The law has a number of different--and often confusing--definitions of "navigable" rivers and lakes (all tidal areas are considered navigable). For purposes of determining state title to the beds of rivers and lakes, they must have been capable of carrying commerce at the time the state entered the union. Commerce includes more than boats carrying persons and cargo. The courts have found streams to be navigable where they have carried saw logs or shingle bolts. For purposes of some federal regulatory programs, a waterway must have carried, or be capable of carrying, interstate commerce. Other federal regulatory programs (e.g., the Federal Power Act) include waterways which could carry interstate commerce with reasonable modifications. Finally, the Clean Water Act defines navigable waters to include all waters of the United States which may affect or be affected by interstate commerce. This includes most water bodies in the nation.