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Securing a Sustainable Supply

The Colorado River has been the backbone of Southern California’s imported water supply for nearly 80 years. Built and operated by Metropolitan, the Colorado River Aqueduct carries water from the river 242 miles across the desert to Southern California. It provides about 25 percent of the water used in Metropolitan’s 5,200 square-mile service area.

Lifeblood of the West

Managing Through Change

Since Metropolitan’s first CRA deliveries in 1941, water from the Colorado River has helped transform Southern California into the thriving region it is today. The river also sustains people, farms, businesses, tribal nation and wildlife across six other states and Mexico. But while demands for Colorado River water have grown, supplies from the river have not, resulting in an imbalance that will likely grow as the climate warms, reducing run-off in the river’s watershed. This is the latest challenge in the enduring struggle to share the Colorado River among the 40 million people and 5 million acres of farmland that rely on it.

A New Era of Sustainability

Living Within Limits

California put itself on the path toward Colorado River sustainability in 2003, when it agreed to reduce its use to its basic apportionment of 4.4 million acre-feet of river water. For decades, California was able to use more than this amount, relying on surplus water and water unused by Arizona and Nevada. But in the 1990s, those states began using their full apportioned supplies and California was compelled to cut back. The groundbreaking 2003 Quantification Settlement Agreement, and related agreements, set aside decades-old disputes and facilitated water transfers from farms to cities, funded the lining the All-American and Coachella canals to reduce seepage and led to new agricultural conservation in California and partnerships with Metropolitan.

Filling the Aqueduct

Ag-Urban Partnerships

Since losing access to surplus Colorado River water in 2003, Metropolitan has invested millions of dollars to restore the reliability of its CRA deliveries. Through partnerships developed with agricultural agencies, Metropolitan pays participating farmers to conserve water while also ensuring the continued success of the agricultural economy. The water saved through these programs – which include partial land fallowing, crop rotation and irrigation improvements – is then made available to the communities Metropolitan serves. These efforts help fill the CRA and provide Metropolitan greater flexibility to withstand times of shortage.

Water District

Seasonal Land Fallowing ProgramFarmers paid to not plant lower-value, water-intensive crops during spring and summer

Palo Verde
Irrigation District

Land Fallowing and Crop Rotation ProgramFarmers paid to fallow up to 28 percent of their land

Irrigation District

Water Conservation Program
Metropolitan funds water conservation improvements within IID

Building the Colorado River Aqueduct

Originally conceived by William Mulholland and designed by Metropolitan’s first Chief Engineer Frank Weymouth, the Colorado River Aqueduct was the largest public works project built in Southern California during the Great Depression. Over seven years, 35,000 people toiled across the desert to construct the engineering feat.

Learn more about the history of the CRA

Collaboration on the Colorado

Building Climate Change Resiliency

As climate change reduces flows on the Colorado River and levels of the system’s two largest reservoirs – Lake Mead and Lake Powell – drop, Metropolitan is forging valuable partnerships outside California as well. This new era of collaboration is helping ensure the continued reliability of Colorado River supplies across the West.

Intentionally Created Surplus

Through the ICS program, Metropolitan can store more than 1.65 million acre-feet of water in Lake Mead for use during dry years. Metropolitan led other states in the development of this program – creating valuable surface storage through cooperation rather than construction.

Drought Contingency Plan

Signed in 2019, Metropolitan worked with the seven Basin states to develop the DCP, which helps prevent Lake Mead and Lake Powell from reaching critically low levels. Under the DCP, each Lower Basin state agreed to store defined volumes of water in Lake Mead at certain elevations, and the Upper Basin received approval to store conserved water in Lake Powell.

Tribal Nations

Metropolitan has collaborated with several Native American tribes in the Colorado River Basin to develop water management programs, including a forbearance agreement with the Quechan Tribe and an exchange agreement with the San Luis Rey Band of Mission Indians.

Lower Colorado River Multi-Species Conservation Program

To balance the use of Colorado River resources with ecological needs, federal and state partners created the LCR MSCP in 2005 to work toward the recovery of endangered and threatened fish and wildlife along the Lower Colorado. The program will create more than 8,100 acres of new habitat.

Lower Colorado River Water Quality Partnership

To protect the source water quality of Colorado River supplies, Metropolitan is partnering with the Central Arizona Project and Southern Nevada Water Authority on initiatives to address water quality challenges including salinity, invasive species and industrial contaminants.

Other Partnerships

Metropolitan also has partnered with agencies in Nevada and Arizona to fund other projects important to protecting Colorado River supplies, including Warren Brock Reservoir, Yuma Desalting Plant and the Mexico Water Treaty Pilot Conservation Project (Minute 319 and 323).

Law of the River

How the Colorado River’s resources are divided among the seven Colorado River Basin states and Mexico is governed by a series of interstate compacts, statutes, Supreme Court decrees, a treaty with Mexico, contracts and regulatory guidelines, all collectively known as the Law of the River.  

View from Above

The CRA is comprised of two reservoirs, five pumping stations, 63 miles of open canals, 92 miles of tunnels, 55 miles of concrete pipe and 28 miles of pressurized siphons, with a delivery capacity of over 1.2 million acre-feet a year. Join us on a tour of the Aqueduct.