The partial demolition of a dam in southwest Virginia resulted in the drainage of a 35-hectare reservoir. The first-year vegetation which colonized the lake bed included Polygonum lapathifolium, Bidens cernua, Juncus effusus, Leersia oryzoides, Panicum dichotomiflorum, and Muhlenbergia frondosa. The lake bed was colonized primarily by weedy annuals (including grasses) which apparently germinated from seeds buried in bottom sediments. Cover values were affected by slope but not by grazing. Similarities are noted between this vegetation and that of exposed mudflats in either marsh or riverine environments.