Drop at Blue Mesa heightens concern about spring runoff
Blue Mesa Reservoir will drop precipitously through the rest of the year to a level similar to that of drought year 2002, according to managers of the Aspinall Unit on the Gunnison River.
Blue Mesa, Colorado’s largest lake, harbors about 420,000 acre- feet of water now, but it will drain to about 300,000 acre-feet near the end of October, Erik Knight, a hydrologist with the U.S. Bureau of Reclamation, said Friday. That’s about the amount of water that was left in the reservoir in the drought a decade ago, Knight said.
Operators hope that early snowfall will translate into a bit more water in the reservoir, bringing its volume to 304,000 or 306,000 acre-feet, Knight said.
An acre-foot, or the amount of water needed to cover an acre one foot deep, equals 43,560 cubic feet or 325,851 gallons.
A rule of thumb is that a typical suburban family with a lawn will use about a third of an acre foot of water a year, with 75 percent of that amount going to landscaping.
Blue Mesa and the rest of the Aspinall Unit were built for water storage, electricity generation and irrigation.
Blue Mesa had about 574,000 acre-feet of water in January but likely won’t have that much this coming January, Knight said.
An average year of runoff in 2013 “will not allow us to fill Blue Mesa,” Knight said. “We need something wetter than average.”
The 574,000-acre-foot level is the maximum amount of water the lake can hold over the winter and operators try to start each water year at that level.
Conservation by downstream users can help preserve the amount of water left in the reservoir, Knight said, noting that the storage could be important.
“We can get by this year with what we have in storage,” Knight said. “Another dry year on top of this year would really put us in a bind.”