The Iowa Department of Natural Resources says torrential rains in northwest Iowa overnight and this morning forced the wastewater treatment plants in several cities to released untreated sewage. Neal Cook in the D-N-R’s Spencer field office says the releasing the wastewater is safer than the alternative of having it back up into people’s homes. He says the sewage is usually extremely dilute, and while it still has all the organisms of regular sewage, it’s diluted as far as its waste strength. Cook says they’ve been working to improve some of the older sewer systems in the area to help alleviate the problem. But, he says this year there’ve been plenty of big rains that’ve caused trouble. He says it certainly seems like they’ve had their share of heavy precipitation events — but until now they seemed localized to one town or county. Cook says the latest one seemed to hit all of northwest Iowa. He says if you looked at the weather radar last night they “had a regular conga line of storms cells marching right up from Sioux City right up to the northeast through Spencer and the lakes area.” Cook says cities could build large storage areas to handle unusually heavy rains, but he says that would be very expensive. He says it’s not practical to build treatment systems large enough to handle those volumes of water. Cook says bypassing the sewage is the best way to get rid of the excess without creating big health problems with backed up sewage in people’s basements.