Ashley Overhouse

California’s wetlands need some love on February 2, World Wetlands Day. In California, marshes and seasonal vernal pools in the Central Valley support imperiled species such as the giant garter snake, riparian trees and migrating birds along the Pacific Flyway. The San Francisco Bay-Delta Estuary – the West Coast’s largest – is also a critically important wetland complex, where freshwater tributaries come together to form tidal wetlands that serve as unique habitat for native fisheries.  

Mokelumne River near confluence with the San Joaquin River in the Sacramento-San Joaquin Delta, CA
The Mokelumne River  in the Sacramento-San Joaquin Delta, California.

Wetlands serve as nature’s sponges. These freshwater habitats capture water for underground aquifers and naturally detoxify water above ground by filtration through vegetation. Wetlands also have high water storage capacity. In times of high rainfall, as we have had this winter, they are naturally designed to help stormwater retention and keep soil in place on the coast during storm surges.  

Wetlands make our environment – for both wildlife and people – more resilient to the climate extremes our state is facing. Yet, only 10 percent of California’s once flourishing system of complex waterways remains. Agricultural draining and diking in the mid-1800s and subsequent urban sprawl all contributed to the sorry state of our wetlands.  

Wetland in California

Wildlife refuges across the state, again, did not receive their mandatory minimum water allocations under a 1992 federal law. With a base release of only 18 percent of required refuge water supplies last fall and now a series of strong storms, it is clear wildlife and their habitat have faced additional challenges.  

In the Central Valley, supply cannot meet the state’s demand for agricultural and urban water supplies and nearly a quarter of the nation’s food production - let alone the legal share for wildlife.  

With water allocations cut, hundreds of wells drying up across the state and now entire communities underwater, this moment must be a wake-up call.  

Lawmakers must expand protected wetlands to help California residents build resilience and flexibility to the climate extremes. Absent such action, these periods of severe drought and floods will continue to wreak havoc. 

We need to use this moment to work together to expand wetlands in the Central Valley.  

Wetland in California with algal bloom

As a member organization of the Central Valley Joint Venture, Defenders of Wildlife coordinates with state and federal agencies, corporations and other conservation groups to advocate for the full implementation of legal water supply mandates.  

Some of this work includes population targets and species assessments via the 2020 Central Valley Joint Venture Implementation Plan to incorporate new science and identify the modern constraints of water availability in the region. The Plan estimates that an additional 285,000 acres of semi-permanent wetland habitat is needed to prevent further decline of species. That is approximately the size of Los Angeles. A tall order, but one that California and the Federal Government can afford and must prioritize. If this past year has taught us anything, it's that we need more wetlands, as soon as possible. Lawmakers need to ensure critical groups like Joint Ventures are empowered and funded to help make this goal happen.  

For World Wetlands Day 2023, please join us as we celebrate this year’s theme of “wetlands restoration” by urging lawmakers to make that vision a reality in California. Our landscape, wildlife and communities can no longer rely on only 10 percent of inland wetlands in the face of the climate crisis. 



Ashley Overhouse

Ashley Overhouse

Water Policy Advisor
Ashley is the Water Policy Advisor for Defenders’ California Program and engages on a variety of issues statewide, including water transfers, water rights and the enforcement of environmental laws.

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