dam up(redirected from damming up)
To block something from flowing freely, typically water in a stream, river, etc. A noun or pronoun can be used between "dam" and "up." If we don't dam up the river, this rain will cause a flood.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
dam something up
to erect a barrier in a river, stream, brook, etc. We are going to have to dam this stream up to make a pond for the cattle. Let's dam up this stream. Why is this river dammed up?
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.