Recent rains have not washed away the growing threat of water scarcity in the San Joaquin Valley, California’s largest agricultural region. Over time it could bring disruptive changes not only to the region’s farmers but also to rural communities, the local economy and the state as a whole. Resolving this problem will take creativity and cooperation.
While agriculture is a relatively small piece of the state’s economic pie, it’s vitally important in the Valley. The region’s farms are a nationally important source of produce and dairy. The Valley’s farm sector accounts for 25 percent of local revenue, 16 percent of local jobs – and 89 percent of annual net water use. Large parts of the Valley depend on unsustainable pumping of groundwater.
Our new research shows that over the past three decades, the region has been pumping nearly 2 million acre-feet per year more than what is being replenished – and much more during the latest drought. The result is sinking land and damaged infrastructure, drying wells in some rural communities, and declining reliability of this vital drought reserve.
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The state’s groundwater law will bring significant changes to Valley agriculture in coming years.
On top of water shortages, the Valley must also respond to related concerns, including nitrate contamination of groundwater and a broad decline in riverine, wetland and upland ecosystems.
It’s impractical to address these problems farm by farm. An “all hands on deck” approach and new levels of cooperation and coordination are needed. Here are some examples of promising approaches:
▪ Capture and store more local runoff. Increasing groundwater recharge by spreading more flood flows onto fields and into recharge basins is key to restoring depleted underground water basins. The Department of Water Resources estimates that about 300,000 acre-feet per year might be available for recharge.
▪ Jointly manage groundwater and surface water storage. Surface reservoirs have limited capacity to store water for dry years because they also need to make space every spring to capture flood flows. Storing more water in aquifers can free up space to capture larger flood flows in surface reservoirs and increase the total volume of water stored. Better coordination among federal, state and local water projects can also make it easier to take advantage of recharge opportunities.
▪ Explore multibenefit strategies. Groundwater recharge can be managed to improve water supply and quality. For example, alfalfa – an important food for the region’s dairy cows – can be watered more flexibly than most crops. When water supplies are short, farmers can reduce irrigation on alfalfa – then lease their excess water to others with reduced supplies. And in wet years, alfalfa fields can be ideal for recharging groundwater. Because it needs no nitrogen fertilizer – a source of nitrate pollution in water – alfalfa even has the potential to clean up groundwater in nitrate-contaminated areas.
▪ Foster urban-rural partnerships to bring basins into balance. Some partnerships already exist in recharging groundwater, supplying farms with treated wastewater, and upgrading infrastructure to manage water more efficiently. More can be done. Cooperation to protect recharge areas can be valuable, because many lands with good recharge potential are on the urban fringe. Cities can also help address problems of safe drinking water by connecting rural systems to larger, safer, more cost-effective urban systems where feasible.
Each of these examples represents opportunities to tackle problems using new partnerships and approaches. Perhaps one of the greatest challenges is developing cooperative strategies to seize these opportunities in a region with a complex mix of entities and institutions managing water and land. The entire San Joaquin Valley – and California as a whole – will benefit if solutions to the Valley’s problems support the economy while improving public health and environmental conditions.
Ellen Hanak is the director of the PPIC Water Policy Center and can be contacted at firstname.lastname@example.org. Sarge Green is a water management specialist with the California Water Institute at California State University, Fresno, and can be contacted at email@example.com. They are coauthors of a new PPIC report, Water Stress and a Changing San Joaquin Valley.