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Lower Corte Madera Creek Improvement Study Project

About

The Lower Corte Madera Creek Improvement Study is an assessment of the current condition of the levee and creek system downstream of the concrete channel.  Work was largely completed in 2021 and includes:

  • Assessing the need for future projects
  • Identifies any potential project concepts that could be partially funded for final design and construction under the Local Levee Assistance Program or from other funding sources
  • Identify and provide recommendations for improvements

In 2018, a contract was awarded to conduct:

  • Bathymetric and land surveying
  • Hydrological and hydraulic analysis
  • Geotechnical engineering
  • Assessment of remedial alternatives

A separate analysis addressing sea level rise and conceptual adaption measures in the Corte Madera Bay Lands was conducted by San Francisco Bay Conservation and Development Commission.

District staff, supported by Watershed Sciences, completed a first draft concept layout for a "geomorphic dredge" approach. This is a "design with nature" approach to dredge design. It is favored by permitting and granting agencies as well as the larger environmental community. This effort is separate from the Contractor's work.

The geomorphic dredge approach consists of a channel dredge geometry designed to be in equilibrium with the available daily tidal prism (volume of water that comes in and out on the daily tides). The goal is to design a more sustainable creek cross section by requiring less dredging for maintenance. This results in fewer impacts, less cost, and facilitates environmental review while also attracting potential grant funding. Learn more about this by reviewing the materials from the May 23, 2019 advisory board meeting.

A visual photo rendering of one of several structural floodwall options was completed in February 2020. This previews recommendations based on creek water level modeling during 100-year tide with sea level rise at three locations along Corte Madera Creek.

Funding

The study is funded by a Local Levee Assistance Program (LLAP) grant from the California Department of Water Resources. It will provide 55% reimbursement of costs for both past and future work covered under the grant.

Zone

Zone 9: Ross Valley

Agencies and partners

  • Marin County Flood Control & Water Conservation District
  • California Department of Water Resources
  • City of Larkspur
  • Unincorporated areas of Marin County

Contact

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