The driver for The Dave Matthews Band has been charged with reckless conduct for allegedly dumping human waste onto a busy river cruiser.
The band's driver Stefan Wohl is charged with dumping human waste
Stefan Wohl, 42, who drives a bus assigned to the band's violinist, was released ahead of a March US hearing.
Wohl was said to be alone when tonnes of waste were dumped over a bridge, falling onto passengers on a boat cruising the Chicago river.
Some retched and tore off their clothes after the incident last August.
No-one was seriously injured, but 100 passengers were said to be affected by what happened.
At least one of them has taken legal action against the band and the driver.
The Dave Matthews Band contributed to environmental groups
Wohl was also charged with polluting the river but denies all the charges, each of which carries a penalty of up to a year's imprisonment.
The bus was identified with the help of a surveillance camera at a nearby health club, prosecutors said.
The Dave Matthews Band co-operated with the investigation into the incident and offered $100,000 (£53,953) to environmental groups involved in keeping the Chicago River clean.
The band offered their "deepest apologies" to the boat's passengers, who were on an architectural tour at the time.
They are an accomplished live act and won a Grammy award in 1996 for their single So Much To Say.