A “grit buildup” in a South-end sewage line caused a few thousand gallons of sewage to spill into Lake Washington on Nov. 14. Four days later, the city was able to unclog the pipeline successfully.

“It is official; our lakeline is once again conveying sewage normally,” said City Maintenance Director Glenn Boettcher.

At first, city workers thought that the spill was caused by grease buildup. But once they reached the problem, they realized their mistake.

“It appears that this event was not caused by grease but rather by grit buildup associated with lower velocity flows and limited cleaning access,” he said.

City Communications Coordinator Joy Johnston said that, despite how it sounds, the leak “was minor” as the sewage was diluted with storm water.

Johnston said that sewage leaks, which usually occur from backed-up or broken pipes, are not common on the Island, although they do occur from time to time.

The Department of Ecology and the King County Health Department were notified of the incident over the weekend.

For questions, call Johnston at 275-7791.