To reduce dependence on imported water, communities in California are following Arizona’s lead and taking a second look at contaminated groundwater supplies.
A recent article in the Los Angeles Times reported that the Los Angeles Department of Water and Power (DWP) is planning to undertake a large project that involves treating contaminated groundwater for use as drinking water. The ambitious $800M project will not only treat tainted groundwater, but it will also reduce the area’s dependence on imported water, which has accounted for nearly 90 percent of the city’s supply over the last decade. The vast majority of this imported water comes from two sources: the Los Angeles Aqueduct system in eastern California and the Metropolitan Water District, which imports supplies from the Colorado River and northern California.
LA’s plan calls for building one of the country’s largest groundwater treatment systems at one of its largest Superfund sites. Groundwater in the San Fernando basin has elevated levels of chromium, perchlorate, nitrates, and trichloroethylene — the result of decades of industrial operations. Ultimately, the two required treatment plants are expected to be operational by 2022. By 2035, the utility expects that this treated groundwater can be used to reduce the amount of water it imports by a factor of one-half.
Building treatment plants is a costly proposition, but the alternative — relying on imported supplies — is no bargain either. MWD’s water wholesale delivery rates, which have nearly doubled since 2006, will approach $900/AF in 2014. The project will be funded by ratepayers through low-interest bonds.
Water providers in Arizona’s major metropolitan areas have long recognized the value of using local supplies, even if water quality is compromised and treatment is required prior to potable use. The cities of Scottsdale and Tucson use treated groundwater that is part of cleanup operations at Superfund sites. In both cases, existing and newly constructed municipal wells are directly incorporated into EPA-mandated remedies to contain and clean up groundwater.
At the Arizona sites, treatment plants are constructed by the responsible parties and run by the cities, so both the process and product are controlled locally. In addition to providing valuable water, this solution avoids the conflicts that arise when municipal pumping interferes with pumping required for plume containment. Municipalities in AMAs also benefit from using groundwater from a mandated remediation program; not only does this approach help them balance their water supply portfolios but it also facilitates compliance with restrictions on the use of nonrenewable resources.
This is just one part of a comprehensive strategy to reduce dependence on imported water. Other strategies include conservation, storm water capture, effluent reuse, and water transfers. All are smart investments in the future.
Juliet McKenna, MS, PG, Editor