The signature hill in downtown Denver’s Commons Park was flush with small American flags on the evening of Sept. 11, 2001. But 14 years later, it’s often been littered with marijuana smokers and transients. Now it’s even referred to as Stoner Hill on Google Maps.

The hill and the area surrounding it have been fenced off by Denver Parks and Recreation since April; the department is now trying to engage residents who live near the park on how to make improvements.

“This is the first opportunity since the park opened to come together to talk about the park,” Denver Parks and Rec project manager Mark Bernstein said. “Once a park hits 15 years old, it becomes tired.”

Residents in the Riverfront Park neighborhood have complained about park users, ranging from homeless people spilling over from the 16th Street Mall to a younger transient population that came to Colorado for legalized marijuana. Residents have cited people forming trails through the grassy areas, trash and the general feeling of not being safe as the biggest issues.

Since the hill was fenced off, the transients have moved down to the meadow area and the grass has suffered. Another problem is that about 40 irrigation valves were stolen, hampering efforts to improve the landscape.

Commons Park facilities manager Jennifer Buchholz said she first noticed changes shortly after the legalization of marijuana.

“We’ve seen a huge influx of people from out of state,” Buchholz said. “We had to call police more because of fighting and drugs.”

The community and Parks and Rec presented ideas to improve the dynamic of the park, which opened in 2000. The idea of filling in the Sky Garden structure on top of the park’s noted hill was met with mixed feedback. The garden dips down at the top of the hill, making visibility almost impossible until near the top. Community-led movements, such as cleanup days and the possibility of banning smoking, were also introduced.

Denver Parks and Rec interim executive director Scott Gilmore is confident the park can be revitalized and cited the success of Civic Center Park after it was fenced off for improvements when it was rampant with drug deals. There is no timetable to remove the Commons Park fences.

“It’s not going to happen overnight,” Gilmore said. “I want to pull the fence down, but they’ll go right back to the top of the hill.”

Denver Police Lt. Mike Wyatt is responsible for staffing officers to patrol the area and said the park has some challenges such as visibility on the hill and the Commons Grounds sculpture, the public art project that accompanied the park.

The sculpture has hidden areas that have fostered graffiti and drug use. Much of the stone used to build the long sculpture has been damaged, and it has been used as a place to stash drugs. The fence also surrounds the sculpture.

Bernstein and Gilmore have enlisted the help of the community to brainstorm on how to fix problems and will continue to take feedback as they plan the next step. The park’s original designer, Mark Johnson with Civitas, is also involved.

Johnson said when the park was designed, a task force made up of nearby residents said they didn’t want it to be an active park.

“Interestingly, people wanted the park to be passive — no ballfields. They wanted it to be very natural,” Johnson said.

The Glass House condos, which opened in 2007, give residents on the higher floors a bird’s-eye view into the park, leading some residents to see some unsightly things, such as drug use and prostitution.

Jill Janov lives on the 21st floor and has been active in talking to Parks and Rec about the problems.

She said she thinks the park needs a more clear path as to what it is before determining what steps to take to fix problems.

“My feeling as a homeowner is there needs to be a criteria that defines what the park should be,” she said.”For me, the use of the park should dictate what happens to the park.”

Joe Vaccarelli: 303-954-2396, jvaccarelli@denverpost.com or twitter.com/joe_vacc