Snapshot Day

Snapshot Day is the oldest and largest single-day annual water quality monitoring event in California.

On the first Saturday in May each year hundreds of volunteers join the Coastal Watershed Council and Monterey Bay National Marine Sanctuary staff to take a “snapshot” of the health of rivers and streams flowing into the Sanctuary.

This favorite event draws people of all ages from all over California’s Central Coast to collect scientifically valid water quality data and to learn more about their local watersheds. Data from field measurements and lab analysis are collected and analyzed to determine the biggest threats to water quality and best management practices to address them.

A family tradition

Since 1999 volunteers have been testing water quality for Snapshot Day. That’s nearly two decades of water quality monitoring that gives Santa Cruz and surrounding counties a look into what’s affecting the health of rivers, creeks, streams and the Monterey Bay. Over the years, volunteers have signed up time and time again to participate in this beloved event.

“When I first heard about Snapshot Day in early 2003 my son and I signed up to volunteer – he was interested in playing in creeks and I was looking to pass on my adoration of the outdoors to my family. Our baby Natalie soon joined the family and my wife and daughter both came along to the next Snapshot Day. Circumstances moved us away from Santa Cruz to the Chico area, but year after year we made the family trip down to Santa Cruz for Snapshot Day. Little did I realize how “our baby” Natalie would take to monitoring like she was born doing just that. In 2015, Natalie was even interviewed on the news at Snapshot Day! She will never forget that experience. I cannot tell you how proud I am of both of my children to be volunteers with CWC and how willing and caring they are to travel 250 miles each way in order to help others keep their water clean.”

— Gary Smith and his daughter Natalie

Connect with your inner scientist

As a Snapshot Day volunteer you’ll be trained by professional scientists to monitor temperature, dissolved oxygen, pH, electrical conductivity and transparency in the field. You’ll also learn how to properly collect water samples for laboratory analysis of nutrient and bacteria levels. The valuable data collected by Snapshot Day volunteers is used to drive action for clean water. Together with local experts and our partners in government, CWC uses that data to drive improvements in our stormwater infrastructure and also manage erosion and stormwater runoff which are threats to clean water.

18th Annual Snapshot Day: May 6, 2017








volunteer testing water quality

Dig in!

In nearly two decades of water quality monitoring on California’s Central Coast, we’ve collected a lot of data. You can dig in to some of this data in the reports below, including a multi-year report demonstrating trends from 2000-2013. To see a full list of CWC water quality reports, visit our Resources page today.

Create your own Snapshot Day story

You too can be a part of Snapshot Day. Mark your calendar for the first Saturday in May each year to save the date. The next Snapshot Day will be happening on Saturday, May 6th, 2017 and we’d love for you to be a part of it.

Snapshot Day Volunteer Sign Up