The Tulare Lake Basin and Salinas Valley were chosen as pilot study areas because communities in these regions are faced with the need to manage high nitrate loads from agricultural lands and dairies, have a high risk of exposure to nitrate contamination in groundwater, and often cannot afford treatment or alternative water supply options. These factors combine to make the Tulare Lake Basin and Salinas Valley highly susceptible to health effects from nitrate in drinking water.
There are 371 active community public water systems (CPWS) and 30 state small water systems (SSWS) in the study area (281 and 120 in the Tulare Lake Basin and Salinas Valley, respectively). These systems supply water to about 2.4 million people. An estimated additional 245,490 people in these regions get their drinking water from an estimated 74,400 private domestic wells (self-supplied households or local small water systems with fewer than five connections) that are unregulated and largely unmonitored.