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

Ruedi releases coincide with increased streamflow on the lower Fork

The USGS gauge located on the Roaring Fork River below Maroon Creek measured streamflow at 56.1% of average, or 225 cfs, on July 31. That’s down from July 24, when the river was flowing at 237 cfs; however, as a percentage of average, this week’s value rose from last week’s 51.7%.

Near Emma, the Roaring Fork was flowing at 513 cfs on July 31, or 79.2% of average. That’s up from 478 cfs on July 24 and from that day’s 64.8% of average. Streamflow has been on the rise since July 29.

After recent reports of dead trout on the lower Roaring Fork last week, the Ruedi Water and Power Authority has allowed certain owners of water contracts in Ruedi Reservoir to partially release some water, according to the Aspen Daily News. The water release has helped the trout and bumped our local streamflow located below the reservoir, which could explain why the Fork has been up near Emma but down below Maroon Creek.

The Crystal River above Avalanche Creek, near Redstone, flowed at 185 cfs, or 61.9% of average, on July 31. That’s up from July 24 when the river was flowing at 174 cfs and up from 46% of average last week.

Downstream, the Crystal River at the CPW Fish Hatchery bridge ran at 131 cfs on July 31, up from 89 cfs on July 24.

Lake Powell’s water level has dropped about eight inches since last week

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 began increasing in 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 month.

On July 31, the reservoir was 25.54% full (with a total capacity based on a 1986 sedimentation survey) or 26.65% full (based on 2017-18 sedimentation data), down from July 24, when it was 25.71% full (1986 data) or 26.82% (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 31, 2021, it was 32.34% full (1986 data).

On July 31, Lake Powell’s elevation reached 3,536.2 feet, or 163.8 feet from full pool, down from 3,536.9 feet on July 24. Last year, on July 31, the reservoir reached 3,553.88 feet, or 146.12 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.

Air temperature reached close to 90°F in Aspen in mid-July.

High air temperatures at the Aspen airport were for the most part above normal between mid- and late July. It peaked at 89°F on July 17, or about nine degrees above normal, and it dropped to 75°F on July 24, or about five degrees below normal. Meanwhile, the minimum remained above normal, from 48°F on July 21, which is less than one degree above normal, to 58°F on July 18, which represents around 11 degrees above normal.

‘Good’ air quality reported in Aspen last week

The air quality in Aspen was “good” this past week. The AQI index for ozone ranged from 32 July 28 and 31 to 49 on July 27.

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,...