Wells are at risk of running dry during the drought, but new research from the United States Geological Survey found another danger of decreasing water levels: nitrates and other contaminants were being drawn into the groundwater.
"There have been anecdotal reports of water quality issues with groundwater during drought in the past, and this study actually establishes a concrete linkage between the two," Dr. Zeno Levy, a research geologist with the United States Geological Survey, told KNX.
Researchers for the study, published in Geophysical Research Letters, looked at 30 years of data from the Central Valley. They found that higher nitrate concentrations in wells were more frequent in areas where groundwater levels had dropped during a drought.
"We found that when pumping increases during drought this can actually pull down shallower levels of groundwater to deeper depths in the aquifer," he said. With the shallower levels of groundwater came a higher presence of nitrates, which have been linked to birth defects and various forms of cancer.
Previous research on groundwater has focused on the risk of wells running dry during a drought. Building on this past research, the study helps to understand the related effects of over-pumping on water quality.
As the state’s drought intensified this past summer, Gov. Gavin Newsom called on Californians to reduce their water usage by 15 percent. State officials estimated a 15 percent voluntary reduction in water usage could save enough to supply more than 1.7 million households for a year.
"The realities of climate change are nowhere more apparent than in the increasingly frequent and severe drought challenges we face in the West and their devastating impacts on our communities, businesses and ecosystems," said Newsom in June.
"The entire state is in a drought today."
That same day, drought emergency proclamations expanded to include Inyo, Marin, Mono, Monterey, San Luis Obispo, San Mateo, Santa Barbara, Santa Clara and Santa Cruz counties, bringing the total number of counties under the emergency orders up to 50.
However, keeping the increasing amount of contaminants out of the state’s drinking water poses additional challenges.
"Water quality problems from legacy groundwater pollution could get worse, faster, when pumping increases during drought," said Levy. "This could lead to more public drinking-water wells being shut down if costly treatment or cleaner water sources to mix with are not available."
The research was a cooperative effort between the United States Geological Survey and the California State Water Resources Control Board’s Groundwater Ambient Monitoring and Assessment Program.
Related
