In summary

The Department of Water Resources should enhance groundwater protection with changes to California’s Sustainable Groundwater Management Act.

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By Jeanette Howard

Jeanette Howard is the director of the freshwater science team at The Nature Conservancy, California,

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Melissa M. Rohde

Melissa M. Rohde is a groundwater scientist at The Nature Conservancy, California,

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Barton H. Thompson, Special to CalMatters

Barton H. Thompson is a senior fellow of the Woods Institute for the Environment, and faculty director of Water in the West at Stanford University,

While California’s landmark Sustainable Groundwater Management Act promised comprehensive protection of the state’s groundwater, significant gaps remain in its coverage. 

The Department of Water Resources now has an opportunity to reduce or eliminate those gaps and should seize the moment. We know all Californians will experience another year of water shortages and warmer, drier conditions that will require conservation and which are likely to fuel destructive wildfires in our forests and around our communities.

We are all in this together. Groundwater is critical for California, particularly in dry years when it provides up to 60% of the water supply for farms and people.  But a recent Stanford Water in the West publication, “Mind the Gaps: The Case for Truly Comprehensive Sustainable Groundwater Management,” finds that the groundwater management act currently protects less than 2% of our groundwater. While it covers those groundwater basins where the vast majority of pumping occurs today, it does not protect many important groundwater sources. This leaves the majority of our groundwater at risk of over-pumping, now and in the future, with no state oversight to safeguard rural domestic wells, sensitive habitats and other beneficial uses of water.  

The Sustainable Groundwater Management Act claims to protect all groundwater. In practice, however, it authorizes local management only in “basins” that the Department of Water Resources defines and inventories in a technical document titled “California’s Groundwater,” (formally “Bulletin 118”). The groundwater act, moreover, requires local management only in those basins that the department ranks as high or medium priority. How the Department of Water Resources defines and prioritizes basins is therefore critical to the groundwater act’s effectiveness.

Until now the department has inventoried only large alluvial basins, primarily found in the Central Valley and in coastal counties such as Santa Cruz, Monterey, Ventura and Los Angeles. While this covers the most populous and agriculturally-intensive regions, it does not protect beneficial uses of groundwater that lie outside these alluvial basins. 

About 40% of all wells are found in the Coastal and Sierra mountains that overlie fractured rock or volcanic aquifers. While accounting for only 6% of the state’s total groundwater extractions, these wells can cumulatively deplete local streamflow and reduce local access to drinking water. 

The Department of Water Resources has noted that wells in these areas experience reduced production in summer months when demand is greatest. Also, increased wildfire frequency and intensity over the past decade is raising concerns that groundwater deficits may be contributing to increasing water stress for forests. The Department of Water Resources, however, labels these regions as “non-basin areas,” denying groundwater act protection to the underlying aquifers. The Department of Water Resources also does not define alluvial basins in a way that guarantees protection of brackish groundwater, which is increasingly usable by farms and cities.

In setting basin priorities, the department currently focuses on the degree of human groundwater use. It awards higher priorities to basins with large populations, numbers of wells, acres of irrigated agriculture and groundwater reliance. As a result, local agencies are not required to develop groundwater sustainability plans for many remote desert basins that can be unsustainable at even low levels of pumping.

The Department of Water Resources currently has an opportunity to improve the groundwater act’s coverage via a new draft of California’s Groundwater (Bulletin 118) and is accepting public comments through April 26. 

The Department of Water Resources should consider several changes. First, it could delineate fractured rock or volcanic aquifers into discrete basins using watershed boundaries. This would give local governments the authority to engage in sustainable management planning and practices. The department could similarly require that usable brackish groundwater be included in the delineation of alluvial basins. Finally, the department could increase the priority of basins that, despite low extraction levels, are still vulnerable to pumping impacts because of low natural recharge rates. This would ensure that basins most sensitive to pumping, such as desert basins, are actively managed.

California needs proactive policies and planning that can build a more resilient water future throughout our state.  The Department of Water Resources can and should enhance groundwater protection through changes to California’s groundwater law. If the Department of Water Resources does not act, the Legislature ultimately might need to amend or supplement the Sustainable Groundwater Management Act to close the existing gaps in coverage and ensure sustainability. 

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