Members from an Oregon fraternity and sorority left a half-mile-wide swath of trash, empty bottles, tents and coolers at a California lake campsite following their annual trip over the weekend.

The National Forest Service said dozens of workers spent at least five hours cleaning up the mess on Slaughterhouse Island in Lake Shasta.

Pictures surfaced on social media showing the mess, including items branded with University of Oregon logos and a cooler with the Lambda Chi Alpha Greek fraternity letters on it. The Los Angeles Times reported condoms, tampons, human waste and about 90 tents were among some of the items found at the lake.

The University of Oregon said it’s investigating whether other fraternities or sororities were responsible for the mess, university spokesman Tobin Klinger said. The investigation won't be easy given the large number of people there and possibility that other schools were involved, he added.

"You're going to have a variety of people, not exclusively one fraternity or sorority, not exclusively one university, not exclusively Greek, non-Greek," Klinger explained.

Robin Holmes, vice president for student life at the university, said in a statement that fraternities and sororities all along the West Coast take trips to the area each year and called the remnants left by the members “disgraceful.”

"We are working with authorities to learn all we can and determine who is responsible," she said.

Rangers said they were unsure whether the area would be totally clean before the Memorial Day holiday weekend, according to SF Gate.

"Their attitude is we'll pick it up later," Shasta Boating Safety Unit Sgt. Rob Sandbloom told the Daily Emerald Monday. "If you're at your mom's house are you just going to throw a can down and pee on her couch and say you'll clean it up later? No, you wouldn't. And they say they wouldn't, so don't do it here."

The national Lambda Chi Alpha fraternity suspended the activities of its University of Oregon chapter, Holmes said.

The chapter is cooperating with the university's investigation and will hold the people involved accountable, it said in a statement posted on the university's fraternity and sorority life Facebook page.

The group also said it had reached out to the forest service to help with the cleanup.

The Associated Press contributed to this report.