Materials, compositions, substances and methods and systems for stormwater treatment in wet ponds, dry ponds and a green roof system. A first embodiment provides in-situ treatment unit within the retention pond by withdrawing the stored stormwater to circulate the stored stormwater into the in-situ treatment unit to sorb nitrogen from the stored stormwater. A second embodiment provides uses a riprap apron, a perforated riser located at the bottom of the riprap apron and a geotextile media encased in a sorption media jacket around the perforated riser. A third embodiment provides a green roof stormwater treatment system that includes protection for waterproofing and insulating the roof, a pollution control media layer for filtration and sorption of solids and dissolved materials found in stormwater, a growing media for growing vegetation, and a cistern to store the runoff stormwater between irrigation events. The green roof system includes recycling runoff stormwater by irrigating the green roof with the stored stormwater.