Aquifer recharge reduced nitrate levels in groundwater, USGS study shows
According to results from a new study carried out by the U.S. Geological Survey (USGS) and the Hi-Desert Water District, artificial replenishment of groundwater aquifer systems can lead to a drop in nitrate concentrations in groundwater and a rise in water levels.
The research was conducted in the Warren groundwater basin in San Bernardino County's Yucca Valley in California, the USGS said. The federal agency examined the impact of adding 9,800 acre-feet of water from the California State Water Project into three replenishment ponds in the west hydrogeologic unit, with the first recharge taking place in June 2006.
Artificial replenishment of the groundwater system also resulted in detection of low levels of dissolved organic carbon in the groundwater. Scientists explained that lower concentration levels of dissolved organic carbon contribute to a reduced risk of formation of carcinogenic trihalomethanes during water treatment processes.
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Lead researcher Christina Stamos commented that the replenishment contained levels of nitrate that were lower than those in the native groundwater. "There was no increase in nitrates at the water table below the ponds because the water did not spread far enough laterally to intercept any high-nitrate sources," she added.
The study was launched in 2004 with the purpose of thoroughly examining concerns that artificial replenishment caught septic-tank effluent while flowing, thus resulting in higher nitrate concentration levels in the groundwater.