Constructed wetlands are similar to [[SWM ponds]] in function and design, with the most significant difference being that they are designed to incorporate shallow zones for wetland [[plants]]. A facility is normally characterized as a wetland if shallow zones (<0.5 m deep) make up more than 70 % of its volume.
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Free-water surface flow wetlands are most commonly employed for stormwater treatment and are similar to [[SWM ponds]] in function and design The most significant difference is the extent to which they are designed to incorporate shallow zones for wetland [[plants]]. A facility is normally characterized as a wetland if shallow zones (<0.5 m deep) make up more than 70 % of its volume.