Aspen Skiing Co. ...took a chance last October and let an independent, third-party auditor assess what they were doing. The gamble paid off...[when the company] learned earlier this month that it will retain [an environmental] certification, formally known as ISO 14001, after going through its annual audit... It might mean additional pressure on major ski companies, such as Vail Resorts, to follow suit. Many ski areas in the country participate voluntarily in the Sustainable Slopes Program... But critics contend Sustainable Slopes is just a way for the ski industry to dupe customers into thinking it's environmentally friendly without taking meaningful action. In a study last year, two professors concluded that...the program [is] a "symbolic self-regulatory scheme that does not appear to effectively improve industry-wide environmental protection." [They] said the industry needed third-party audits - like the Skico undertakes - to be credible. [also refers to Sun Peaks]