WATER LINES: Local drought eases with recent rains; Colo. Basin water crisis one step closer | PostIndependent.com

WATER LINES: Local drought eases with recent rains; Colo. Basin water crisis one step closer

Hannah Holm
WATER LINES
Free Press Weekly Columnist

Last Friday, Aug. 23, torrential rains sent mud and boulders across I-70 west of Parachute. In eastern Colorado, one downpour hit so hard it knocked watermelons off their vines and pushed them into ditches. Even stranger, perhaps, was the gentle rain that fell steadily in Grand Junction from late Sunday morning on Aug. 25, well into the night, with temperatures that never climbed above 70 degrees F — that’s a record low high temperature for the date.

Across the Upper Colorado River Basin, and across Colorado, a generous monsoon season has made August nice and wet, with the exception of northwestern Colorado and adjacent areas of Utah and Wyoming. The Four Corners region and Colorado’s Eastern Plains, both areas where the drought has been particularly persistent and extreme, have received some of the highest rainfall totals.

Little by little, this moisture is starting to put a dent in drought conditions, although there is still a lot of ground to make up from a very dry winter on the heels of a very dry 2012. Current stream flows are starting to get back up into the normal range, with the exception of the White River Basin in northwestern Colorado, which is experiencing very low flows. Cumulative stream flows for the 2013 water year, which started Oct. 1, 2012, remain significantly below average across the region. In southwestern Colorado, dry soils have soaked up a lot of the recent rain, blunting its impact on stream flows.

Vegetation remains drier than average across most of the Upper Colorado River Basin, with the most extreme conditions in southwestern Wyoming and northeastern Utah. The northern and central Colorado mountains, on the other hand, are showing normal-to-wet vegetation moisture levels.

Forecasters are anticipating that the next few weeks will bring more monsoon moisture to western Colorado and the rest of the Colorado River basin, but the 3-month forecast is totally up in the air for Colorado and the rest of the Southwest.

Although conditions have been improving, the U.S. Drought Monitor still shows over 98% of Colorado under some level of drought classification, with similar conditions in surrounding states. Long-range forecasts are only moderately optimistic about any improvement.

Meanwhile, reservoir levels, our best indicator of the long-term water supply-demand balance, continue to drop, as they normally do in August. Blue Mesa Reservoir, Colorado’s largest, and Lake Powell, the Upper Colorado River Basin’s largest, are both at about 45% of capacity, containing just over half their historical average August volumes.

Water levels in Lake Powell have dropped to the point where releases from Lake Powell to Lake Mead for the lower Colorado River Basin states will be limited to 7.48 million acre feet in 2014, the lowest amount since Lake Powell was filling in the 1960s. Lake Mead levels are already well below average and dropping, so reduced releases from Lake Powell could hasten the date when the lower basin water users will face cuts in their Colorado River deliveries.

It’s lovely to see my garden perking up from the recent rains, but I’m not expecting the alarm bells about the long-term water crisis in the Colorado River Basin to stop ringing any time soon.

For more information:

• Most of the climate data discussed in this article came from the Aug. 27 Weekly Colorado Drought Assessment Webinar broadcast by the Colorado Climate Center. You can find the briefing materials here: http://climate.colostate.edu/~drought/ .

• Information on reservoir operations and long-term supply and demand in the Colorado River Basin come from the U.S. Bureau of Reclamation, which has a wealth of information on its website: http://www.usbr.gov.

This is part of a series of articles coordinated by the Water Center at Colorado Mesa University in cooperation with the Colorado and Gunnison Basin Roundtables to raise awareness about water needs, uses and policies in our region. To learn more about the basin roundtables and statewide water planning, and to let the roundtables know what you think, go to http://www.coloradomesa.edu/WaterCenter.

Hannah Holm is coordinator of the Water Center at Colorado Mesa University.


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