Springbrook Creek Evaluation and Feasibility

The Springbrook Creek Evaluation and Feasibility (Assessment) Project assessed the condition of Springbrook Creek, its tributaries, and the 999 acre Springbrook Creek watershed using existing and new data/information, including a significant amount of on the ground field work.

Within the watershed, there are just over seven miles of stream of which approximately 4.7 miles are typed as fish habitat. Springbrook Creek is one of the largest and most productive salmon-bearing streams on Bainbridge Island. Springbrook Creek contains one of only two stream reaches on Bainbridge Island designated as Critical Habitat for Puget Sound steelhead. The stream currently hosts populations of a number of fish species including cutthroat trout, coho and chum salmon, sculpin, Western brook lamprey, and more.

The project identified limiting factors affecting ecosystem functions, reported on those conditions for planning activities within the watershed, conducted a watershed restoration and protection project feasibility analysis, and identified and prioritized potential protection and restoration projects addressing ecological health and fish passage limitations in the Springbrook Creek Watershed.

An important element of the project included landowner and community interaction to learn from those living in the watershed about stream function and use, to engage them in caring for stream and watershed resource, and to share information developed during the project. 123 landowners who lived along the stream were contacted about the project. During the project over 54 properties were visited encompassing over 240 acres. By the end of the project, about 65% of the watershed’s stream length was field surveyed (about 4.7 miles of 7.2 miles of stream). Using remote and primary data, the team achieved a comprehensive inventory of stream and riparian conditions throughout the watershed.

A comprehensive inventory of fish passage barriers in the watershed was accomplished by Wild Fish Conservancy. 46 culverts were identified: 8 on city-owned property and 38 on private property. Of these, 10 (43%) were full passage barriers, 6 (26%) were rated 33% passable, and 7 (30%) were rated 67% passable. None of the assessed culverts were found to be fully passable, and about 1.8 miles of fish habitat exist upstream of what are considered full barriers.

Water monitoring performed to identify limiting factors such as temperature, sediment, and fecal coliform. A total of 14 sites were selected and monitored for one or more parameters.

A watershed characterization was performed by Washington Department of Ecology using their Puget Sound Watershed Characterization model. This work led to the identification of specific Assessment Units within the watershed in order to focus information on conditions within sub areas of the watershed. The results of this work provided information on the functionality or degradation of important watershed conditions or functions such as areas for sediment sources, water flow, surface recharge, surface storage and water discharge. The result of this work not only helped understand which areas of the watershed provided which important watershed function, but also what actions (protection or restoration) might need to occur to protect or improve these functions.

As a result of the work performed, the Springbrook Creek Watershed Assessment Report, November, 2018, contains a compilation of watershed resource information, identifies appropriate, feasible, and cost-effective solutions to address limiting factors in the watershed, and presents conceptual designs for five high-priority projects. Restoration opportunities such as removing fish passage barriers and enhancing riparian habitats, evaluating the possibility of returning the stream to its historical path, and protecting intact fish habitat through acquisition or cons

By evaluating historical information, collecting new information, conducting on the ground assessments and engaging and having discussions with landowners, a comprehensive inventory and understanding of stream and watershed conditions was achieved. This information led to the identification of factors limiting stream and watershed function, and restoration and protection actions along Springbrook Creek, a historical steelhead stream and one of the most productive salmonid streams on Bainbridge Island supporting populations of cutthroat trout, coho, and chum, that could improve conditions. The project engaged a number of people who can assist in caring for the watershed by engaging in stewardship, restoration and protection actions. The expected benefit of this project will be the implementation of 5 high priority projects in the watershed which will improve and/or protect stream habitat conditions for fish, utilization of the assessment report for guiding or informing future restoration and protection or planning actions in the watershed, and having an engaged public caring for the stream and associated riparian habitats.