Lower Fivemile Wetlands Floodplain Restoration

The project area is located on the first private property upstream of Tahkenitch Lake along Fivemile Creek, the lakes largest tributary. The project area is located on lands owned by the Confederated Tribes of Siletz Indians that were acquired with OWEB funds. Tahkenitch Lake supports one of the healthiest wild Oregon coast coho salmon runs in Oregon. Although, land uses practices over the past 150 years have greatly reduced runs compared to historical levels due to the reduction of high quality habitat through the draining and diking of wetlands, the clearing of valley bottom vegetation, timber practices, and the channelization of streams as well as the introduction of warm-water fish species. The Siuslaw Coho partnership has prioritized restoration actions that increase the quality and quantity of the highly productive cold-water marsh habitats found along the tributaries of Tahkenitch Lake to increase the rearing capacity for Oregon coast coho throughout the Tahkenitch Lake Frontal Pacific 6th field HUC. Proposed work includes re-grading the valley floor and filling a portion of Fivemile Creek to reestablish floodplain connectivity. The remnants of two cross valley dikes will be removed by regrading them down to the elevation of the floodplain. Additionally, large wood will be placed, native plants will be established, and invasives will be removed throughout the project area. Project partners include the Siuslaw Coho Partnership, the US Forest Service, the Natural Resource Conservation Service, the US Fish and Wildlife Service, and the Siuslaw Watershed Council.

This project will benefit salmon and steelhead by directly addressing major stressors and limiting factors for Oregon coast coho production that have been identified at the local level by the SCP as well as at the state (Oregons Coast Coho for the State of Oregon, ODFW 2007) and federal levels (Federal Recovery Plan for Oregon Coast Coho, NOAA 2016).

The floodplain regrade in this project will restore broad floodplain connectivity, increase stream complexity, and restore riparian function. Additionally, the project will increase riparian biodiversity and promote long-term wood recruitment through the control of invasive species and planting of native trees, shrubs, and graminoids. The floodplain regrade and native plant establishment will also help address the water quality limitations listed under section 303(d) of the Clean Water Act for Fivemile Creek by increasing groundwater exchange, increasing shade cover, and filtering excess nutrients.