Local Storage: A Vital Water Resource
San Diego County’s semiarid climate means that truly wet years are few and far between, and dry years are very common. Since 1976, the amount of local surface water used to help meet annual demand has been as high as 140,300 acre-feet and as low as 4,071 acre-feet. Consequently, runoff from local rainwater that flows into
reservoirs – commonly called surface water – represents a vital but small portion of San Diego County’s water supply needs.
Over the past 10 years, an average of about 7 percent of the region’s total annual water supply came from local surface water. San Diego County has not relied solely
on its local water sources since 1947, when imported water flowed through the region’s first aqueduct, making Colorado River water available to fuel the region’s post-World War II growth.
Local Rainfall and Reservoirs
San Diego County Reservoirs
DIVERSIFICATION
Enhancing Water Supply Reliability
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Fallbrook
Oceanside
Carlsbad
Encinitas
Solana Beach
Del Mar
La Jolla
Coronado
Chula Vista
National City
LemonGrove
San Diego
La Mesa
El Cajon
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Poway
EscondidoSan Marcos
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ORANGE COUNTY
SAN DIEGO COUNTY
MEXICO
RIVERSIDE COUNTY
LAKE MAERKLE LAKE WOHLFORDSUTHERLAND
RESERVOIR
EL CAPITANRESERVOIR
SAN VICENTERESERVOIR
LOVELANDRESERVOIR
LAKE HODGES
OLIVENHAIN RESERVOIR
SAN DIEGUITORESERVOIR
MIRAMARRESERVOIR
LAKE RAMONA
LAKE POWAY
LAKE MURRAY
LOWER OTAY RESERVOIR
DIXON RESERVOIR
SWEETWATER RESERVOIR
TURNER LAKE
RED MOUNTAINRESERVOIR
BARRETT LAKE
CUYAMACARESERVOIR
MORENARESERVOIR
LAKE JENNINGS
MORRO HILL RESERVOIR
LAKE HENSHAW
Maerkle, Red Mountain and Morro Hill store treated water and do not capture local runoff.
Enhancing Water Storage Today, the Water Authority and its mem-
ber agencies have 24 reservoirs that store im-ported and local runoff water for normal use, emergency conditions and imported water shortages. Combined water storage capacity now totals approximately 723,000 acre-feet. This is a 30 percent increase since 2003, created by the Water Authority’s $2 billion Capital Improvement Program to improve the region’s water infrastructure.
AF = acre-footOne acre-foot is approximately 325,900 gallons, enough to supply 2.5 single-family households of four for a year.
The San Diego County Water Authority sustains a $245 billion regional economy and the quality of life for 3.3 million residents through a multi-decade water supply diversification plan, major infrastructure investments and forward-thinking policies that promote fiscal and environmental responsibility. A public agency created in 1944, the Water Authority delivers wholesale water supplies to 24 retail water providers, including cities, special districts and a military base.
February 2020
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Lindbergh Field: Actual vs. Normal Rainfall
Local Rainfall and Reservoirs
4677 Overland Ave.San Diego, California
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Lake Henshaw: Actual vs. Normal Rainfall
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Lake Cuyamaca: Actual vs. Normal Rainfall
A crucial component of this program is the $1.5 billion Emergency & Carryover Storage Project, which created new emer-gency water storage at the Oliv-enhain, Hodges and San Vicente reservoirs. This new system ensures the region has up to a six-month supply of water should an earth-quake or other disaster disrupt imported water deliveries.
Olivenhain Dam and Reservoir and Lake Hodges
The Olivenhain Reservoir, completed by the Water Author-ity in 2003, was the region’s first new major dam and reservoir in 50 years. The reservoir holds 24,000 acre-feet of water and is designed to withstand a major earthquake to keep water avail-able and flowing to the region.
Improvements to Lake Hodges began in 2005 and were completed in 2012. The proj-ect connects Lake Hodges to the Olivenhain Reservoir and to the Water Authority’s Second Aque-duct, and makes spillovers from Lake Hodges during heavy storms less likely.
San Vicente Dam RaiseThe largest piece of the Emer-
gency Storage Project was rais-ing 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. Comple-tion 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.
Why can’t we get more water from underground?
Groundwater basins are underground reserves of water that may take the form of a single aquifer or a group of linked aquifers. They are a major sup-ply source in many parts of Southern California. Unfortunately, San Diego County’s geologic makeup has relatively limited groundwater assets to complement surface water stored in reservoirs.
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