Ross Valley
Flood Control Zone 9
Ross Valley
  • Background
  • Meetings
  • Projects
  • Maintenance
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Watershed Overview

The 28-square mile Corte Madera watershed extends from Mt. Tamalpais and White’s Hill through the communities of Fairfax, Sleepy Hollow, San Anselmo, Ross, Kentfield, Greenbrae, Larkspur, and Corte Madera to San Francisco Bay. The watershed includes 44 miles of stream channels. Ross Creek drains the northern slope of Mt. Tamalpais; San Anselmo Creek and its tributaries drain the northwestern portion of the watershed. The two channels join to form Corte Madera Creek, which continues through more than a mile of concrete-lined channel past the confluences of Larkspur and Tamalpais Creeks and into the salt marsh at the mouth.

Despite the dense development in the valley floors, the Corte Madera watershed supports a great diversity of habitats from redwood forest to serpentine outcrops, chaparral, oak woodlands, grasslands, and tidal wetlands. It is home to many protected species including at least 17 plants, steelhead trout, spotted owls, San Pablo Song Sparrow, California clapper and black rails, and salt marsh harvest mouse. Corte Madera Marsh Ecological Reserve is recognized as an Important Bird Area by the Audubon Society.

In 2006, the County of Marin, City of Larkspur and Towns of Fairfax, Ross and San Anselmo formed the Ross Valley Flood Protection and Watershed Program (RVFPWP) to develop and implement a flood management program that promotes with healthy watershed processes.

Learn more about the history and habitat of the Ross Valley watershed

Events & Meetings

Event Date: Time: Location:

There is no December 2017 Ross Valley Zone 9 Advisory Board meeting scheduled.  Stay tuned for our next meeting in March 2018 tbd.

Thank you!

Event Date: Time: Location:

Interested community members joined staff for a meeting & site tour of

Event Date: Time: Location: Larkspur Town Hall, 400 Magnolia Ave., Larkspur
District staff provided a presentation update to the Larkspur City Council on the Program, hydraulic modeling, Lower Corte Madera Creek Improvement Study, creek & rainfall gages, and 2017 creek maintenance.
Event Date: Time: Location:
Two neighborhood meetings were held with residents and businesses along Sir Francis Drake, Poplar, and Sylvan to discuss conceptual Frederick Allen Park Riparian Corridor and removal of Ross Fish
Event Date: Time: 7:00 P.M. – 9:00 P.M. Location: Larkspur City Hall 400 Magnolia Avenue Larkspur
Event Date: Time: Location:
Statement of Proposed Action: Options to Purchase Agreement - 634 San Anselmo Ave., San Anselmo
Event Date: Time: 9:30 am Location: Fairfax Community Center, 16 Park Rd.

Fellow nature enthusiasts joined in clearing out trash & debris, opening up the creek flow, and restoring natural habitat along Fairfax's creeks.

Event Date: Time: 5:00-9:00 PM Location: Ross School Gym at 9 Lagunitas Road, Ross CA

5:00-6:30 PM Workshop for Phoenix Lake IRWM Grant Migration Alternatives
7:00 PM - 9:00 PM Advisory Board Meeting

Event Date: Time: Location:

Staff provided an update to the Ross Town Council on the Phoenix Lake project and options to migrate Prop 1E grant funds to alternative flood prevention options in the Ross Valley.

Event Date: Time: Location: Isabel Cook Community Center

Residents in the Morningside neighborhood in San Anselmo held a community conversation about flooding issues and possible options to address flooding with staff from the County and the

Capital Projects

  • The Project is located along the Corte Madera Creek in Ross and Kentfield, is currently in the Feasibility Study phase, and is being implemented under the US Army Corps of Engineers planning process. Proposed Phase 1 would include the flood plain restoration at the Frederick Allen Park Riparian Corridor, removal of the fish ladder, and installation of floodwalls near the Granton Park neighborhood in Kentfield. The full Project is currently in the environmental review phase.
  • The San Anselmo Flood Risk Reduction (SAFRR) Project will reduce the acute risk of flooding in Ross Valley by implementing flood mitigation projects on two parcels along San Anselmo and Fairfax Creeks: one to remove a channel-constricting building and one to construct a flood diversion and storage basin. It is currently in the environmental review phase.
  • Learn about hydrology & hydraulic modeling in general as well as specific models for proposed projects in the Ross Valley Flood Protection and Watershed Program. Review 2-D videos of aerial views of flooding over time and 2-D change maps comparing the maximum water level depths and extents of two different conditions for a specific rainfall event.
  • The San Anselmo Bridge Projects are local planning projects seeking community input as part of the bridge redesign process for the Nokomis Avenue, Madrone Avenue, and Center Boulevard bridges. These projects are managed by the Town of San Anselmo and are in the environmental review and design phases.
  • Request for Proposals - Corte Madera Creek Levee Evaluation

    Documents indicated in bold text are below.

  • The proposed Sunnyside detention basin is located west of Fairfax at the former Sunnyside Nursery growing grounds. Envisioned as a naturalistic basin with grassy side slopes and a natural bottom, it would work by temporarily holding back excess floodwaters during high creek flows to reduce the risk of downstream flooding. This project is currently in the environmental review phase.
  • The Azalea Avenue Bridge Project is a local planning project seeking community input as part of the bridge redesign process. This project is managed by the Town of Fairfax and is in the environmental review and design phases.
  • The Lower Sleepy Hollow Creek Project Improvements are proposed along Sleepy Hollow Creek from Broadmoor Avenue Bridge down to the Taylor Street Bridge by creating additional creek flow capacity through various measures in order to reduce the risk of flooding. The proposed project is currently in the feasibility phase and environmental impacts will be evaluated under the Ross Valley Flood Risk Reduction Program EIR.
  • The proposed project would improve Lefty Gomez Field at White Hill Middle School in Fairfax to allow it to serve dual community uses: White Hill Middle School and community recreation, and flood flow detention. A real-grass turf field would primarily operate as a recreational resource for the community and school, and occasionally provide much needed temporary water storage during infrequent, but severe, flood events such as in 1982 and 2005. The proposed project remains in the feasibility phase pending community support and funding.
  • The Phoenix Lake Integrated Regional Watershed Management (IRWM) Retrofit project would modify the reservoir to allow it to serve as a detention basin, thereby reducing downstream flood risk in lower Ross Valley resulting from creek overflow during storms. Other related benefits include improved water quality in Phoenix Lake and Ross Creek, opportunities for increased water supply, and new recreational amenities. This project remains in the feasibility phase. Due to timeline challenges, Department of Water Resources (DWR) grant funds awarded to this project were migrated to the USACE Corte Madera Creek Flood Risk Management Project to ensure funding remains in Ross Valley for flood risk reduction and water quality improvement purposes.

Maintenance Projects

  • The creek maintenance program is a partnership between the District and Fairfax, San Anselmo, Ross, and Larkspur that conducts annual creek inspections and coordinates removal of vegetation and other debris that could block flows and contribute to flooding. Homeowners are still responsible to keep the creek unobstructed on private property.
  • Learn about Ross Valley Flood Zone 9's facility maintenance, sediment removal, levee/floodwall maintenance & rodent control, precipitation & stream gauge maintenance and storm response.

Ross Valley Flood Protection and Watershed Program

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Felix Meneau - Zone Engineer
Telephone No. (415) 473-3223

Zone 9 was established in 1966 to act as a sponsoring agency for a major U.S. Army Corps of Engineers flood control project on Corte Madera Creek.  The Zone boundary was amended In January 2007 to include all territories within the incorporated areas of the towns of San Anselmo and Fairfax.  This change was undertaken in response to the flood of December 31, 2005 and the subsequent creation of the Ross Valley Flood Control and Watershed program.  

Zone 9 covers over 29 square miles, including the towns of Fairfax, San Anselmo, Ross and Larkspur as well as the unincorporated communities of San Anselmo, Fairfax, Kentfield, and Greenbrae. There are 21,095 parcels in the Zone.

The boundaries of the Zone and the Corte Madera Creek Watershed closely align. Corte Madera Creek is a substantial perennial stream. Tributaries that join the mainstem before it flows into San Francisco Bay include Fairfax, San Anselmo, Ross, Sleepy Hollow, Kittle, and Larkspur Creeks. 

The Zone 9 work program includes regular maintenance of 1 mile of flood protection levees, maintenance of the USACE concrete channel, maintenance of tidegates and trash racks, and an annual vegetation maintenance program along 0.6 mile of creek. Zone 9 periodically dredges lower Corte Madera Creek to remove accumulated sediment and to improve flow conveyance.


Overview of the Ross Valley Flood Protection & Watershed Program

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