DESCRIPTION
The City of Cle Elum is seeking to stabilize an eroding bank
on the Yakima River adjacent to the Hanson Ponds, a series of old gravel borrow
pits. The borrow pits have been
connected to the river via a constructed channel that was part of an earlier
habitat restoration project sponsored by the Yakama Nation (Figure 1). The banks of the river in the vicinity of the
constructed channel are eroding (Photos 1 to 3). The entrance to the constructed channel was
placed just downstream of two rock spurs, which were placed to protect the bank
from erosion. The spurs were intended to prevent the dynamic Yakima River from
changing its course to flow through the ponds.
However, bank erosion is occurring between these spurs, and the
downstream spur is at risk of failure from the channel cutting behind it. Its failure would allow more flow into the
constructed channel, which would increase the likelihood of the ponds capturing
the full flow of the Yakima.
Continued erosion could have several negative impacts on habitat
and infrastructure in the area, including:
1) The City of
Cle Elum Wastewater Treatment Plant has an outfall that crosses under the
constructed channel, which may be damaged by continued erosion, or may require
relocation if the river changes course.
2) The river
may need to be re-directed back into the existing channel, requiring
Kittitas Conservation Trust (KCT) used grant funding to assess the potential for restoration and develop conceptual designs to enhance 81.7 acres and 2.34 miles of salmonid habitat. The project area is located at Hanson Ponds and the adjacent Yakima River in Kittitas County, south of Cle Elum and I-90. The goals of the project are to increase the quality of main-stem and off-channel habitat for rearing salmonids when the future restoration project is constructed. KCT assessed limiting factors and the feasibility of restoration alternatives to improve habitat function and values. Assessment included evaluation of whether alterations to existing levee infrastructure were impairing floodplain functions. Furthermore, KCT worked with partners to develop an outreach plan to engage the community in salmon recovery at this popular recreational area.
The project site provides habitat for Endangered Species Act-listed steelhead, Coho Salmon, Spring Chinook Salmon, Rainbow Trout, and Cutthroat Trout. KCT will build on the previous work of the Yakama Nation to provide off-channel refugia for salmonids at Hanson Ponds. The project was timely because the City of Cle Elum received funding for bank stabilization to protect critical infrastructure, and enhance recreation opportunities at Hansen Ponds. Once implemented, KCT's habitat enhancement designs will ensure that past habitat expansion projects and current projects by our partners continue to benefit salmonids, resident fish, wildlife, and human experience.
