TOPEKA, Kan. (AP) — Topeka officials are encouraging anyone using the Kansas River to take precautions after an equipment failure allowed 3 million of gallons of raw sewage to seep into the waterway. Water Pollution Control general manager Bob Sample says the leak began about 1 pm Friday when the South Kansas River pump station had a power outage. The Topeka Capital-Journal reports it wasn't discovered until noon Sunday when an operator noticed unusually low flows at a wastewater treatment plant. Sample says the leak went unnoticed because it was the weekend, and because a backup generator also failed and didn't send notification to a monitoring system. The city on Tuesday said it still didn't know what caused the malfunction. Sample says it's the largest Topeka overflow he has seen.