Much of the information published on loss of water at Lake Powell was done by organizations that have the goal of decommissioning Glen Canyon Dam and draining Lake Powell.

"But at Powell, no such research has been conducted since the mid-1970s. What’s more, the USU assessment learned that no studies of water seeping into the relatively porous Navajo sandstone bedrock of Lake Powell had been conducted since the mid-1980s."

and

"Seepage losses into the Lake Powell bedrock, meanwhile, likely are ten percent of what Fill Mead First advocates claim. The USU study noted that some of the seepage water returns to the Colorado River above Lee’s Ferry."