management actions may be necessary to avert or minimize such impacts.
B. Reference Site(s)
Because the HOODS site has been used as an interim disposal site, pre-dumping
conditions cannot be used as a reference for site monitoring. A reference site, or sites, as
appropriate, shall be used to document background conditions for comparison in site
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monitoring activities at Tiers 2 and 3, and to evaluate the suitability of sediment for ocean
disposal as part of the sediment testing program. A reference site will serve as a basis for
determining natural variability in the future at a site not affected by dredged material
disposal.
IV. TIERED MONITORING AND MANAGEMENT DECISION OPTIONS
Appropriate management responses will be decided by EPA Region IX and the
Corps' San Francisco District on a case-by-case basis. This SMMP does not attempt to
specify particular responses to any predicted or actual adverse impact resulting from disposal
activities. It does address possible management options, including those defined within the
Ocean Dumping Regulations. The timing of monitoring surveys and other activities will be
governed by agency funding resources, the frequency of disposal at the HOODS and
acceptance or rejection of null hypotheses. The following information provides examples
of actions to be considered for each tier.
A. Tier 1 Sediment Transport Evaluation
The concerns for the sediment deposition and transport are: identifiable progressive
movement or accumulation of disposed dredged materials that may affect any shoreline,
marine sanctuary or critical biological area; and consistent detection of significant amounts
of dredged material outside the disposal site using side-scan sonar, bathymetric surveys, sub-
bottom profiling, sediment profile camera surveys, or other appropriate oceanographic
survey methods. It is expected that Tier 1 (target) mapping surveys of the deposits within
the disposal site would be conducted annually. If the null hypothesis for Tier 1 is rejected,
then management decisions could include:
1. Revise size or location of the dump zone, or move dump zone to the upcurrent
portion of the HOODS based on current data.
2. Enforce permit conditions on navigation and placement of barges.
3. Limit the amount of dredged material disposed at the site each year.
4. Reconfigure the disposal site boundaries.
5. Specify dredged material density or modify the consistency (i.e., percent
clumping) of disposal material.
6. Evaluate the effect of sediment movement outside the HOODS site on sensitive
benthic communities under Tier 2 or 3.
7. Implement other feasible and responsible management options that are
developed as the monitoring program progresses.
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8. Limit designation of the HOODS to a finite time and initiate environmental
studies for a new disposal site.
9. Designate a new disposal site.
B. Tier 2 - Physical Impacts on Biological Resources of Concern
If dredged material moving out of the HOODS site is affecting sensitive biological
resources identified by EPA Region IX and the Corps San Francisco District, then
identification of these impacts will occur in Tier 2. An assessment of the sensitive benthic
resource will be made by comparing the specific resources of concern at the HOODS to the
same type of resources at a reference site or sites. Resources of concern could be benthic
infauna, benthic epifauna, recreational fisheries or commercial fisheries resources.
Possible responses to rejection of the Tier 2 null hypothesis could include:
1. Restrict disposal to specific locations within the dump site to allow portions of
the disposal site to recolonize.
2. Restrict disposal to upcurrent portions of the disposal site based on seasonal
current patterns to prevent material from moving outside the site boundaries.
3. Enforce permit conditions on navigation and placement of barges.
4. Determine extent of adverse impacts on commercial and recreational fisheries
resources or human health.
5. Evaluate body burden impacts on bioaccumulation effects in Tier 3.
6. Reconfigure the disposal site boundaries.
7. Implement other feasible and responsible management options that are
developed as the monitoring program progresses.
8. Initiate environmental studies for a new disposal site.
9. Designate a new disposal site.
C. Tier 3 - Body Burden Analysis of Biological Resources
During the permitting process, proposed sediment is tested to determine whether
there is a potential for the sediment to cause test species to bioaccumulate contaminants at
a higher level than those animals exposed to the reference sediment. Proposed dredged
material that shows the potential to cause significant bioaccumulation cannot be permitted
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for ocean disposal without the District Engineer seeking a waiver from the EPA Ocean
Dumping Regulations.
If sensitive benthic resources outside the HOODS boundaries are significantly
affected by disposal, then monitoring of body burdens of resident species will occur in
Tier 3. EPA Region IX will conduct Tier 3 monitoring as part of its oversight
responsibilities for site designation. Body burdens of chemicals of concern will be assessed
by comparing tissues of specific resources of concern at the HOODS to the same resources
at a reference site. These tests should not be confused with testing of proposed dredged
materials that must be conducted for each permit application. The resources of concern
would be the same as those identified in Tier 2 or higher trophic levels that feed on the
benthic resources.
Possible responses to rejection of the Tier 3 null hypothesis could include:
1. Re-evaluate bioaccumulation testing and analytical procedures before issuing
disposal permits.
2. Define the levels of contaminants in dredged material that would be suitable for
ocean disposal, or restrict the quality of material to be dredged.
3. Determine extent of adverse impacts on commercial and recreational fisheries
resources or human health.
4. Implement other feasible and responsible management options that are
developed as the monitoring program progresses.
5. Initiate environmental studies for a new disposal site.
6. Designate a new disposal site.
D. Periodic Confirmatory Monitoring
The EPA may require confirmatory monitoring activities periodically on an other
than annual basis. This monitoring may include but not be limited to periodic sediment
chemistry, studies of sediment transport, bathymetric surveys, mound stability evaluations,
or additional water current studies if it is determined that the dredged material is
accumulating or moving more than expected. Confirmatory monitoring may also include
conducting bioassays of sediments taken from the disposed dredged material footprint using
one or more appropriate sensitive marine species consistent with applicable ocean disposal
testing guidance ("Green Book" or related Regional Implementation Agreements), as
determined by the Regional Administrator, to confirm whether contaminated sediments are
being deposited at the HOODS despite pre-disposal testing of sediments. Other
confirmatory activities may include testing for bioaccumulation by placement of near-surface
arrays of appropriate filter-feeding organisms (mussels) in and around the disposal site for
at least one month during active site use, to confirm whether substantial bioaccumulation
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of contaminants may be associated with exposure to suspended sediment plumes from
multiple disposal events.
If a concern for water column impacts develops, EPA Region IX and the Corps' San
Francisco District may require the permittees to monitor their discharge plumes as a special
condition of the MPRSA Section 103 permit. The agencies would require the permittee to
comply with the Limiting Permissible Concentration of the disposed dredged material and
prevent unacceptable impacts on pelagic fisheries resources or coastal areas from the
disposal plumes. If required, plume tracking would occur on a limited basis only, unless a
management decision is made to continue these measurements.
E. Cancellation of the Designated Site
An overall management decision to cease all disposal activities at the site, either on
a temporary or permanent basis, is also an option if other corrective actions are ineffective
hi preventing adverse environmental impacts beyond the site boundary. Temporary halts
will allow the opportunity for further study to investigate means of preventing further
impacts. If EPA Region IX and the Corps' San Francisco District determine that the
HOODS has caused unacceptable environmental impacts, permanent cessation of disposal
operations could be required. Closing the disposal site may be preceded by identification
of an acceptable alternative ocean disposal site. Monitoring of the closed site may continue
to ensure that adverse effects do not worsen and to allow remedial actions to proceed in a
timely manner.
V. REFERENCES
U.S. Environmental Protection Agency, Region IX. 1995. Draft environmental impact
statement (DEIS) for the designation of an ocean dredged material disposal site off
Humboldt Bay, CA.
U.S. Environmental Protection Agency, Region IX. 1991. EPA Region IX general
requirements for sediment testing of dredged material proposed for ocean dumping.
U.S. Environmental Protection Agency and U.S. Army Corps of Engineers. 1991.
Evaluation of dredged material proposed for ocean disposal, testing manual. EPA
Report 503/8-91/001. Prepared by EPA Office of Marine and Estuarine Protection,
Washington, DC.
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EXHIBIT A
HUMBOLDT BAY (HOODS) OCEAN DREDGED MATERIAL DISPOSAL SITE
SITE MONITORING PROGRAM
I. INTRODUCTION
Disposal of dredged material is expected to change benthic conditions inside the
HOODS boundary because the variation of grain sizes in dredged material disposed at the
HOODS is expected to allow different species to colonize the area. Site monitoring
activities are necessary to assure that long-term unacceptable adverse environmental impacts
do not occur within the HOODS site or beyond the site boundaries. A three-tiered
monitoring program has been designed to evaluate conditions at the HOODS. Tier 1
consists of periodic physical surveys of the disposal site to determine the areal extent of
disposed dredged material and whether material is being deposited outside of the disposal
site boundaries. If significant adverse impacts on selected biological resources are suspected
based on the Tier 1 survey, data on physical impacts (Tier 2) and body burdens of chemicals
of concern (Tier 3) at the HOODS site and adjacent areas will be compared to a reference
site.
The HOODS site monitoring activities are a part of the overall HOODS SMMP. The
site monitoring program is based on testing specific hypotheses at three sequential tiers.
Several aspects of the site monitoring program were developed in direct response to
concerns identified in the HOODS Draft Environmental Impact Statement (DEIS). These
concerns include questions on the movement of dredged material disposed at the HOODS
and possible associated impacts on resident marine resources or fisheries resources if the
disposed sediments move outside the site boundaries. Procedures defined in the site
monitoring program should provide data required to make management decisions; however,
the site monitoring program will be managed with the flexibility to modify, delete or
substitute new monitoring procedures as other needs are identified.
II. OBJECTIVES
One of the major objectives of the HOODS site monitoring activities is to detect
potentially adverse impacts beyond the HOODS site boundaries. Adjustments in site use
will be selected to prevent adverse impacts from occurring in areas adjacent to the HOODS.
Scientific analysis of the fate of the disposed dredged material is essential to meet this
objective. With regard to physical sedimentation impacts, the objective is to determine
whether benthic biological resources of concern have been adversely affected by sediment
movement out of the site. The objective of biological monitoring is: (1) to determine if the
ODMDS is causing detrimental bioaccumulation in resident infauna, epifauna or fisheries
resources, (2) to provide early detection of potential threats to marine community structure,
and (3) to evaluate whether potential impacts on biological resources will adversely affect
higher trophic levels.
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III. SITE MONITORING OVERVIEW
The site monitoring activities designed for the HOODS involve sequential collection of
physical and biological data to help achieve the objectives outlined above. These objectives
are defined to ensure compliance with state and federal laws, to provide guidance for EPA
Region IX and Corps' San Francisco District staff for site management, and to address the
concerns raised by other interested parties. The following concerns are addressed:
A. Sediment Impacts at the HOODS and Outside the Site Boundary
Adverse physical environmental impacts on benthic communities near the
ODMDS boundary.
Habitat alterations displacing resident benthic communities near the ODMDS.
B. Water Column Impacts Outside the HOODS Site Boundaries
Potential violation of established criteria at or beyond the site boundary at any
time, or violation of criteria within the site boundary 4 hours after disposal.
C. Biological Impacts at the HOODS and Outside the Site Boundary
Bioaccumulation of contaminants.
Significant alteration in benthic communities based on bioaccumulation of
contaminants.
Significant changes in the resident epifauna or fish communities.
Each of these concerns is addressed in the site monitoring activities summarized hi
Table 1. Monitoring in a particular tier is based upon a testable hypothesis. If the null
hypothesis for a specific tier is accepted, advancement to the next tier is not necessary. If
the null hypothesis is rejected, an appropriate management action can be considered, or the
prescribed monitoring from the next tier may be required. Information on management
actions is provided in the HOODS SMMP.
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Table 1. Tiered Monitoring at the HOODS Ocean
Dredged Material Disposal Site
TIER1
Periodic bathymetric, side-scan sonar and/or sub-bottom surveys of the
HOODS funded by the Corps' San Francisco District based on site use.
TIER 2
Assessment of sedimentation impacts on biological resources of concern as
identified by EPA Region IX and the Corps' San Francisco District. This
tier is triggered if dredged material moving out of the disposal site is
determined by Tier 1 analysis to be a potential adverse impact to benthic
resources.
TIER 3
Body burden analyses of chemicals of concern in identified biological
resources based on EPA Region IX's site designation and management
oversight responsibilities. This tier is triggered if dredged material deposited
outside of the disposal site is found to contain contaminants which could
potentially cause adverse impacts to benthic resources.
CONFIRMATORY MONITORING
> Additional monitoring requirements imposed as needed by EPA Region IX
or the Corps' San Francisco District to confirm sediment dispersion and
quality.
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Tier 1 bathymetric, side-scan sonar and/or sub-bottom surveys are expected to be
scheduled on an annual basis, although this schedule may be modified based on the
frequency of disposal, the amount of dredged material disposed at the HOODS, and the
results of the monitoring activities. EPA Region IX and the Corps' San Francisco District
will evaluate the survey data to test the Tier 1 hypothesis. We will determine whether
movement of material out of the HOODS may cause adverse impacts on biological
resources of concern adjacent to the site. If management options require additional
monitoring, then physical (Tier 2) or biological impact (Tier 3) evaluations will be
conducted as needed.
Monitoring actions described in Tiers 2 and 3 involve analyses of data from the
HOODS in relation to a reference site described in Section II.A of the SMMP. The
characteristics of the reference site or sites will represent the conditions of the HOODS
before disposal of dredged material occurred. Thus, meaningful comparisons can be made
between the sites to determine the impacts of dredged material disposal operations at the
HOODS. Future reference site measurements will provide information on natural
variability and periods of any unusual conditions in the region.
IV. DETAILS OF TIERED MONITORING
A. Tier 1 - Bathymetric Survey of the Site
Hypothesis: Dredged material accumulation outside of the HOODS boundary
averages less than 0.5 inches (1.3 centimeters) relative to the bottom
sediment surface defined at the time of site designation.
Monitoring at Tier 1 is designed to determine whether significant amounts of dredged
material move beyond the HOODS boundary, thus providing an indication of potentially
adverse impacts to nearby benthic resources of concern. Tier 1 monitoring is designed to
evaluate the accumulation of dredged material outside of the disposal area, relative to
baseline conditions at the time of site designation. Equipment such as precision bathymetry,
side-scan sonar, sub-bottom profiling, or other similar oceanographic survey techniques will
be used to detect accumulation of dredged material greater than 4 inches (10 centimeters)
relative to the bottom sediment surface at the time of site designation. These data will be
used to estimate the 0.5 inch contour as a test of the Tier 1 hypothesis. If Tier 1 analyses
show sediment movement outside the site boundary and the null hypothesis is rejected, then
management options will be evaluated to mitigate the impacts, or monitoring in Tier 2 can
be scheduled.
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B. Her 2 - Sediment Impacts on Biological Resources of Concern
Hypothesis: Dredged material accumulation at or beyond the HOODS boundary
does not show significant adverse impacts on biological resources of
concern based on sediment physical properties compared to similar
biological communities at a reference site or sites.
Tier 2 monitoring activities are designed to detect significant changes in biological
resources of concern as a result of dredged material movement outside the HOODS.
Biological resources of concern will be identified by EPA Region IX and the Corps' San
Francisco District based on information contained in the HOODS EIS, the survey of the
HOODS and information on fisheries resources in the area.
If benthic infauna are identified as a resource of concern, then analysis of this
community can be accomplished by examining sediment profiles using techniques including
but not limited to sediment profiling camera surveys taken in areas where dredged material
has accumulated significantly. This type of information can be compared to other locations
within the HOODS, zones outside the HOODS that have not been affected by dredged
material disposal, or a reference site(s). The sediment profiling camera method has the
advantage of providing in situ estimates of grain size distribution and infaunal community
structure (Rhoads and Germano 1982). In addition, depending on the characteristics of
previously deposited materials, newly deposited material can be differentiated by the
photographs to indicate the rate of deposition at the site boundary for accumulation depths
of from 2-8 inches (5-20 centimeters). Publications on this photographic profiling technique
indicate that oxidized surface layer of previously deposited dredged material can be
identified photographically when covered by similar material for up to a year (Germano and
Rhoads 1984).
If resident benthic epifauna (invertebrates or fish) are identified as biological
resources of concern, then bottom trawls can be used to sample areas where dredged
material has accumulated. Samples can be compared to locations within the HOODS, zones
outside the HOODS, or a reference site(s). The Tier 2 sampling is limited to assessment
of physical impacts, such as the loss of a biological resource based on sediment movement,
grain size changes or other effects from direct contact with disposed dredged material.
Disposal of dredged material with a different grain size than the ambient sediments at the
disposal site will change the biological community characteristics of the HOODS. Different
species may colonize the disposal area because they can live in the finer or coarser grained
dredged material. Simple changes in community structure in response to grain size changes
are not considered significant impacts at the HOODS. If Tier 2 analyses show significant
adverse impacts to biological resources of concern and the null hypothesis is rejected, then
management options will be evaluated to mitigate the impacts, or monitoring in Tier 3 can
be scheduled.
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C. Tier 3 - Analyses of Body Burdens in Biological Resources
Hypothesis: Contaminant body burdens in biological resources of concern at
stations where dredged material has moved out of the HOODS and
within the HOODS are not significantly greater than body burdens
detected in similar biological communities at a reference site or sites.
Analysis of contaminant body burdens will be conducted as part of EPA Region IX's
site designation and management oversight responsibilities. If chemicals of concern (listed
in EPA Region IX's August 1989 sediment testing guidance) bioaccumulate to a higher
degree at the HOODS compared to a reference site(s), significant adverse impacts could
affect resident biological communities at the HOODS or the adjacent areas where dredged
material has moved out of the site. Tier 3 monitoring is designed to determine whether the
HOODS is a site of significant bioaccumulation and to provide early detection of the
potential for adverse impacts on nearby biological resources or human health.
Tier 3 monitoring will assess the concentration of chemical contaminants in resident
infaunal or epifaunal organisms at the HOODS or other areas where dredged material has
moved outside the site. The body burdens of organisms collected at or adjacent to the
HOODS will be compared to similar organisms at a reference site(s). Collection of resident
organisms for this analysis does not need to be quantitative. However, a large enough
sample of the target species should be collected to provide adequate tissue for analysis.
Sampling devices such as box cores, grabs or benthic sleds may be used. Selection of target
species for this portion of the monitoring program should follow the protocols outlined in
U.S. Environmental Protection Agency (1987) guidance.
If the Tier 3 hypothesis is rejected, management decisions will be evaluated to
mitigate any impacts, or EPA Region IX and the Corps' San Francisco District will consider
closing the HOODS and initiating the designation process for another suitable site.
V. REFERENCES
Germane, J. D. and D. C. Rhoads. 1984. REMOTS sediment profiling at the Field
Verification Program (FVP) disposal site. Dredging '84: Proceedings of the conference,
ASCE, November 14-16, Clearwater, FL, pp. 536-544.
Rhoads, D. C. and J. D. Germane. 1982. Characterization of organism-sediment relations
using sediment profiling imaging: an efficient method of Remote Ecological Monitoring
of the Seafloor (REMOTS system). Marine Ecology Progress Series, 8:115-128.
U.S. Environmental Protection Agency. 1987. Bioaccumulation monitoring guidance: 1.
Selection of target species and review of available bioaccumulation data. EPA 430/9-
86-005.
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U.S. Environmental Protection Agency, Region IX. 1995. Draft environmental impact
statement (FEIS) for the designation of an ocean dredged material disposal site off
Humboldt Bay, CA.
U.S. Environmental Protection Agency, Region IX. 1991. EPA Region IX general
requirements for sediment testing of dredged material proposed for ocean dumping,
effective date: August 1989, 8 pages.
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Appendix B
Common and Scientific Names of Species
Mentioned in Text
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Appendix B. Common and Scientific Names of Species Mentioned in Text
Common Name
Scientific Name
Fish
Butter sole
Dover sole
English sole
Petrale sole
Rex sole
Sand sole
Starry flounder
Pacific sanddab
Speckled sanddab
Rockfish
Black rockfish
Blue rockfish
Bocaccio rockfish
Canary rockfish
Chilipepper rockfish
Darkblotched rockfish
Widow rockfish
Yellowtail rockfish
Salmon
Chinook salmon
Coho salmon
Coastal cutthroat trout
Steelhead trout
Curlfin turbot
Pricklebreast poacher
Tubenose poacher
Warty poacher
Plainfin midshipman
Staghorn sculpin
Showy snailfish
California halibut
Ungcod
Brown smoothhound shark
Longnose skate
Black rattail
Giant rattail
Roughscale rattail
Blacktail snailfish
Isopsetta isolepsis
Microstomus pacificus
Parophrys vetulus
Eopsetta jordani
Gfyptocephalus zachirus
Psettichthys melanostictus
Platichthys stellus
Citharichthys sordidus
Citharichthys stigmaeus
Sebastes sp.
Sebastes melanops
Sebastes mystinus
Sebastes paucispinis
Sebastes pinniger
Sebastes goodei
Sebastes crameri
Sebastes entomelas
Sebastes flavidus
Oncorhynchus sp.
Oncorhynchus tshawytscha
Oncorhynchus kisutch
Oncorhynchus clarld clarld
Oncorhynchus myldss
Pleuronichthys decurrens
Stellerina xyostema
Pallasina barbata
Occella verrucosa
Porichthys notatus
Leptocottus armatus
Liparis pulchellus
Paralichthys californicus
Ophiodon elongatus
Mustelus henlei
Raja rhina
Coryphaenoides acrolepis
Coryphaenoides pectoralis
Coryphaenoides acrolepis
Careproctus melanurus
B-l
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Appendix B. Continued
Common Name
Scientific Name
Twoline eelpout
Spiny dogfish
Pacific tomcod
Pacific herring
Northern anchovy
Night smelt
Whitebait smelt
Eulachon
Shiner surfperch
Spotfin surfperch
Silver surfperch
Walleye surfperch
White seaperch
Bay pipefish
Pacific cod
Crustaceans
Dungeness crab
Bay shrimp
Coon-stripe shrimp
Pink ocean shrimp
Sand shrimp
Market squid
Echinoderms
Brown mud star
Short-spined star
Pacific sand dollar
Bothrocara brunneum
Squalus acanthias
Microgadus proxitnus
Clupea harengus pallasi
Engraulis mordax
Spirinchus starkis
Allotments elongates
Thaleichthys pacificus
Cymatogaster aggregata
Hyperprosopon anale
Hyperprosopon ellipticum
Hyperprosopon argenteum
Phanerodon furcatus
Syngnatus leptorhynchus
Gadus macrocephalus
Cancer magister
Crangon franciscorum
Pandalus danae
Pandalus jordani
Crangon nigricauda
Logigo opalescens
Luidia foliolata
Pisaster brevispinus
Dendraster excentricus
Molluscs
Olive snail
Coastal and Sea Birds
Turnstone
Snowy plover
Loon
Cormorant
Double-crested cormorant
California brown pelican
Olivella pycna
Arenaria sp.
Charadrius alexandrinus
Gavia sp.
Phalacrocorax sp.
Phalacrocorax auritus
Pelecanus occidentalis
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Appendix B. Continued
Common Name
Scientific Name
Western gull
Tern
Phalarope
Shearwater
Jaeger
Short-tailed albatross
Marbled murrelet
Aleutian Canada goose
Marine Mammals
Northern (Stellar) sea lion
Harbor seal
California sea lion
Northern elephant seal
Northern fur seal
Ball's porpoise
Harbor porpoise
Gray whale
Humpback whale
Minke whale
Blue whale
Finback whale
Sperm whale
Northern right-whale
Risso's dolphin
White-sided dolphin
Reptiles
Leatherback turtle
LOTUS occidentalis
Sterna sp.
Phalaropus sp.
Puffmus sp.
Stercorarius sp.
Diomedea albatrus
Brachyramphus marmoratus
Branta canadensis leucopareia
Eumetopias jubatus
Phoca vitulina richardi
Zalophus californianus
Mirounga angustirostris
Callorhinus usinus
Phocoenoides dallii
Phocoena phocoena
Eschrichtius robustus
Megaptera novaeangliae
Balaenoptera acutorostrata
Balaenoptera musculus
Balaenoptera physalus
Physeter catodon
Lissodelphis borealis
Grampus griseus
Lagenorhynchus obliquidens
Dermochefys coriacea
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