Those who care about Skinner Butte should check this Bob Welch RG column from 2007 on how  open access to the butte was saved in 1997:  https://www.thefreelibrary.com/On+butte+top%2C+good+works+look+sharp-a0162133969
Welch describes how the City of Eugene was going to lock the gate and limit access to the top of Skinner Butte because of the noise, littering and vandalism.  But Ray Wiley, a leader of the Eugene Rotary Club, recognized the significance of the butte to the community and organized his club to volunteer to clean it up if the city would agree to keep it open.
This succeeded then, but as many have noted, it's a continuous process to keep up with the destruction and mess left behind by the thoughtless.  
Just complaining about it doesn't work,  for as Wiley showed sometimes we have to get out with a bag and pick up the trash ourselves.