Millions of people rely on crops and cattle that feed off the aquifer. As streams dry up, conservation becomes key.
Overall, the river serves more than 40 million people in cities, farms and tribes in Arizona, California, Colorado, Nevada, New Mexico, Utah and Wyoming. Mexico also gets a share.
Utah wants cleanup compensation and unspecified damages in the 3-million-gallon Gold King Mine spill that was accidently triggered by EPA contractors.
"The Air Force does not have the authority to reimburse communities for costs incurred in dealing with environmental contamination issues.
The agency started work on safety standards after the spill and expects to soon finish them, investigators from the EPA's Office of Inspector General said.
Farmers are getting paid not to plant for part or all of this season. Water managers hope the pilot program will help them prepare for drought in the future.
Denver nonprofit Bayaud Enterprises launched The Laundry Truck, which can wash 300 to 450 pounds of laundry a day, earlier this month.
A New Yorker staff writer traveled the length of the river to see where all the water comes from, and where it ends up.
A group of ranchers near Kremmling will move forward with an ambitious plan to rehabilitate about 12 miles of the river.