Mountain snowpack

Mountain snowpack is above the 30 year average in many areas of southern Montana and northern Wyoming.

BRETT FRENCH, Gazette Staff

It's still early in the winter season but mountain snowpack for the Bighorn, lower Missouri and Yellowstone rivers is looking strong.

Mountain snowpack that feeds the Bighorn River is above 100 percent, according to the Bureau of Reclamation. The agency's January forecast for the April through July runoff is encouraging for anglers and farmers.

Inflow to Bighorn Lake is forecast to be about 1.66 million acre feet, which is 143 percent of the 30 year average. Projected inflows to other reservoirs in the system are: Buffalo Bill Reservoir 950,000 af, or 135 percent; Boysen Reservoir 900,000 af, 156 percent; and Bull Lake Reservoir 180,000 af, 135 percent. The Wind River above Bull Lake Creek is forecast to be 650,000 af, which is 160 percent of the 30 year average.

With inflows to Bighorn Reservoir predicted to be high, the dam on Wednesday increased its releases from 3,700 cubic feet per second to 3,900 cfs.

Likewise, releases from Fort Peck Dam were increased to 10,500 cfs in January, up from 6,800 cfs in December, and are expected to jump to 11,000 cfs during February. Snowpack above Fort Peck Reservoir is about 109 percent of average. By this time of the year only 44 percent of the snowpack has accumulated. The reservoir is sitting at an elevation of 2,235.8 feet and is expected to fall another 1.2 feet this month.

Elsewhere, the Smith, Judith and Musselshell river basins are at 108 percent of normal and the upper Yellowstone is at 125 percent while the lower is at 76 percent. The Tongue and Powder river basins are at 74 and 89 percent, respectively.

Bureau of Reclamation's January forecast of the April through July runoff predicted for the Bighorn Basin is as follows:

  • Bighorn Lake - Bighorn River April through July inflow to Bighorn Lake is forecast to be approximately 1,668,700 acre-feet (af), which is 143 percent of the 30 year average of 1,165,700 af.
  • Buffalo Bill Reservoir - April through July inflow to Buffalo Bill Reservoir is forecast to be approximately 950,000 af, which is 135 percent of the 30 year average of 704,400 af.
  • Boysen Reservoir - April through July inflow to Boysen Reservoir is forecast to be approximately 900,000 af, which is 156 percent of the 30 year average of 577.7 af.
  • Bull Lake Reservoir - April through July inflow to Bull Lake Reservoir is forecast to be approximately 180,000 af, which is 135 percent of the 30 year average of 140,400 af.
  • Wind River - April through July discharge from the Wind River above Bull Lake Creek is forecast to be 650,000 af, which is 160 percent of the 30 year average of 406,900 af.
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