Valley Water refills ponds near Penitencia Creek Trail after repairs to concrete spillway

By Richard P. Santos, representative for District 3

Community members who use the Penitencia Creek Trail can once again enjoy water-filled percolation ponds near Toyon Avenue in San José.

In April, Valley Water drained two of the five Dr. Robert W. Gross Recharge Ponds along the trail to make repairs to an aging concrete spillway. Despite some challenges with late-season rain and the COVID-19 pandemic, Valley Water finished repairs to the spillway on July 2.

During construction, we maintained water in the three smaller ponds and installed a pump to divert water to the City of San Jose’s City Park Pond in Penitencia Creek Park, located next to the percolation ponds.

The newly poured concrete needed a few weeks to dry, and Valley Water began filling the two larger ponds on July 20. The ponds were gradually filled over the span of about one week.

I’d like to thank the public and trail enthusiasts for their patience as Valley Water made these necessary repairs. This work is part of Valley Water’s commitment to maintain our infrastructure in order to ensure a reliable supply of safe, clean water.

Percolation ponds are water supply facilities built strategically in areas throughout Santa Clara County where permeable material such as gravel and sand allow water to seep into our aquifers, which are essentially underground water basins. The ponds’ primary and most important purpose is to allow water to filter underground to maintain healthy groundwater conditions.

These groundwater aquifers store more water than all 10 of Valley Water’s surface reservoirs combined.

The ponds were not created to support wildlife, although many types of birds, fish and other animals take advantage of these ponds when water is available. When the ponds are dry, animals often find other nearby bodies of water to enjoy.

The Dr. Robert W. Gross Ponds are part of a system of 18 ponds in the northeastern part of the county. The system’s ponds and spillways allow water to flow from one pond to the other.

In the Penitencia Creek area, the various ponds are connected in a series so that there is a “cascading” effect. Once one of the ponds that make up the Dr. Robert W. Gross Ponds system is full, water flows to the next pond, and then the next, and so on downstream. The City Park Pond also received additional water through this cascading effect and filled up.

Although we are refilling the Dr. Robert W. Gross Ponds, other percolation ponds throughout Santa Clara County are dry, which means that the groundwater levels below them are healthy and don’t need recharging, a good sign for our water supply.

Our groundwater aquifers, which provide nearly half the water used in our county, are full and healthy. Santa Clara County residents’ diligent conservation efforts, as well as two robust rainfall seasons over the winters of 2017 and 2018, have allowed our groundwater levels to recover to pre-drought conditions.

I’d also like to ask the public to not place fish, turtles or other animals in the ponds, as all these ponds periodically go dry. And as a friendly reminder, please throw away your trash when visiting the ponds.

As always, I am available for questions or comments as your District 3 representative for the north San Jose and Berryessa communities; the northern areas of Sunnyvale and Santa Clara; Alviso and Milpitas. Feel free to contact me at (408) 234-7707.

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