About 22,000 gallons of untreated sewage was dumped into the Jones Falls at 3300 Clipper Mill Road on Wednesday and early yesterday morning after a sewer line broke. The overflow came as the city's Department of Public Works works on a $900 million upgrade of the sewer system. In 2002, Baltimore officials signed a consent decree with the Environmental Protection Agency to eliminate overflows. A city spokesman said the overflow occurred on a sewer line that is being replaced and was contained by 3:30 a.m. yesterday. The spokesman said the cause of the break was unknown.