Tomorrow (Thursday) on the North Shore, state biologists will be looking for insect larvae in the Beaver River. Last week a broken pipline at Northshore Mining in Silver Bay spilled tons of taconite tailings into the river. Researchers say the spill will likely suffocate the tiny creatures on the river bottom, and cut into the food supply for the river's fish in coming years. The spill is reviving memories of past concerns about tailings pollution. Minnesota Public Radio's Chris Julin starts our two part report.