As the great glacier that once covered most of the surface of New York State retreated towards the end of the Pleistoncene Epoch, Lake Champlain’s outlet to the north remained blocked. Champlain Valley remained mostly underwater until present day drainways emerged, and the land returned to their current elevations.

Water levels dropped in the valley and the Ausable River was building a delta at Wickham Marsh… until something caused the Ausable to abandon its delta for another at Ausable Point. What caused the Ausable River to divert its Wickham Marsh delta?

Stream Piracy (or stream capture) is a common event, where a river or a stream is diverted into the channel of a nearby river.  They are kept under control by feats of engineering. In the case of the Mississippi River, the Old River Control structure. “a mammoth floodgate system costing hundreds of millions of dollars for construction, operation, and maintenance that keeps the Mississippi on its course to New Orleans.”

Read the full story, written by Gary Henry, a Stream Restoration Associate of the Ausable River Association, by following this link to Ausableriver.org