Karlson Island Tidal Wetlands Restoration

Karlson_AerialLocated within the U.S Fish and Wildlife Service’s Lewis and Clark National Wildlife Refuge on the lower Columbia River, HENDERSON breached levees at nine locations in the Karlson Island tidal wetlands. CREST’s project goal was to re-open Karlson Island to tidal influence and restore full estuarine processes to improve juvenile salmonid access into approximately 320 acres of tidal wetland habitat in the Columbia River mainstem.

Karlson Island was historically composed of spruce and marsh wetland systems and tidal channels connecting across the entire island during regular tidal cycles. The Island was diked and farmed from 1883 through 1976, when the island was integrated into the Wildlife Refuge. FloatingExcavatorsLack of access and simplified aquatic habitat limit juvenile salmonid use limited of the site. Reduced hydrologic connectivity impacts habitat quality, development of natural systems, and nutrient transfer.

HENDERSON’s restoration team accessed the levee breach sites via barges for equipment and native material import (large wood), then tasked the barges for transferring approximately 18,000 cubic yards of excavated materials from the breaches for placement as topographic/habitat enhancement on the remaining island levees. Large wood structures were placed at the levee breaches for tidal velocity reduction and to act as tidal habitat.

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