GLENWOOD SPRINGS, Colo. (AP) — Colorado River District officials are expressing concerns over a pipeline proposal to deliver water from the Flaming Gorge Reservoir in Wyoming to Colorado.

The district handles water policy and planning for the Colorado River Basin within Colorado.

Federal regulators are still reviewing Aaron Million's pipeline proposal, which would use water from the Colorado River system.

Colorado River District officials are telling regulators the cost for the pipeline, which would stretch more than 500 miles, will be "enormous." They also say the proposal could cause Colorado to use up its allocation of Colorado River system water under a multistate compact and hurt existing users of that water.

Million contends there's enough water available for his proposal. Federal and state studies on Colorado River water availability aren't complete yet.