Brackish Water Desalination
Desalination or the process of “desalting” removes minerals and salts from either ocean water or “brackish” water. The term “brackish” is used to identify water that has high concentrations of nitrates (saline) and total dissolved solids (TDS), however it is not as salty as ocean water. Ocean water has approximately 35,000 mg/l of TDS, while brackish water can range from 1,000 to 10,000 mg/l of TDS. Total dissolved solids are both inorganic and organic salts found in water.
Several groundwater basins in the Santa Ana River Watershed suffer from elevated levels of nitrates and TDS, which have much to do with the region previously serving as an agricultural and dairy production hub. Early founders established the area as primarily a farming and crop growing community along with major dairy production. As a result, residual salts and nitrates are present. In order to protect our drinking water supplies from these minerals and salts, it is removed and desalinated before it is used for groundwater recharge or as a supplemental drinking water source for local Inland Empire water agencies.
“The desalination process involves both reverse osmosis technology, as well as ion exchange to remove TDS and nitrates from the water. In order for the water to become available as a potable (drinking) water source the desalination process is necessary,” shares Curtis Paxton, General Manager/ CEO for the Chino Basin Desalter Authority. “The Chino Basin Desalters are an integral part of overall groundwater management for the region. Our flows contain high levels of TDS and nitrates. Once the brackish water is treated, it can become part of our local drinking water supplies.”
The Chino Basin Desalter Authority produces 24,600 acre-feet (AF) of water each year. One AF of water is enough to fill a football field with one foot of water or 326,000 gallons. Located at the base of the San Gabriel Mountains, the Chino Basin Desalters treat subsurface water that flows down from the upper Chino basin and contain excessive levels of nitrates and TDS. Treating the water increases water resource reliability, therefore minimizing the need for reliance on costly imported water. Additionally, groundwater extraction and desalination treatment plays a critical role in clean up of the Chino Basin.
Minerals and salts occur naturally in all drinking, however external elements play a role in the elevated salt levels in our local groundwater supplies. One of the necessary steps and effective processes in removing the salt involves the process of desalination. Within the boundaries of the Santa Ana River Watershed, there are several desalter facilities. These desalters utilize the process of reverse osmosis and ion exchange to remove nitrates and TDS from brackish water. Local brackish water desalters include: the Arlington Desalter (Western Municipal Water District), Chino Desalters (Chino Basin Desalter Authority), Irvine Desalter (Irvine Ranch Water District), Perris Desalters (Eastern Municipal Water District) and Temescal Desalter (Corona Department of Water and Power).
Wastewater reclamation facilities, also known as water recycling centers, can also have high salinity levels. Discharging treated wastewater, with increased salt and nutrient content, can be harmful to the wildlife and can eventually seep into groundwater basins. In the Santa Ana River Watershed, the Santa Ana Watershed Project Authority’s (SAWPA) Inland Empire Brine Line, serves as a resource for collecting the excess salts, also known as “brine,” from various industries and desalters, and then conveys this flow by pipeline to Orange County for further treatment before being discharged to the ocean in Orange County. By redirecting high saline brines to the brine line, groundwater basins and habitat are protected.
Salinity in local drinking water supplies is a concern for our region. Local special districts and water agencies work tirelessly to protect these resources and habitats. Looking into the future, Californians will rely heavily on technologies, such as desalting to provide a reliable source for maximizing drinking water supplies.