Teton County officials say they've detected a carcinogenic chemical in groundwater near an old landfill.
County Engineer Sean O'Malley says methylene chloride has been turning up for the past two years in monitoring wells near the landfill in Horsethief Canyon. The dump operated from the 1950s until the late 1980s.
State standards allow up to 5 parts per billion of methylene chloride in water samples. A test in October showed water from a monitoring well had 28 parts per billion of the chemical.