University of Oregon officials say they are investigating whether other campus fraternities and sororities were responsible for a trash-strewn mess at a California lake after one fraternity was suspended. University spokesman Tobin Klinger said the task of determining whether other University of Oregon fraternities and sororities were involved won't be easy given the size of the weekend outing and the participation of groups from multiple schools. Pictures on social media show some of the mess, including several items branded with University of Oregon logos and a cooler with the Greek letters Lambda Chi Alpha.