President Barack Obama has given the Department of Energy 90 days to look at ways to improve the safety of drilling for natural gas. The Environmental Protection Agency has already started an extensive review of how drilling affects drinking water.

EPA Administrator Lisa Jackson said the study is the first of its kind.

In the debate over natural gas drilling, one side says not enough is known about hydraulic fracturing.

The other side says there have been sufficient studies and further reviews will cause bureaucratic delays. Fracking, as it's known, uses a mix of water and chemicals to help extract the gas. The industry says frack water has never contaminated drinking water.

But EPA Administrator Lisa Jackson wants to set the record straight.

"Because there was a 2004 EPA study that has been widely over-read to mean that EPA has reviewed hydro-fracking and deemed it safe for drinking water. That's not an accurate statement at all," she said. "EPA has done a literature study of fracking, made some general comments about what we learned from that review. But this is a full-scale study with case studies and other work."

Some gas industry representatives say the scope of the study goes too far. But the Marcellus Shale Coalition director Katherine Klaber says her organization actually wants it to go further.

"And I think it's important, long term, to do the same kind of study across multiple energy sources," said Klaber. "We have to understand as the public, how we get our energy and what's involved in that."

The EPA's study will take two years to complete. In the meantime, Jackson said, states should aggressively enforce any current regulations.