The results of the 20th Annual Snapshot Day are here!

During Snapshot Day 2019, 60 volunteers collected field measurements and water samples from rivers, streams and sloughs across Santa Cruz County. To determine the health of waterbodies sampled during Snapshot Day, CWC compares the results of field measurements and samples to water quality objectives set by regulatory agencies to determine if a waterway supports beneficial uses like swimming, irrigation or fishing. When a water quality objective is met, the water may be considered safe for those beneficial uses.

Snapshot Day 2019 findings:
  • Nutrient levels decreased relative to 2018. Nitrate and otrhophosphate are nutrients that occur naturally in the environment. However, human activities can elevate nutrient levels in local streams beyond normal levels. High nutrient levels can contribute to the growth of algae and cyanobacteria, particularly when they co-occur with low flows and ample sunlight. Some algae and cyanobacteria can release harmful toxins such as microcystin, which is toxic to humans, pets and wildlife. This year’s monitoring results showed that similar to last year, all sites in Santa Cruz County successfully met the nitrate water quality objective (WQO). For orthophosphate, 80% of sites met the WQO, an improvement relative to the 62% of sites that met the WQO in 2018.

Take action! Residents can continue to lower nutrient inputs to local streams by limiting the use of chemical fertilizers, reducing runoff from gardens and lawns, washing pets and cars in places where the wash water won’t run into a storm drain, avoiding outdoor use of phosphate-containing cleaners, and getting sewer laterals and septic tank systems inspected.

  • A majority of Santa Cruz County watersheds met bacterial WQOs. Water samples collected during Snapshot Day were analyzed for several kinds of fecal indicator bacteria, including total coliform, E.coli and Enterococcus. In particular, high levels of E.coli and Enterococcus can indicate human health risks due to the presence of human or animal feces in water. CWC compared Snapshot Day 2019 bacteria findings with updated state bacterial WQOs, which are standards designed to protect recreational water users from the effects of water-borne pathogens. We are happy to share that a majority of local waterbodies across the county met these water quality standards on Snapshot Day 2019. Specifically, 93% of sites met the total coliform WQO, 80% of sites met the E. coli WQO and 65% of sites met the Enterococcus WQO. Urban watersheds are particularly challenged by bacterial pollutants.
  • Four streams were identified as bacterial hotspots: Four streams in Santa Cruz County exceeded WQOs for both E.coli and Enterococcus, flagging them as potential hotspots for bacterial pollution. These streams include Arana Creek, Moore Creek, Pilkington Creek and Soquel Creek. 

Take action! Everyone can help to reduce bacteria sources in local waterways by implementing proven best management practices, such as inspecting sewer laterals or septic tank systems, cleaning up pet waste at home and on walks, and removing trash from local streets and storm drains.


Snapshot Day is the largest single-day water quality monitoring event in California. This year’s 20th annual event united community scientists to collect water quality data from local watersheds that flow into the Monterey Bay National Marine Sanctuary, including 40 stream sites in Santa Cruz County. Snapshot Day data provides a “snapshot” of regional water quality data on a given day. Environmental data is highly variable and conclusions are difficult to make based on limited and single “point-in-time” data points. However, Snapshot Day data can help identify pollution hotspots for further study or remediation and can also inform the development and implementation of best management practices by local residents, businesses and agencies. Data collected by Snapshot Day volunteers also contributes to a long-term water quality data set for Central Coast watersheds. In the coming months, the Monterey Bay National Marine Sanctuary plans to do a twenty-year trend analysis of regional water quality data.

Complete Snapshot Day results and methodologies are summarized in the Snapshot Day 2019 Report. Snapshot Day 2019 results can also be viewed in an interactive online ArcGIS story map developed in collaboration with volunteers Vai Campbell and Alex Johnson.

Thank you to all the Snapshot Day partners, supporters and volunteers that made this 20th year of water quality monitoring possible. A huge thank you to the Monterey Bay National Marine Sanctuary who has led Snapshot Day activities beyond Santa Cruz County and in partnership with CWC within Santa Cruz County since Snapshot Day began, 20 years ago. Many thanks to the City of Santa Cruz, City of Scotts Valley and Santa Cruz County for supporting this ongoing community science monitoring effort. Thank you also to our Snapshot Day 2019 sponsors: Balance Hydrologics Inc., Patagonia Outlet Santa Cruz, Whole Foods Market, Trader Joe’s, Charlie Hong Kong and Woodstock’s Pizza.

Save the date for the 21st Annual Snapshot Day on May 2, 2020! Sign up below to join the fun and reserve your spot on a Snapshot Day monitoring team.

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