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.

The Crystal and Roaring Fork rivers exceed historical averages after rainy days

Recent rains brought local streamflows back up, surpassing historical averages.

The USGS gauge on the Roaring Fork near Aspen at Stillwater, located upstream of town and two major diversion ditches, measured streamflow at 43.5 cfs on Oct. 10, which represents 101.2% of average. A week before, the river was flowing at 37.7 cfs. On Oct. 10, 2020, the river ran at 29.9 cfs. The flow rate started to increase between Oct. 8 and 9, from 28.8 cfs to 39.6 cfs.

The ACES gauge, located near the Mill Street Bridge in central Aspen, measured the Roaring Fork at an average of 39.18 cfs on Oct. 10, up from 22.7 cfs on Oct. 3. The river ran at 19.59 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 now exceed the minimum instream flow of 32 cfs established by a 1976 water rights decree.

The Crystal River above Avalanche Creek, near Redstone, flowed at 132 cfs, or 123.4% of average on Oct. 10. That’s 36% up from last week’s 97 cfs and 175% up from last year, when the river ran at 48 cfs on Oct. 10, 2020. The Crystal River at the CPW Fish Hatchery bridge ran at 119 cfs on Oct. 10. The current streamflow rate doubled from 44.8 cfs on Oct. 8 to 108 cfs on Oct. 9, and it now exceeds the minimum instream flow set at 100 cfs set by the 1979 water rights decree.

Air temperature above normal in Aspen

Maximum air temperature measured in Aspen dropped between Sept. 26 and 30, down to 57°F on Sept. 30. Since then, the maximum temperature has been above normal, up to 73°F on Oct. 5, or about 13°F above normal, before going down to 62°F on Oct. 6, or 1.5 degrees above normal. Meanwhile, the minimum temperature remained above normal, from 32°F on Oct. 7, or 1.2 degrees above normal, to 39°F on Oct. 1, or 6.2 degrees above normal.

Clean air reported last week in Aspen

The air quality in Aspen was “good” this past week. The AQI index ranged from 32 to 39 for ozone between Oct. 4 and Oct. 10.

Slower decline in Lake Powell’s water level

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 Oct. 10, when the reservoir was 29.77% of full.

Last week, on Oct. 3, the reservoir was 29.83% of full. The reservoir’s capacity has fallen since last year, when on Oct. 10, 2020, the reservoir was 46.23% of full.

The surface elevation of Lake Powell is also in decline and hit a record low on Oct. 10, 2021, when the reservoir’s elevation dropped to 3,545.1 feet, or 154.9 feet from full pool. But the reservoir’s decline is slower than past weeks as it has lost only two inches since Oct. 3, when the elevation was at 154.7 feet from full pool. Last year, on Oct. 10, the reservoir reached 3,594.62 feet or 105.38 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,...