(Salem, OR) -- Officials in Marion County want to know why the U.S. Army Corps of Engineers hasn't produced a report on the deep drawdown of Detroit Lake. The goal of the lower level of the lake during the fall and winter is to allow salmon smolt to get past the dam. County Commissioners have raised concerns about the plan, potential environmental impacts, and how it could affect drinking water for the more than 200-thousand people who live downstream. They also say it's unclear whether the drawdown would achieve the intended biological benefits. The missing turbidity report was supposed to be published January 4th.