Flood control, improvements coming to Nathanson Creek Preserve

The flood-prone Nathanson Creek Preserve, which includes two Sonoma city parks and a stretch of well-traveled bike path, will be improved with the construction of a floodplain and habitat enhancement project.

Sonoma Ecology Center and the City of Sonoma have completed planning and design to enhance the Preserve, a quarter mile reach from above East MacArthur Street through Nathanson Creek Park.

Nathanson Creek has a history of flooding in this area, with significant impacts in the past to local schools and surrounding residents. The goal of the project is to implement flood reduction and habitat restoration, along with recreation and educational elements.

The Preserve also includes a scenic riparian area and Native Plant Demonstration Garden that provide critical habitat for birds, fish, and other wildlife. The garden, installed in 2010, demonstrates a range of related benefits through its use of rain gardens, bird boxes, interpretive elements, park amenities, and colorful spring flower displays.

The current project builds on previous habitat enhancement efforts along Nathanson Creek by adding more restoration sites and constructing a flood plain restoration project to demonstrate how flood flows can be managed to improve fish and wildlife habitat without increasing flooding or erosion.

Flood reduction on the current project site is limited due to existing road culverts, but the project will help reduce impacts to neighboring properties and demonstrates principles that can be incorporated into urban creek restoration and flood control.

The project required extensive analysis through hydraulic modeling of multiple scenarios, including conceptual plans that can help reduce flooding and provide 50-year flood interval protection along school District property, while improving riparian habitat along the entire length of the Preserve.

Sonoma Ecology Center held public meetings with landowners and neighboring residents to present conceptual designs and modeling results, as well as answer questions and get feedback on the project. After incorporating feedback from landowners and the public, full designs were developed for two projects on City of Sonoma property, one of which is the current project to be constructed.

The second project design, developed for the Demonstration Garden Park site, as well as conceptual designs developed for the School District property, are contingent on future funding.

Sonoma Ecology Center worked closely with the City of Sonoma on finalizing plans and securing permits. The project is now going out to bid and construction of the floodplain basin is scheduled to occur between September 14 and October 15.

This project is made possible by a grant through the Department of Water Resources Urban Streams Restoration Program, Proposition 84 funds. Partners and stakeholders on the project include the City of Sonoma, Sonoma Valley Unified School District, Sonoma County Water Agency, Sonoma Agricultural Preservation and Open Space District, Prunuske Chatham Inc. and Sonoma Ecology Center.