CHICAGO (WLS) -- Thick oil is showing up in part of the Chicago River. Investigators are trying to figure out where it's coming from.The oil was reported in Bubbly Creek , a waterway off the river's south branch. The U.S. Coast Guard blocked that section of the river for the Environmental Protection Agency's investigation.The EPA used a containment boom to keep the oil within Bubbly Creek. Teams used an absorbent material to collect the oil, but it could be a couple weeks before it's all cleared out."We're working on the cleanup. We've got Bubbly Creek boomed off from the Chicago River and the sanitary ship canal, so were going to contain the oil on the creek," said Len Zintak, on-scene coordinator, EPA.The extent of the damage is still unknown. Teams are testing samples.The EPA estimates there are hundreds of gallons of oil in the south branch of the Chicago River, which also includes a stretch from South Ashland Avenue and South Pulaski Road. That part of the river is still open, but the EPA and Coast Guard plan to take another look.Chicago fish and wildlife service put up Mylar tape and fired off pyrotechnics to try and keep bird away as crews tried to help those animals affected. So far one Canada goose was found dead."We don't have a lot of birds using the area so that is good, we didn't find a lot of dead stuff, we're not finding a lot of sick birds, I saw maybe four geese that were oiled and a couple of herons that were oiled, so it could be worse," said Fish and Wildlife Biologist Ed Karecki.Bubbly Creek is a popular spot for rowers. Row boats inside the Chicago Park District boat house were covered in a black coating. Some of them reported seeing an oily film on the riverbank and several geese covered in it."We noticed this on Monday and Tuesday - that we'd come in and our boats were very greasy. We wiped them down every day and it was pretty messy. It got messier. So on Wednesday, we had hoses and were brushing them off and wiping them down," St. Ignatius Girls Rowing Coach Leonard Richards said.Due to the shutdown, the team was restricted to practicing indoors during the investigation."We've got our last regatta coming up on Sunday and we want to practice for it, but now we can't. It nicer to get the live training out on the water," Richards said.