Simcoe Creek Fish Passage and Habitat Restoration, RM 10.5

This project targeted recovery of the Toppenish Creek population of the Yakima Basin major population group of middle Columbia steelhead. We restored full fish passage at two box culverts, restored aquatic habitat in 0.4 miles of existing channel using large wood structures, re-wetted 1,600 feet of side channel that was previously dry due to channel incision, restored flow and sediment transport continuity by installing a new bridge, created alcove habitat in 3 small inset floodplain areas, treated two headcuts using designed riffles to maintain channel grade, and revegetated 1.6 acres of riparian habitat. Project outcomes are increased quality and quantity of instream habitat in a documented spawning and rearing reach for middle Columbia steelhead, full fish passage up and downstream, and improved stream processes of flood conveyance, floodplain and side channel engagement, and sediment transport.

The total project cost was $1,196,637. PCSRF funds ($96,637) paid for a portion of the logs and root wads needed for the large wood structures. 129 30 foot long X 18-24 inches diameter logs and logs with rootwads were generated and delivered to the project site. The logs were used to construct wood structures that will function as habitat and channel stabilization features. The overall number of logs used in the project is 280, so PCSRF funding provided a substantial portion of the required wood materials. Please see attached final report for photos of these wood materials. Other funds paid for project design, the remaining materials, and construction.

Worksite #1: Simcoe Creek, River Mile 10.5

We addressed the following limiting factors using the methods described.

1) Impaired aquatic habitat: Increased quality and quantity of available aquatic habitat by installing large wood structures and adding riffles and pools and creating 5 seasonally wetted and 1 flood-event activated side channel, all located in historic channel pathways. Created alcove rearing habitat at the outlets of 3 of the side channels. Will maximize duration of wetted channel conditions during dry season via consolidating low or base-flow conditions into single channel. Improved shade and nutrient contributions by creating floodplain benches that can support riparian vegetation;

2) Impaired fish passage: Installed bridge with fish-passable roughened riffle next to existing box culvert under W.White Swan Road. Converted existing east box culvert into an over-flow flood route with fish-passable roughened apron up and downstream. Constructed roughened apron downstream of existing west box-culvert crossing under W. White Swan Rd to improve downstream migration flood flow hydraulics;

3) Active Incision: Reduced risk and impact of continued incision (vertical and lateral) through construction of designed riffles in the mainstem that provide grade control. Created opportunities via installation of large wood structures and side channel creation for inset floodplains. Created opportunities for development of inset floodplain and increased channel sinuosity via installation of Large Wood to produce hydraulic roughness and flow deflection;

4) Disconnected floodplain: Created narrow floodplain benches that will be inundated during 1.5-year flood event and slightly set-back existing vertical banks to increase available floodplain. Will increase frequency and area of historical flood inundated by creating seasonally activated side channels;

5) Lack of Riparian Zone: Improved riparian zone vegetation by planting native seed and live plants in areas created to support and maintain riparian vegetation such as the created floodplain benches, slightly laid-back vertical banks, and reactivated historical flow routes through the floodplain. Installed 1.5 miles of fencing to protect stream riparian area from grazing, and added a fenced livestock crossing (water gap).

The proposed project will result in two major benefits to the Toppenish Creek steelhead population. First, full passage will be restored in a spawning and rearing reach of Simcoe Creek, the major tributary of Toppenish Creek. There are 20 miles of spawning habitat upstream of the project site with no known passage barriers, resulting in a significant gain in access to spawning grounds for returning adults. In addition, this project restores full downstream passage to juvenile fish out-migrating in the spring. Second, the project restores complexity and cover to 0.4 miles of main channel and creates 1,600 feet of off-channel habitat in an area of highly degraded habitat, which should enhance spawning and rearing opportunities, in addition to providing increased high-flow refuges. A secondary benefit is the treatment of active headcuts which will conserve existing spawning and rearing habitat upstream of the project area.