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

Local snowpack reaches 145% of normal

Note: Local snowpack readings and chart are now using the percent of median instead of percent of average.

Snowpack in the Roaring Fork basin, which is exceeding the basin-wide median seasonal snow-water equivalent peak of 17.1 inches that typically occurs in mid-April, reached an average of 21.9 inches of snow-water equivalent per site on March 26 or 145% of median according to NRCS. Snowpack gained about three inches of SWE since last week on average per site after recent snow storms.

SNOTEL sites that monitor snowfall throughout the winter measured the snowpack at Independence Pass at 106.6% of median on March 26 with a “snow water equivalent” (SWE) of 16.2 inches, up from 15 inches on March 19. Last year on March 26, the SNOTEL station up the pass (located at elevation 10,600 feet) recorded an SWE of 13.2 inches.

The monitoring station at McClure Pass located at elevation 8,770 feet recorded a SWE of 27.5 inches on March 26, or 181% of median. That’s up from a SWE of 24.1 inches on March 19. Snowpack has gained three inches of SWE since March 21. Last year, on March 26, the station measured a snowpack holding 16.6 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 16.9 inches of SWE on March 26, or 125.2% of median.

Snowpack at Schofield Pass, which boasts some of the largest SWE accumulations in the basin, reached 46 inches on March 26, which represents 160.8% of median. Snowpack at this site gained six inches of SWE last week, the largest increase of SWE among these five Roaring Fork basin stations over the past week. Schofield Pass sits at an elevation of 10,700 feet between Marble and Crested Butte.

Snowpack at that site has been exceeding its median seasonal peak of 35.1 inches since March 11, which typically doesn’t come until mid April. McClure Pass, which as we reported earlier in March is seeing especially high snowpack readings this winter like other mid elevations stations, topped its median seasonal peak of 16.6 inches on Feb. 14 this year.

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.

Lake Powell’s water levels on the rise

Lake Powell‘s storage dropped to its lowest level recorded since it began filling in the 1960s as of our last post, but water levels at the reservoir began their seasonal rise in mid-March as rising temperatures boosted snowmelt. On March 26, the reservoir was 22.05% full (with a total capacity based on a 1986 sedimentation survey) or 23.01% full (based on updated 2017-18 sedimentation data). That’s up from March 19, when the nation’s second-largest reservoir was at 21.86% of capacity (1986 data) or 22.8% (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 March 26, 2022, it was 24.02% full (based on 1986 data).

On March 26, Lake Powell’s elevation reached 3,521.8 feet, or 178.2 feet from full pool, up from 3,521 feet on March 19. The reservoir’s water level on March 26 was 3.2 feet below the target elevation of 3,525. In the last water year, Powell’s surface elevation peaked at 3,539.84 feet on July 3, after it dipped to what was then its lowest level since filling of 3,522.24 on April 22. Last year, on March 26, the reservoir reached 3,523.61 feet in elevation, or 176.39 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.

Dropping air temperatures at ASE

High air temperatures at the Aspen airport dropped from 47°F on March 14 to 32°F on March 17 before going back up to 37°F on March 24, or 8 degrees below normal. Meanwhile, low temperatures decreased from 31°F on March 15 to 3°F on March 18 before reaching 22°F on March 20. Low temperatures then dropped agin to 10°F on March 24, which is 11 degrees below normal.

Three days of ‘moderate’ air quality last week in Aspen

The air quality in Aspen was “moderate” last week for three consecutive days, March 22-23-24, when the AQI index reached up to 67 for ozone on March 22. For the remainder of the week, the AQI index for ozone ranged from 45 on March 20 to 48 on March 26.

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,...