PORTLAND, Ore. (KATU) — Heavy rains over the weekend caused a rare combined sewer overflow (CSO) into the Willamette River as the Big Pipe system reached capacity around 2:30 p.m. on Sunday, Feb. 23.

Portland’s Big Pipe hit 100% capacity Thursday after heavy rains, triggering a combined sewer overflow advisory that remains in effect for the Willamette River. The overflow began about 4:20 p.m.

Portland’s Big Pipe hit 100% capacity at about 6:26 a.m. Thursday. That does not mean the system failed. It means the city’s giant underground overflow tunnels filled up during heavy rain, leaving no ...