What is the Irvine Desalter Project?

• The Irvine Desalter Project (IDP) is a joint groundwater quality restoration project by the Irvine Ranch Water District (IRWD) and the Orange County Water District (OCWD), with financial participation by the U.S. Navy, the Metropolitan Water District of Southern California (MWD) and the State of California. OCWD is the wholesale agency charged with managing the Orange County Groundwater Basin.
• In 1985, portions of the groundwater basin beneath the former El Toro Marine Corps Air Station and the central area of Irvine were found to contain aircraft cleaning solvents known as volatile organic compounds (VOCs). These chemicals resulted from past disposal and waste management practices on the base that were common before the development of stricter environmental regulations in the mid-1970s.
• A one-by-three mile plume of contamination extends off the base. The contamination is about 150 feet deep beneath the base and 300-1,000 feet deep in the community area. The plume is slowly moving toward the main Orange County underground water basin.
• The plume does not affect IRWD’s drinking water since IRWD’s wells are several miles from the affected area. The IDP project will keep the plume from threatening Orange County’s main water supply.
• The IDP is actually two projects in one. The IDP consists of three water purification plants with separate wells and pipeline systems:
  
  Irrigation Water System
  Two purification plants remove volatile organic compounds from the groundwater contaminated by solvent degreasers used at the El Toro Marine Base and use that cleaned water only for irrigation and other non-drinking water uses. The Department of the Navy has accepted full responsibility for contaminant cleanup.
  
  Drinking Water System
  A third purification plant treats water from outside the plume of contamination to remove salts and nitrates caused by the natural geology and past agricultural drainage. This provides a new drinking water supply at the same cost as buying imported water, but with much higher reliability because it is a local supply. In addition, this portion of the project is important because it helps control the migration of the plume. IRWD, with assistance from the MWD (the regional surface water wholesale agency), pays the costs to purify this groundwater.