Our Water Supply
MNWD, like most south Orange County water providers, does not have the benefit of access to local supplies of water, so the majority of the District’s water is imported from the Colorado River and the Sacramento-San Joaquin Delta. MNWD supplements these sources by treating and delivering recycled water for irrigation purposes, which diversifies our supply and adds greater reliability during times of drought and other emergencies.
Even if Mother Nature provides the state enough water to meet everyone’s needs, court rulings, environmental regulations, a shortage of water reservoirs, and an outdated delivery system limit our ability to capture water and move it from where it falls in the north to where it’s needed in the south. That means MNWD customers must always be as efficient as possible to protect our region’s limited water resources.
Primary Supply Sources
Approximately 78 percent of MNWD’s water is purchased through
the Municipal Water District of Orange County from the Metropolitan Water District
of Southern California, a regional water wholesaler that delivers water from
Northern California and the Colorado River.
The State Water Project, also known as the
California Aqueduct, transports water 600 miles from Northern California to
the Central Valley and the southern portion of the state. It is owned and operated
by the State of California and is the longest aqueduct system in the world,
featuring 23 dams and reservoirs, 22 pumping plants that lift water to heights
of 3,500 feet, and six power plants. The aqueduct is comprised of 473 miles
of canals, 175 miles of pipeline and 20 miles of tunnels.
The Colorado River Aqueduct brings water 242 miles from the Colorado River
through deserts and over mountain ranges to its terminal reservoir, Lake Mathews,
in Riverside County. The aqueduct system includes five pumping plants that lift
the water 1,617 feet.
MNWD produces approximately 25 percent of our supply by capturing
water that normally would run out to sea, treating it, and re-using it for irrigation
and other non-potable, or non-drinking, uses. Every gallon of recycled
water we use saves a gallon of drinking water. In total, we save 2.7 billion
gallons of water each year through recycling.
MNWD has taken steps to increase our emergency water supply capacity
from a 10-day to a 31-day supply, to allow the District to continue providing
customers water in both planned and unplanned service interruptions. To achieve
this three-fold increase in emergency storage, the District is partnering with
other South County water agencies to construct a number of water supply reliability
improvement projects. These include the Upper
Chiquita Reservoir in Rancho Santa Margarita, which will store up to 266
million gallons of emergency water, and the Baker
Treatment Plant in Irvine, which will allow south Orange County to treat
its own water when regional treatment plants shut down. MNWD is also working
with other water districts in the area to build interconnections, so alternative
means of delivering water will be possible. These interconnections could make
it possible in emergencies to gain access to alternative groundwater sources
in north Orange County, which normally aren’t available to MNWD.
Water Supply Updates