More than 3,500 needles have been collected on the Cherry Creek trail and in other downtown Denver parks this year, an official said Wednesday, and that uptick in open drug use has spurred a new crackdown.

Beginning Friday, Denver police will issue 90-day park or trail suspension notices to people they observe involved in illegal drug activity, whether it’s use, possession, selling or buying.

Denver Parks and Recreation executive director Allegra “Happy” Haynes issued a temporary directive, lasting six months, that allows the Denver Police Department to issue the suspensions. Violating a parks directive could result in a fine of up to $999 or a year in jail under city ordinance, but targets could appeal their suspensions.

The new directive quickly drew criticism from the American Civil Liberties Union of Colorado.

“I have to question the assertion that the parks director has the authority to do something like this,” said Mark Silverstein, the ACLU of Colorado’s legal director.

While the directive gives police an easier way to crack down on drug activity that’s already illegal, he questioned its legal basis since police officers could issue a suspension immediately based on their observations rather than waiting for a conviction for proven law-breaking. He cited a five-page memo issued by Denver Parks and Recreation that says the city charter allows the director to “prohibit certain uses or activities within parks.”

“The parks director has the authority to ban activities (and) has the authority to ban uses in the park,” Silverstein said. “The executive director does not have the authority to ban people.”

In a statement Wednesday, Parks and Recreation explained the rationale: “The Cherry Creek bike trail has become a hub for drug sales and use, jeopardizing the public’s ability to safely enjoy one of Denver’s signature amenities in our outdoor recreation system. The purpose of the directive is to protect public health and parkland, increase safety and improve the overall experience for trail users.”

The DPD supports the directive, according to the statement.

A parks spokeswoman said park rangers and police have started enforcing new rules that include no stopping or standing on the trail near ramps and certain other areas in the trail system.

The moves are the city’s latest response to drug use, homelessness, panhandling and other issues that have spurred complaints from the 16th Street Mall to downtown waterways.

Last week, a group of homeless people who are part of the group Denver Homeless Out Loud sued the city over sweeps of encampments on downtown streets this year.

“There’s a huge epidemic of heroin use right now,” said Cynthia Karvaski, a spokeswoman for the parks department, and it’s been especially visible along Cherry Creek near downtown.

Police officers patrolling the trail often are accompanied by paramedics and representatives of Denver Human Services and the Mental Health Center of Denver, she said, in an effort to connect addicts with available resources.

But in the meantime, she said the prevalence of used needles has been such a concern that the city hired a specialized contractor to help with cleanup in some areas. The contractor has picked up 2,400 needles since April, Karvaski said, making up the largest portion of the 3,500 collected on city parks property this year — most of those on the Cherry Creek trail.

That number include needles deposited into a disposal kiosk installed on the Cherry Creek trail near Colfax Avenue late last year. Officials said then that public safety concerns led to the container’s installation, but people still are discarding used needles on the ground.

Silverstein, from the ACLU, didn’t dispute the problem but said the city’s approach was wrong-headed.

“There already are laws against drug-related activity anywhere in the city, including the parks,” he said. “So there are already laws that forbid the targeted behavior. The city apparently finds those laws inconvenient because they require the due process (guaranteed in) the Bill of Rights to enforce them.”

Karvaski said police have made 128 felony arrests along the trail, with most of on suspicion of selling illegal drugs.

A temporary directive was used by a previous parks director in 2014 to deal with increasing weekend crowds jockeying for volleyball space in Washington Park. This time, Karvaski said, the six-month directive — which goes through Feb. 26 — also will allow for a trial period of sorts for new rules.

“We’re going to see how this goes for the duration of this directive, and then we’re going to look at with DPD at whether this might become permanent,” Karvaski said.