Heavy erosion along Milk Creek prior to the construction project
Milk Creek, in the Molalla River basin, is home to a number of fish species: Chinook and Coho salmon, winter steelhead, cutthroat trout, and Pacific lamprey. So when the Clackamas Soil and Water Conservation District was presented with the opportunity assist a local landowner to improve fish habitat and reconnect the creek to the flood plain, staff eagerly got to work to help protect and support these native fish.
A Little Background
In the summer of 2017, the Conservation District completed an in-stream construction project on Milk Creek in collaboration with the owners of a private property in Mulino. Milk Creek flows into the Molalla River just southeast of Canby. The District has completed nine projects benefiting water quality and fish habitat on this stream.
Goals for the Project
At the project site there was active erosion on the banks and fish habitat was impaired due to lack of large wood in the creek. The first project goal was to shift the fast-moving current away from the bank by adding large wood pieces.
Hundreds of willow stakes were planted into the large wood structures as part of the construction project.
The large wood placed in Milk Creek not only helps to reduce bank erosion at the site, it also creates resting places and pools for juvenile salmonids and resident fish.
A second goal of the project was to plant native trees, shrubs, and grasses in the floodplain adjacent to the in-stream project. Halting the stream bank erosion was critical in order to effectively establish a functioning streamside buffer at the project site.
Our long-term objective is to develop a robust buffer that protects the stream edge where only non-native pasture grasses previously grew. This riparian area will help protect against the eroding forces of Milk Creek.
Next Comes the Planting
Large wood, gravel beds, and native grasses
Last winter our contractor, Biohabitats, installed over 1,000 trees and shrubs at the site. These trees and shrubs will grow, expanding their root systems to help stabilize the bank in future years. Over time, wood and leaves in the creek will provide fish and insect habitat and nutrients. Also, as the trees grow, their shade will help reduce the stream temperature, keeping the water cool.
How Did We Do?
Conservation District staff recently visited the project site to evaluate the in-stream structures and the vegetation planting. We were pleased to find that the plants are growing beautifully and that the large wood structures are beginning to create habitat complexity in the stream. The root wads are creating deep pools and the slowed water velocity is helping to retain spawning gravels in the channel bottom.
Conservation District staff plan to annually visit the site to monitor the status of the in-stream project and planting over the next five years.
