A subsurface flow constructed wetland planted with the common reed (Phragmites australis) and softstem bulrush (Scirpus validus) was built in East Central Indiana. The objective of this study was to determine if temperature had an effect on nitrogen (N) removal from the wetland. The research was conducted from the first week of October 3, 1995 to the first week in December 5, 1995 why the wetland froze. Water samples were taken from 5 samplings sites in the system. Each sample was analyzed for organic-N, ammonia, nitrate, and total-N. In the system statistically significant amounts of organic-N, nitrate, and total-N were removed. Ammonia lever reductions, however, were not significant. Organic-N had a mean removal of 37% (8 mg/1) 'Nitrate had a mean removal of 96% (2.3 mg/1). Total-N removal over the sampling period averaged 30% (12 mg/1). The N results were regressed against air and wastewater temperatures. Wastewater temperature was more important because it had a direct impact can the plants and microbes in the system. Warmer temperatures sustained a higher metabolism for the biota in the system. Air temperature had an indirect impact on efficiency of N removal from the wastewater flowing through the wetland. The primary impact .: f the air temperature was on water temperature which then affected the metabolism of or a nc ns in the wetland cell. Greater removal efficiencies were seen during high temperature periods and lower removal efficiencies were noted when the temperatures were low. / Department of Natural Resources and Environmental Management