Greenwood officials are scrambling to find the source of a possible E. coli contamination in a city creek where children often swim in the summer.Pleasant Creek flows through several city parks and is set to play a major role in plans to revitalize downtown Greenwood.But recent samplings done by the Indiana Department of Natural Resources showed high levels of E. coli, roughly five times the state standard, 6News' Ben Morriston reported.The news took city officials by surprise."I immediately called the sanitation supervisor and told him I wanted from one end of the city to the other tested," said Mayor Charles Henderson.Since E. coli contamination is often caused by raw sewage, the city is now inspecting sewer lines that run near the creek. They're also looking at farm field runoff as a possible cause.There have been no reports of anyone falling ill from the virus. Still, residents said they were anxious as summer draws closer."It would definitely be a concern. Yes, I'm surprised in fact," said resident Max Murphy.City officials said they hoped to pinpoint the cause of the E. coli before Greenwood unveils plans next month to revitalize its old downtown.