Last week, EPA Administrator Lisa Jackson said she knew of no cases where hydraulic fracturing had affected water supplies. This week, state officials chimed in.

Speaking to an Energy Department panel studying the extraction of natural gas and oil from subterranean rock, state regulators said they, too, haven't heard of any instances where "fracking" has tainted groundwater. Arkansas Oil & Gas Commission Director Larry Bengal:

"We have drilled 3,500 wells in Arkansas and explored every complaint of a compromised well. We have found no fracturing fluid in any of those well complaints."

Here's Elizabeth Ames Jones, chairman of the Texas Railroad Commission, which oversees the oil and natural gas industry in that state:

"In Texas we have never had any cases of groundwater contamination from hydraulic fracturing. ... It is geologically impossible for fracturing fluid to reach an aquifer a thousand feet above. ... Best practices, casing and cementing will ensure that groundwater aquifers will be protected."

Best practices, yes. API and industry officials have developed standards and best practices though a process that includes stakeholders and is reviewed every five years. These have played a key role in effective state regulation - with 184 API Standards cited more than 3,300 times by state regulators.

"From well design to water use and site management, API standards and guidance documents have been used for decades with effective oversight by state environmental regulators," API Director of Standards David Miller said during the industry phase of the DOE panel's hearing.

The panel is scheduled to submit recommendations to Energy Secretary Steven Chu in August. It should make the most of the two months left in its mandate by building on industry's standards and best practices. "We need to ensure we continue developing this nation's vast natural resources in the safest manner possible," Miller said. "However, duplicative efforts by multiple federal agencies could be costly, and counterproductive."

Additional resource:

API government-cited and safety documents