Aspen Journalism is compiling a data dashboard highlighting metrics of local public interest, updated at least every Tuesday. Check back for updates as we add more features.

Sky Mountain Park soils remain drier in September compared to past years

The Aspen Global Change Institute maintains a network of monitoring stations throughout the Roaring Fork watershed that track soil-moisture levels. The station at Sky Mountain Park measures soil moisture at a 2-inch and an 8-inch depth. While the 8-in depth measurement captures changes in soil moisture across seasons, drying events and moderate or heavy rains, the 2-inch depth data also reflects air temperature.

The soil at the Sky Mountain Park station was drier than the 2016-2020 average at the start of the year for both depths. On Jan. 1, 2021, the Sky Mountain Park station recorded an average of 0.06 m3/m3 of water for the day at 2-inch depth, compared to 0.09 m3/m3 on average between 2016 and 2020. On that same day, the station measured an average of 0.13 m3/m3 of water at 8-inch depth, lower than the 2016-2020 average of 0.19 m3/m3.

As has been observed throughout the Colorado River basin, these dry soils led to decreased runoff and streamflow in the spring. Dry soils early in the season can increase fire risk and plant stress, Elise Osenga, community science manager at AGCI, wrote in an email.

Rain storms that occurred this summer brought a short boost in moisture to 2-inch soils, but soils tended to drain and dry quickly in the following days, according to AGCI and Osenga. From May through July 2021, soil moisture at 2 and 8-inch depths caught up with the 2016-2020 average, but starting in August, soils at Sky Mountain Park became drier than the historical average.

On Sept. 14, 2021 (the last date available on our dataset), the soil contained 0.05 m3/m3 of water at 2-inch depth at the Sky Mountain Park station, lower than the 2016-2020 average of 0.07 m3/m3. At 8-inch depth, the Sky Mountain Park station recorded 0.11 m3/m3 of water, compared to 0.13 on average between 2016 and 2020.

At the Glenwood Springs station, another AGCI station highlighted in last week’s dashboard, the soil contained 0.06 m3/m3 of water at 2-inch depth on Sept. 26, lower than the 2016-2020 average of 0.1 m3/m3. At 8-inch depth, the Glenwood Springs station recorded 0.13 m3/m3 of water, compared to 0.14 on average between 2016 and 2020. Last week, the station recorded 0.07 m3/m3 of water at 2-inch depth and 0.13 m3/m3 of water at 8-inch depth.

The Roaring Fork and Crystal rivers keep running below their minimum instream flow

The USGS gauge on the Roaring Fork near Aspen at Stillwater, located upstream of town and two major diversion ditches, measured streamflow at 24.5 cfs on Sept. 26, which represents 52.1% of average. Last week, the river was flowing at 26.4 cfs. On Sept. 26, 2020, the river ran at 33.4 cfs. 

The ACES gauge, located near the Mill Street Bridge in central Aspen, measured the Roaring Fork at an average of 11.31 cfs on Sept. 26, down from 11.8 cfs on Sept. 19. The river ran at 16.3 cfs on that day last year.

The ACES gauge measures the river, which is already diminished by the diversion to the eastern slope, in an especially compromised stretch — below the Wheeler and Salvation ditches that divert water for upper valley users, and before the channel is replenished by Hunter, Castle and Maroon creeks.

Roaring Fork streamflow levels are lower than the minimum instream flow of 32 cfs established by a 1976 water rights decree.

The Crystal River above Avalanche Creek, near Redstone, flowed at 57 cfs, or 51.5% of average on Sept. 26. That was 3.6% up from last year, when the river ran at 55 cfs on Sept. 26, 2020. The Crystal River at the Dow Fish Hatchery bridge ran at 5.8 cfs on Sept. 26. The current streamflow remains below the minimum instream flow set at 100 cfs set by the 1979 water rights decree.

Air temperature dropping in Aspen

Over the past week, air temperature measured in Aspen decreased, down to 61°F on Sept. 20, or 5.8°F below normal. The minimum temperature was also below normal, down to 34°F on Sept. 20 or 2.7 degrees above normal.

Clear skies in Aspen this past week

The air quality in Aspen improved this past week, with only one day during which the air was reported as “moderate.” The AQI index reached 51 for ozone on Sept. 21. Besides that Tuesday, the air quality was “good” with an AQI index for ozone down to 41 on Sept. 22.

Lake Powell keeps getting emptier

Lake Powell‘s storage kept getting lower this past week, reaching its lowest level recorded since it began filling in the 1960s and ’70s on Sept. 26, when the reservoir was 30.01% of full.

Last week, on Sept. 19, the reservoir was 30.33% of full. The reservoir’s capacity has fallen significantly since last year, when on Sept. 26, 2020, the reservoir was 46.95% of full.

The surface elevation of Lake Powell is also in decline and hit a record low on Sept. 26, 2021, when the reservoir’s elevation dropped to 3,546 feet, or 154 feet from full pool. The reservoir’s elevation has lost more than one foot since Sept. 19, when the elevation was at 152.9 feet from full pool. Last year, on Sept. 26, the reservoir reached 3,596.51 feet or 103.49 feet from full pool.

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,...