TACOMA - City officials are issuing a warning to residents: don't go near Wapato Lake.

Officials say someone connected a sewer line to the stormwater system and raw sewage spilled into the lake.

An investigation at the Tacoma Mall exposed the problem on Wednesday. City inspectors learned the food court sewer line had been connected to the stormwater system by accident.

"They then went in with dye and actually flushed the toilets inside the mall and were able to see the dye come out on the surface water, and confirmed that there was a problem," said Rob McNair-Huff with the city of Tacoma.

Put simply, a pipe routed food court toilets to the marsh near Wapato Lake, which meant waste from the mall leaked into the lake every time someone flushed the toilet.

"I wouldn't want to be someone that's drinking the water," McNair-Huff said.

City crews shut down the sewer line immediately and rerouted the sewage through pumps.

But the problem is they don't know how long the leak has been going on, because they haven't inspected the lines in 15 years.

"The inspectors had some suspicions that this was been going on so that's why they came out here this week," McNair-Huff said.

Patricia Ware, an area resident and a regular at the mall, says she's had her suspicions.

"Over the past summer, they had wildlife dying, fish, turtles, ducks, birds, just they found lots of them dead along the bay," she said.

But Ware says the park never put out proper warning signs.

"There's actually swimming and fishing that go on around here. We talk to fisherman everyday on our walk around the lake," she said.

City officials said they're digging through building records to try and figure out when the problem occurred. They've also asked the Department of Ecology and the Health Department to look into the impact to wildlife.

Officials expect to have test results back early next week.