Between the leafy trees that occupy Denver’s 200-plus city parks, there’s a recreational activity prompting stern reactions from park officials: slacklining. You’ve probably seen where slackliners rig specially-designed ropes to trees and walk along the taut lines like a circus performer (we wrote about slacklining earlier this spring).

In my last two trips to Denver parks—one a West Denver neighborhood park and the other the uber-populated Washington Park—people in my group have set-up slacklines between trees and have been told by rangers to take them down. According to the Denver municipal code that governs the city’s parks, attaching foreign objects to trees is prohibited. Angela Casias of Denver Parks and Recreation says that developing slacklining areas in parks is being considered, but is still in the very preliminary stages.

Ed O’Brien, founder of the Denver-based slackline company Brand44, says he hopes for a change in the city’s vision of the sport. “It’s amazing that it is a black and white issue,” O’Brien says. “It’s a social activity. It’s about engaging kids and adults to get outdoors. It’s like Frisbee. Go outside and enjoy it.” In order to protect the trees, Brand44 offers a product called Tree Huggerz, which acts like a shield to the tree by wrapping around the trunk to protect the bark.

What do you think? Is slacklining no more harmful to the environment than skiing or kayaking?

—Image courtesy of Shutterstock