Surprising Levels of Pollution from two South Bay Cities

Mar 1, 2020
Sejal Choksi-Chugh
by Sejal Choksi-Chugh

During the last few rainy seasons, Baykeeper’s scientists spent many weeks scrambling down hillsides and wading into mud to collect water samples from storm drain outfalls. Our field team was looking for the source of pollution to South Bay creeks and rivers that feed into San Francisco Bay.

We got surprising results. The water samples from the cities of Sunnyvale and Mountain View contained bacteria pollution at levels 50 times higher than the legal limits. The samples revealed especially dangerous levels of E. Coli from raw sewage.

The runoff also likely contains other pollutants associated with sewage and stormwater, including petroleum hydrocarbons, heavy metals, microplastics, mold spores, pharmaceuticals, and numerous cancer-causing toxics.

We believe aging water infrastructure and inadequate pollution controls are the cause.

Many of the two cities' older clay sewer pipes are cracked and probably leaking raw sewage into the stormwater pipes. The cities also have inadequate urban pollution controls, so that contaminants flow freely from streets into storm drains.

This toxic stew runs directly into Stevens Creek, Calabazas Creek, Sunnyvale East Channel, and Guadalupe Slough, which empty into the south end of San Francisco Bay.

And sadly, wildlife is on the receiving end of Sunnyvale and Mountain View's polluted runoff.

Stevens Creek, for instance, is one of the last remaining viable fish habitats for the threatened Central California Coast Steelhead. Birds exposed to the pollution in the impacted areas include the California clapper rail, the western burrowing owl, and the western snowy plover.

City residents also face harm. Parks and trails, including the Bay Trail, near the polluted waterways are popular destinations—despite the fact that these beautiful neighborhood creeks may have toxic water that's unsafe for human contact.

So, in February, Baykeeper filed lawsuits under the Clean Water Act. We’re working to ensure Sunnyvale and Mountain View control this harmful pollution.

Fortunately, both cities have indicated a commitment to solving the problem.  Mountain View and Sunnyvale have said they want to do the right thing for the Bay and their residents.

We're now collaborating with the cities on a plan for stopping the flow of pollution to creeks and the Bay. We’ll be advising the cities to fix broken sewer pipes and install Bay-friendly green infrastructure that captures pollutants before they enter storm drains. These upgrades will also improve drought resistance by capturing more rainwater flow.

Stemming the flow of toxic pollution from Sunnyvale and Mountain View will reap benefits beyond just these two cities—for people and wildlife in every corner of the Bay.

Sejal's headshot by Gail Odom. 

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