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

Roaring Fork Basin snowpack is at 122% of average

Snowpack in the Roaring Fork basin reached 122% of average for Dec. 11 with 5.6 inches of snow-water equivalent, according to NOAA.

SNOTEL sites that monitor snowfall throughout the winter measured the snowpack at Independence Pass at 91.9% of average on Dec. 11, with a “snow water equivalent” (SWE) of 4.69 inches, up from 4.21 inches on Dec. 4. Last year on Dec. 11, the SNOTEL station up the pass (located at elevation 10,600 feet) recorded an SWE of 4.49 inches, or 88% of average.

The monitoring station at McClure Pass located at elevation 9,500 feet recorded a SWE of 5.51 inches on Dec. 11, or 134.4% of average. That’s up from a SWE of 4.29 inches on Dec. 4. Last year, on Dec. 11, the station also measured a snowpack holding 2.28 inches of water.

On the northeast side of the Roaring Fork Basin, snowpack at Ivanhoe, which sits at an elevation of 10,400 feet, reached 5.31 inches on Dec. 11, or 118.1% of average.

Snowpack at Schofield Pass reached 10.39 inches on Dec. 11, which represents 116.8% of average. Schofield Pass sits at an elevation of 10,700 feet between Marble and Crested Butte.

Snow water equivalent — the metric used to track snowpack — is the amount of water contained within the snowpack, which will become our future water supply running in local rivers and streams.

Air temperatures getting closer to normal

High air temperatures at the Aspen airport reached as high as 45°F on Dec. 4 and as low as 30°F on Dec. 8, which is about two degrees below normal. Meanwhile, low temperatures increased from 1°F on Dec. 8 to 30°F on Dec. 5 before dropping to 1°F on Dec. 8, which about eight degrees below normal.

The Fork ran at about 122% of average below Maroon Creek

The Roaring Fork River below Maroon Creek flowed at 123 cfs on Dec. 11, or 121.8% of average, according to the USGS gauge. That’s up from Dec. 4, when the river was flowing at 95 cfs, or 93.3% of average.

At Stillwater, located upstream of Aspen, the Fork on Dec. 11 ran at 15 cfs or 53.6% of average, down from 15.2 cfs but up from 52.4% of average on Dec. 4.

The upper Fork’s flow is impacted by the Independence Pass transbasin diversion system that sends Roaring Fork headwaters to Front Range cities. Water flowing through the tunnel under the Continental Divide between Grizzly Reservoir on Lincoln Creek and the South Fork of Lake Creek measured 13.6 cfs on Dec. 11.

The Roaring Fork at Emma, below the confluence with the dam-controlled Fryingpan, saw on Dec. 4 streamflow of 240 cfs, or about 87.6% of average. That’s down from 263 cfs, or 96% of average, on Dec. 4.

Meanwhile, the Crystal River above Avalanche Creek, which is not impacted by dams or transbasin diversions, flowed at 60 cfs, or 105.6% of average, on Dec. 11. Last week, the river ran at 65 cfs, or 110.7% of average.

Lake Powell’s water levels two feet above target elevation

Lake Powell‘s storage remains at one of its lowest levels recorded since it began filling in the 1960s. On Dec. 11, the reservoir was 23.27% full (with a total capacity based on a 1986 sedimentation survey) or 24.27% full (based on updated 2017-18 sedimentation data). That’s down from Dec. 4, when the nation’s second-largest reservoir was at 23.42% of capacity (1986 data) or 24.44% (based on 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. Aspen Journalism in July published a story explaining the that drop in storage due to sedimentation.

The reservoir’s capacity has fallen since last year, when on Dec. 11, 2021, it was 28.41% full (based on 1986 data).

On Dec. 11, Lake Powell’s elevation reached 3,527 feet, or 173 feet from full pool, down from 3,527.6 feet on Dec. 4. The reservoir’s water level on Dec. 11 was two feet above the target elevation of 3,525. Powell’s surface elevation this year peaked at 3,539.84 feet on July 3, after it dipped to its lowest level since filling of 3,522.24 on April 22. Last year, on Dec. 11, the reservoir reached 3,540.26 feet in elevation, or 159.74 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.

‘Clean’ air recorded last week in Aspen

The air quality in Aspen was “good” last week with an AQI index ranging from 14 on Dec. 7 for PM2.5 to 38 on Dec. 9-10-11 for ozone.

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,...