Native American reservations could produce much more of the country's solar and wind energy, but the U.S. Bureau of Indian Affairs largely has hindered energy development on tribal lands, the investigative arm of Congress has found.

The BIA often has the final say in approving documents that would clear the way for solar, wind, oil, gas and other projects on reservations, although a process is in places for tribes to take control.

But the agency has been slow to identify land and resource ownership, and lacks adequate staffing to review energy-related documents, the U.S. Government Accountability Office said in a report released this week. The study was requested by Republican Sen. John Barrasso of Wyoming, who chairs the Senate Committee on Indian Affairs.

The delays cause tribes to miss out on opportunities to generate revenue, the report said.

"Unless BIA takes steps to address the factors we identified, these factors may continue to contribute to developers avoiding Indian energy resources in favor of developing non-Indian resources," the GAO wrote. "Further, these factors place the agency at risk of not fulfilling its trust responsibility to Indian tribes and their members."

The Southern Ute Tribe in Colorado estimated it has lost out on an estimated $95 million in revenue from oil and gas severance taxes, permit fees and royalties as dozens of applications for easements waited years for BIA review. The Rosebud Sioux Tribe in South Dakota said the BIA took 18 months to review a wind lease, halting the project.

The GAO recommended that the BIA do a better job of tracking data, and review times so the process is transparent and moves forward without unnecessary delays. The BIA said it is getting ready to deploy a system nationally that would do so, and acknowledged it needs to give more guidance to tribes on how to take over certain federal responsibilities, according to the report. Agency spokeswoman Nedra Darling did not immediately respond Wednesday to a request for further comment.

A 2005 federal law allows tribes to enter into agreements with the federal government to approve leases, business agreements and easements for energy development on tribal land, but no tribe has done so, the report said. Tribal officials interviewed by the GAO said the regulations were unclear, they lacked funding to pursue control, and the process was confusing and time-consuming.

Barrasso said he'll work with Congress to ensure the right steps are taken to allow tribe to develop their resources quicker.

According to the GAO report, tribal lands could produce 5 percent of the country's solar energy and more than 3 percent of electricity from wind.

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