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Groundwater Studies

Zone of Benefit Study
The water district protects and replenishes local groundwater supplies to ensure water supply reliability for Santa Clara County. Management of the sustainable groundwater supply is funded by groundwater charges, which are applied to groundwater pumpers within zones benefitting from district activities. These activities include replenishing groundwater with local and imported surface water, monitoring and protecting groundwater from pollutants, and constructing, operating, and maintaining facilities that help sustain groundwater supplies.

The district is currently conducting a study to evaluate the extent of the zones of benefit to ensure they accurately reflect the areas receiving benefit from district activities to protect and replenish groundwater. The study is not evaluating the rates that are charged within the zone of benefit. This study will provide the district with a scientific, transparent basis for proposing changes to the current zones of benefit, if necessary.

Salt and Nutrient Management Plans

The district lead the effort to prepare Salt and Nutrient Management Plans (SNMP) for the Santa Clara and Llagas Groundwater Subbasins in Santa Clara County. This stakeholder-driven process assessed all salt and nutrient loading in the subbasins to evaluate existing and projected future assimilative capacity, as required by the State Water Resources Control Board 2009 Recycled Water Policy.

Santa Clara Subbasin SNMP

Llagas Subbasin SNMP

Recycled Water Irrigation and Groundwater Study (August 2011)
The district initiated this multi-year study in 2007 to advance water district policies of aggressively protecting groundwater and supporting recycled water development in Santa Clara County. The goal of this study was to evaluate the potential effects of recycled water used for irrigation on groundwater quality and to identify best management practices to protect groundwater quality. The study included laboratory testing of soils irrigated with recycled water and an 18-month field study at a site using recycled water for irrigation.

Individual report volumes (including appendices) are also available below:

Groundwater Vulnerability Study (October 2010)
The goal of this study was to predict the vulnerability of groundwater to potentially contaminating land use activities to allow the District to prioritize groundwater protection efforts and resources on the most vulnerable areas, evaluate groundwater quality impacts from land use changes, and provide information to decision makers at the District, land use agencies, and regulatory agencies to improve groundwater protection.

City of San Jose South Bay Water Recycling Groundwater Data Evaluation (2008)
The district conducted an evaluation of 10 years of groundwater quality data in an area where recycled water is used for irrigation in the Santa Clara Subbasin. This study assessed the presence of water quality trends prior to and following the use of recycled water.

Study of Potential for Groundwater Contamination from Past Dry Cleaner Operations in Santa Clara County (2007)
This study ranked current and historical dry cleaner sites according to their potential to impact groundwater quality to help prioritize dry cleaning sites for further investigation. The study catalogued the locations and years of operations for current and former dry cleaning operations in Santa Clara County and explored past operational practices, groundwater subbasin vulnerability, and municipal supply well vulnerability to develop a system to rank the relative risk of groundwater contamination from dry cleaner solvent releases.