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

Roaring Fork basin snowpack reaches 136% of normal as of March 19

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 19.6 inches of snow-water equivalent per site on March 19 or 136% of median according to NRCS.

SNOTEL sites that monitor snowfall throughout the winter measured the snowpack at Independence Pass at 104.9% of median on March 19 with a “snow water equivalent” (SWE) of 15 inches, up from 14.5 inches on March 12. Last year on March 19, the SNOTEL station up the pass (located at elevation 10,600 feet) recorded an SWE of 12.7 inches.

The monitoring station at McClure Pass located at elevation 8,770 feet recorded a SWE of 24.1 inches on March 19, or 163% of median. That’s up from a SWE of 22.9 inches on March 12. Snowpack at this site peaked on March 16 with 24.4 inches of SWE or 165% of median. Last year, on March 19, the station measured a snowpack holding 14 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 15.8 inches of SWE on March 19, or 124.4% of median.

Snowpack at Schofield Pass, which boasts some of the largest SWE accumulations in the basin, reached 40.1 inches on March 19, which represents 150.7% of median. Snowpack has been plateauing at 40 inches since March 16 after receiving the largest increase of SWE among these five Roaring Fork basin stations over the March 10 weekend. 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 last week, which typically doesn’t come until mid April. McClure Pass, which as we reported last week 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 elevation has gained six inches since last week

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 last week as rising temperatures boosted snowmelt. On March 19, the reservoir was 21.86% full (with a total capacity based on a 1986 sedimentation survey) or 22.8% full (based on updated 2017-18 sedimentation data). That’s up from March 12, when the nation’s second-largest reservoir was at 21.74% of capacity (1986 data) or 22.68% (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 19, 2022, it was 25.24% full (based on 1986 data).

On March 19, Lake Powell’s elevation reached 3,521 feet, or 179 feet from full pool, up from 3,520.5 feet on March 12. The reservoir’s water level on March 19 was 4 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 19, the reservoir reached 3,524.42 feet in elevation, or 175.58 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.

High air temperatures on the rise

High air temperatures at the Aspen airport increased from 38°F on March 10 to 47°F on March 14, or 4.6 degrees above normal. Meanwhile, low temperatures increased from 18°F on March 10 to 27°F on March 11 before dropping to 19°F on March 14, which is only 0.6 degrees above normal.

Overall good air quality in Aspen last week except one day

The air quality in Aspen was “good” last week except for one day on March 17 when the AQI index was in the “moderate” range with 58 for ozone. For the remainder of the week, the AQI index for ozone ranged from 39 on March 15 to 49 on March 16 and 19.

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,...