The Dave Matthews Band (search) says it is cooperating with authorities to determine what happened when a tour boat with more than 100 passengers was doused with raw sewage.

A lawsuit by Illinois' attorney general contends the band's tour bus emptied its septic tank while crossing a grated bridge over the Chicago River on Aug. 8.

The band issued a statement on its Web site saying members have offered to provide DNA evidence (search) to help authorities determine the source of the sewage.

In its statement, the band also said that if its bus is found to be responsible for the incident, the band will "work quickly to make amends, with the people on the boat and with Chicago."

"We care deeply about what happened to the people on the boat that day, which was terrible, and the damage that occurred to Chicago's environment," the letter states. "We are not attempting to avoid any responsibility we may have for the incident."

Attorney General Lisa Madigan's lawsuit against the band and driver, Stefan Wohl, accuses them of violating state water pollution and public nuisance laws.

No criminal charges have been filed.