9. Estuary


Restore ecosystem function to protect and enhance critical habitat and spawning and rearing grounds in the estuary and lower Columbia River.


The Columbia River estuary is an important ecological area that stretches from the mouth of the Columbia River to the Bonneville Dam tailrace including tidally influenced mouths of tributaries. Ecological functions in the estuary have been altered by upriver actions including the construction and operation of the hydropower system and local habitat change. The storage, release, and impoundment of water changes the pattern of flows and water temperatures downstream from hydroelectric dams and changes the characteristics of the estuary. Scientific research suggests that habitat-improvement actions in the estuary have the potential to improve survival benefits for fall and spring Chinook salmon, sockeye, and steelhead.


  • A functioning ecosystem sustains abundant, productive, and diverse communities of fish and wildlife.
  • Habitat restoration supports and enhances ecosystem functions and species survival.
  • Long-term monitoring helps ensure that (1) habitat-restoration projects remain effective, and (2) fish populations affected by the hydropower system including salmon, steelhead, and lamprey, respond to mitigation projects designed to improve survival in estuary habitat, the lower Columbia River, and the near-shore plume marine environment.
  • In an environment as diverse as the lower Columbia River and estuary, partnerships are essential in planning, monitoring, evaluating, and implementing mitigation activities.

General measures

The Council incorporates as program measures estuary actions in the Federal Columbia River Power System Biological Opinion (BiOp). The program, however, is broader than the Endangered Species Act both in terms of species affected by the hydrosystem and the ultimate objective of the program that goes beyond just delisting endangered species. Today, the Columbia Estuary Ecosystem Restoration Program (CEERP) developed by the federal BiOp action agencies directs implementation of BiOp actions in the estuary. The CEERP, along with the Council’s estuary and Lower Columbia subbasin plans and locally developed recovery plans, will guide implementation, monitoring, and evaluation of habitat actions in the estuary.

The Corps and Bonneville shall implement in partnership with fish and wildlife agencies and tribes and other organizations:

  • Assessments of opportunities for floodplain reconnection and removal or lowering of dikes and levees that block access to habitat, or installing fish-friendly tide gates for habitat reconnection, protection, and restoration of riparian areas and off-channel habitat
  • Effectiveness monitoring of habitat-restoration actions using a programmatic approach to mirror effectiveness monitoring elsewhere in the Columbia Basin
  • A long-term, continuous, status and trend monitoring and evaluation program for salmon, steelhead, and Pacific lamprey migration and survival that shall include monitoring habitat in the lower Columbia River, estuary, and the near-shore plume environment
  • Research and evaluation on the effects of flow regulation, dredging, and water quality (Including toxics) on estuary habitat and food webs to better understand the relationship between estuary ecology and salmon and steelhead productivity, abundance, and diversity

The Council will:

  • Work with partners in the estuary to establish biological objectives and estuary indicators for habitat restoration and ecosystem function that will serve to prioritize future actions.
  • Receive from Bonneville and the Corps, a summary report on the results of action-effectiveness, status, and trend monitoring and research uncertainties in March 2015. The report must provide information to help improve and substantiate the effectiveness of habitat actions implemented in the estuary by parties that do not monitor their own habitat actions.

Link to subbasin plans

See the Council’s subbasin plans for information pertaining to the estuary and lower Columbia.

← 8. Mainstem hydrosystem flow and passage operations

10. Plume and nearshore ocean →

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