A mesh or set of bars at the inlet of a hydro system that catches leaves, branches and other debris, and prevents it from obstructing or damaging the turbine. See also: Diversion, Forebay, Penstock

A structural device used to prevent debris from entering a pipe spillway or other hydraulic structure.Underdrain. A small diameter perforated pipe that allows the bottom of a detention basin, channel or swale to drain.

Grill placed across stormwater channels to collect rubbish and other pollution.

A type of stormwater quality improvement device (see above) in the form of a metal grate installed in a stormwater system and designed to screen litter and other debris from stormwater. An integral component of gross pollutant traps.

A screen comprising metal or reinforced concrete bars located in the waterway at an intake so as to prevent the ingress of floating or submerged debris.