Update: The Duwamish River was reopened Sunday morning.

Seattle Public Utilities estimates a blocked sewer line spilled 320,000 gallons of sewage  near the Duwamish Waterway on Thursday.

The Duwamish River is now closed to water activities, like fishing, from around the Museum of Flight to Harbor Island, according to a statement from Seattle Public Utilities (SPU) and Public Health – Seattle & King County. Signs are posted along the 3,000 feet of waterway affected. Officials will continue to sample the water until it’s determined to be safe for contact.

SPU received a report Thursday of suspected sewage in a ditch near Boeing Field and found a piece of plywood lodged in a sewer line, according to the statement. Spokeswoman Sabrina Register said the agency does not believe all the spilled sewage reached the waterway, but she did not provide an estimate for how many gallons entered the water.

SPU said it had alerted local tribes and the city of Tukwila, as well as regulators including the Washington Department of Ecology and Department of Fish and Wildlife.

Correction: Seattle Public Utilities clarified Saturday that it does not believe all the sewage from the spill reached the waterway. An earlier version of this story said the 320,000 gallons spilled directly into the waterway.