On behalf of Chesapeake Energy, Weston Solutions ran tests on split water samples at 14 water wells and 1 spring, where EPA is also testing water in Bradford County, as part of its Congressionally mandated hydraulic fracturing study. The results are released in the following massive, 360-page document:
Weston states in the executive summary that the testing found no contamination due to gas drilling. Methane, chloride, sodium, barium were among the contaminants for which testing was run.
I have not yet done a full review of the document and would be interested in any observations others may have.