:* Perched. A perched stream is either a losing stream or an insulated stream that is separated from the underlying ground water by a zone of aeration.<ref>http://water.usgs.gov/wsc/glossary.html#S</ref> | :* Perched. A perched stream is either a losing stream or an insulated stream that is separated from the underlying ground water by a zone of aeration.<ref>http://water.usgs.gov/wsc/glossary.html#S</ref> |