This project has three main hypotheses: 1) Increased water temperatures, decreased salinity, and increased flow rate will enhance transport of protozoal oocysts through wetland systems. 2) Larger vegetation, increased vegetation density, and increased wetland length will enhance retention of protozoal oocysts in wetland systems. 3) Factors found to maximize protozoal retention in the laboratory-based models will also significantly affect protozoal transport in a natural and constructed wetland.