A group that grades the environmental friendliness of ski areas in the West says 53 of the 83 resorts it reviewed this year boosted their scores -- but seven received failing grades.
The resorts with the highest and lowest scores are both in Colorado.
The Ski Areas Citizens' Coalition says Aspen Mountain got an 'A' with a top score of 85.7, while Copper Mountain ranked lowest at 31.9 for an 'F.'
Coalition research director Hunter Sykes says Copper's low score was almost entirely due to an expansion of terrain and real estate development. Aspen was credited for trying to minimize impacts of development.
Copper Mountain spokeswoman Lauren Pelletreau says the group's scorecard doesn't credit resorts' sustainability initiatives or community involvement.
Squaw Valley landed at No. 5 overall for the coalition's Top Ten list.
In addition to Squaw, other California resorts -- out of a total of 18 -- that scored an A based on the Coalition's standards are:
The worst-scoring resort in California is Northstar-at-Tahoe with a score of 48.9. That means the ski area gets a grade of D. The aspects that give the resort such a low score are mostly development-related, with real estate development and endangered species habitat protection the biggest offenders.
Besides Copper Mountain, other resorts receiving Fs this year are: