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.

Aspen traffic increased in September, August was low compared to past averages

While August 2021 hit summer occupancy records in Aspen and Snowmass Village, the car counts recorded by the city of Aspen at the intersection of Highway 82 and Cemetery Lane, located at the entrance of town, remained low compared to averages over the last 20 years.

On average, the city counted 24,341 cars each day passing through the intersection in August, up to 28,158 on Aug. 8. That is 6.7% below August 2019’s daily average 26,083 and 4.3% below the 20-year average. August 2021’s count is the fourth lowest over the past 20 years. The lowest average car count for the month was recorded in August 2020 with 22,939. In the last 20 years, the highest August average car count was set in 2005 at 27,998.

But while August’s average car count was on the lower end of 20-year averages, September 2021 was the sixth busiest September in the last 20 years, with a daily average of 22,852 cars, up 3% from September 2019, a year which was on par with the 20-year September average. (September 2021 was also a record month for occupancy in Aspen.) The highest car count recorded this year in September was on Sept. 3, the Friday starting the Labor Day weekend, with 25,783 cars passing though the intersection. In the last 20 years, the highest average car count was recorded in 2004 with 23,879, while the lowest was set in 2018 with 17,474.

Snow days bring wide temperature swing

Aspen experienced a wide temperature swing, from a high of 37°F on Oct. 16, when snowfall visited the area and the temperature was 20.3 degrees below normal, to a high the next day of 66°F, which is 10 degrees above normal. After a low of 20°F on Oct. 15 — more than eight degrees below normal —the minimum temperature spiked to 31°F on Oct. 18.

Local streamflows down this past week

The USGS gauge on the Roaring Fork near Aspen at Stillwater, located upstream of town and two major diversion ditches, measured streamflow at 18.4 cfs on Oct. 24, which represents 48.4% of average. A week before, the river was flowing at 37.4 cfs after several rainy days. On Oct. 24, 2020, the river ran at 27.9 cfs.

The ACES gauge, located near the Mill Street Bridge in central Aspen, measured the Roaring Fork at an average of 20.98 cfs on Oct. 24, down from 37.78 cfs on Oct. 17. The river ran at 29.51 cfs on that day last year.

Roaring Fork streamflow levels are back to being below the minimum instream flow of 32 cfs established by a 1976 water rights decree.

The Crystal River above Avalanche Creek, near Redstone, flowed at 86 cfs, or 95.7% of average on Oct. 24, which is down from 98 cfs on Oct. 17. That’s still double the streamflow last year, when the river ran at 43 cfs on Oct. 24, 2020. The Crystal River at the CPW Fish Hatchery bridge ran at 97.1 cfs on Oct. 24. That puts the river near the minimum instream flow set at 100 cfs set by the 1979 water rights decree.

Clean air in Aspen this past week

The air quality in Aspen was “good” this past week, besides Oct. 19 when the air quality was reported as “moderate” with an AQI index for ozone reaching 51.

Lake Powell’s storage and elevation keep getting lower, setting new records low

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. 24, when the reservoir was 29.57% of full.

Last week, on Oct. 17, the reservoir was 29.67% of full. The reservoir’s capacity has fallen since last year, when on Oct. 24, 2020, the reservoir was 45.46% of full.

The surface elevation of Lake Powell is also in decline and hit a record low on Oct. 24, 2021, when the reservoir’s elevation dropped to 3,544.4 feet, or 155.6 feet from full pool. But the reservoir’s decline over the past three weeks has slowed as it has lost only four inches since Oct. 17, when the elevation was at 155.2 feet from full pool. Last year, on Oct. 24, the reservoir reached 3,592.6 feet or 107.4 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,...