(KDAL) - This year the U-S celebrates the 40th Anniversary of the federal Clean Water Act.  It transformed many polluted rivers and lakes into clean, usable waterways.  Among those who played a key role in writing the legislation was Jim Oberstar, who was then on the staff of Congressman John Blatnik of Minnesota.  Oberstar considers the act as one of his proudest legislative accomplishments.  Conservationists are now worried that some of the protections in that bill are in danger of being rolled back, the result of court decisions and the desire of some public officials.