Why We're Studying Groundwater in San José's Coyote Valley

We are at the beginning of our work to restore one of the Bay Area’s largest freshwater wetlands known as Laguna Seca in San José’s Coyote Valley. Earlier this year, we made significant progress in this effort to develop our understanding of one of the land’s most important natural resources: groundwater.

This work has critically important implications for both wildlife and humans. As a refuge for migratory birds on the Pacific Flyway, a site of significant groundwater recharge and a critical piece of flood protection for downstream San José, this landscape provides an essential “green infrastructure” and is a key part of ensuring the resilience of our region, especially in the face of a rapidly changing climate.

Reviving and restoring this ancient wetland has been a top priority since protecting this landscape with our partners at the City of San José and the Santa Clara Valley Open Space Authority (Authority). It’s a complex undertaking that will take time, collaboration and a strong reliance on the best available scientific data. We’re starting by developing a better understanding of the wetland’s groundwater, one of its most vital ingredient.

Photographs from the early part of the 20th century (above) provide some insight into what the Laguna Seca once was, its destruction and an inspiring vision of what it can be again. 

Lay of the Land

Understanding the history of this landscape has helped us to envision its future. We know from historical research conducted by our partners at the San Francisco Estuary Institute and the Authority that most of the water on the western side of Coyote Valley never moved through a defined channel or creek. Instead, the water slowed and fanned out across the landscape, creating a 1,000+ acre mosaic of wet meadows and ponds. Think of it as a complex of independent but interrelated parts and a hotspot for a wide range of life.

But a lot has changed in Coyote Valley in the last century. In early 1916, the Laguna Seca Reclamation District was formed to “reclaim” about 1,200 acres of wetlands and wet meadows, which were drained and subsequently burned to make room for a new booming industry in the valley — agriculture. To accomplish this, farmers installed a four-mile-long drainage canal that we now call Fisher Creek. Much of the water that once created habitat and recharged the aquifer in Coyote Valley was instead directed out of the valley and fed into Coyote Creek — exacerbating the flood risk for downstream locations in San José.

Despite these changes, some things in this landscape have remained the same. The movement of water in Coyote Valley still involves a system of interrelated parts. The Laguna Seca, Fisher Creek and Coyote Creek (controlled by the Anderson Reservoir upstream) are all a part of a collective whole. Generally, when water is low in Coyote Creek, for example, it’s low in Fisher Creek and the Laguna Seca, too. The inverse is also true. So, our understanding of groundwater in Coyote Valley will offer a small window into the balance of this larger hydrologic system — a closer pulse on the lifeblood of this living landscape.

The seven wells and nine subsurface instruments we installed this summer (pictured here) will provide the data needed to keep our finger on the pulse on this landscape’s most vital resource. 

Finding the Pulse of an Ancient Wetland

Earlier this summer, we drilled seven wells in Coyote Valley and installed nine subsurface instruments to monitor the land’s groundwater from season to season and year to year. We’re also monitoring water flow in nearby Fisher and Coyote creeks. As data is gathered over the next few years, we’ll get a clearer picture of the availability of this vital resource and what’s possible­ in this landscape in the years ahead.

Our investment in monitoring the Laguna Seca’s groundwater levels will also be essential as the Authority embarks on a science-and community-based planning process, which will include wildlife crossings and public access in addition to wetland restoration. Data will ensure we make restoration decisions that benefit key species for whom this is truly a last chance landscape, and help us appropriately balance recreation with sensitive habitat.

It’s the beginning of a new beginning for this ancient wetland.