IWC - Iowa Low Head Dams Reference

Obvious Impoundment: A pooling of the river upstream of the dam to a great enough width (i.e. - much wider than the riverbed itself) that it is obvious to the casual river user that there is an impoundment of the river at this location.

Types of Hazards	Description
debris	rebar; steel; other underwater obstructions; sharp edges on rocks/concrete
drowning	one or more recorded drowning(s) at dam
height	dam height of 10 feet or greater
portage	egress from river above the dam can be difficult and/or hazardous
urban	urban setting with greater number of people recreating near the dam
usage	river section with above average recreational usage - particularly paddling
varying	sometimes (usually at higher flows) the river looks safe
visibility	dam can be difficult to see from upstream
other