Project description:Prolific heterotrophic biofilm growth is a common occurrence in airport receiving streams containing deicer and anti-icer runoff. This study investigated relations of heterotrophic biofilm prevalence and community composition to environmental conditions at stream sites upstream and downstream of Milwaukee Mitchell International Airport in Milwaukee, WI, during two deicing seasons (2009–2010 and 2010–2011). Modern genetic tools (such as microarray) have not previously been applied to biofilm communities in this type of setting. We used microarray results to characterize biofilm community composition as well as the response of the biofilm community to environmental factors (i.e., organic content (using chemical oxygen demand concentration) and temperature).