Do you know what is in your stormwater?

During a rain event, an accumulation of rain drops hitting the sidewalks, roads and driveways collect and move particles downstream. This stormwater takes everything from dog waste, fertilizers, paint and soap and by the time it reaches local streams or the Monterey Bay National Marine Sanctuary, it can be a cocktail of household chemicals, bacteria from human and natural sources, trash and more.

Every year, the Coastal Watershed Council conducts First Flush, a water quality monitoring event to determine what in stormwater in the City of Capitola that’s heading down your street, into the drain, into Soquel Creek and the Monterey Bay. The monitoring event occurs during the first significant rain after a long dry summer, so the stormwater that we sample is filled with months of pollutant build up. This first flush data can give a good sense of what pollutants build up during the summer and what we, as watershed residents, should be working to reduce throughout the year.

For First Flush 2016, 19 volunteers bravely collected samples and ran field tests at Soquel Creek and nearby storm drains during an evening rainstorm in mid-October. Based on our monitoring we found that:

  • Residents in Capitola are doing a great job to keep nitrate levels in Soquel Creek low. Nitrate is a naturally occurring source of nitrogen, but high levels come from fertilizers and wastewater and cause harmful algal blooms, a rapidly growing problem in California.
  • Bacteria levels (measured as E. coli and Enterococcus) remain high at all storm drains and in Soquel Creek. While this is common for first flush events it’s a reminder of the opportunity to reduce bacteria coming from controllable sources. We can do this by picking up pet waste before a rain event, reporting smells and signs of leaking sewage and reducing litter.
  • Finally, some of the highest levels of zinc, copper and lead were measured at Creekside Storm Drain and the receiving waters of a Soquel Creek site nearby and the downstream Auto Plaza Storm Drain. While this could result from a range of nearby pollutant sources, notably these sites are right next to Cabrillo Highway; a good reminder that lead deposited from car exhaust, and zinc and copper from the wear and tear of brakes and tires can easily be transported into your waterway. Just one more reason to ride a bike when the weather’s nice!

Learn more about what you can do to care for your watershed in CWC’s Stewardship Toolkit. For more information please contact CWC River Scientist Alev Bilginsoy at


Read the 2016 First Flush Report Today!

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