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.

Lake Powell hits record low

Lake Powell‘s storage kept getting lower this past week, reaching its lowest level ever recorded on July 28 when the reservoir was 32.45% of full, or 98,828 acre-feet lower than the previous all-time low set in 2005.

Last week, on July 21, the reservoir was 32.8% of full. The reservoir’s capacity has fallen significantly since last year, when on July 28, 2020, the reservoir was 51.01% of full.

The surface elevation of Lake Powell is also in decline and hit record low on July 28, 2021, when the reservoir’s elevation dropped to 3,554.24 feet, or 145.76 feet from full pool. The reservoir’s elevation has lost more than one foot since July 21, when the elevation was at 144.45 feet from full pool. Last year, on July 28, the reservoir reached 3,606.77 feet or 93.23 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 the operation of 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.

Northwestern Colorado still in ‘exceptional drought’

The Roaring Fork River at Glenwood Springs flowed at 528 cfs on July 28, which represents 38.82% of average. On July 28, 2020, the river ran at 777 cfs — or 57.13% of average. Nearby, the Colorado River below Glenwood flowed at 2,010 cfs on July 28, which represents 54.18% of average. The Colorado River’s stream flow decreased by 13.7% compared to last year, when the river ran at 2,330 cfs. 

The USGS gauge located upstream of Aspen at Stillwater measured the Roaring Fork River flowing at 32.4 cfs on July 28, which represents 32.7% of average for the day. The Roaring Fork River’s stream flow dropped by 67% compared to last year when the river ran at 99 cfs on July 28, or 80.4% of average. 

As of July 27, about 15% of Colorado, including nearly all of Garfield County, is in “exceptional drought,” according to the U.S. Drought Monitor, with the worst conditions centered on the northwest part of the state. Last year, the state didn’t report exceptional drought at this time of year but still experienced widespread drought at a lower level, as 99% of the state was at least abnormally dry. With wet conditions eliminating any drought on the Front Range and Eastern Plains, 43% of the state this year this year is at least abnormally dry.

Credit: U.S. Drought Monitor

‘Moderate’ air quality recorded this past week

Since July 22, the air quality sensor maintained by the city of Aspen has reported four days with”moderate” air quality, which means the daily average index reading has been between 51 and 100. July 24 was the worst day of this past week, with an AQI index up to 71.

Maximum air temperature getting closer to normal

Since July 22, maximum air temperature measured at Aspen has been relatively closed to normal. The highest maximum air temperature recorded this past week was 86°F on July 23, or about six degrees above normal. On July 25, the maximum temperature was 84°F, about four degrees above normal.

The minimum temperature has been higher than normal, up to 56°F on July 24, which represents about nine degrees above normal. On July 25, the minimum temperature was 53°F, which is six degrees above normal.

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,...