Inflow into McPhee Reservoir from the Dolores River has dropped to a historic low, falling below the 2002 levels that were the previous driest year since the reservoir was built.
As a result, supply in the reservoir has also dropped slightly to 16.7 inches per acre, down from earlier estimates of 17 inches per acre for full-service irrigators. During full supply, the rate is 22 inches per acre.
“After one good storm the first week of May, it was all downhill, and the Dolores River inflows are coming in below 2002 levels,” said Ken Curtis, an engineer with the Dolores Water Conservancy District, which manages McPhee.
The water district has tightened water allocations, and more conservatively estimated inflows evaporation and conveyance losses, he said.
Since April 1, estimates by the Colorado Basin River Forecast Center for Dolores River inflow into McPhee dropped by nearly half, from 89,000 acre-feet to 46,000 acre-feet.
“It is now almost certain that McPhee will go into the 2019 water year with effectively no carryover storage,” Curtis said. “The only foreseeable change possible is strong monsoon rains, never certain until they arrive.”
McPhee Reservoir municipal supplies for Cortez, Towaoc and Dove Creek are not subject to shortages.
Because of an extremely low snowpack this winter and a hot, dry summer, the runoff forecast is at 15 percent of the 30-year average of 295,000 acre-feet for April through July. Precipitation for the 2018 water year at McPhee, as measured at the Great Cut Dike, is the lowest recorded in the last 35 years.
A bright spot is that the recent rains produced a measurable bump in flows on the Dolores River and McElmo Creek.