Back-Water

That water in a stream which, in consequence of some obstruction below, is detained or checked in its course, or overflows.

Every riparian owner is entitled to the benefit of the water in its natural state. Whenever, therefore, the owner of land dams or impedes the water in such a manner as to back it on his neighbor above, he is liable to an action; for no one has a right to alter the level of the water, either where it enters, or where it leaves his property.
   

This entry contains material from Bouvier's Legal Dictionary, a work published in the 1850's.