Dick Spotswood: Flood mitigation solutions will be gigantic public projects
Marin just simultaneously experienced two natural phenomena: extreme king tides accompanied by wet storms. Unless wildly expensive mitigation measures are promptly pursued, the flooding we’ve experienced will gradually increase until we reach the time when it will be the new normal.
California’s Coastal Commission explains, “King tides themselves are not related to climate change, but they allow us to experience what higher sea level will be like. King tides are the highest high tides of the year, one to two feet higher than average high tides, which is a good approximation of how high we expect everyday tides to be over the next few decades due to human-caused sea level rise.”
It doesn’t matter whether folks believe sea-level rise is “human-caused” or a natural event. What matters is that we understand that it is coming. Those who believe President Donald Trump that climate change is “the greatest con job perpetrated on the world” should invest in Florida coastal real estate.
Recently, I went on a tour of flooded bayside locations led by North Bay/North Coast Rep. Jared Huffman, along with Marin County Executive Derek Johnson, County Fire Chief Jason Weber and staff. Two Marin mayors – Larkspur’s Stephanie Andre and Corte Madera’s Rosa Thomas – joined us.
We started in the low-lying Santa Venetia neighborhood east of Marin’s Civic Center on Gallinas Creek. Before the area was filled in 1914, it was marshland. The development was modeled on Venice, which in Italy is known as Venezia.
It has always been understood that Santa Venetia was at risk. The current levee, built after catastrophic flooding in 1983, wasn’t engineered for long-term resilience. Recent king tides saw its levee breached. The county’s plan is for a proper flood wall at a cost of $25 million. Federal funds were granted, but last March, for no stated reason, Trump canceled them.
Last week, Corte Madera Creek crested its banks and tide waters flooded across Highway 101. Lucky Drive businesses were hit. Flooding was severe on the bay side of the freeway, which is home to Larkspur’s industrial sector and two mobile home parks. The manager of SF Fitness on Lucky Drive thought he was prepared by deploying stockpiled sandbags. To his amazement, tidal water crept over the makeshift dam and flooded his business.
Marin City provided good news. The county placed portable pumps at its lowest points in advance of the flooding. Locals reported no blockages on Donahue Road at Highway 101, the community’s primary access. Pumps are a temporary measure. Like elsewhere, permanent remedies are required.
We drove across Highway 101 to Gate 6 Road in unincorporated Sausalito, the site of floating home communities. The tides caused $350,000 damage including to partially submerged vehicles. The adjacent Waldo Point Harbor demonstrated a permanent solution. They spent $22 million elevating their parking lot by 3 feet, hopefully making it long-term resilient.
Along 101, tidal flooding blocked the freeway at Larkspur’s Lucky Drive and along Richardson Bay’s Shoreline Highway. The county and Marin’s 11 municipalities know what to do. Each has a “Climate Action Plan.” Low lying stretches of Highway 101 need to be elevated by 4 feet. Along Marin’s 40 miles of bay shoreline, sea walls and levies are essential.
What local governments don’t have is sufficient funding. Depending on fickle federal assistance is a fool’s errand and California’s state government is broke.
Some of the costs will be addressed by impacted property owners, as at Waldo Point Harbor. Most adaptability measures will be a gigantic public works project. Here’s the reality check: There’s no free lunch. If shoreline mitigation is to happen, impacted communities must impose new taxes to fund the job.
To learn how sea-level rise will impact your neighborhood via an interactive online map, go to bit.ly/4qaVQVM.
Columnist Dick Spotswood of Mill Valley writes on local issues Sundays and Wednesdays. Email him at spotswood@comcast.net.