USGS Water Well Study Finds 25 States at Risk for Lead

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By Llewellyn Hinkes-Jones

July 15 — An assessment of more than 20,000 wells nationwide by the U.S. Geological Survey shows 25 states with a high prevalence of corrosivity in untreated groundwater, most of them located in the Northeast, Southeast and Pacific Northwest.

Prevalence of corrosivity in groundwater creates a high risk for lead leaching in homes serviced by untreated private water sources, such as wells, springs and cisterns. “Corrosive groundwater, if untreated, can dissolve lead and other metals from pipes and plumbing fixtures,” the USGS report concluded. But the July 13 report also said that “additional work would be needed to better understand the relations between potential corrosivity of groundwater and the occurrence of lead.”

Some states with the highest prevalence of potentially corrosive groundwater in the South include Mississippi, Georgia and South Carolina. In the Northeast, Maine, New Hampshire, Massachusetts, Connecticut, Rhode Island, New Jersey and Maryland ranked among the highest.

Interactive Map

A interactive map from Bloomberg BNA on the CDC’s childhood lead poisoning data is available at

The USGS did not specify the causes of corrosivity in the areas of concern but told Bloomberg BNA that an inquiry into the issue is underway.

Kenneth Belitz, chief of groundwater assessment for the USGS’s National Water Quality Assessment Program, said that the geology of the aquifer supplying the water and sources of chloride, such as salt in the air from nearby oceans, are mitigating factors.

Highest Rate Among Children

Pennsylvania tops the list of states with the highest rate of blood lead levels in children, based on an analysis of CDC state surveillance data by Bloomberg BNA.

More than 2 percent of children tested showed elevated blood levels in Pennsylvania over the last 11 years. Illinois was a close second, with Rhode Island, Ohio and Maine following behind.

The Centers for Disease Control and Prevention (CDC) does not list a safe level of blood lead levels and warns that childhood exposure to lead can lead to brain damage as well as learning, hearing and speech problems.

Pennsylvania also had the highest total number of confirmed cases and the second highest rate of population showing high lead levels even though only a moderate number of homes had been tested–7.7 percent–a relative midpoint among states that submitted data to the CDC.

The information is not complete as the CDC only tests a small portion of the population, and certain states don’t submit any lead surveillance data including: Alaska, Arkansas, Hawaii, Idaho, Montana, North Dakota, Nebraska, Nevada, South Carolina, South Dakota, Utah, Washington and Wyoming. Pennsylvania is also the state with the largest population dependent on private water sources (3.35 million). North Carolina is a close second with 3.3 million people dependent on private water.

Bryan Swistock, a water resources specialist in the Department of Ecosystem Science and Management at PennState Extension, is quoted in the USGS report stating that lead levels in Pennsylvania “exceeded the EPA action level in 12 percent of the 251 drinking water systems monitored” in 2007. A report by PennState Extension on the state’s corrosive water states that “60 percent of the wells, springs, and cisterns serving individual homes” have corrosive water, but that it’s less so in the agricultural valleys underlain by limestone.

Charles Cravotta, hydrologist and geochemist with the USGS, told Bloomberg BNA that Pennsylvania’s geology and local industry have a strong influence on the corrosivity of its groundwater.

“Pennsylvania has mine drainage, sandstone, and acid rain, which is sulfuric from burning coal and nitric from automobile exhaust. The sandstone and quartz are unreactive and have no effect on neutralizing the acidic rainwater,” he said.

Maine Also a Concern

While it didn’t have the highest incidence of elevated blood lead levels, Maine was the only state showing both very high lead levels in the CDC data as well as very high potential for corrosive groundwater in the USGS report. The state also has the highest rate of households dependent on private water sources.

To contact the reporter on this story: Llewellyn Hinkes-Jones in Washington at

To contact the editor responsible for this story: Larry Pearl at

For More Information

The USGS report, “Potential corrosivity of untreated groundwater in the United States,” is available at

The PennState report, “Corrosive Water Problems,” is available at

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