DESCRIPTION
The Confederated Tribes and Bands of the Yakama
Nation will use this grant to restore the floodplain on South Fork Cowiche
Creek, a tributary to the Naches River in the Oak Creek Wildlife Area in Yakima
County. The partners will install tree root wads and large logs along 2 miles
of the creek on land owned by the Washington Department of Fish and Wildlife. These
woody materials create places for fish to rest, feed, and hide from predators.
They also slow the river, which reduces erosion and allows small rocks to
settle to the riverbed, creating areas for salmon to spawn. Finally, they
change the flow of the river, creating riffles and pools, which give salmon
more varied habitat. The composition of the streambed and length of time that
water spends flowing through the substrate reduce stream temperature and
increase nutrient cycling that is beneficial to aquatic organisms. The work
will reconnect South Fork Cowiche Creek with its floodplain. During seasonal
high flows, the woody material will cause flood waters to leave the channel and
disperse over large areas. The overland flow will recharge the groundwater,
increasing flows to the stream during summer, and reducing flood risk
downstream. The South Fork Cowiche Creek is used by middle Columbia River
steelhead, which are listed as threatened with extinction under the federal
Endangered Species Act.
Yakama Nation and Mid-Columbia Fisheries Enhancement Group worked together to restore instream and floodplain function in South Fork Cowiche Creek, a right bank tributary to the Naches River located on the Cowiche unit of the Oak Creek Wildlife Area in Yakima County. The property is owned and managed by Washington Department of Fish and Wildlife. Alluvial stream reaches on the east slope of the Cascade mountain range are often poorly connected to associated floodplains. This typically stems from road construction, logging, and grazing. These practices often included removal of instream wood, riparian logging of large trees, stream channel relocation, creation of revetments and informal levees associated with roads, and decades of livestock grazing that prevented re-establishment of functional riparian habitat. Wood is a critical component of stream ecosystems. The project added 31 structures (comprised of a total of 1400 logs) along two miles of stream to restore in-channel complexity, reverse channel incision, and re-engage the creek with its floodplain. Log structures can be cost-effective applications that reduce stream velocities at high flows, thereby trapping sediment to help reverse channel incision. SF Cowiche Creek supports ESA-listed Middle Columbia River steelhead.