The 19th Annual Snapshot Day took place on Saturday, May 5, 2018. Led by the Coastal Watershed Council, volunteers from Santa Cruz joined volunteers across the Central Coast in studying water quality in local streams running to the Monterey Bay and nearby ocean waters. During the event, 60 volunteers visited 41 sites from Año Nuevo Creek to Corralitos Creek to get an annual “snapshot” of water quality in Santa Cruz County.

At each site, volunteers gathered important data on different water quality parameters like dissolved oxygen, pH, E. coli, nitrate and orthophosphate. Monitoring results were then compared to water quality objectives (WQOs), standards set by the EPA and other regulatory agencies for good water quality, and to outcomes from previous Snapshot Day monitoring. CWC compiled the methodology, WQOs and monitoring outcomes in the annual Snapshot Day Report.


Compared to previous years, Snapshot Day 2018 findings indicate an increase in common human-caused pollutants, particularly in urban streams. Orthophosphate, a naturally occurring nutrient which spikes in stream waters due to fertilizers, soaps and sewage, was measured above the orthophosphate WQO in 34% of all sites sampled during the event. That is an increase from the 7% of sites that exceeded the WQO in 2017. E. coli and Enterococcus, harmful bacteria that indicate the presence of human and non-human feces in water, exceeded the WQOs at 15% and 22% of sites, respectively. Based on high bacteria levels, certain urban streams were identified as potential hotspots of pollution. Volunteers measured high E. Coli levels in upper and lower Arana Creek. Water samples collected at two sites on Pilkington Creek in the Seabright neighborhood exceeded the Enterococcus WQO eight-fold. Samples collected from multiple Carbonera Creek sites in Scotts Valley exceeded both E. coli and Enterococcus WQOs.

Snapshot Day data provides a “point-in-time” view of water quality data. Environmental data is highly variable and conclusions are difficult to make based on limited data points. Snapshot Day findings can help identify hotspots of pollution or problem areas and incite further study and remediation. Volunteers gather important data on the condition of historic stream sites and some sites that are only visited once a year. What we learn from Snapshot Day data can inform how municipalities manage water resources and the most important actions for residents to take to protect local streams.

Sign up below to download the full report. Please contact Alev Bilginsoy at with any questions.

Subscribe to Download Snapshot Day 2018 Report

Thank you to the dedicated 2018 Snapshot Day volunteers that made our 19th year of monitoring possible. Many thanks to the City of Santa CruzCity of Scotts Valley and County of Santa Cruz for their support of community science monitoring and to our events sponsors: Balance Hydrologics, New Leaf Community Markets and Whole Foods Market.

Save the date for the 20th Annual Snapshot Day on Saturday, May 4, 2019. Sign up below and reserve your spot on a Snapshot Day Team.


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