Water Update: Snowpack in S. Platte basin at 311 percent of average; runoff may have peaked early
Snowpack and Reservoir Levels Across Colorado
Figures represent percentage of historic average on June 1.
Basin Snowpack Reservoir Storage
South Platte 311 113
Colorado 223 95
Gunnison 158 109
North Platte 193 NA
Yampa/White 139 114
Arkansas 132 56
Rio Grande 39 66
San Miguel (others in SW Colo.) 59 89
Statewide 197 95
Source: Natural Resources Conservation Service
A new report shows that snowpack in the South Platte on June 1 was at 311 percent of its historic average for that date, narrowly putting it behind the mark set in 2011, which is widely referred to as one of the best-ever snowpack years for the area.
On June 1, 2011, snowpack was at 313 percent of historic average — farther ahead of normal than any other date on record in the South Platte basin.
The Natural Resources Conservation Service’s snowpack data — consisting of reports that collect data for the first day of winter and spring months — date back to 1968, although its Jan. 1 reports for the South Platte Basin only go back to 1985, and its June 1 reports only date back to 1986.
While data is somewhat limited, there’s no doubting there’s a lot of snow in the South Platte mountains right now.
Because of that large snowpack, along with recent heavy rains, there’s been some flooding in the area, particularly along the Poudre River.
As far as the potential for more flooding, water experts say river flows in the area are trending down, doing so earlier than normal, and if there is any more flooding, it will be caused by rains — not necessarily by how much melting snow is coming down from the mountains.
Dave Nettles, the Colorado Division of Water Resources Division 1 engineer, based in Greeley, explained that, in general, this year’s apparent peak runoff for snowmelt up in the mountains came at about May 31 — roughly 10 days earlier than normal.
Flows in the Poudre River peaked on May 31, flowing at about 6,000 cubic feet per second (the historic average is about 1,600 cfs for that date), and had fallen to about 4,300 cfs by Thursday afternoon (the historic average for June 5 is about 1,800 cfs).
Similar to the Poudre, the Big Thompson River above Lake Estes peaked on May 31 as well, flowing at about 1,350 cfs (the historic average for that date is about 440 cfs), and had fallen to 815 cfs by Thursday afternoon (the historic average for June 5 is about 520 cfs).
“Depending on what the weather does, we may have seen the rivers get as high as they’re going to get,” Nettles said. “But as full as the rivers already are … and as saturated as the ground is … it won’t take much rain to make them rise again.”
In addition to large snowpack, reservoirs in the South Platte Basin remain full.
Reservoir levels in the South Platte basin on June 1 were collectively at 113 percent of the historic average for that date, up slightly from the May 1 report this year, when they were 110 percent of historic average.
Minus the flooding in some areas, it’s continued good news for water users in the region.
Snowpack and reservoir measures have been at normal levels, or better, all year.
A healthy water supply is vital for Colorado’s agriculture industry which, according to the Colorado Division of Water Resources, uses about 85 percent of the state’s water.
And it’s especially critical for northeast Colorado, where the bulk of the state’s production takes place, including Weld County, where the ag industry’s market value is $1.86 billion annually, ranking ninth nationally.
In addition to being good for northeast Colorado, the NRCS report showed that water supplies are in good shape across much of the state.
The Colorado River Basin had similar numbers to those of the South Platte basin.
Snowpack for the Colorado basin stood at 223 percent of average on May 1, while reservoir levels were at 95 percent of average.
Statewide, snowpack is at 197 percent of normal, and reservoirs are filled at 95 percent of normal.
Some Rebound In Other Parts of Colorado, Getting Worse in Others
While snowpack measurements throughout the year have shown conditions across the southern mountains tracking at average or below normal, some areas saw improvement during May.
The Arkansas Basin snowpack went from 99 percent of average on May 1, up to 132 percent of average on June 1, although reservoir levels remained about the same as the month before — filled to levels at 66 percent of average.
The Gunnison Basin snowpack went from 97 percent of average on May 1, up to 158 percent of average on June 1, but likewise, reservoir levels remained about the same as the month before — filled to levels at 109 percent of average.
But things are getting worse in the Rio Grande River Basin and the combined San Juan, Animas, Dolores and San Miguel river basins.
The Rio Grande Basin snowpack dropped from 50 percent of average on May 1, down to 39 percent of average on June 1, while reservoir levels remained about the same as the month before — filled to levels at 66 percent of average.
The combined San Juan, Animas, Dolores and San Miguel river basins dropped from 68 percent of average on May 1, down to 59 percent of average on June 1, while reservoir levels improved slightly from the month before — filled to levels at 89 percent of average. ❖