Crews with the Metropolitan St. Louis Sewer District, or MSD, are cleaning up after a force main break Saturday in Oakville in south St. Louis County released 260,000 gallons of sewage into a tributary of the Mississippi River.

The main runs through a heavily wooded area along Christopher Drive in the southeast corner of the Oakville area.

A small leak was discovered Thursday during routine preventative maintenance, MSD said in a news release. While contractors were excavating the pipe early Saturday morning, the force main failed.

An estimated 260,000 gallons of wastewater or sewage overflowed into Sugar Creek, a tributary of the Mississippi River.

The force main has been repaired and is no longer overflowing, and MSD has begun cleaning and disinfecting the affected area. Cleanup is expected to be done this weekend.

Warning signs have been posted in the area advising the public of the overflow.

While there is no immediate threat to public health or safety, everyone is asked to avoid contact with the creek and affected areas through the weekend.

Anyone who comes in contact with sewage should immediately and thoroughly wash with soap and water, MSD warns.

A force main sewer is a pressurized sewer line that uses pumps to transport wastewater. Pumps and force mains are necessary when gravity alone is not enough to move wastewater through flat areas or over hills to a wastewater treatment plant.

MSD said that it has reported the break to the Missouri Department of Natural Resources.