Our model will take into account basic stream structures such as "barriers", pools, riffles, bends, point source, and nonpoint source. Each of these parameters will represent a different section within our map. While we have existing datasets for barriers, point, and nonpoint sources, data for bends, riffles, and pools are still needed. In order to obtain such data, we will be using an acoustic Doppler velocimeter (ADV; Nortek, AS, Rud, Norway) to configure a three-dimensional velocity profile of the sampling sites. Each stream section will have the same velocity with the exception of the stream and pool. In addition, we will be measuring the concentration of dopamine released as a chemical tracer, using an electrochemical detection system (Epsilon, Bioanalytical Systems, West Lafayette, Indiana). The microelectrode attached to the Epsilon system will be placed close to the substrate (1-6 cm) in order to evaluate the chemical exposure benthic organisms experience. The dopamine will be released 0.5 meters from the bend, riffle, and pool.