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Columbia River Estuary Cormorants: Environmental Impact Statement

About the double-crested cormorants

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Click here for more about the western population of double-crested cormorants.

The Corps has been conducting research studying the impact of avian predation on juvenile salmonids in the Columbia River Estuary since 1997. The research on East Sand Island contributes to understanding of the impacts cormorants have on juvenile salmonids migrating out to the ocean. Click here to see two graphics demonstrating the impact of the cormorant colony on East Sand Island to salmonids. The first graph shows the increasing trend in the rate of predation of the colony on juvenile salmonids. The second graph shows the seasonal proportion of salmon of double-crested cormorants throughout their nesting season.

In 2008, the Corps began to investigate certain non-lethal methods to dissuade double-crested cormorants from nesting in specific locations on East Sand Island. Methods tested to date include hazing with lights, reducing nesting habitat, and using human presence to flush double-crested cormorants off potential nesting sites.

Map showing multi-year dissuasion efforts

In 2011, the studies focused on reducing the amount of available nesting habitat for double-crested cormorants, which is approximately 11 acres on the western portion of the island and tracking dispersal of radio and satellite tagged individual double-crested cormorants. Habitat reduction was primarily accomplished by installing barrier fences and using human hazers to flush birds from the non designated nesting area.

In 2013, double-crested cormorants were restricted to 4.4 acres. 83 adult double-crested cormorants were marked with satellite transmitters and several hundred adults were banded with leg bands to provide information about where double-crested cormorants would move during the dissuasion efforts. In spite of a 70% reduction in available nesting habitat, the colony grew to 14,900 pairs. Near-term dispersal locations of radio and satellite tagged double-crested cormorants during the 2011-2013 breeding seasons were generally to four main areas identified in geographic proximity to East Sand Island:

  1. Columbia River Estuary (defined as tidally influenced areas near Bonneville Dam);
  2. Outer Washington coast (Willapa Bay and Grays Harbor)
  3. Puget Sound; and
  4. Northern Salish Sea (San Juan Islands, Strait of Georgia, Vancouver, BC (BRNW 2014).

The U.S. Army Corps of Engineers has prepared a draft Environmental Impact Statement and management plan to reduce predation of juvenile salmon and steelhead by double-crested cormorants in the Columbia River Estuary.  In the past 15 years, double-crested cormorants on East Sand Island consumed approximately 11 million juvenile salmon and steelhead per year. The Corps is working with its cooperating agencies, the U.S. Fish and Wildlife Service, the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service, the Oregon Department of Fish and Wildlife and the Washington Department of Fish and Wildlife to develop the EIS.

The Corps knows managing double-crested cormorant predation could cause significant impacts to the western population of double-crested cormorants. Therefore we must analyze those impacts and evaluate them when making a decision. It is important to note that we are not taking any action at this time, except to request comments on our draft EIS and management plan. Only after a final EIS is completed and a Record of Decision is signed later this year would the Corps begin to implement the preferred alternative.

Several of these areas, the Columbia River Estuary and outer Washington coast, have had the highest levels of use by double-crested cormorants during dissuasion research in 2012 and 2013. There were no confirmed detections of radio- or satellite-tagged double-crested cormorants at inland sites east of The Dalles Dam or coastal sites south of Cannon Beach, Ore.

The Corps will publish a public notice in the Federal Register on June 19, 2014, announcing a 45-day public comment period beginning June 19, 2014 and ending on Aug. 4, 2014.

The draft EIS is the Corps’ best plan to date. Biologists and researchers from all cooperating agencies arrived at the alternatives by studying research on predation and survival data, in-person research at East Sand Island, and working with experts from tribal, federal and local agencies.

The draft EIS is important because the Corps knows managing double-crested cormorant predation could cause significant impacts to the western population of double-crested cormorants. Therefore we must analyze those impacts and evaluate them when making a decision. It is important to note that we are not taking any action at this time, except to request comments on our draft EIS and management plan. Only after a final EIS is completed and a Record of Decision is signed later this year would the Corps begin to implement the preferred alternative.

In 2008, NOAA Fisheries issued a Biological Opinion on the operations of the hydropower dams that make up the Federal Columbia River Power System. NOAA Fisheries concluded that through implementation of the Biological Opinion’s recommended reasonable and prudent alternatives, operation of the FCRPS would not likely jeopardize 13 ESA-listed species of salmon affected by the system. The reasonable and prudent alternatives include improving fish passage at dams, managing flow, controlling predators that prey on young salmon, improving tributary and estuary habitat and reforming hatchery practices. Two RPAs from the 2008 FCRPS Biological Opinion specifically address management of DCCOs in the Columbia River Estuary.

  • RPA- 46- requires the development of a management plan for DCCOs in the Columbia River Estuary and implementation of warranted actions in the estuary.
  • RPA- 67- requires the DCCO population in the Columbia River Estuary and its impact on out-migrating juvenile salmonids to be monitored and implementation of a management plan to decrease predation rates, if warranted.


In 2014, NOAA Fisheries released the Supplemental FCRPS Biological Opinion with a revised Reasonable and Prudent Action for reducing double-crested cormorant predation. RPA 46 was revised to read: “The FCRPS Action Agencies will develop a cormorant management plan (including necessary monitoring and research) and implement warranted actions to reduce cormorant predation in the estuary to Base Period levels (no more than 5,380 to 5,939 nesting pairs on East Sand Island)”(NOAA Fisheries 2013).
The EIS alternatives will address the targets recently identified in revised RPA 46. This equates to an approximate 60 percent reduction in the current colony size.


The range of alternatives under consideration to reduce double-crested cormorant predation of juvenile salmonids will include implementing non-lethal and lethal actions to reduce the colony size on East Sand Island and limit their dispersal within the Columbia River estuary. Non-lethal methods include various hazing techniques to prevent colony establishment, modifying available habitat to limit colony size and conducting hazing activities off East Sand Island if these birds establish new colonies throughout the estuary. Lethal methods include take of eggs and shooting individual double-crested cormorants.

For a complete listing of alternatives, monitoring requirements and adaptive management actions, refer to the draft Environmental Impact Statement.

As part of our responsibility under NEPA, the draft EIS evaluates alternatives designed to reduce cormorant predation of ESA-listed juvenile salmon and steelhead to the 2008 population levels. These levels are based on predation rates from analysis completed by NOAA Fisheries. To return to the 2008 base period of predation levels for the double-crested cormorant colony, the colony population needs to be reduced by 56 percent to about 5,600 nesting pairs on East Sand Island.

Alternative A: No action
No actions would occur to manage the colony on East Sand Island. The Corps would not meet its statutory responsibilities to fulfill reasonable and prudent alternative 46. Survival improvements for juvenile salmonids would need to be made up with other actions within the purview of the Federal Columbia River Power System.

Alternative B: Non-lethal management focus with limited egg take
Phase I ((Years 1-4): Use primarily non-lethal methods to achieve target colony size of ~5,600 double-crested cormorant breeding pairs by dispersing >7,250 breeding pairs off East Sand Island over a 4-year period. Incremental dispersal (approximately 2,000-3,000 pairs per year) would occur by reducing available acreage incrementally and hazing elsewhere on the island to preclude nesting.

An application for a depredation permit for minimal eggs take on East Sand Island (500 eggs) and in the Columbia River Estuary (250 eggs) would be submitted to USFWS annually to support the effectiveness of hazing efforts after the beginning of the breeding season. Off-island land- and boat-based hazing could occur throughout the Columbia River Estuary.
Boat-based and land-based monitoring and hazing efforts within the Columbia River Estuary concurrent with management actions on East Sand Island through July 31. Five to eight boat crews would survey and haze double-crested cormorants throughout the Columbia River Estuary.

Phase II (Years 5-10): Terrain modification to inundate the western portion of the island and preclude nesting, combined with continued monitoring and hazing efforts, supported with limited egg take, as needed, to ensure the colony target size is not exceeded. A colony size of ~5,600 breeding pairs could remain. No management actions would be taken to ensure a minimum colony size.

Alternative C: Culling with integrated non-lethal methods including limited egg take (Preferred Management Plan)
Phase I ((Years 1-4): Culling of individuals to achieve target colony size of ~5,600 breeding pairs. Culling would occur over 4 years, with the ability to achieve the target size in a shorter duration (3 or 2 years) under Adaptive Management. Under the 4-year strategy, 20.3 percent of the colony would be culled per year. In total, 15,955 double-crested cormorants and associated nests would be taken in all years (5,230, 4,270, 3,533, and 2,923 double-crested cormorants and associated nests in years 1 to 4, respectively). Take would occur on- and off-island within the foraging range (25km) of the East Sand Island colony. Concurrent with culling, hazing supported with limited egg take would occur to prevent colony expansion on the island, along with land- and boat-based hazing and efforts to prevent double-crested cormorants from relocating in the Columbia River Estuary, similar to Alternative B.

Phase II (Years 5-10): Same as Alternative B

Alternative D: Culling with Exclusion of Double-crested Cormorant Nesting on East Sand Island in Phase II
Phase I ((Years 1-4): Same as Alternative C.
Phase II (Years 5-10): The same primarily non-lethal methods described in Phase II of Alternatives B and C (terrain modification, supplemented with hazing supported with limited egg take, as necessary) would be used to disperse all remaining double-crested cormorants (~5,600 breeding pairs) from East Sand Island and exclude future double-crested cormorant nesting. Hazing efforts in the Columbia River Estuary would be the same as Phase I of Alternative B.

For more information

Phone: 503-808-4510

Email us about the Cormorant EIS

East Sand Island images

Studies, plans and reports

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The Pacific Flyway Council is an administration composed of directors or appointees from the public wildlife agencies in each state and province of the western United States, Canada, and Mexico. In the U.S., the Pacific Flyway includes Alaska, Arizona, California, Idaho, Nevada, Oregon, Utah, Washington, and those portions of Colorado, Montana, New Mexico, and Wyoming west of the Continental Divide.

In July 2012, the Council finalized A Framework for the Management of Double-crested Cormorant Predation on Fish Resources in the Pacific Flyway. This plan provides a framework to follow when addressing fish depredation issues involving double-crested cormorants, and includes information concerning biology, status, resources conflicts, management options, regulatory requirements and recommended management strategies. The Corps is evaluating this plan for consistency with the alternatives. http://pacificflyway.gov/Documents/Dcc_plan.pdf

In 2013, the Pacific Flyway Council published a Monitoring Strategy for the Western Population of Double-Crested Cormorants. The Corps plans to follow the guidelines identified in this monitoring strategy during any proposed management of the East Sand Island colony the EIS. http://pacificflyway.gov/Documents/Dcc_strategy.pdf

Public involvement information

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The Corps has released its Draft Environmental Impact Statement on June 12, 2014. The 45-day public review and comment period begins June 19, 2014 and ends Aug. 4, 2014. 


Comments may be made in writing, either electronically or by mail. You can submit comments on the draft EIS by email: Cormorant-EIS@usace.army.mil or by sending written comments to:

Sondra Ruckwardt

U.S. Army Corps of Engineers, Portland District

Attn: CENWP-PM-E / Double-crested cormorant draft EIS

P.O. Box 2946

Portland, OR 97208-2946

  • Ongoing: Agency and tribal coordination
  • March / April 2014: Internal agency EIS review
  • May / June 2014: Notice of Availability for Draft EIS
  • Summer 2014: Public discussion and open houses
  • Late summer 2014: Respond to public comments and prepare Final EIS
  • October / November 2014: Notice of Availability for Final EIS
  • December 2014: Record of Decision

The Corps will host two open house public meetings and two public webinar/conference calls in July during the comment period.


Open house informational meetings:

July 10, 2:30 p.m. to 5:30 p.m.

Matt Dishman Community Center,

77 N.E. Knott St., Portland, Ore.



July 24, 3:00 p.m. to 6:00 p.m.

Best Western Lincoln Inn

555 Hamburg Ave., Astoria, Ore.


For open house support to the hearing impaired, contact the Corps at 503-808-4510 or email us at Cormorant-EIS@usace.army.mil 72 hours in advance.


By Webinar and Conference Call

Both webinar/conference call sessions will be accessed using the same telephone, web meeting and access information.

Tuesday, July 15, 2014

9:30-11:00 a.m.


Monday, July 21

1:30-3:00 p.m.


By phone (toll-free):  888-431-3632

Access code: 2766983



Web meeting: log into https://www.webmeeting.att.com

Meeting number: 888-431-3632

Access code: 2766983

Both webinar/conference call sessions will be accessed using the same telephone, web meeting and access information.

To participate, first dial into the conference call by dialing: (888) 431-3632. When prompted, enter the access code: 2766983. You may be asked to state your name, afterward you will be connected to the audio portion of the meeting.


As soon as you are connected to the conference call, use your computer’s web browser and go to:  https://www.webmeeting.att.com.  Please note your web browser must be Microsoft® IE6, IE7, IE8, Safari 5 or Firefox 9 or 10 to participate in ATT Web Meeting.

When you reach the ATT Web Meeting page, you will be asked to enter the following information in order to log in:

(888) 431-3632

Access Code: 2766983


You will be asked for your name and email address. Once all the fields are complete, select ‘submit’ and wait for the connection to be established. The Corps will let participants know what they should be seeing on the computer screen to confirm the connection has been made.

To join the Cormorant EIS email list, click this link to email us at Cormorant-EIS@usace.army.mil. You will be sent periodic updates in the form of informational emails. Information in the updates may include scoping meeting announcements, availability of the new information, publication of the draft Environmental Impact Statement, and availability of a final Environmental Impact Statement.