Aspen Journalism is compiling a data dashboard highlighting metrics of local public interest, updated weekly by mid-day Tuesday.

Local streamflow keeps slowing down

The USGS gauge located on the Roaring Fork River below Maroon Creek measured streamflow at 61.4% of average, or 402 cfs, on July 10, down from 485 cfs on July 4.

Near Emma, the Roaring Fork was flowing at 665 cfs on July 10, or 56.4% of average. That’s down from 797 cfs on July 4.

The Crystal River above Avalanche Creek, near Redstone, flowed at 344 cfs, or about 46.7% of average, on July 10. That’s down from July 4 when the river was flowing at 474 cfs.

Downstream, the Crystal River at the CPW Fish Hatchery bridge ran at 321 cfs on July 10, down from 473 cfs on July 4.

Lake Powell’s surface elevation and storage begin decrease

Lake Powell‘s storage remains at one of its lowest levels recorded since it began filling in the 1960s. While the amount of water stored in the reservoir had been increasing since April due to seasonal runoff, both the storage and surface elevation values reported at the reservoir have been on the decline the over the last week.

On July 10, the reservoir was 26.37% full (based a total capacity based on a 1986 sedimentation survey) or 27.5% full (based on 2017-18 sedimentation data), down from July 4, when it was 26.46% full (1986 data) or 27.6% (2017-18 data).

On July 1, 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.

“After inputting the new data on July 1, 2022, storage values at the current elevation were updated, resulting in a decrease of 443,000 acre-feet,“ bureau officials wrote in an email. 

Aspen Journalism published a story explaining the recent drop in storage due to sedimentation.

The reservoir’s capacity has fallen since last year, when on July 10, 2021, it was 33.65% full (1986 data).

On July 10, Lake Powell’s elevation reached 3,539.5 feet, or 160.6 feet from full pool, down from 3,539.8 feet on July 4. Last year, on July 10, the reservoir reached 3,558.18 feet, or 141.82 feet from full pool. The surface elevation of Lake Powell came back up above the target elevation of 3,525 feet on May 16, after dipping below it on March 15.

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.

Aspen’s maximum air temperatures dropped in late June

High air temperatures at the Aspen airport dropped below normal in late June, from 81°F on June 29 to 64°F on June 30, which is about 14 degrees below normal. Meanwhile, the minimum increased from 41°F on June 27 to 50°F on June 30, or about six degrees above normal.

‘Good’ air quality recorded in Aspen last week

The air quality in Aspen was “good” this past week. The AQI index for ozone ranged from 31 July 5 to 44 on July 8.

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,...