Mitigation Projects

Blue Heron Slough Conservation Bank

The Blue Heron Slough Conservation Bank (Bank) is located in the lower Snohomish River Estuary, near the mouth of the Snohomish River. The 353-acre site is located on land that historically was part of an extensive estuary complex that was supported by daily flooding from Possession Sound and intermittent flooding from the Snohomish River. In the 1800s, the area was cleared, diked, and drained for agriculture.

The ecological goal for this site is to restore and estuary complex to this 353-acre by creating a mosaic of channels, marsh, mud flat, and riparian habitats which will be reconnected to riverine and tidal influence by breaching the existing dike in three locations once the site has stabilized. The proposed restoration activities on the Bank will increase the tidally-influenced acreage in the Snohomish River Estuary by approximately 13 percent.

The project’s restored habitats, including marsh, mud flat, riparian, and channel habitats, will provide habitat for and assist in the recovery of the Puget Sound Chinook salmon and bull trout. The Bank site was identified as one of the key locations for salmon recovery in the 2005 Snohomish River Basin Salmon Conservation Plan. Wildlands is currently in the process of entitling wetland credits on this Bank.

Habitat construction began during the summer of 2008, and a portion of the interior channels and corresponding berms were constructed and planted with native trees and shrubs. In 2014 habitat construction activities resumed and a portion of the interior channels near the western boundary of the site was constructed.

Project Highlights

Chinook Salmon
  • Within Water Resource Inventory Area (WRIA) 7
  • Cleared, diked and drained for agriculture in the 1800’s
  • Will provide habitat for Puget Sound Chinook salmon and bull trout
  • Restored habitats to include channels, marsh, mud flat, and riparian

354 acres

Location: Snohomish County, Washington

Mitigation Types

  • Salmonids
  • DSAYs

Service Area


The greater Puget Sound Basin, representing the evolutionary significant units of the listed Chinook salmon and the range of bull trout.

Approving Agencies

  • National Marine Fisheries Service

For additional information on the Blue Heron Slough Conservation Bank, please contact Julie Maddox at (916) 435-3555 or