sentences:  According to the 2010 census, the county has a total area of , of which (or 79.63%) is land and (or 20.37%) is water.The northern and southern portions of the county (north of U.S. 30 and south of Lowell) are mainly low and flat, except for a few sand ridges and dunes and were both once very marshy and had to be drained.The lowest point, at , is along the Lake Michigan shoreline.