This project is a continuation of Statewide Lake study that revealed the obiquitous presence of endrocrine active compounds (EACs) in many MN Lakes. The initial project findings suggested two potential knowledge gaps in our understanding of EACs and their effects in lake environments. First, the sources of EACs and their entrance points into lakes need to be better defined than was possible in our previous statewide lake study. Second, fish habitats within the littoral zone of lakes where greatest biological production occurs, need to be matched with detailed, site-specific exposure patterns. SCSU will test the hypothesis that Biological Responses in Fish are Correlated with Microhabitat Exposure to Endocrine Active Compounds (EACs) within a lake rather then Mean EAC Exposure Across a Lake during this study. MPCA EAO staff will also provide technical assistance and oversight of the project.