The sewer systems in 11 northeast Iowa cities and a mobile home park overflowed into area rivers and streams as a result of yesterday’s flooding. Kevin Baskins of the Iowa Department of Natural Resources says the situation was unavoidable. Baskins says it’s better than having the icky stuff back up into homes, which is a greater health threat. Baskins says when as much as nine inches of rain falls, it’s more than the treatment systems can handle. Baskins says with high-volume flood levels in many streams and rivers, the waste dissipates quickly and isn’t a threat to fish or humans. He says bypassed during low water levels are more of a problem. Wastewater treatment plants in Monticello, Sherrill, Shellsburg, Anamosa, Cedar Rapids, Hopkinton, DeWitt, Greeley, Farley, Dyersville and Asbury overflowed, as did the plant at the Timber Ridge Mobile Home Park near Shellsburg.