On February 3, 2022 a “Listening Session” was held to discuss flooding in Tam Junction, Birdland, and Kay Park in Tam Valley. Nearly 100 participants joined the meeting on Zoom. We are thankful for our community’s engagement with the complex issues related to flooding and sea level rise.
The “Listeners” included:
Stephanie Moulton-Peters, Marin County Supervisor District 3
Dennis Rodoni, Marin County Supervisor District 4
Mike McGuire, State Senator, District 2
Steffen Bartschat, Member, TCSD Board of Directors
Chris Choo, Senior Planner, Marin County Department of Public Works
The Tam Valley Sea Level Rise Task Force – Doug Wallace, Alan Jones, Kim Rago, Chris Dorman, Ted Barone
The discussion was broad and varied. In an effort to synthesize the comments, we have organized the community’s thinking into six categories – sea level rise projections; clogged drainage and maintenance issues; Tam Valley’s historic wetlands; subsidence at Manzanita and Birdland/Kay Park; adaptation strategies; and community organization.
Sea Level Rise Projections
The Manzanita interchange has flooded for decades but the frequency has been increasing. Senator McGuire called it the “Canary in the Coal Mine” for sea level rise in the Bay Area. The State of California is directing its agencies to plan for 3 ½ feet of sea level rise by 2050 and up to 10 feet of rise by 2100. Most of the lower elevation areas of Tam Valley are under 10 feet in elevation. The most recent king tides rose above 7 feet on a sunny day. Imagine a storm surge of up to 3 feet plus just one foot of sea level rise. Our levees would be easily breached. A large majority of the affordable housing units that the County is proposing for Tam Valley as part of their SB9 obligations are located in low-elevation areas, at high risk for flooding from sea level rise.
Clogged drainage and maintenance issues
During the October, 2021 storms, culverts, storm drains, and garbage gates were clogged with debris from the hills. Residents expressed concern about frequency of maintenance both of the drainage resources and pump stations. There was general agreement that clearing flood gates and drainage should be a priority. Some suggested that neighbors could be trained to clear the drainage in anticipation of storm events but better coordination among agencies is needed. The Flood Control District 3 meetings are important places to lobby for greater focus on Tam Valley.
Tam Valley’s Historic Wetlands
Much of Birdland, Kay Park, and the Tam Junction business district are built on historic wetlands. Coyote and Nyhan Creeks, once the home of spawning salmon, were redirected into concrete channels or hemmed in by levees in response to flooding decades ago. Sedimentation of the creeks exacerbates the problems associated with rising tides. Several residents expressed interest in the development of an “ecological health plan” to help guide our decision making.
Subsidence at Manzanita and Birdland/Kay Park
Increasing road closures, and sea water encroachment in Birdland and along Shoreline Highway are evidence not only of sea level rise but subsidence of roads and homes built on the historic wetlands. Highway 1 under the freeway has subsided approximately 4 inches from its original height and creates problems not only for Tam Valley but all of West Marin. The roadway on either side of the Flamingo Street bridge is dramatically lower than it was when first built in the 1950s. How much have house elevations subsided? Several participants advocated for raising the roadway elevation as a short term fix. Others wondered whether raising the freeway itself was inevitable. Similarly, is raising the elevation of houses, roads, and other infrastructure in the low elevation residential and business neighborhoods of Tam valley also inevitable?
Adaptation strategies
There is a spectrum of solutions from grey mitigation such as sea walls to green adaptation such as ecotone slopes. Multiple strategies at various points along the spectrum are likely to be needed. There were several comments about learning from the Dutch who have had to deal with encroaching seas for centuries. One resident suggested that Tam Valley has a chance to become the “Netherlands of the Bay Area” as we figure out how to deal equitably and publicly with adaptations to sea level rise. A few questions arose, including what are limits on green solutions and where might be best utilized in our area? And what are the costs and benefits of different strategies? A really good place to get an overview of different kinds of adaptation strategies that might be relevant to our situation is the Richardson Bay Resilience website in the section called “What’s Possible?”
Community Organization
A cohesive Tam Valley voice will be needed to ensure that decisions made are appropriate for our desired future. We need to be assertive in claiming our share of state, federal, and regional funding sources. The Tam Valley Neighborhood Response Group Network, which hosted the February 3 event, is a great way for residents to organize in small neighborhood clusters and build resiliency as we face disasters such as wildfire, earthquakes, and flooding. The low elevation neighborhoods of Tam Valley are not currently well-represented so block captains are needed now. For more information, email TamValleyNRG@gmail.com.
Next Steps
The Tam Valley Sea Level Rise Task Force will conduct a series of community forums and surveys to help residents and business owners learn about different adaptation strategies and develop prioritized guiding principles. Please email TamValleyNRG@gmail.com if you would like to host a small neighborhood meeting.
The Task Force will continue our collaboration with elected officials, agencies, and partner organizations to find resources and solutions to the problems we face.
We will, by December 2022, produce prioritized guiding principles for Sea-Level-Rise adaptation in Tam Valley that are science-based, realistic, and reflects the will of residents and businesses. These guidelines can then be used to guide decision-making at the local, state, and federal levels.
After the meeting, we sent a list of questions to Supervisor Moulton-Peters, Chris Choo from the Department of Public Works, and Senator McGuire’s office for answers. Here are our questions and responses:
From Chris Choo, Department of Public Works
Questions that came up
What are the plans to upgrade the pump station that failed during the October storms? What is the maintenance schedule for those pump stations? What can neighbors do when they see a pump station isn’t working?
A meeting to review the work plan and baseline budget for Flood Zone 3 (which includes Tam Valley) is being scheduled for March. The meeting packet will include a staff report with updates on pump station, levee, and channel maintenance including Coyote Creek. (Note: We will post the meeting link on the Tam Valley NRG/Sea Level Rise website when it becomes available)
Given the subsidence of the roadway under the Manzanita interchange, can the roadway be raised by a couple of feet as a temporary fix?
Shoreline Highway is in Caltrans’ jurisdiction. The Sea Level Rise Task Force will reach out to our contact there for their input.
Regarding $455 million in FEMA (HMGP) funding, are County officials requesting any of those funds?
The county is actively working on several grants from FEMA. We are updating our Marin County Multi-Jurisdictional Hazard Mitigation Plan, designing improvements to Marin City drainage, and improving the Santa Venetia earthen levee.
When will the County or Army Corps of Engineers dredge Coyote Creek from Flamingo Road to Richardson Bay? Is that in the plans?
The community has a resource in the Richardson Bay Resilience website. Reports on sea level rise and flooding improvements specific to the Tam Valley shoreline are available in the “What’s Been Studied” section of the site.
From Senator Mike McGuire (posed to Summer Cassel, his District representative):
Senator McGuire spoke about short term and long term fixes during his introductory comments. Can we get some detail about what the short-term fixes would be and what he is thinking about for long-term fixes?
The short term fixes would be solutions similar to what Caltrans has implemented on Highway 37 to mitigate flooding as it happens. This could include added drainage, constructing a flood wall, and controlling flood water. The long term plan could consist of raising the road, which would require a full environmental review and planning process, which would take years. We are planning to discuss this with Caltrans District 4 Director Dina El-Tawansy during a tour (of Manzanita and Tam Valley) in April, to hear about the actual long term plan they have for the area.
Resources
Richardson Bay Resilience provides information about sea level rise and the history of relevant studies
USGS sea level rise viewer allows you to see flooding or sea level rise alone or together
Flood Control District 3 There is an advisory board that meets regularly
Evolving Shorelines has drafted a plan to move the multi-use path across Bothin Marsh to help restore some of the historic wetlands of Tam Valley
Bay Adapt Regional Platform which provides a roadmap for sea level rise adaptation in the Bay Area
San Francisco Estuary Institute Adaptation Atlas which is a broadly used science-based framework for developing adaptation strategies in the Bay Area.
For more information, please email TamValleyNRG@gmail.com.
The Facts
1-foot sea level rise and storm surge
Realistic predictions for additional Sea-Level-Rise (SLR) range from 1 foot by 2035 and 2 feet by 2045 to 4 to 6.5 feet by 2100.
The State of California’s Sea-Level Guidance calls for agencies to plan for a 3.5 foot rise by 2050 and 7.6 foot rise by 2100.
In Tam Valley, a one-foot rise combined with a storm surge (see image above) would breach levees and inundate almost all of Birdland and Kay Park. Access to Miller Avenue and Highway 101 would be blocked.
There is no simple answer! Solutions will be expensive, inconvenient, and take years to implement.
We are not going to stop sea level rise. We have to adapt to it.
To learn more about our options, visit Richardson Bay Resilience.