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

Snowpack at Indy Pass has increased by 45% since last week

Snowpack in the Roaring Fork basin reached 120.5% of average for Dec. 4 with 4.7 inches of snow-water equivalent, according to NOAA.

SNOTEL sites that monitor snowfall throughout the winter measured the snowpack at Independence Pass at 93.6% of average on Dec. 4, with a “snow water equivalent” (SWE) of 4.21 inches, up from 2.91 inches on Nov. 27. Last year on Dec. 4, the SNOTEL station up the pass (located at elevation 10,600 feet) recorded an SWE of 3.19 inches, or 70.9% of average.

The monitoring station at McClure Pass located at elevation 9,500 feet recorded a SWE of 4.29 inches on Dec. 4, or 130% of average. That’s up from a SWE of 3.5 inches on Nov. 27. Last year, on Dec. 4, the station also measured a snowpack holding 0.39 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 4.8 inches on Dec. 4, or 126.1% of average.

Snowpack at Schofield Pass reached 8.31 inches on Dec. 4, which represents 109.3% 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.

Most streams keep running close to the average

The Roaring Fork River below Maroon Creek flowed at 95 cfs on Dec. 4, or 93.3% of average, according to the USGS gauge. That’s down from Nov. 27, when the river was flowing at 101 cfs, or 103.1% of average.

At Stillwater, located upstream of Aspen, the Fork on Dec. 4 ran at 15.2 cfs or 52.4% of average, down from 15.4 cfs but up from 51.3% of average on Nov. 27.

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 12.2 cfs on Dec. 4.

The Roaring Fork at Emma, below the confluence with the dam-controlled Fryingpan, saw on Dec. 4 streamflow of 263 cfs, or about 96% of average. That’s down from 270 cfs, but up from 94.4% of average, on Nov. 27.

Meanwhile, the Crystal River above Avalanche Creek, which is not impacted by dams or transbasin diversions, flowed at 65 cfs, or 110.7% of average, on Dec. 4. Last week, the river ran at 66 cfs, or 104.6% of average.

High air temperatures gained 20 degrees in three days

High air temperatures at the Aspen airport increased from 28°F on Nov. 28 to 48°F on Dec. 1, which is about 14 degrees above normal. Meanwhile, low temperatures dropped from 20°F on Nov. 27 to -4°F on Nov. 30, which about 14 degrees below normal, before going up to 12°F on Dec. 1.

Lake Powell’s water levels have dropped about seven inches since last week

Lake Powell‘s storage remains at one of its lowest levels recorded since it began filling in the 1960s. On Dec. 4, the reservoir was 23.42% full (with a total capacity based on a 1986 sedimentation survey) or 24.44% full (based on updated 2017-18 sedimentation data). That’s down from Nov. 27, when the nation’s second-largest reservoir was at 23.57% of capacity (1986 data) or 24.59% (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. 4, 2021, it was 28.67% full (based on 1986 data).

On Dec. 4, Lake Powell’s elevation reached 3,527.6 feet, or 172.4 feet from full pool, down from 3,528.2 feet on Nov. 27. The reservoir’s water level on Nov. 27 was about 3.2 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. 4, the reservoir reached 3,541.23 feet in elevation, or 158.77 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 in Aspen

The air quality in Aspen was “good” last week with an AQI index for ozone ranging from 26 on Dec. 3 to 42 on Dec. 1.

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,...