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

Heavy rain temporarily boosted local streamflow

Local streamflow peaked around Aug. 2 after some parts of the watershed received more rain on August 1 than the entire month of July, according to the Roaring Fork Conservancy’s last week report. Streams across the Roaring Fork Watershed saw a temporary spike in flows and muddy water before returning to summer baseflow conditions.

The USGS gauge located on the Roaring Fork River below Maroon Creek measured streamflow at 303 cfs on Aug. 2 or 85.1% of average before dropping to 59.9% of average, or 184 cfs, on Aug. 7. That’s down from July 31, when the river was flowing at 225 cfs; however, as a percentage of average, this week’s value rose from last week’s 56.2%.

Near Emma, the Roaring Fork was flowing at 649 cfs on Aug. 2, or about 104% of average, and then dropped to 481 cfs on Aug. 7, or 80.3% of average. That’s down from 513 cfs on July 31 but up from that day’s 79.2% of average.

The Crystal River above Avalanche Creek, near Redstone, flowed at 415 cfs, or 154.3% of average, on Aug. 2. The river ran at 148 cfs, or 62.2% of average, on Aug. 7, which is down from July 31 when the river was flowing at 185 cfs but slightly up from 61.9% of average.

Downstream, the Crystal River at the CPW Fish Hatchery bridge ran at 81 cfs on Aug. 7, down from 131 cfs on July 31. It peaked at 382 cfs on Aug. 2 after last week’s heavy rainfall.

Lake Powell is just a quarter full

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 Aug. 7, the reservoir was 25.3% full (with a total capacity based on a 1986 sedimentation survey) or 26.39% full (based on 2017-18 sedimentation data), down from July 31, when it was 25.54% full (1986 data) or 26.65% (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 Aug. 7, 2021, it was 34.67% full (1986 data).

On Aug. 7, Lake Powell’s elevation reached 3,535.2 feet, or 164.8 feet from full pool, down from 3,536.2 feet on July 31. Last year, on Aug. 7, the reservoir reached 3,552.82 feet, or 147.18 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 gets closer to normal at the beginning of the month

High air temperatures at the Aspen airport dropped from 85°F on July 27 to 69°F on July 28, or about ten degrees below normal. It went back up reaching 81°F on July 31, or about two degrees above normal. High temperatures were very close to normal at the beginning of August. As of Aug. 2, it was around 79.3°F, or less than one degree above normal. Meanwhile, the minimum remained above normal except July 30 when it dipped to 47°F, or 0.6 degrees below normal. On Aug. 2, minimum temperature was hovering around 49°F, or less than two degrees above normal.

Clean air reported in Aspen

The air quality in Aspen was “good” this past week. The AQI index for ozone ranged from 37 Aug. 2 and 46 on Aug. 4.

Avatar photo

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,...