In summary

Audubon reviewed eight groundwater management plans and found that they fell short in their consideration of managed wetlands.

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By Samantha Arthur, Special to CalMatters

Samantha Arthur is the Working Lands Program Director at Audubon California and serves on the California Water Commission,

When the first European explorers arrived in California’s Central Valley, they found a vast mosaic of seasonal and permanent wetlands, as well as oak woodlands and riparian forests. What remains of those wetlands are still the backbone of the Pacific Flyway; along with flooded agricultural fields, they support millions of migrating waterbirds each year. 

According to a just-released study from Audubon, tens of millions of land birds rely on the Central Valley as well, including 60% of all Tree Swallows, 40% of Anna’s Hummingbird and other backyard favorites.

But today, the situation is dire. More than 90% of wetlands in the Central Valley – and throughout California – have disappeared beneath tractors and bulldozers. So it’s not surprising that multiple studies show a similar decline in bird populations that depend on them, in California and beyond. 

The number of birds in North America has dropped by one-third over the past 50 years, likely due in large part to loss of suitable habitat, at the same time Audubon research shows that remaining birds face an uncertain future as the continent warms.

That precipitous decline makes remaining Central Valley wetlands even more important. Birds migrating through the Central Valley today must rely on scattered patches of wetlands across a landscape of agriculture and urban development. 

Central Valley wetlands are managed wetlands and are, therefore, tied in closely with state and local water management systems and management decisions. Because of the damming of California’s rivers for development, agriculture and flood control, wetlands in the Central Valley are disconnected from natural water sources and maintained through applied water. Surface water delivered through a series of aqueducts and canals or groundwater pumped from local wells is applied to shallow ponds to create flooded wetland habitat.

In 2014, in the midst of a historic drought, the California Legislature passed the Sustainable Groundwater Management Act to finally bring California on par with other western states, requiring sustainable groundwater management by 2040. Local agencies are now required to develop plans to chart a course to 20-year sustainability in overtapped basins. If these plans meet the requirements of the groundwater management act regulations, they will include robust stakeholder participation, integrate climate change projections, and address the impacts of overpumping on ecosystems and water quality.

The first set of plans were submitted to the state in January 2020 for critically overdrafted basins, primarily in the San Joaquin and Salinas valleys. Audubon reviewed eight of these plans that included large managed wetland complexes and found that they largely fell short in their consideration of managed wetlands. Several plans didn’t accurately identify managed wetland areas and seven of eight plans did not include managed wetlands as a distinct water use sector in their water budgets, as required by groundwater management act regulations.

State oversight is needed by the Department of Water Resources and the State Water Resources Control Board to ensure that California’s last, precious wetlands are protected in the process of long-overdue water management fixes. As local groundwater sustainability agencies implement groundwater allocations to curb overpumping, managed wetlands that rely on groundwater need consideration as a public trust resource, and the state should ensure they have adequate water supplies.

Central Valley wetlands provide habitat to millions of migratory birds and public lands for all Californians. Groundwater, often overlooked even as it sits under our feet, sustains key areas of California’s decimated wetlands. These wetlands need reliable water supplies, both surface and groundwater, to provide benefits to birds and people.  

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