The state's Water Quality Board upheld the decision of state regulators by a vote of 9-2.
Board members turned down an appeal Wednesday by a Moab-based environmental group that argued the project in eastern Utah's Book Cliffs area will contaminate groundwater.
State regulators and the company insist there is no significant groundwater to pollute in the desert area.
U.S. Oil Sands Inc. says it's now ready to go after working since 2005 to obtain or defend its state approvals.
Living Rivers says it will take up its fight with the Utah Court of Appeals. The group argues that snowmelt and infrequent rain can saturate the project site at times during the year.
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