Board discusses brackish water treatment

Board discusses brackish water treatmentBy BRIAN COSNER

News Review Staff Writer

What is “brackish” groundwater, and might it act as an alternate water supply for the Indian Wells Valley? The IWV Water District heard a presentation on brackish water treatment from Hydrologist Anthony Brown during its regular meeting on Monday, May 13.

Brown is a consulting hydrologist for Mojave Pistachios and is also a member of the IWV Groundwater Authority’s Technical Advisory Committee.

While District Legal Counsel Jim Worth cautioned the board not to delve into how the GA may or may not use brackish water in its Groundwater Sustainability Plan, Brown gave information on how the use of filtered brackish water might affect some of the GA’s pumping scenarios.

Brown discussed the origins of the IWV Brackish Groundwater Project and how it may act as a potential additional source of groundwater. The project received $370,000 in contributions from the IWV Water District, Mojave Pistachios, Coso Operating Company and Searles Valley Minerals, of which roughly half has been used according to Brown.

The groups partnered in 2015 and are projected to have a contract for a $700,000 feasibility study grant by the end of the month.

Brown explained that brackish water is groundwater that doesn’t have as high a salt content as seawater, but still has too many dissolved particles for safe consumption. But treating and filtering brackish water will probably be less expensive than importing water, and allows pumping in areas where the groundwater is brackish to mitigate pumping in freshwater areas.

Treating the water results in about 80-percent fresh water with a 20-percent highly concentrated saline solution.

“We’re lucky enough to have two parties here in the valley that can take the concentrate,” said Brown. “Coso would be willing to take the brackish groundwater because they need it to maintain their energy production. Searles Valley Minerals is in the business of recovering minerals from brackish and highly saline water. We’d be giving them saline water or just pure salts.”

Brackish water treatment is not considered a long-term solution, but Brown suggested it could act as a “bridge” while authorities figured out more concrete long-term solutions for alternative water supplies.

Brown said the project looks at how brackish water pumping could affect other pumping in the valley. According to the GA’s “worst-case scenario” pumping model where pumpers in the valley continue to pump as they do now, with some growth, through 2070 – the drawdown of the water table is about 60 feet. Pumping roughly 10,000 acre-feet per year of brackish groundwater is projected to reduce the drawdown of freshwater areas by about 20 feet.

“You’re still pulling water from the same basin,” said Brown. “But the declines in freshwater are lessened because you’re pumping the brackish.” He added that he would expect brackish water pumping to help mitigate freshwater consumption for about 25-30 years.

It would take about five years to get the brackish water project up and running by Brown’s best estimates, but he still expects it to be in place more quickly than finding a source and building the infrastructure for imported water.

Brown named three prospective drilling sites – the most promising a single well in Pearsonville, the northwestern portion of the basin.

The other two sites are in the southwest and southeast areas of the basin, but each has its drawbacks such as proximity to existing wells or lower groundwater yields.

IWVWD Director Stan Rajtora asked Brown if the group had determined the recurring and non-recurring costs of such a project.

“We have not done any detailed cost estimates,” said Brown, adding that determining costs would be part of the feasibility study. “All I can say is it’s less than $1,000 per acre-foot.”

Recent GA estimates for imported water have been in excess of $2,000 per acre-foot.

The discussion turned toward groundwater sustainability criteria, what the state Department of Water Resources might accept as sustainable decline and what pumping scenarios might be ideal.

But Worth again cautioned boardmembers to keep the discussion focused on the brackish water feasibility study.

“The brackish water study will be evaluated and considered as part of the GSP development,” said Worth. “But right now, you’re just getting Mr. Brown’s opinion on what they may or may not do, and I don’t think that’s proper.”

The IWV Groundwater Authority met yesterday, and details were not available at press time.

Pictured: IWV?Water District boardmembers Stan Rajtora (left) and Ron Kicinski — Photo by Laura Austin

Story First Published: 2019-05-17