Aspen Journalism is compiling a data dashboard highlighting metrics of local public interest, updated weekly.

Most streamflows are down from last week

At Stillwater, located upstream of Aspen, the Roaring Fork River ran at 36.2 cfs on Sept. 24, or 75.4% of average, up from last week when the river ran at 30.9 cfs and 63.1% of average.

Water through the tunnel that sends Roaring Fork flows east of the Continental Divide dropped from 14.2 cfs on Sept. 17 to 1.7 cfs on Sept. 24.

The USGS sensor below Maroon Creek recorded the Fork running at 127 cfs on Sept. 24, or 106.7% of average, down from 133 cfs and 107.3% of average, on Sept. 17.

At Emma, below the confluence with the dam-controlled Fryingpan, the Sept. 24 streamflow of 362 cfs represented about 81.7% of average. That’s down from 383 cfs on Sept. 17 and from 84% of average.

Meanwhile, the Crystal River above Avalanche Creek, which is not impacted by dams or transbasin diversions, flowed at 73 cfs or 61.5% of average. Last week, the river ran at 86 cfs, or 72% of average.

The Colorado River ran at 2,260 cfs at Glenwood Springs, or 102.7% of average, on Sept. 24, up from 2,460 cfs last week, while the Colorado flowed at 3,850 cfs near the Colorado-Utah stateline, or 96.3% of average.

Aspen Journalism is compiling real time streamflow data. You can find all the featured stations from the dashboard with their real-time streamflow on this webpage.

Lake Powell’s water levels have remained relatively unchanged since last week

Lake Powell‘s water levels began their seasonal rise in mid-March as warming temperatures initiated snowmelt, after the reservoir in the winter dropped to its lowest level on record since filling. Water levels peaked in early July and are now slowing decreasing. On Sept. 24, the reservoir was 37.72% full (based on updated 2017-18 sedimentation data). That’s slightly down from Sept. 17, when the nation’s second-largest reservoir was at 37.73%.

Last year, on July 1, 2022, the Bureau of Reclamation revised its data on the amount of water stored in Lake Powell, with a new, lower tally taking into account a 4% drop in the reservoir’s total available capacity between 1986 and 2018 due to sedimentation. Aspen Journalism in July published a story explaining the that drop in storage due to sedimentation. We will be now using the 2017-18 sedimentation data only.

On Sept. 24, 2022, the reservoir was 24.92% full.

On Sept. 24, Lake Powell’s elevation reached 3,573.6 feet, or 126.4 feet from full pool, which is the same as Sept. 17. Last year, on Sept. 24, the reservoir reached 3,529.54 feet in elevation, or 170.46 feet from full pool.

The “minimum power pool” for turbines generating hydropower at the Glen Canyon Dam is 3,490 feet, and 3,525 feet has been set as a buffer to ensure that the reservoir and the turbines can continue to function properly.

Minimum air temperatures close to freezing point

High air temperatures at the Aspen airport went from 60°F on Sept. 15 to 74°F on Sept. 20, which is about four degrees above average. Meanwhile, low temperatures dropped from 40°F on Sept. 14 to 34°F on Sept. 20 before going up to 43°F on Sept. 21.

One day of ‘moderate’ air quality recorded last week in Aspen

The air quality in Aspen was “good” — except on Sept. 22 when the AQI index for ozone was “moderate,” reaching 58. For the remainder of the week, the index for ozone ranged from 33 on Sept. 20 to 47 on Sept. 23.

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,...