2024 Snapshot Day: Annual Volunteer Water Quality Monitoring Report

Since Earth Day 2000, volunteers have assembled on the first Saturday morning of May each year (except for 2020 due to the COVID-19 pandemic) to collect water quality samples from waterbodies entering Monterey Bay National Marine Sanctuary (MBNMS). This day, known as Snapshot Day, has become an annual event that has created partnerships, drawn over 3,500 volunteers, and has helped foster an ethic of watershed stewardship for local citizens. The 24 years of data collected by volunteers has become a valuable source of water quality data for the region. MBNMS and the California Marine Sanctuary Foundation organized Snapshot Day 2024 with regional support from the San Mateo Resource Conservation District, Morro Bay National Estuary Program, Watsonville Wetlands Watch, and the Coastal Watershed Council.

In 2024, volunteers ventured out on the morning of May 4th to watershed sites in four counties bordering MBNMS. On their journey to specific sites along creeks and rivers, volunteers carried with them sample equipment and bottles to collect water samples for laboratory analysis and field measurements at assigned sites. This year, 90 community scientists donated between four and six hours of their time to monitor 80 sites. Of the 76 sites with flowing water, all measured parameters at 21 sites (28% of sites) met all of the Water Quality Objectives (WQOs) or Action Levels.

Results reveal that pH was the most common field measurement and E. coli was the most common lab measurement that did not meet WQOs. pH measurements tended to be more acidic than objectives and did not meet the WQO at 39% of the sites where it was measured, compared to 40% in 2023 and 12% in 2022. E. coli concentrations exceeded the WQO at 43% of sites in 2024, compared to 22% in 2023 and 26% in 2022.

Twenty-three Areas of Concern, or sites that exceeded three or more WQOs or Action Levels, were identified this year, compared to 13 in 2023, 14 in 2022, 11 in 2021, and 12 in 2019. The 23 Areas of Concern for 2024 spanned 19 waterbodies in all four counties. This increase in Areas of Concern compared to previous years is most likely due to the high amount of rainfall that occurred in the latter half of the morning on Snapshot Day, flushing contaminants from urban and agricultural areas through the watershed into local streams.

The 24 years of data gathered by trained Snapshot Day volunteers are used to help resource managers focus attention on problem areas. Programs such as Snapshot Day are an important way for communities to connect to their local waterways and to inspire actions focused on improving water quality. Snapshot Day is used to inform public policy through inclusion of data collected by volunteers in the set of information used to determine 303(d) listing of impaired waterbodies by the Central Coast Regional Water Quality Control Board.

Key Words

water quality, citizen science, community science, Monterey Bay National Marine Sanctuary, Areas of Concern, watershed, contaminants