Salt Management Plan Should Improve Southern California Water Quality

In Southern California every water user -- from agricultural to commercial, business and residential – is affected in some way by the presence of salts in the water supplied to them. This has a significant bearing on the local economy and the development of recycled water resources, according to Andy Sienkiewich, the local resources program manager of the Metropolitan Water District (MWD).

Now, a regional action plan aimed at correcting the widespread problem of salt build-up in the region's water supply has been approved by the MWD board of directors.

The soluble salts found in water supplies contain such elements as calcium, magnesium, sodium, sulfur and chlorine. More than half the salt load in Southern California tap water comes from imported Colorado River and State Water Project supplies delivered by Metropolitan, with the rest coming primarily from local sources, including urban runoff and agricultural discharge.

The key element of the action plan is a salinity goal of no more than 500 milligrams per liter (mg/l) for water delivered by the MWD to its member agencies. Salt content in water distributed by the utility has historically varied from as low as 350 mg/l in wet years to more than 700 mg/l in dry years.

The agency blends lower salinity water from the State Water Project with the somewhat saltier Colorado River resource to reduce overall salt levels, according to Sienkiewich. He added that, "Allowing for the inevitable dry years and reduced availability of supplies from the State Water Project, we expect to meet our objective for salt levels in the water we serve in seven out of 10 years."

He said, "Water consumers could save more than $100 million in repair costs for residential and industrial plumbing systems damaged by high salinity, as well as additional treatment costs necessary to use recycled water and groundwater."

"Southern California is a national leader in wastewater recycling," Sienkiewich continued. "We run into problems, though, because recycled water tends to have high salinity concentrations that build up as the water is reused, limiting its application."

The Metropolitan Water District of Southern California is a consortium comprising 27 cities and water agencies serving more than 16 million people in six counties. The District imports water from the Colorado River and Northern California to supplement local supplies, and helps its members to develop increased water-recycling, desalination, conservation, storage and other water-management programs.