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Palo Alto tide gates, which prevent flooding in low-lying areas on peninsula, to be replaced

June 22, 2020
Palo Alto flood basin tide gates

Pictured above: The Palo Alto Tide Gate Structure, which are a valve between the creeks and the bay; keeping bay water out when the tide is high and letting creek water out when the tide is low, is 63 years old and needs to be replaced.

Driving on Highway 101 from the South Bay, up the Peninsula, commuters zoom by nearly invisible infrastructure keeping the highway and nearby communities dry. Beyond the highway, at the edge of the San Francisco Bay, are levees and tide gates protecting roads and neighborhoods against high tides and storm flooding. Unless you visit the bay lands to walk the levee trails, you might never know these important structures exist.

In 1957 Valley Water, City of Palo Alto, and the County of Santa Clara constructed the current tide gate structure to prevent flooding of the low-lying areas of Palo Alto around Matadero, Adobe, and Barron Creeks that would otherwise have happened during storms and high tides. The levee surrounds a 600-acre basin – the Palo Alto Flood Basin – that holds creek water away from nearby homes, businesses and Highway 101 during storms. The gates are a valve between the creeks and the bay; keeping bay water out when the tide is high and letting creek water out when the tide is low.

The Palo Alto Tide Gate Structure is now 63 years old, has had a long life of service, and needs to be replaced.

Retiring and replacing important infrastructure can be complicated. Valley Water is taking into consideration a variety of factors, including:

  • the sensitive habitat in the area that supports migrating and local birds, fish, and mammals;
  • future sea level rise;
  • recreational access to the levee trail and public safety around a large construction project;
  • keeping the existing tide gates working while building the new tide gate structure;
  • and designing the whole system to also provide critical flood protection in a future of changing climate.

This important project is also working around challenging circumstances. Valley Water will work to protect endangered species by timing activities to have the least impact on breeding and nesting birds. For this project, that means construction during the wet season. But to build the new tide gate structure, crews will need to isolate the work area and pump out the water, which is harder to do in rainy weather.

It’s important that access to the beauty and recreational opportunity of the Bay Trail is maintained. But an active construction site on the levee trail is not compatible with public safety, so a detour is planned.

Design and planning processes have many steps: data collection, conceptual design, preliminary design, environmental review, final recommended design, then final approved design. The process includes public input, working with regulatory agencies, partnering with local governments and selecting qualified contractors. Once the replacement tide gate structure has been designed and approved, the construction process will take about four years of winter-season construction to complete.

Flood protection will be in place during the project. The final tide gate structure will keep homes, businesses, schools and Highway 101 safe and dry during storms and rising seas and ensure continued protection of existing habitat and the walking trail.

We hope you will join us for a virtual public meeting via webinar on Wednesday, June 24 at 5:30 P.M. We will share information about the Flood Basin, the Tide Gate and the envisioned project. Participants will have an opportunity to ask questions and provide comments. The meeting will be hosted on Zoom at The meeting will also be streamed live at If you would like more information on the project, please visit

Valley Water manages an integrated water resources system that includes the supply of clean, safe water, flood protection and stewardship of streams on behalf of Santa Clara County's 2 million residents. The district effectively manages 10 dams and surface water reservoirs, three water treatment plants, an advanced recycled water purification center, a state-of-the-art water quality laboratory, nearly 285 acres of groundwater recharge ponds and more than 294 miles of streams. We provide wholesale water and groundwater management services to local municipalities and private water retailers who deliver drinking water directly to homes and businesses in Santa Clara County.