Forebays: Gallery

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  Forebay connected to drainage area in the roadway with a curb cut, overflow visible in the centre of forebay area, level spreading is encouraged with the rock check dams, Milwaukee, WI, Photo credit: Aaron Volkening

The total surface area upstream of a point on a stream that drains toward that point. Not to be confused with watershed. The drainage area may include one or more watersheds.

A pretreatment basin at the inlet of a practice that allow settling out of sediment and associated contaminants suspended in urban runoff.