Oklahoma's senators joined eight other Republicans on Friday in urging the Environmental Protection Agency to require the strictest scientific standards in judging a high-stakes study over whether hydraulic fracturing contaminated ground water in Wyoming.

Sens. Jim Inhofe, R-Tulsa, and Tom Coburn, R-Muskogee, joined a letter to EPA Administrator Lisa Jackson saying that the outcome of the agency's report could have a major financial impact on the oil and gas industry.

The senators say that should trigger a decision by Jackson that the study is a “highly influential scientific assessment” subject to “the most rigorous, independent and thorough external review process.”

Inhofe said Friday, “On December 8, I spoke with Administrator Jackson on the phone to ask if she would proceed with the Pavillion study under the requirements of a (highly influential scientific assessment). I have yet to receive her answer.