Smithville Lake means the area of pooled water at the headwaters of Smithville Ditch, a tributary of Marshyhope Creek north of a line beginning at a point, at or near Lat. 38° 46.428’ N., Long. 75° 43.852’ W., then running 89° (True) to a point, at or near Lat. 38° 46.430’ N., Long. 75° 43.742’ W., in Caroline County, formed by the dam and the lake bottom. Smithville Lake has a 6-knot speed limit all year.