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Desalination Can Address Major Threat Salt Poses to California's Water Supplies

Beneficial in the right amounts but harmful in excess, salt is one of the most common minerals in the natural environment. Salt buildup in agricultural soils and water sources has destroyed mighty civilizations in the past and, if left unmanaged, can do so readily again. For water-limited California, salt is a growing challenge to the state's long-term water future.

With rising levels of salt threatening to affect water quality and environmental health over time in some regions of the state, water managers are working to balance salt and nutrient loads in both surface water and groundwater supplies. CalDesal is helping lead the effort to manage salt problems that could degrade water quality, increase treatment costs, jeopardize food production and render some water supplies unfit for use.

CalDesal is a non-profit organization composed of water industry leaders dedicated to developing sensible, cost-effective solutions to growing salinity threats in California.

Salinity: Nature and Human Activities Play a Role

Since salt is found in many rocks and soils, it is present to some degree in nearly all surface and groundwater supplies. A highly soluble compound, it is easily picked up and dissolved as rainwater flows over the ground surface into streams or percolates through soil into groundwater basins.

In addition to being introduced through the natural hydrologic cycle, salts can also enter water and the environment through fertilizers, wastewater discharges, agricultural drainage, water softeners, detergents, compost and other salt-containing items. When sufficiently diluted, salts are generally not a problem for most water uses and can be beneficial to plants and other life forms. That can quickly change, however, when salts build up and become concentrated at levels detrimental to the survival of plants and animals (including humans).

To a certain extent, salt buildup is unavoidable. Nearly every way in which humans use water contributes additional salt or concentrates the salts that are already present. Since water is routinely reused and recycled throughout California, salinity problems can be multiplied. In addition, large-scale water delivery systems such as the State Water Project, Central Valley Project and Colorado River Aqueduct add to the salt load in some regions by transporting salts along with the water supplies they carry to meet urban and agricultural demands. As the water is put to beneficial use, the majority of the salt load is left behind.

With California's water supplies under increasing pressure to meet a variety of needs, managing salts and maintaining an appropriate salinity balance within key watersheds and basins is emerging as one of the most critical challenges of the 21st century.

In recognition of the problem, the State Water Resources Control Board has set a 2014 deadline for groundwater basins to develop plans to manage salt and nutrients. As a result, local water and wastewater agencies are working with stakeholders to craft regional plans to address salinity and protect groundwater basins and other water supply sources for the future.

Where is Salinity a Problem?

Though salinity issues may not be high on the radar for the general public in California, some regions have been grappling with salinity management for many years and even decades. For other areas, salinity is an emerging issue that will require attention and resources to avoid reaching critical mass.

In the Central Valley, salinity is a chronic and worsening problem that threatens water quality for both urban and agricultural uses. Valley soils are richly productive but in many cases high in naturally occurring salts and other trace minerals such as selenium. Since there is no natural discharge outlet for some areas, particularly the Tulare Lake Basin, salts continue to build up and concentrate in the soil, eventually choking the root zone for plants and making thousands of acres unfit for farming. Water imported through the State Water Project and Central Valley Project brings in tons of additional salt each year.

In Southern California, the Santa Ana River watershed is also dealing with a buildup of salts from nearly 100 years of agricultural and industrial use. Fast-growing cities in close proximity to historic dairy areas and ongoing use of imported water have added to the salt load. Though the region continues to put technologically advanced water treatment and wastewater controls in place, existing salts threaten water quality and the use of water management strategies such as groundwater storage and water recycling.

As part of the solution, the Santa Ana Watershed Project Authority (SAWPA) constructed the Inland Empire Brine Line to collect high salinity water throughout the upper watershed, convey it to advanced wastewater treatment facilities in Orange County and deliver the treated discharge to the ocean. With significant growth projected for the region, this 100-mile long pipeline will continue to be a critical factor in the watershed's overall plan to achieve salt balance and protect water quality.

Perhaps the most striking example of harmful salt buildup is found at the Salton Sea – California's biggest inland sea serving as North America's largest nesting area for migratory waterfowl outside the Everglades. This sea is fed by Colorado River water flowing through one of America's most productive agricultural regions. Evaporation reduces fresh water flowing into the sea, and salt dissolved in the water stays behind in the increasingly salty sea.

What is Being Done about Salinity?

Organizations such as CV-SALTS (Central Valley Salinity Alternatives for Long-Term Sustainability) and SAWPA are on the front lines of promoting plans and initiatives to address salinity. These efforts rely on regional collaboration and the latest science to pursue salinity control measures and develop large-scale, multi-solution salt management plans to bring their regions in balance and protect water quality for beneficial uses.

CalDesal is also working to highlight salinity issues and advocate for funding and policies to address salt management challenges throughout the state.

Developed and maintained by California Advocates, Inc.