Stormy Weather in San Francisco

Stormy Weather in the Sunshine State

Posted: February 27, 2023 at 2:59 pm

San Francisco rang in the new year with a series of atmospheric river events that had catastrophic impacts across California. These record-breaking storms beg the question: 

“​​What is it called when two 100-year storms hit the Bay Area in one week? Is it a 200-year storm? A statistical anomaly? Or the new normal?”

– Sejal Choksi-Chugh, Executive Director and Baykeeper at San Francisco Baykeeper from Stormy Weather

Photo by Intricate Explorer on Unsplash

The Baykeeper is right; unpredictable weather has been the new normal. In fact, 2022 has been earmarked as “the year of record-breaking extreme weather events,” and 2023 hasn’t been off to a great start. According to the National Weather Service, between December 2022 and January 2023, the city of San Francisco received over 20 inches of rain.

For a state that’s been plagued with extreme droughts, the large quantity of rain could seem like a good thing, and many people were primed to think exactly that, but it’s not that simple. These storms brought other issues to the forefront which were impossible to ignore. “People were astounded,” said Sejal Choksi-Chugh, the San Francisco Baykeeper, “We saw a lot of social media posts of people being inconvenienced by the levels of water and the flooding, and it was a wake-up call for a lot of people who usually don’t pay attention to these kinds of issues.” 

This placed an emphasis on the stormwater and wastewater infrastructure in San Francisco – the only city in the Bay area that has combined sewers (an issue we are not unbeknownst to here in Canada). These storms triggered more than 14 million gallons of raw sewage to be released into the San Francisco Bay due to outdated infrastructure that simply couldn’t handle the sheer volume of rain. To the city’s credit, they have been incredibly transparent on the matter, with real-time sewage monitoring available online. 


Photo from San Francisco Examiner via California Office of Emergency Services

Those that would normally find solace in the water had to keep away, as sewage in the water poses a serious health risk due to bacteria and viruses. The impacts also extend further than human life, through pharmaceutical and industrial pollutants in wastewater that can have serious repercussions for wildlife and the environment.  Excessive levels of nitrogen and phosphorus in wastewater also encourage the presence of algal blooms – an issue that the San Francisco Bay faced last summer. These harmful blooms impact the functioning of the ecosystem and can be deadly for animal and plant life. 

So how do these issues get solved? The stormwater and wastewater infrastructure is already in place, and it’s not exactly feasible to rip them all out and start over. At the end of the day, “unless we’re making huge financial investments to upgrade what’s already there now, we won’t see much improvement,” Choksi-Chugh tells us. Placing importance on upgrades and changes to infrastructure is pivotal, and an example of this is just up the coast, in Vancouver. They’ve implemented a generational project called the Healthy Waters Plan “consisting of a long-range sewage and rainwater management plan to address a range of key issues, including:

Pollution from combined sewer overflows (CSOs), which occur when combined sewers are over capacity causing a mixture of rainwater and sewage to release into Burrard Inlet and other water bodies. Many pipe systems in Vancouver still transport rainwater and sewage in the same pipe. The need for increased sewer capacity to accommodate population growth and development. Sewage includes all water that goes down the drain from household, industrial, and commercial activities. Pollution from rain that lands on streets and other hard surfaces, picking up dust from vehicle tires and brakes, and other pollutants. This is also known as urban rainwater runoff. Climate change impacts on our sewage and rainwater system, including more frequent and intense rain events, prolonged drought, and sea level rise Aging infrastructure in need of repair or replacement”

The Baykeeper has a similar plan that they’re helping implement through litigation in the city of San Jose. Together, they are working to implement more green infrastructure throughout the city. Choksi-Chugh mentioned the effectiveness of green infrastructure in San Francisco during the recent atmospheric river events, “The few places that have done green infrastructure projects experienced really cool outcomes where they didn’t see a lot of damage or flooding – it’s important to think about it at a larger scale and push cities to install more of this type of infrastructure.” 

Aside from green infrastructure, Choksi-Chugh says another solution could be community-led action. The Baykeeper would love to see all parties come together to protect the Bay watershed. This includes a push for federal and state investment in infrastructure upgrades, more advanced wastewater treatment and recycling, and upgrading the current stormwater system. 

As organizations, like Baykeeper, advocate for bigger, more institutional changes, it’s worth noting that sampling for recreational water quality actually plays an intricate role in understanding the health of any waterbody. At Swim Drink Fish, we use swimming as an indicator of a healthy waterbody. The prevalence of unpredictable weather helps underscore the importance of year-round sampling. 

If you’re interested in learning more about the data we collect from affiliates all around the globe, it’s publicly available on our Swim Guide platform. There you can find the latest data, pass or fail rates, and even find swimmable locations near you. 


Author: Walter Cook