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

Streamflow on the Roaring Fork has approximately doubled since last week

Streamflows in the Roaring Fork basin have increased by 40-107% since last week, while Twin Lake Tunnel has started diverting. Aspen Journalism is also compiling real time streamflow data. You can find all the featured stations from the dashboard with their real-time streamflow on this webpage.

At Stillwater, located upstream of Aspen, the Fork ran at 113 cfs or 100% of average on May 7. That’s up from 54.8 cfs and 71.2% of average, on April 30.

The USGS sensor on the Roaring Fork river below Maroon Creek recorded the Fork running at 354 cfs on May 7, or 118.8% of average. That’s up from 187 cfs on April 30.

At Emma, below the confluence with the dam-controlled Fryingpan, the May 7 streamflow of 904 cfs represented about 142.4% of average after spiking to 973 cfs on May 5. That’s up from 550 cfs, and 102.2% of average, on April 30.

Transbasin diversion resumed last week. The transbasin diversion that sends Roaring Fork basin headwaters to Front Range cities was flowing at 107 cfs on May 7, up from 13.7 cfs on April 30.

Meanwhile, the Crystal River above Avalanche Creek, which is not impacted by dams or transbasin diversions, flowed at 782 cfs, or 152.1% of average, on April 30 after reaching 1,040 cfs on May 4. Last week, the river ran at 548 cfs, or 158.4% of average.

Snowpack drops but remains well above normal

Snowpack in the Roaring Fork basin has dropped from last week but remains well above normal for most sites, reaching an average of 14.5 inches of snow-water equivalent per site on May 7, or 138% of median, according to NRCS.

SNOTEL sites that monitor snowfall throughout the winter measured the snowpack at Independence Pass at 86.7% of median on May 7 with a “snow water equivalent” (SWE) of 11.7 inches, down from 16.1 inches and 100.6% of normal on April 30. Last year on May 7, the SNOTEL station up the pass (located at elevation 10,600 feet) recorded an SWE of 8.2 inches.

The monitoring station at McClure Pass, located at elevation 8,770 feet, recorded a SWE of 16 inches on May 7, or 308% of median. That’s down from a SWE of 23.3 inches on April 30, but up from 274% of median. Last year, on May 7, the station measured a snowpack holding 0.3 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 14.9 inches of SWE on May 7, or 104.9% of median.

Snowpack at North Lost Trail, which sits at an elevation of 9,219 feet, has reached 25.9 inches of SWE on May 7, or 227% of median, down from 23.4 inches last week.

Snowpack at Schofield Pass reached 46.7 inches on May 7, which represents 152.1% of median. 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.

Lake Powell’s water levels reach five feet above target elevation

Lake Powell‘s water levels began their seasonal rise in mid-March as warming temperatures initiated snowmelt, after the reservoir in the winter dropped to its lowest level on record since filling. On May 7, the reservoir was 24.16% full (with a total capacity based on a 1986 sedimentation survey) or 25.21% full (based on updated 2017-18 sedimentation data). That’s up from April 30, when the nation’s second-largest reservoir was at 22.8% of capacity (1986 data) or 23.78% (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 May 7, 2022, it was 23.87% full (based on 1986 data).

On May 7, Lake Powell’s elevation reached 3,530.7 feet, or 169.3 feet from full pool, up from 3,525 feet on April 30. The reservoir’s water level on May 7 was five feet above the target elevation of 3,525. Last year, on May 7, the reservoir reached 3,523.03 feet in elevation, or 176.97 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.

Air temperatures on the rise

High air temperatures at the Aspen airport increased from 38°F on April 22 to 70°F on May 1 before dropping to 68°F on May 3, or 10 degrees above normal. Meanwhile, low temperatures went from 24°F on April 22 to 40°F on May 2 before going down to 34°F on May 3, or about three degrees above normal.

Air quality remains ‘moderate’ in Aspen

The air quality in Aspen was “moderate” for four days last week, on May 2, 4-6, when the AQI index for ozone reached up to 61. For the remainder of the week, the AQI index ranged from 39 on May 7 to 48 for ozone on May 1 and 3.

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,...