Long after the Glen Canyon Dam was built and continuing to the present day, controversy remains between supporters of dam removal and those who believe it should be left in place. One of the earliest debates regarding the dam was its impact on Rainbow Bridge National Monument, whose high natural arch is the highest in North America, and is a sacred site to the Navajo people. The environmental lobby wanted the Bureau of Reclamation to keep Lake Powell at or below a level of , to prevent it from intruding into the monument. The Bureau of Reclamation proposed to build a barrier dam and pump system in order to keep water out of the monument. However, with the potential damage that would be caused to the remote environment, "the cure would be far worse than the disease." The proposal was fought over and litigated for years until it was permanently shelved in 1973.