Groundwater

Santa Clara County’s groundwater basins are an important but unseen part of our water supply. In fact, these basins hold more water than all 10 of our surface reservoirs combined, and nearly half of all water used comes from groundwater. Groundwater basins are naturally replenished by rainfall and other sources, but pumping far exceeds natural recharge. For many decades, Valley Water has managed groundwater and surface water to ensure continued sustainable water supplies.

As the groundwater management agency for the Santa Clara County, Valley Water works to safeguard groundwater by:

• Replenishing groundwater with local and imported surface water.
• Reducing demands on groundwater through treated surface water deliveries, water conservation, and water recycling.
• Monitoring groundwater and implementing programs to protect against contamination.

Valley Water's Annual Groundwater Report provides detailed information on recent groundwater conditions and activities.

• Download the 2023 Annual Groundwater Report (PDF 20 MB)

For other topics related to groundwater, please visit the links below:

• Sustainable Groundwater Management (including SGMA compliance)
• Groundwater Supply
• Groundwater Quality
• Groundwater Monitoring
• Well Information and Groundwater Elevation App
• Groundwater Studies
• Groundwater Benefit Zone Study
• Subsidence
• Free testing for domestic well owners
• Certified Laboratories