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

Streamflows slowing down

Local streamflows are slowing down as snowpack is entirely melted and temperatures keep rising.

At Stillwater, located upstream of Aspen, the Roaring Fork River ran at 84.9 cfs on July 23, or 71.9% of average, down from last week when the river ran at 96.7 cfs, but up from 58.3% of average.

Water through the tunnel that sends Roaring Fork flows east of the Continental Divide keeps dropping from 114 cfs on July 16 to 40.5 cfs on July 23.

The USGS sensor below Maroon Creek recorded the Fork running at 464 cfs on July 23, or 97.7% of average, down from 604 cfs, or 96.5% of average, on July 16.

At Emma, below the confluence with the dam-controlled Fryingpan, the July 23 streamflow of 878 cfs represented about 118% of average. That’s down from 1,070 cfs on July 16, or 117.5% of average.

Meanwhile, the Crystal River above Avalanche Creek, which is not impacted by dams or transbasin diversions, flowed at 540 cfs or 136.4% of average. Last week, the river ran at 797 cfs, or 146.5% of average.

The Colorado River ran at 4,210 cfs at Glenwood Springs, or 98.8% of average, on July 23, down from 5,260 cfs last week, while the Colorado flowed at 5,760 cfs near the Colorado-Utah stateline, or 100.9% 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 level down 1.5 feet from 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 July 23, the reservoir was 40.72% full (based on updated 2017-18 sedimentation data). That’s down from July 16, when the nation’s second-largest reservoir was at 41.26%.

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 July 23, 2022, the reservoir was 26.88%.

On July 23, Lake Powell’s elevation reached 3,582.5 feet, or 117.5 feet from full pool, down from 3,584.02 feet on July 16. Last year, on July 23, the reservoir reached 3,537.08 feet in elevation, or 162.92 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.

Air temperatures as high as 90°F in Aspen

High air temperatures at the Aspen airport reached 90°F on July 17, or about 10 degrees above normal, before dropping to 80°F on July 20. In 2020, air temperatures also reached 90°F on July 17 — the highest air temperature ever recorded since 1998 is 92°F on July 21, 2005, June 20, 2016 and July 9, 2021. Meanwhile, low temperatures ranged from 44°F on July 15 to 53°F on July 19.

Clean air in Aspen

The air quality in Aspen was “good.” The AQI index for ozone ranged from 38 on July 18 to 45 on July 21.

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,...