The U.S. Senate has wrapped up weeks of debate on an energy bill. The senate's bill calls for a wide array of incentives to encourage conservation, including the increased use of corn based ethanol. Supporters of a planned expansion of an ethanol plant in Preston say it will be a boon for farmers in Southeast Minnesota who face the lowest grain prices since the Great Depression. But some environmentalists and an angling group are concerned about the potential threat the expansion might pose to the Root River, one of Minnesota's best trout streams. They say the increased demand for corn would lead to more farm chemicals getting into the river. The plant expansion will also put more pressure on Preston's waste water treatment facility. Minnesota Public Radio's Laurel Druley prepared this report as a part of our series, "Changing currents."