The GWRS Meets the Need

North and Central Orange County's Vast Groundwater Basin

North and central Orange County in Southern California overlie a very large groundwater basin or aquifer that is managed by the Orange County Water District (OCWD). The basin provides approximately 60% of the potable water supply for 2.4 million people. Although the basin is vast, the average annual withdrawals must be balanced by recharge from a variety of sources. The primary sources of groundwater basin recharge include flows from the Santa Ana River, direct percolation of rainfall from local wintertime storms, and imported water from distant sources.

In the past few years, OCWD has seen significant decreases in water flow along the Santa Ana River. Much of this is a result of dry weather conditions and water conservation upstream. According to the California Department of Water Resources (DWR), 2009 was the third consecutive dry year for the state. Due to the multi-year drought caused by below-average rainfall, the U.S. Department of Agriculture declared 21 California counties Primary Natural Disaster Areas and 29 others Natural Disaster Areas (DWR California Water Plan, Update 2009).

Southern California's Water Supply Challenges

A significant portion of Southern California's water comes from Lake Oroville via the Sacramento-San Joaquin River Delta (the Delta), which is located in Northern California. The State Water Project (SWP) is a system that delivers water from Northern California to Southern California. Recent environmental legal mandates to protect habitat in the Delta greatly reduced SWP water deliveries. The SWP has been described by some as "99 miles of superhighway and one mile of dirt road."  Solving the complex issues associated with conveyance of water through the sensitive Delta is likely to take many years and significant financial investments.

Southern California also relies on imported water from the Colorado River, as do six other western states, Mexico and several Native American Indian tribes. Each of these users competes for this limited resource in conformance with their specific water rights and allocations. In 2003, Southern California had its share cut by 50%. New land fallowing, water conservation and storage programs with agencies that share the Colorado River have allowed Southern California to recover most of the lost supplies for the time being. However, continued drought conditions in the Western United States may force additional supply reductions in the next few years. North and central Orange County rely on Lake Oroville, the Delta and the Colorado River to provide approximately 40% of the region's water supply needs. Historically, OCWD has been able to purchase water from these sources to recharge the groundwater basin, but these water supplies are not always available and will be more difficult to rely on in the future.

Faced with these challenges, and an expected population growth of more than 300,000 people by 2035 in north and central Orange County (Source: Cal State CDR), OCWD has to find new ways to maximize the annual sustainable yield of the groundwater basin.

GWRS – Water You Can Count On

The need for a new, reliable and locally-controlled supply of water is more important than ever before and critical to north and central Orange County's public health and economy. The GWRS has become an essential element of local water supply. It is an effective and innovative solution to Orange County's current and future water needs and serves as an example for other regions around the country and the world that have challenging water supply issues.

The GWRS takes highly-treated wastewater from the Orange County Sanitation District that is normally discharged into the ocean and purifies it using a three-step advanced treatment process consisting of microfiltration, reverse osmosis and ultraviolet light with hydrogen peroxide. The process produces high-quality water that exceeds all California and United States Environmental Protection Agency drinking water standards.

Operational since January 2008, the GWRS produces up to 70 million gallons (265,000 cubic meters; 215 acre-feet) of high-quality water every day; a total production of 23.5 billion gallons (89 million cubic meters; 72,000 acre-feet) per year. This is enough water for nearly 600,000 residents in north and central Orange County. The facility provides approximately 15% of this region's water supply. GWRS water is reliable, safe and locally-controlled. It is also more cost-effective and energy efficient to produce GWRS water than it is to import water supplies from the Delta and Colorado River. Of considerable significance is the uninterruptible nature of the wastewater supply, providing a measure of protection from imported water supply variability and curtailments.

North and central Orange County's future depends on reliable water supplies. The GWRS provides the region with water it can count on and serves as a model project for other regions throughout the United States and the world that are, or will be, facing natural and man-made water supply challenges.