Groundwater quality monitoring wells are monitored for a variety of parameters depending on their location in the groundwater basin. Most wells are monitored for common groundwater constituents such as calcium, sodium, and iron. Other wells are monitored primarily for nitrate or chloride. Additional constituents, such as organic solvents or gasoline additives, are monitored in some areas also. The type and frequency of monitoring depends on the well location, historic and current land use, and the availability of groundwater data in the area.

Samples are collected on different schedules. Some wells are sampled quarterly and others are sampled annually, depending on the constituents that are being monitored.

The water district is not the only organization that conducts groundwater quality monitoring in Santa Clara County. Public water suppliers monitor their wells regularly to ensure the water meets applicable water quality standards. In addition, responsible parties and property owners conduct groundwater monitoring at contamination sites to evaluate the extent and severity of contamination, and to monitor the effectiveness of their cleanup efforts.

Results
Groundwater quality in Santa Clara County is very good. Cleanup is ongoing at a number of contamination sites and elevated nitrate concentrations have been observed in some areas. However, these problems are being managed. Public water supply wells throughout the county deliver high quality water to consumers, almost always without the need for treatment.

Additional information
If you would like additional information on the water district's groundwater monitoring program, you can contact Randy Behrens, (408) 265-2607 ext. 2642 or Mark Merritt, (408) 265-2607 ext. 2229.