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Watershed Assessment of Manzanita
Manzanita watershed on Bainbridge Island presents an opportunity to design and implement stormwater improvements in accordance with landowner willingness, cost effectiveness, and greatest ecological lift.
Other studies have recognized that this watershed has great potential to regain hydrologic balance and provide intact riparian habitat to support Puget Sound recovery.
This project will assess how an ‘out of basin mitigation’ program could fund retrofit projects in the Manzanita watershed.
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The city is currently working with their consultant and other project partners to understand the watershed processes through data gathering, GIS analysis and field observations.
July 2022: Project locations were identified by the Steering Committee and ranked based on their effectiveness to restore streamflow. Out of 13 feasible locations, 6 projects were identified as having opportunity to treat unmitigated stormwater and improve streamflow. Of the 6 projects, the 2 highest ranking projects were selected to move on to the design phase. The city’s design consultant is currently working to develop preliminary designs for these sites. See attachment under “related documents” for site locations.
- 01/12/23 Steering Committee
The Steering Committee, Consultant Herrera, and City staff met onsite to review the 30% design details for the stormwater retrofit at the Bainbridge Island Native Food Forest (BINFF) on Charles Place.
- 7/21/22 Field trip to top 2 sites
Representatives from Friends of the Farms, Squamish Tribe, Bainbridge Island Land Trust, and the Bainbridge Island Watershed Council joined city staff to look at the top 2 scoring sites in the field and provide design input.
7/11/22 Steering Committee
Staff from Herrera Environmental Consultants and Kitsap Conservation District joined the Steering Committee to show us progress on private rain garden designs and the scoring criteria for public stormwater retrofits the watershed.
12/15/21 Project Scoring Meeting
Staff from the City and Herrera Environmental led the steering committee through a "story map" highlighting 13 conceptual project ideas that met feasibility requirements. Next the committee reviewed a draft scoring matrix to help guide the project towards two top projects. These top projects will move on to the next phase and begin the design process.
10/14/21 Initial Site Review
Staff from the City and Herrera Environmental Consultants visited over 20 sites in the watershed to review the feasibility of conceptual stormwater retrofit ideas. The sites will be further reviewed for infiltration potential, utility conflicts and contributing basin size to establish a ranked list of projects.
8/21/21 Walk the Watershed: Learn about Manzanita watershed planning
City staff will be leading a guided walk on a 2-mile route through the hills and valleys of Manzanita watershed on Saturday, August 21 at 10 AM in support of the Watershed Assessment of Manzanita. This walk will showcase some of the recent successes while highlighting future challenges facing the aquatic habitat of Manzanita Creek. We will visit an inactive gravel mine, wetlands, fish passable culverts and stormwater ponds along the way. Participants will learn about recent legislation regarding streamflow restoration and how the city is using Federal grant funds that address a disrupted hydrologic cycle. The walk is mainly on quiet roads and trails but also crosses a busy road and should last about 2 hours. Participants should dress appropriately and will be asked to fill out a waiver prior to participating. Due to social distancing needs and challenging road crossings, the tour will be capped at 10 participants. Please RSVP for more details by emailing Christian Berg at firstname.lastname@example.org.
5/26/21 Steering Committee
Discussed the geology of the watershed, outreach material and approaches to selecting areas for to focus the outreach based on GIS analysis. Geology for infiltration Link.
3/25/21 Steering committee
Discussed the use of the Puget Sound Watershed Characterization tool and delineated project assessment units for the model.
02/25/21 Kick-off Meeting
A project kick-off meeting was held virtually on February 25 with City Staff and the Natural Resource Management Team. see video link here.
- Restore & Protect Presentation by Kate Macneale, King County Presentation:
- WAM Story Map Presentation:
- Stormwater Control Transfer Program Overview:
- National Estuary Program, EPA
- Administered by the Stormwater Initiative, WA DOE
This project has been funded wholly or in part by the United States Environmental Protection Agency under assistance agreement PC-01J18101 to the Washington State Department of Ecology. The contents of this document do not necessarily reflect the views and policies of the Environmental Protection Agency, nor does mention of trade names or commercial products constitute endorsement or recommendation for use.
- Final Issue Paper on Alternative Funding Mechanisms
- Kitsap Conservation District Rain Garden Report
- Preliminary (30%) Design Summaries
- Site Locations
- Infiltration Feasibility Assessment Technical Memo
- WRIA 15 Streamflow Restoration Planning
- King County Restore and Protect
- COBI Surface Water Management Plan 2001
- Near Term Action (NTA) Puget Sound Partnership
- Watershed Assessment of Manzanita - Fact Sheet
- Manzanita Water Flow & Sediment Export Potential Assessment - August 2021
- Manzanita Watershed Analysis Map
Title VI Notice:
The City of Bainbridge Island fully complies with Title VI of the Civil Rights Act of 1964 and related statues in all programs and activities. Language services are available upon request. Those requiring disability accommodations and/or materials made available in alternate formats, please contact the City Clerk at 206.842.2545 or email@example.com