Entire letters are available at the links.
Morrison Mayor Early Auckland to Kent Rice, Manager of Arts & Venues, August 1, 2011
The Town’s elected officials have received complaints from residents of the Town concerning the apparently later hours and louder volumes of the concerts this season. The sense is that the concerts are going later than 12:30 a.m. or 1:00 a.m., and the music is being broadcast at a higher volume than in the past.
Morrison Mayor Earl Auckland to Kent Rice, Manager of Arts & Venues, August 14, 2013
In the time between my last letter and today however, the problem has grown significantly. The kind of music and sound now frequently heard at Red Rocks, the “techno sound” is different, and its impacts on the residents greater, than has been the case in the past. These concerts are also going later.