ARCHBOLD The ditch law of 1859 forever changed the landscape of northwest Ohio from a swamp to some of the most fertile land in the state. The drainage of the great Black Swamp will be highlighted on a historical marker which will be placed at Northwest State Comm-unity College at a ceremony on Saturday. Pete Wilhelm, coordinator of the schools new Heritage Arts Center was first approached by the Ohio Bicentennial Commission and the Ohio Historical Society about finding a location to place a marker in the category of agriculture. He had written a thesis on the drainage of the Black Swamp and says he believes that is why he was contacted.