Not just about Marin County

Nicasio Reservoir, Marin County Sept. 26, 2018. (Alan Dep/Marin Independent Journal) 

The 2020 West Coast wildfire season continues. So much loss of human life, communities flattened, thousands of homes gone, millions of acres burned, habitat for birds, fish and animals incinerated – and water supply for hundreds of thousands of people is now at risk. 

Could this happen in Marin? Yes, it can.

Op-ed Marin Independent Journal September 21, 2020.

The 2020 West Coast wildfire season continues. So much loss of human life, communities flattened, thousands of homes gone, millions of acres burned, habitat for birds, fish and animals incinerated – and water supply for hundreds of thousands of people is now at risk. 

We all know that our county is overdue for a major wildfire. A number of smart steps are being taken to mitigate that risk. What we’re not paying close attention to is what a catastrophic wildfire could do to our water supply. 

Seventy-five percent of our water supply comes seven reservoirs – five on the slopes of Mt. Tam and two near Nicascio. What’s at risk?

 We’re all familiar with the horrific wildfires in Santa Rosa and Sonoma. Let’s take a look at what just one of the costs the water agency has been dealing with after the 2017 wildfire. Benzene is the main component in commonly-used HDPE plastic water pipes. It’s a chemical that can cause anemia, immune system issues, and leukemia. When pipes burn, the chemical is released. The first instance of fire-related benzene contamination of a public water system in California happened in Santa Rosa – cost of repairs $8 million. 

Then, in 2018, the town of Paradise, California, was nearly obliterated by the Camp Fire, which, in addition to killing 85 people, destroyed 90 percent of the town’s structures and inflicted substantial damage to the area’s drinking water system. The current estimate to replace - $53 million.

A cautionary tale from just last month: The San Lorenzo Valley Water District, (Santa Cruz county) lost more than seven miles of an HDPE plastic water supply pipeline in the CZU Lightning Complex Fire. The list of other infrastructure damage includes booster pumps, transmission mains, tanks, intakes, water meters, and sampling stations. The preliminary, back-of-the-envelope damage estimate is $10 million. This water district has 7,000 customers. 

What are we at risk for in Marin? Our reservoirs are for the most part surrounded by dry trees and brush. When big rain storms hit a heavily burned area, there’s almost always a huge surge of ash and debris that heads down the watershed. That surge can easily overwhelm water treatment plants and blow out river banks, with severe consequences to water quality. 

To date, Denver has spent $28 million over the last ten years removing sediment from one reservoir from a 2002 wildfire. More than 80% of the water that Denver uses to supply 1.5 million people flows through this reservoir. 

Albuquerque, Phoenix, Santa Barbara, Colorado Springs and so many other western communities, can tell similar stories - along with the millions of dollars spent post-fire to repair their water supply and infrastructure.  

 Could this happen in Marin? Easily. The last time Mt. Tamalpais had a major wildfire was in 1929. In 1930, Marin’s population was 41,648. Today it’s 252,000. That’s not just more roads and houses, it’s higher water supply needs. 

 As with many other utilities, Marin Municipal Water District (MMWD) is updating their treatment plants. It is unclear, from a technology and science perspective, whether or not any community’s treatment plant could handle sediment runoff from a big rain storm post a catastrophic, climate-driven wildfire. MMWD, like most water utilities, uses HDPE pipes. 

Over 3.1 million acres have already burned this year in California. The Creek Fire is still roaring through the San Joaquin river watershed – critical water for Fresno and farmlands. We don’t yet know what the impact of the North Complex wildfire (270,000 acres and counting) will have on the Feather River and the Oroville Dam. 

There are so many actions we can take to make Marin’s lands more resilient and our water supply more secure. Smart western communities are already investing in their public land watersheds with science-based forest thinning, evidence-based prescribed burning, and yes – reintroducing beavers. 

Unlike many other western communities struggling to find funding for this work, Marin is a wealthy county. We can do this. Now would be good.