Aspen Journalism: A check of key spring indicators
Streamflow on the rise
Streamflows in the Roaring Fork basin are flowing around 86%-150% of average. Aspen Journalism is also compiling real time streamflow data, which you can find at http://www.aspenjournalism.com
At Stillwater, located upstream of Aspen, the Roaring Fork River ran at 137 cfs, or 86.7% of average on May 14. That’s up from 113 cfs but down from 100% of average, on May 7.
The USGS sensor below Maroon Creek recorded the Fork running at 409 cfs on May 14, or 119.9% of average. That’s up from 354 cfs on May 7.
At Emma, below the confluence with the dam-controlled Fryingpan, the May 14 streamflow of 968 cfs represented about 129.9% of average. That’s up from 904 cfs, but down from 142.4% of average, on May 7.
The transbasin diversion that sends Roaring Fork basin headwaters to Front Range cities and farms was flowing at 111 cfs on May 14, up from 107 cfs on May 7.
Meanwhile, the Crystal River above Avalanche Creek, which is not impacted by dams or transbasin diversions, flowed at 963 cfs, or 147.2% of average, on May 14. Last week, the river ran at 782 cfs, or 152.1% of average.
The Colorado River ran at 2,600 cfs at Glenwood Springs, or 141.3% of average on May 14, up from 2,320 cfs last week, while the Colorado flowed at 27,000 cfs near the Colorado-Utah stateline, or 210.9% of average.
Snowpack keeps dropping but still 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 13.7 inches of snow-water equivalent per site on May 14, or 167% of median, according to NRCS.
SNOTEL sites that monitor snowfall throughout the winter measured the snowpack at Independence Pass at 95.1% of median on May 14 with a “snow water equivalent” (SWE) of 9.7 inches, down from 11.7 inches but up from 86.7% of normal on May 7. Last year on May 14, the SNOTEL station up the pass (located at elevation 10,600 feet) recorded an SWE of 9.4 inches.
The monitoring station at McClure Pass, located at elevation 8,770 feet, recorded a SWE of 10.2 inches on May 14, or 2,550% of the median at 0.4 inches. That’s down from a SWE of 16 inches on May 7, but up from 308% of median. Last year, on May 14, the station measured a snowpack holding zero 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 12.7 inches of SWE on May 14, or 97.7% of median.
Snowpack at North Lost Trail, which sits at an elevation of 9,219 feet, has reached 11.6 inches of SWE on May 14, or 414% of median, down from 25.9 inches last week.
Snowpack at Schofield Pass reached 44.2 inches on May 14, which represents 158.4% 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 water levels continue seasonal rise
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 14, the reservoir was 26.02% full (with a total capacity based on a 1986 sedimentation survey) or 27.15% full (based on updated 2017-18 sedimentation data). That’s up from May 7, when the nation’s second-largest reservoir was at 24.16% of capacity (1986 data) or 25.21% (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 14, 2022, it was 24.2% full (based on 1986 data).
On May 14, Lake Powell’s elevation reached 3,538.1 feet, or 161.9 feet from full pool, up from 3,530.7 feet on May 7. The reservoir’s water level on May 14 was 13 feet above the target elevation of 3,525. Last year, on May 14, the reservoir reached 3,524.35 feet in elevation, or 175.65 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 close to 70°F
High air temperatures at the Aspen airport dropped from 68°F on May 3 to 55°F on May 7 before reaching 68°F on May 10, or about eight degrees above normal. Meanwhile, low temperatures were around 35°F, which is close to normal.
Better air quality reported in Aspen last week
The air quality in Aspen was “good” last week except on May 10 when the AQI index for ozone reached up to 64. For the remainder of the week, the AQI index ranged from 39 on May 11 to 47 for ozone on May 8.