Aspen Journalism is compiling a data dashboard highlighting metrics of local public interest, updated at least every Friday. Check back for updates as we add more features.

Cooler temperatures and the rainiest day in three years

The NOAA station located at the Aspen-Pitkin County Airport recorded 1.08 total inches of rain for the month July 2021, compared to 0.6 inches of rain for July 2020. The monthly 30-year average rainfall in Aspen is 1.71 inches for July and 1.68 inches for August. On Sunday, Aug. 1 of this year, it rained a total of 0.86 inches in Aspen, which is the highest daily precipitation since April 2018, when 0.98 inches of rain was measured at the Aspen-Pitkin County Airport. Also on Aug. 1, the maximum air temperature dropped to 76°F, or 3.5 degrees below normal.

Out-of-state wildfires impact air quality

This past week, the air quality in Aspen was reported as “good,” but on Aug. 5, the sensor reported “moderate” air quality, up to an AQI index of 84 for PM2.5 at 8 a.m on Thursday. The poor air quality was caused by smoke from wildfires in Canada and northwestern U.S. The National Weather Service in Boulder predicted that shifting winds would clear the skies on Friday but blow in smoke from California fires on Saturday.

Monsoon rain helps local stream flow

Monsoon rains that fell over a multi-day period running from late last week until Tuesday boosted streamflows. According to the Roaring Fork Conservancy weekly report, “The much needed rain caused river levels to increase temporarily, which also elevated the turbidity, or ‘muddiness’ of the water.” The report said that the prolonged turbidity could impact water quality.

The Roaring Fork River at Glenwood Springs flowed at 801 cfs on Aug. 4, which represents 72.16% of average. That was up 52% from July 29. On Aug. 4, 2020, the river ran at 614 cfs, or 55.33% of average. Nearby, the Colorado River below Glenwood Springs flowed at 2,870 cfs on Aug. 4, which represents 89.69% of average and an increase of 42% from before last weekend’s rain. The Colorado River’s stream flow increased by 33% compared to last year, when the river ran at 2,150 cfs. 

The USGS gauge located upstream of Aspen at Stillwater measured the Roaring Fork River flowing at 46.7 cfs on Aug. 4, which represents 55.6% of average for the day. The Roaring Fork River’s stream flow dropped by 20% compared to last year when the river ran at 58.4 cfs on Aug. 4, or 69.5% of average. 

Lake Powell keeps getting lower

Lake Powell‘s storage kept getting lower this past week, reaching its lowest level ever recorded on Aug. 4 when the reservoir was 32.18% of full, or 165,490 acre-feet lower than the previous all-time low set in 2005.

Last week, on July 29, the reservoir was 32.43% of full. The reservoir’s capacity has fallen significantly since last year, when on Aug. 4, 2020, the reservoir was 50.52% of full.

The surface elevation of Lake Powell is also in decline and hit record low on Aug. 4, 2021, when the reservoir’s elevation dropped to 3,553.3 feet, or 146.7 feet from full pool. The reservoir’s elevation has lost 0.83 inches since July 29, when the elevation was at 145.76 feet from full pool. Last year, on Aug. 4, the reservoir reached 3,605.55 feet or 94.45 feet from full pool.

If the surface elevation of the reservoir on the Utah-Arizona state line, which stores Colorado River basin water, drops below 3.525.5 feet, it would trigger a host of consequences, including impacts to Glen Canyon Dam affecting hydropower production and potential litigation between the seven states that share water under the 1922 Colorado River Compact. The federal Bureau of Reclamation has begun releasing more water from reservoirs upstream in the basin to avoid this scenario.

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Laurine Lassalle

Laurine Lassalle is Aspen Journalism’s data desk editor, where she works to catalogue and analyze local public data. She also heads our our “Tracking the Curve” project, documenting COVID-19 in Pitkin,...