Authorized under the Municipal Water District Act of 1911, EMWD's duties and responsibilities are further delineated in the California Water Code. In 1951, EMWD annexed to The Metropolitan Water District of Southern California (MWD). The population within the current 542-square-mile service area is about 687,000. EMWD's operating budget for 2009/2010 is $217 million with net assets of approximately $1.5 billion (as of June 2009).