A holding tank at the Ypsilanti Community Utilities Authority overflowed Wednesday evening, sending an estimated 2,000 gallons of waste backwash water into the storm water system, officials said.

The storm water system flows into Willow Creek, which eventually ends in Belleville Lake.

Perry Thomas of YCUA said the overflow was discovered at about 6 p.m. and was stopped by 6:15 p.m. YCUA is located at 2777 State Road in Ypsilanti Township.

Samples were taken from the stream this morning and will be tested for E. coli, Thomas said.