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once over-drafted groundwater basin has recovered to levels that are
stable and sustainable.
Figure 1. Long-term hydrograph showing past overdraft, then recovery
following implementation of conjunctive use operations.
After chronic overdraft for over 40 years, implementation of conjunctive use actions
has resulted in reversal of the downward water level trend. Water levels declined
during California’s 2014-16 drought, but recovered under wetter hydrologic
conditions in 2017-18.
Tested During Drought
California’s recent historic drought served to expand and
deepen the region’s commitment to conjunctive use and prompt a
renewed focus on long-term water reliability planning.
The 2014-15 drought hit the Sacramento region especially hard.
Folsom Reservoir, the primary water supply source for 500,000
people, fell to historic lows. Conditions were so dire that the U.S.
Bureau of Reclamation, which operates the reservoir, installed
portable pumps on barges as a standby option to continue providing
water for public supply. A winter storm lifted the region out of an
immediate emergency, and conjunctive use helped keep water
flowing to customers and down the American River for fish and
wildlife. During the drought, water providers successfully shifted
to using more groundwater, using 61 percent for supplies in 2014
compared to 45 percent in 2011 (a wet year).
The region also expanded conjunctive use infrastructure during
the drought with $10 million in emergency grant funding from
the California Department of Water Resources. Through RWA,
water providers had identified priority projects for funding that
would augment water supply and increase the region’s ability to
move water to areas most impacted by drought. Projects included
constructing or rehabilitating groundwater wells that increased
production capacity by about 15 million gallons per day (MGD), a
series of interconnections to enhance the region’s ability to transport
water between water districts by more than 50 MGD, booster pumps
Reservoir's top recreational option from boating to hiking.