§204.220. Adverse Impact on Visibility

"Adverse impact on visibility" means visibility impairment that interferes with the management, protection, preservation or enjoyment of the visitor's visual experience of the Federal Class I area.  This determination must be made on a case-by-case basis taking into account the geographic extent, intensity, duration, frequency and time of visibility impairment, and how these factors correlate with:

 

a)         Times of visitor use of the Federal Class I area; and

 

b)         Frequency and timing of natural conditions that reduce visibility.