Colorado State University is urging its students not to run around campus in their underwear.

The Fort Collins university is asking participants in a traditional end-of-the-year event called the Undie Run — during which students dart across campus in their skivvies — to skid to a halt, citing safety concerns.

In an email to students’ parents with the subject line “CSU needs you to potentially have a conversation with your student(s),” Blanche Hughes, vice president for student affairs, and Jody Donovan, dean of students, discuss why the run is unsupported and unapproved by the campus.

The gathering is typically around sundown on the Friday evening of the last week of classes before finals. An unofficial event page called CSU Undie Run 2019 lists this year’s event as happening on May 10.

“While this may sound like a harmless, fun tradition that allows students to blow off steam, we have significant and real concerns about it,” Hughes and Donovan wrote.

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Some of their concerns include:

People showing up to take pictures or videos of participating students “for their personal use or to post online”

People showing up with drugs or alcohol

Participants climbing volleyball poles and diving into the crowd

Unwanted touching

After-parties where students remain in their underwear, creating a “tone that breeds harmful situations for our students”

CSU officials estimated they’ve spent more than $150,000 in student tuition and fee money to cover the costs of property damage and security related to the annual undie run. The university said around 3,000 to 5,000 people show up for the event, including non-students or younger high school students.

“The run invokes an atmosphere of public intoxication and behavior that risks personal injury or serious injury to others and sexual misconduct,” university officials wrote in an advertisement they plan to run in CSU’s student newspaper. “Past participants, particularly women, have reported groping and sexual assault during the run and at after-parties. The run creates an environment where this sort of behavior more easily occurs.”

At the University of Colorado’s Boulder campus, alumni organization The Herd has put on a similar event called The Nearly Naked Mile for more than 10 years, said Sara Abdulla, Herd program manager.

Abdulla said the event, which features students running a campus course in their underwear, goes through a CU approval process that includes meetings about safety. The alumni association hosts a dance party before the event and a philanthropic clothing drive.

“We have additional volunteers who man the perimeter to make sure we don’t have anyone who isn’t pre-registered trying to get in,” Abdulla said. “All registrants have to be students with a valid student ID card, and they have to sign a waiver. We take safety seriously with this event, but it’s a successful charity drive, and it’s one of our favorite events. We love this event.”

CSU officials said they recognize that some won’t heed their warning and will participate in the Undie Run anyway. But they will be faced with police monitoring the situation who will take “enforcement action for any criminal offenses.”

Volunteers will be on campus to prevent crowds from gathering, the university said. If people assemble, police will take video of the area to be used for any follow-up on complaints and potential criminal incidents to identify individuals who “behave inappropriately,” CSU said.

CSU officials said they will take enforcement action and share information with the proper authorities — be it a high school, other universities or police agencies — to hold participants accountable.

Anyone who is touched inappropriately is asked to note their location and try to get a detailed description of the person who touched them and report it to CSU police as soon as possible.

“If you touch others inappropriately, the university will choose to share your description or an image of you with the public in an effort to identify you and hold you accountable for your actions,” the university said.

Anyone who needs to talk about unwanted sexual touching, sexual assault or sexual misconduct can contact the victims’ advocate team at CSU on its confidential, 24-hour hotline at 970-492-4242.

“Please help us end this unauthorized gathering, which causes harm to your fellow Rams,” CSU officials wrote in their newspaper ad.

Next fall, CSU is creating a committee that will include students to talk about proposals for an “alternative, safe” spring event.