Colorado River: January Forecast

The January Colorado River forecast for 2009-10, out last Friday, is the lowest at this point in the year since 2002-03:

Forecast calls for low flows into Lake Powell

Forecast calls for low flows into Lake Powell

The range of uncertainty right now is enormous. In an average year, about 8 million acre feet flows into Lake Powell in the April-July period, which is the peak of the runoff season. This year’s forecast is for anywhere from 9.6 maf (the 90th percentile, the top red triangle in the graph above) to 3.2 maf (the bottom red triangle, the 10th percentile), with a median forecast of 6.2 maf (the red dot in the middle, which would be 78 percent of normal flow).

If the forecast stays low between now and April 1, that would trigger a minimum release this year from Lake Powell downstream into Lake Mead under current operating rules. That would likely mean a continued lowering of Lake Mead’s levels. Water storage in Lake Mead is currently the lowest it has been at this point in the year since the reservoir was first filled in the 1930s.

Other infobits:

  • December inflow into Lake Powell: 309 thousand acre feet, 71 percent of normal
  • January forecast inflow into Lake Powell: 330 kaf, 81 percent of normal
  • Colorado Basin snowpack: 76 percent of normal


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  1. Pingback: jfleck at inkstain » Chances of Extra Water for Mead Diminish

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