Heavy rains Wednesday evening and into Thursday overloaded wastewater treatment systems throughout southwest Iowa, including Guthrie Center, Adair and Stuart, leading to a number of wastewater overflows.
      In Guthrie Center, 6.5 inches of rain was recorded and more than 8.3 inches fell in a four day span.
      Heavy rain can overload wastewater collection systems, which are the underground sewer pipes that carry sewage to a treatment plant. With the
sewage pipes overwhelmed, the excess water has nowhere to go, and can
backup into basements through floor drains. Bypassing can lower the water level in the collection system, keeping sewage from backing up into basements, which would present greater and more immediate health
risks than discharging wastewater into a stream.
      These types of situations can occur when large amounts of rainwater or snowmelt, also called storm water, enter a sanitary sewer from cracks in sewer pipes, or improper connections, such as roof drains or sump pumps hooked up to the sanitary sewer system instead of the storm water system. The storm water should enter the storm sewer system, which receives no treatment before entering a stream or lake. Instead, storm water enters the sanitary sewer system (which treats wastewater from homes and businesses).
      In addition, some communities use equalization basins or storage ponds
to handle excess flow from large rain events. These basins hold incoming
wastewater until the plant catches up and can treat it. However, in extremely heavy rain events, some facilities must discharge from these
basins and ponds to maintain their structural integrity or to prevent the plant from flooding. Other times, lagoons used for treatment can fill up quickly from increased flow and rainfall, and must discharge to maintain their structural integrity.
      According to DNR design standards for construction of new wastewater treatment systems, facilities should be able to handle the amount of water in the collection system from all three of these events happening
at the same time:
      * Peak sewage flows from homes, businesses and industry
      * Peak groundwater levels
      * A storm that drops two inches of water in an hour.
      While many collection systems in Iowa already have or are in the process of upgrading their collection systems to handle these events, many more need to upgrade.
      The DNR tracks bypass reports submitted by facilities and follows up with the facility to determine problems and help them upgrade their systems, although it can be a long-term process. The DNR has also formed a committee to discuss how it handles wet weather bypasses.
      The City of Guthrie Center began discharging untreated wastewater from a lift station at 8:45 a.m. Thursday to prevent sewer backups into basements following intense rains. The wastewater was discharged to a drainage ditch leading to the South Raccoon River. The city's wastewater operator monitored the ongoing bypass. The Des Moines Water Works was notified of the bypass.
Adair County
      Adair: The City of Adair began discharging untreated wastewater from
its treatment plant and a lift station to the Middle River early Thursday. The city monitored the ongoing bypass.
      Stuart: The City of Stuart's wastewater treatment plant was unable to
keep up with excess flows following heavy rains, leading it to begin discharging wastewater early Thursday morning. Some wastewater received partial treatment before it was discharged to Long Branch Creek; other wastewater was discharged directly to the creek without treatment. The partially treated wastewater was discharging at a rate of 160,000 gallons per day, while the untreated wastewater was discharging at a rate 80,000 gallons per day. The city estimated the bypass may last for six to seven days, and was monitoring the situation. Officials at Diamondhead Lake were notified of the bypass.

Highway 25 South closed by flooding
      According to Iowa Department of Transportation (DOT) officials, the overnight rains in southwest Iowa closed at least one road and put several others, including Interstate 80, in danger of closing.
      Iowa 25 wass closed one mile south of Interstate 80 in Adair County. A detour route was established, but those roads were also in danger of flooding.             The highway was reopened late Thursday afternoon.