A top federal official has resumed pressure on states in the Southwest to wrap up long-delayed emergency plans for potential shortages on the Colorado River.
Projections show there's a chance that Lake Mead will fall low enough in 2020 to trigger cutbacks under agreements governing the system.
The Colorado River is expected to only carry 43 percent of the average amount of water into Lake Powell this year.
Officials in Colorado, New Mexico, Wyoming and Utah, who accused the Central Arizona Project of manipulating the water at the expense of others.
The so-called bug flows are part of a larger plan approved in late 2016 to manage operations at Glen Canyon Dam, which holds back Lake Powell.
John Fleck, director of the University of New Mexico Water Resources Program, says there are signs that years of work could be at risk.
The normal staid diplomacy of Colorado River managers was upended in a spat between Denver Water and the Central Arizona Project.
The U.S. Fish and Wildlife Service said Thursday it will consider reclassifying the humpback chub as threatened within the next year.
About 90 percent of the Colorado River's water comes from snowmelt in the Upper Colorado River Basin, a large swath of Colorado, Utah and Wyoming.