Zone 7 begins autumn groundwater recharge in Pleasanton and Livermore

Hydrologists at the Zone 7 Water Agency initiated their annual autumn groundwater banking operation on Friday morning, opening diversion gates along the Arroyo Mocho and Arroyo Valle channels to deliver 6,400 acre-feet of treated surface water into the Livermore-Amador Valley aquifer basin. Operating from the agency's North Canyons Parkway control center in Livermore, water resources engineers are routing excess South Bay Aqueduct allocations into the Chain of Lakes percolation ponds between Pleasanton and Livermore before winter storm runoff occupies channel capacity. The managed recharge campaign is designed to raise regional water table elevations by four to six feet across the central basin prior to the start of the 2027 dry-season pumping cycle.

To maximize infiltration rates across the gravel beds along Stanley Boulevard and El Charro Road, field crews spent the past three weeks grading sediment layers from twelve recharge cells and installing fiber-optic piezometers that report real-time subsurface percolation velocity every fifteen minutes. The new sensor array allows operators to alternate wetting and drying cycles across individual ponds, preventing silt crusting while protecting adjacent riparian willow habitats along the Livermore Area Recreation and Park District trail network.

Retail water providers Served by Zone 7—including the cities of Livermore and Pleasanton, the Dublin San Ramon Services District, and the California Water Service Company—rely on the underground basin as a drought buffer capable of holding more than 120,000 acre-feet of operational storage. Water quality chemists confirmed that all recharge flows pass through ozonation and granular activated carbon filtration at the Del Valle Water Treatment Plant before entering the spreading basins.

Agency directors will present the first weekly infiltration telemetry report during the Wednesday, November 4 board meeting at 100 North Canyons Parkway in Livermore. Residents and trail users walking near the Arroyo Mocho and Shadow Cliffs levees can view live aquifer storage gauges and seasonal flow advisories on the Zone 7 Water Groundwater Management Portal.