Dick Spotswood: Marin needs ‘can do’ spirit to fight sea-level rise

Most Marin residents accept the reality that our shoreline along San Francisco Bay and in West Marin fronting the Pacific Ocean is experiencing the early impacts from sea-level rise.

Recently, Marin County’s Public Works Department published its top-notch Marin Shoreline Sea Level Rise Vulnerability Assessment. Learn how your neighborhood fares at bit.ly/4aPZgad.

There are multiple viable ways to protect literally billions of dollars of homes, apartments and commercial properties plus public sector infrastructure even with a 50-year horizon.

I recently moderated a sea-level rise forum for two homeowner associations bordering Southern Marin’s Richardson Bay. It took place just after this year’s combination of high king tides and storm runoffs. That convergence showcased what Marin’s future will resemble.

The audience’s attention was focused on from the Shoreline Vulnerability Assessment presented by Supervisor Stephanie Moulton-Peters and county staff. It was clear that if steps weren’t taken, the value of impacted real estate would crash. We aren’t alone. Even climate-change-skeptical southerners who own property in the Florida Keys and the Gulf Coast have come to understand what’s to come.

They are wake-up calls like the maps that demonstrate which Marin hillside neighborhoods will likely be incinerated by a wildland fire on a windy day. It’s obvious, unless action is taken, property owners will pay a big price.

A provocative idea at the forum came from past Mill Valley Mayor Garry Lion, chair of the Flood Control Zone 3 Advisory Board. He advocates a tidal barrier adjacent to Richardson Bay’s Highway 101 bridge. Given his passion, some wits have called the tide barrier “Lion’s Gate.”

Much of Richardson Bay’s shoreline is at risk. The greatest impacts will be near Tamalpais Junction, the crossroads of Shoreline Highway and Miller Avenue. Rising seas will be devastating to Tamalpais High School and The Redwoods retirement community. Full disclosure: I live adjacent to Richardson Bay.

Lion’s idea is that when rising sea levels are compounded by king tides and rain waters from fierce storms, the tidal barrier’s navigable flood gates are deployed. When storms and king tides simultaneously risk inundating bayside communities, Lion’s Gate will be a miniature version of the Thames Barrier. For the past 30 years, that tidal wall has successfully protected metropolitan London from rising North Sea waters.

Tidal barriers may also be useful protecting San Rafael’s low-lying Canal and Spinnaker Point neighborhoods. The Mission City’s “Community Informed Technical Feasibility Study” indicates that a tidal flood gate plus barrier walls could protect eastern San Rafael from rising seas for the remainder of the 21st century.

Tidal gates may seem like science fiction fantasy written by Jules Verne. That’s what dubious Londoners thought when the Thames Barrier was first proposed. It’s time to think big, a concept that America seemingly has abandoned. Let’s revive the “can do” spirit that built the Transcontinental Railroad in just four years and forged the Panama Canal in a tropical land wracked with yellow fever.

No tidal barrier will aid bayside Sausalito, Marin City, Corte Madera, Tiburon, Belvedere, Novato, Bolinas or Stinson Beach. There, seawalls, green adaptation strategies and raising buildings up on stilts (as is now common practice in North Carolina’s Outer Banks) are long-term strategies allowing those communities to adapt to inevitable change.

We must acknowledge that what’s absent is a realistic plan to pay for these measures. Support from Uncle Sam is unreliable. The regime in Washington teaches us that the party in power can, on a whim, shift funding to and from states and regions based on party politics.

The reality is that in U.S. coastal communities funding climate change mitigation strategies will be the responsibility of localities and individual property owners. That will be a steep price but the alternative, doing nothing, will cost far more.  Once again, there’s no free lunch.

Columnist Dick Spotswood of Mill Valley writes on local issues Sundays and Wednesdays. Email him at spotswood@comcast.net.