The Southern Ute Tribe of Colorado now requires energy companies to report chemical spills after one went undisclosed for a few months.

Previously, companies could voluntarily report spills of more than one barrel. But after an April 17 incident that caused a nurse to become very sick the tribe is increasing its oversight of oil and gas development.

The spill occurred at a BP well on tribal land. The nurse who treated the worker who cleaned up the spill became "gravely ill," The Durango Herald reported.

The spill wasn't reported to the tribe or the federal government until the nurse came forward with her ordeal. The tribe and the Environmental Protection Agency are now investigating.

Get the Story:
Tribe: Rules tougher than state’s (The Durango Herald 8/6)

Related Stories:
Southern Ute Tribe not told of chemical spill (8/4)
EPA investigates spill on Southern Ute land (8/1)
Colorado to exempt tribal lands from energy rules (7/18)
Colorado's oil and gas rules run into opposition (6/6)