By Valerie Volcovici and Timothy Gardner
WASHINGTON (Reuters) - Fracking has not led to widespread, systemic pollution of drinking water, the U.S. Environmental Protection Agency said on Thursday in a long-awaited study, though it warned that certain drilling activities could pose potential risks.
The study, five years in the making, found some drinking water vulnerabilities to hydraulic fracturing, such as where supplies were scarce and where fracturing took place directly into underground drinking water sources, but overall saw little impact from the drilling technique.
In its review of data sources "available to the agency," the EPA study, requested by Congress, found specific instances where fracking affected water sources but found that they were small relative to the overall number of fracking sites around the United States.
?EPA?s draft assessment will give state regulators, tribes and local communities and industry around the country a critical resource to identify how best to protect public health and their drinking water resources,? Dr. Thomas Burke, EPA?s science advisor and deputy assistant administrator of EPA?s Office of Research and Development, said in a statement.
Other vulnerabilities to water supplies can occur in inadequately cased or cemented wells which result in migration of gases and liquids underground, and when inadequately treated wastewater is discharged into the resource, the statement said.
The draft study will undergo external review by the public and the agency's Science Advisory Board and is due to be finalized by next year.
To view the executive summary of the report, please see: http://1.usa.gov/1HN3mZX
(Reporting by Valerie Volcovici and Timothy Gardner; Editing by James Dalgleish and Chris Reese)