Formed in 1950, IEUA is a member of the Metropolitan Water District of Southern California (MWD) and thus acts as a supplemental water provider. One-fourth of the water used in the region is imported from MWD through the State Water Project. Over the last several years, imported water deliveries from Northern California have declined from a high of 78,872 acre-feet (AF) in 2009 to 59,047 AF in 2013.
IEUA strives to increase regional sustainability through the development of reliable local water supplies. These efforts include using water more efficiently, eliminating waste and unreasonable use, and drought-proofing the region through increasing the use of recycled water. IEUA has invested in water use efficiency efforts and is on track to reduce water use.