Aspen Journalism is compiling a data dashboard highlighting metrics of local public interest, updated at least weekly by mid-day Tuesday.
Streamflow on the rise
The USGS gauge on the Roaring Fork River near Aspen at Stillwater, located upstream of town, measured streamflow at 34.8 cfs on April 10, which represents 87% of average. That’s up from last week, when the river was flowing at 26.6 cfs. On April 10, 2021, the river ran at 34.9 cfs.
The Roaring Fork’s streamflow level is above the minimum instream flow of 32 cfs established by a 1976 water rights decree but is higher than last year.
The Crystal River above Avalanche Creek, near Redstone, flowed at 175 cfs, or about 115.9% of average on April 10. The warmer temperatures of recent weeks kick-started the snow melting process and increased local streamflow. The Crystal jumped from 62 cfs on March 24 to 192 cfs on March 29, before going down to 132 cfs on April 1. A week later, streamflow increased from 150 cfs on April 8 to 175 cfs on April 10. The Crystal River at the CPW Fish Hatchery bridge ran at 163 cfs on Apr. 7 before spiking at 204 cfs on April 10. That puts the river above the minimum instream flow set at 100 cfs set by the 1979 water rights decree.
Lake Powell’s water level drop slows down
Lake Powell‘s storage reached its lowest level recorded since it began filling in the 1960s and ’70s on April 10 when the reservoir was 23.85% of full.
Last week, on March 27, the reservoir was 23.88% of full. The reservoir’s capacity has fallen since last year, when on April 10, 2021, the reservoir was 35.91% of full.
The surface elevation of Lake Powell dipped below the target elevation of 3,525 feet on March 15. The reservoir hit a record low on April 10 when its elevation dropped to 3,522.9 feet, or 177.1 feet from full pool. The drop is slowing down as the reservoir had lost about one inch since April 3, compared to a 6-inch decrease the week before (between March 27 and Apil. 3). Last year, on Apr. 10, the reservoir reached 3,565.32 feet or 134.68 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. Aspen Journalism recently published a story on the impact of last summer’s emergency releases designed to help Lake Powell.
Local snowpack on the decline —but Ivanhoe and Schofield Pass remain above average
“Early April is typically when we reach peak snowpack,” the Roaring Fork Conservancy’s snow report noted on April 7. “Currently, snowpack in the Upper Colorado River Basin (everything upstream of Lake Powell) is 87% of normal for this time of the year. As we move into the warmer months, impacts from below average precipitation and dry soils will be felt locally and downstream, where the inflow at Lake Powell is forecast to be 64% of normal.”
SNOTEL sites that monitor snowfall throughout the winter measured the snowpack at Independence Pass at 80.2% of average on April 10, with a “snow water equivalent” (SWE) of 13.31 inches. The size of the snowpack relative to the 30-year average is down from last week’s 85.3%. Last year on April 10, the SNOTEL station up the pass recorded an SWE of 14.61 inches.
The monitoring station at the lower-elevation McClure Pass recorded a SWE of 11.3 inches, or 70.6% of average, on April 10. A week before, the station reported 12.8 inches of water contained in the snowpack, or 77.1% of average. McClure Pass lost 1.5 inches of SWE between April 7 and 10 when temperatures went up. Last year, on April 10, the station measured a snowpack holding 9.02 inches of water, or 56.3% of average.
On the northeast side of the Roaring Fork Basin, snowpack at Ivanhoe contains higher water levels than the 1991-2020 average, with 16.89 inches on April 10, which is 107.6% of the average of 15.7 inches. It jumped from 15 inches of SWE on March 28. It’s also up from last year’s 15.31 inches of SWE.
Snowpack at Schofield Pass reached 36.81 inches on April 10, which represents 105.2% 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.
Aspen recorded swinging air temperatures last week up to 57°F
Maximum temperature averaged around 50°F between Apr. 1 and 5 and peaked at 57°F on Apr. 2, which is about nine degrees above normal, according to temperatures recorded at the Aspen/Pitkin County Airport. The minimum increased from 19°F on March 31 to 31°F on Apr. 3.
Aspen air quality remains ‘good’
The air quality in Aspen was “good” this past week. The AQI index for ozone ranged from 40 on Apr. 8 to 50 on Apr. 10.
