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The city of Ann Arbor has suspended Geddes Pond stillwater paddles and Argo-Gallup canoe trips until water test results are obtained.

(File photo | The Ann Arbor News)

ANN ARBOR, MI - Ann Arbor officials estimate up to 600,000 gallons of sewage reached the Huron River during another overflow event.

A sanitary sewer overflow was discovered in a construction area on Geddes Avenue near the entrance to Gallup Park at about 7 a.m. Monday, Sept. 19.

The city issued a press release about the incident at about 5 p.m. Monday, saying the cause of the overflow was determined to be construction debris that had accumulated in a sanitary sewer pipe, blocking flow.

City officials said the blockage was immediately removed and flow restored. They believe the overflow occurred sometime between 3 p.m. Saturday, Sept. 17, and 7 a.m. Monday, Sept. 19.

There are no communities downstream that withdraw water from the Huron River for drinking purposes.

In accordance with regulatory protocols, city staff contacted the Michigan Department of Environmental Quality to report the incident.

The city has suspended Geddes Pond stillwater paddles and Argo-Gallup canoe trips until water test results are obtained.

The city reported two other sewage overflows earlier this year, including one near Bird Hills Nature Area where an estimated 36,000 gallons of sewage flowed over land to an unnamed tributary of the Huron River over a period of 60 hours, and another that sent an estimated 400,000 gallons of raw sewage flowing into Malletts Creek over a two-week period.

Ryan Stanton covers the city beat for The Ann Arbor News. Reach him at ryanstanton@mlive.com.