Groundbreaking Nature Conservancy Study & Interactive Online Maps Reveal Drinking Water Sources for 25 Million Californians

Statewide website puts source-to-tap info at fingertips for residents of 492 cities & towns

SAN FRANCISCO, Oct. 12, 2012 /PRNewswire-USNewswire/ -- The Nature Conservancy in California today unveiled a groundbreaking study and online resource that for the first time offers millions of Californians a one-stop website where they can learn the sources and levels of protections of their drinking water.

The "Where Does California's Water Come From?" study is the most extensive and detailed ever done on where the state's surface water originates and how protected the land is in the watersheds that supply it. Eighty-two percent of the water supplied by public water districts for domestic and other uses comes from rivers, lakes, reservoirs and other surface water sources.

Overall, California requires nearly 157 million acres of land and multiple watersheds spanning eight states to collect and deliver drinking water. While water sources vary from city-to-city, much of our in-state surface water originates in the snowpack of the Sierra Nevada, whose runoff into rivers and streams provides drinking water to 65 percent of Californians.

"The study is the first to aggregate California's drinking water information at such a large-scale, and in an interactive and user-friendly way," said Kirk Klausmeyer, a San Francisco-based Nature Conservancy scientist and co-author of the study. "The maps enable residents across the state to understand the status of their local water sources, a key first step in taking action to protect these vital resources."

Although clean, healthy water is widely acknowledged as California's "most precious resource," integral to residents' well-being as well as to the state economy, tracking down water source information has frequently been a burdensome process. Information on California's drinking water sources was often separated into unique watersheds and managed by different entities, making it difficult for consumers to find clear and easily accessible information on where their water comes from.

Now, both in the study and in interactive features at the Conservancy's new California website,, millions of Californians for the first time are able at one site to track the path of their water from source to tap. Twenty-five million Californians in nearly 500 California cities and towns across the state can type in their city and click through screens that feature photos, data and interactive maps on where their water originates. At the site, they can also read the data and analysis contained in the study itself, and take a "Think You're an Expert?" quiz to test their water knowledge.

The site is a growing resource with additional cities and towns being added regularly, expanding the data base and the number of watershed maps to reach even greater numbers of Californians.

The study found that only 16 percent of the watersheds that supply drinking water to Californians are fully protected from human threats. A little over half of the watersheds are under public management and have some level of protection. The remaining third is privately owned with variable levels of protections. Cities and towns around the state vary greatly in the level of protection found in their watersheds—from 27 to 89 percent.

Klausmeyer said that he hopes the study helps illuminate for California consumers not only how far their water travels from source to tap, but also how vital the state's water supply is—and how vulnerable.

"Trees help keep sediment and pollution from flowing into our waters, and help to slow down rainwater, allowing more water to seep into underground water supplies," he said. "Improved land management of Sierra forests, grasslands and river-adjacent 'riparian' habitat will enhance state water resources."

The full name of the study is "Where Does California's Water Come From? Land conservation and the watersheds that supply California's drinking water." The study draws together National Hydrology Datasets, State Department of Public Health Drinking Source Assessments, and 2010 Census information—all to create a standardized, user-friendly examination of Californians' drinking water sources.

The Nature Conservancy is a leading conservation organization working around the world to protect ecologically important lands and waters for nature and people. To date, the Conservancy and its more than one million members have been responsible for the protection of more than 18 million acres in the United States and have helped preserve more than 117 million acres in Latin America, the Caribbean, Asia and the Pacific. Visit The Nature Conservancy on the Web at

SOURCE The Nature Conservancy