Denver (AP) State officials want more time to comment on a proposed oil shale development in western Colorado they fear will drain up to 15 percent of the region's water.

But federal land managers say the Thursday deadline for public comment won't be extended.

The Bureau of Land Management's draft plan for the first oil shale development on federal land was released in December.

The proposal calls for developing nearly 2 million acres of public land in Western Colorado, Utah, and Wyoming.

Local government officials in Western Colorado and eight water providers along the front range want more time to review the 1,400-page document.

Federal officials and industry experts say almost 2 trillion barrels of oil is trapped in the region's oil shale, three times the proven reserves of Saudi Arabia.

To convert the shale into oil, the shale must be extracted from the rock and heated.