New federal research shows drought can increase the risk of unsafe arsenic levels in private drinking water wells -- especially in New Hampshire, Maine and the Midwest, where arsenic in wells is already a problem.
The study from the U.S. Geological Survey comes as forecasters predict the country's worst spring drought since 2013, affecting tens of millions of people, especially in the Western half of the country.
This is the first study to examine how drought affects arsenic in wells, according to author Melissa Lombard of the USGS in Concord.
“Studies regarding drinking water and drought in general, they’re usually about the quantity of water available and not how that may impact the water quality,” she said.
Arsenic can occur naturally in bedrock and raise the risk of cancer and other health problems. Its prevalence in well water has been linked to New Hampshire’s high rates of bladder cancer. Nearly half of the state’s residents use private wells, a much higher proportion than in the rest of the country.
Lombard said her findings raise concerns, especially for parts of the country where droughts will become more likely or severe due to climate change.
"The likelihood of having elevated arsenic increases in private wells as the duration of drought increases," she said.
Her study says that at any given time, 2.7 million Americans on private wells, or about 7% of users, are likely to have arsenic in their water that exceeds the federal limit of 10 parts per billion. New Hampshire and New Jersey are the only states with a lower limit, of 5 ppb.
In simulated droughts, Lombard found, the population likely to be at risk from arsenic in their well water went up to 4.1 million people – an increase of more than 50 percent.
Ohio, Indiana and Michigan saw the greatest increase in affected population, while Maine and New Hampshire had high percentage increases in affected well users. Texas, California, Florida and the Pacific Northwest were also particularly impacted.
Lombard said her findings suggest that public health officials should recommend more private well testing during droughts, as well as water conservation. New Hampshire offers testing resources for home well users through the Department of Environmental Services.
