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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.

East Sand Island is near the mouth of the Columbia River in Clatsop Co., Ore. In 2011 and 2012, respectively, the double-crested cormorant colony consumed approximately 20.5 and 18.9 million hatchery and juvenile salmonids listed under the Endangered Species Act, as the fish migrated through the Columbia River estuary to the Pacific Ocean. Cormorant predation is a significant source of predation affecting juvenile salmonids in the estuary.


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).

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 Federal Register published a Notice of Intent on July 19, 2012 (Fed. Reg., Volume 77, No 139, p. 42487) announcing the Corps’ preparation of an EIS. No comments were received during the 30-day comment period from this notice. Later in the year, the Corps hosted public scoping meetings in Olympia, WA, Portland, OR and Astoria, OR. Representatives from the Corps and cooperating agencies were on hand to answer questions. See the February 2013 e-Newsletter for a summary of scoping period comments under review by the Corps

The project team is now working with the cooperating agencies to identify the significant issues, reasonable range of alternatives and/or other methods that could be implemented to achieve the overall goal of reducing predation on ESA-listed Columbia River basin juvenile salmonids from double-crested cormorants. A draft EIS is planned for public comment by May / June 2014; see the project schedule for more details.

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 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 plans to release a Draft Environmental Impact Statement by June 2014, accompanied by a 45-day public review period. Opportunities for education, discussion and comments will be announced on this web page. You can also add your name to our mailing list, ask a question or provide comments to: Cormorant-EIS@usace.army.mil.

Comments can be made in writing, electronically, by mail or over the phone.

Address all comments to:

    Sondra Ruckwardt, Project Manager

    U.S. Army Corps of Engineers, Portland District

    P.O. Box 2946

    Portland, OR 97208



  • 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 provide email notification and post meeting information on this website when events are scheduled.

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.