LOCAL RAINFALL AND RESERVOIRS an Diego County’s semiarid SAN DIEGO COUNTY RESERVOIRS Sclimate means that truly wet years are few and far between, and ORANGE COUNTY dry years are very common. Since RIVERSIDE COUNTY 1976, the amount of local surface RED MOUNTAIN SAN DIEGO COUNTY water used to help meet annual RESERVOIR Fallbrook demand has been as high as 140,300 MORRO HILL 76 acre-feet and as low as 4,100 acrefeet. RESERVOIR Consequently, runoff from local rainwater LAKE HENSHAW that flows into reservoirs – commonly called 15 TURNER LAKE Vista surface water – represents a vital but small Oceanside 78 DIXON RESERVOIR LAKE MAERKLE LAKE WOHLFORD San Marcos portion of San Diego County’s water supply needs. Carlsbad Escondido SUTHERLAND OLIVENHAIN RESERVOIR Over the past 10 years, an average of about 8 RESERVOIR percent of the region’s total annual water supply Encinitas 5 LAKE HODGES SAN DIEGUITO LAKE RAMONA came from local surface water. San Diego County has RESERVOIR Solana Beach 15 LAKE POWAY CUYAMACA RESERVOIR not relied solely on its local water sources since 1947, Poway SAN VICENTE Del Mar 56 RESERVOIR when imported water flowed through the region’s first EL CAPITAN MIRAMAR RESERVOIR aqueduct, making Colorado River water available to RESERVOIR 805 Santee La Jolla fuel the region’s post-World War II growth. 52 67 LAKE JENNINGS LAKE MURRAY El Cajon 163 LOVELAND 8 ENHANCING WATER STORAGE La Mesa RESERVOIR 5 San Diego 94 MORENA RESERVOIR Lemon SWEETWATER oday, the Water Authority and its member agencies Coronado Grove RESERVOIR National City BARRETT LAKE have 24 reservoirs that store imported and local runoff 54 T Chula Vista LOWER OTAY water for normal use, emergency conditions and imported RESERVOIR water shortages. Combined water storage capacity now totals 905 approximately 723,000 acre-feet. This is a 30 percent increase Maerkle, Red Mountain and Morro Hill store MEXICO treated water and do not capture local runoff. since 2003, created by the Water Authority’s $2 billion Olivenhain Dam sdcwa.org APRIL 2021 waternewsnetwork.com @sdcwa Capital Improvement Program to improve the region’s Lindbergh Field water infrastructure. 14 13.60 12.93 12 12.70 12.73 A crucial component of this program is the $1.5 billion 11.91 10 Emergency & Carryover Storage Project, which created 8 8.18 7.90 new emergency water storage at the Olivenhain, INCHES 6.56 6 Hodges and San Vicente reservoirs. This new system 5.09 4 ensures the region has up to a six-month supply of 3.34 water should an earthquake or other disaster disrupt 2 imported water deliveries. 0 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 WATER YEAR OLIVENHAIN DAM AND ACTUAL RAINFALL LONGTERM AVERAGE RESERVOIR AND LAKE HODGES WHY CAN’T WE GET MORE The Olivenhain Reservoir, completed by the Water WATER FROM UNDERGROUND? Authority in 2003, was the region’s first new major dam and reservoir in 50 years. The reservoir holds 24,000 Groundwater basins are underground reserves of acre-feet of water and is designed to withstand a major water that may take the form of a single aquifer earthquake to keep water available and flowing to the or a group of linked aquifers. They are a major region. supply source in many parts of Southern California. Unfortunately, San Diego County’s geologic Improvements to Lake Hodges began in 2005 and were makeup has relatively limited groundwater assets to completed in 2012. The project connects Lake Hodges to complement surface water stored in reservoirs. the Olivenhain Reservoir and to the Water Authority’s Second Aqueduct, and makes spillovers from Lake MORE INFO Hodges during heavy storms less likely. http://bit.ly/reservoirs-rainfall SAN VICENTE DAM RAISE The largest piece of the Emergency Storage Project was raising the City of San Diego’s San Vicente Dam. The Water Authority project increased the height of the dam by 117 feet – the largest dam raise in U.S. history. Completion in 2014 added 52,100 acre-feet of emergency water storage and more than 105,000 acre-feet of carryover storage to collect water in wet periods for use in dry years. The San Vicente Dam Raise produced the largest increase in regional water storage in San Diego County’s history. San Vicente Reservoir.