DESCRIPTION
Protecting and restoring mainstem and off-channel habitats, especially those that provide thermal refuge, is critical for upstream-migrating adults particularly during the late spring, summer and early fall, as well as out-migrating salmonids. Previous research has documented a persistent cool-water flow along the right bank of the mainstem Yakima River at RM 3.4 - 3.9. This cool-water input originates from a year-round groundwater-fed spring. Previous research also documented a persistent cool-water input at the mouth of Amon Creek at RM 2.5, which is the lowest cool water tributary upstream of the mouth of the Yakima River. The goal of this project is to build upon previous work, conduct feasibility studies and complete preliminary designs using the existing cool water inputs to create functional thermal refuge habitat at both of these locations.
Benton Conservation District (BCD) proposes to complete final designs and permitting for a restoration project that will increase functional thermal refuge habitat for adult salmonids in two locations in the Lower Yakima River. Protecting and restoring mainstem and off-channel habitats, especially those that provide thermal refuge, is critical for upstream-migrating adults particularly during the late spring, summer and early fall when water temperatures are limiting. BCD has documented a persistent cool-water flow along the southern bank of the mainstem Yakima River at RM 4.4 - 4.9, near Richland, WA. This cool-water input originates from a year-round groundwater-fed spring adjacent to the I-182 bridge. The springs feeds a side channel. Previous research also documented persistent cool-water contribution at the mouth of Amon Creek at RM 2.5, which is the lowest cool water input found in the watershed. The thermal influence and spatial extent of these cool-water inputs must be enhanced through this lower river migration corridor to support steelhead and salmon recovery goals throughout the basin. Species to benefit from this project include steelhead, sockey, spring and summer chinook, and Pacific lamprey, as they are all obligate ocean-going species that must migrate as adults through the warm Lower Yakima River. The final designs will meet SRFB Manual 18 Appendix D-3 standards.
