New tests of water surrounding natural-gas-drilling sites near Pavillion, Wyo., have turned up results that are "generally consistent" with earlier findings showing a link between contamination and hydraulic fracturing, the Environmental Protection Agency said Wednesday.

The EPA's announcement could be a blow to natural-gas company Encana Corp., which operates the Pavillion gas field and has routinely denied any link between its drilling and compounds found in the EPA's two monitoring wells.

Encana...