The Iowa Department of Natural Resources is looking for any long-term damage to the Des Moines River in southeast Iowa after a massive sewage spill. Senior environmental specialist Paul Brandt says up to six-million gallons was dumped in the past several days as an Ottumwa wastewater treatment system was shut down for repairs.The plant reopened last night about 7 o’clock. Brandt says fishermen and members of the general public are advised to keep away from the riverside plant in question due to bacteria, though he says the sewage overflow stopped last night when the plant went back online.Brandt works at the D-N-R field office in Washington. He says the water supply for Ottumwa was -not- threatened by the mishap since the city draws water upstream from the “lift station” where the sewage overflow happened. He says the water will be continually monitored for environmental damage.Brandt says he’s not aware of any widespread fish kills in the area. While the plant dumped about one-and-a-half million gallons of sewage each of the last four days, he says the river is flowing at a rate of about 96-million gallons a day — plenty to dilute the pollution.