Project overview: Determine which contaminants of emerging concern (CECs) are present in Yosemite, so we can understand the threat to human and aquatic health.

How your support helps: Contaminants of emerging concern (CECs) are substances found in everyday items, such as soap, medicine, clothing, water bottles, and bug spray. They cannot be removed by wastewater treatment plants, and knowledge of the presence and impacts of CECs is limited. Many CECs are harmful to humans and aquatic animals, but their concentration in the environment is often unknown due to difficulties sampling them and the recent recognition of their significance.

Technological advances now allow us to detect these compounds in the low concentrations in which they occur. A previous study determined CECs were common within Yosemite but didn’t provide the full scope of contamination in the park.

Outstanding water quality is one of the protected values of the Merced and Tuolumne rivers. Given that these watersheds are vitally important drinking-water sources for millions of people, establishing better knowledge of the occurrence of CECs and identifying the most common CECs in the park is essential. This study will direct future research efforts on CECs and help the park understand the size of the threat of CECs to human and aquatic health.

This year: With your support, in 2022, scientists at Sequoia & Kings Canyon National Parks would partner with Yosemite to deploy samplers at 10 sites for 30 to 40 days, and five sites for 60 to 80 days during the busy summer season. The study results will be uploaded to the National Water Quality Monitoring Council’s Water Quality Portal and presented at the Croaking Toad lecture series in the park.

Project partners: Yosemite National Park and Sequoia & Kings Canyon National Parks

Cat Fong

Physical Sciences and Landscape Ecology, Yosemite National Park

Project Notes

"Contaminants of emerging concern (CECs) are substances found in everyday items, such as soap, medicine, clothing, water bottles, and bug spray. They cannot be removed by wastewater treatment plants and knowledge of the presence and impacts of CECs is limited. Only recent technological advances allow us to detect these compounds in the low concentrations that they occur."