A warning sign has greeted visitors all summer long at the beach at Pine Lake State Park near Eldora. Swimming is not recommended due to elevated levels of E. coli. Dawn and Todd Anderson of Cedar Falls bicycled from their campsite to check out the beach. They decided to stay out."I don't want to be in contaminated water. It's not good," Dawn Anderson said."I'm not going to take that chance," Todd Anderson said.The Iowa Department of Natural Resources tests for E. coli every week during the summer swimming season, and every week this year, levels have come back too high at Pine Lake."This system does show up fairly chronically," said Iowa DNR biologist Jason Palmer.He is leading the DNR's efforts to figure out what is happening in the water."Could be geese, it could be shorebirds, gulls, people bringing their dogs to the beach," Palmer said.Palmer's team has been collecting data for two years, trying to figure out whether rain, drought, or something else is the issue."That gives us the ability to diagnose what might be the main drivers of the bacteria problem and how best to address those problems," Palmer said.The DNR has about 80 percent of the data they need, but the lack of rain is slowing down their effort. For now, there is no timeline for a possible solution at Pine Lake.You can find an interactive beach monitoring map on the Iowa DNR's website.