The park service is taking public comment on proposed boundaries for helicopter tours around Mt. Rushmore.
The agency said from 2017 to 2019 an average of 4,000 helicopters passed by the monument every year.
Some estimate tours have increased along with the increase in tourists visiting the Black Hills every year.
The park service said the entire Memorial area experiences audible air tour noise anywhere from 3.5 to 8 hours every day. Seventy percent of the park experiences noise above 35 decibels, which is the sound level known to degrade experiences in outdoor venues.
While the park service is solely focused on Mt. Rushmore, the air tours affect the surrounding region of the Black Hills and can be heard in the wilderness area while hiking Black Elk Peak or climbing granite formations in the Wrinkled Rock Area.
The park service wants to prohibit air tours within a half mile of the park’s boundary and below 5,000 ft. in altitude.
The public has until Tuesday, June 20, to weigh in on the Air Tour Management Plan.
