Why you might notice empty percolation ponds this fall in South San José

If you’ve walked, biked, or jogged along the Guadalupe Creek Trail adjacent to Coleman Road, you’ve likely noticed a collection of percolation ponds west of the path. These ponds have been full for months, but starting Sept. 29, you may see them temporarily empty.

This short pause will allow Valley Water crews to perform routine maintenance at Los Capitancillos Ponds, a system of 11 recharge ponds that replenish our groundwater supply. Crews will prune trees, clear dead branches, and remove overgrown vegetation to keep the ponds working efficiently, allowing water to seep through the sandy soil and recharge the aquifers beneath us. The Guadalupe Creek Trail will remain open, but please keep a safe distance from crews while they work.

During this maintenance period, water deliveries to Los Capitancillos will be paused, which will also affect nearby ponds, including:

• The Alamitos Percolation Pond at Valley Water’s headquarters, to the east of Almaden Expressway
• A smaller mitigation pond at Valley Water’s headquarters near Almaden Expressway and Blossom Hill Road
• The Guadalupe Ponds near Sanchez Drive and Blossom Hill Road

Percolation ponds may look like simple basins, but they play a vital role in our water system. Santa Clara County’s underground aquifers hold more water than all 10 of our surface reservoirs combined, supplying more than 40% of the county’s water. Thanks to recent wet years and a strong recharge program, our groundwater basins are in good shape. In fact, over the past two years alone, Valley Water has directed more than 200,000 acre-feet of water into these aquifers. That’s a lot of water quietly stored underground for when we need it most.

The maintenance at Los Capitancillos will be completed soon, and many of our ponds across the county, from Cupertino to Campbell to Morgan Hill, remain filled and hard at work recharging groundwater. By taking time now to care for these facilities, we’re ensuring they’ll continue doing their job for decades to come.

So, if you see an empty pond or two this fall, know that Valley Water is giving them a little tune-up. Our water future depends on it.