Restoring Aquatic Connectivity and Fish Passage: An Assessment of the Potential Risks from Contaminants

The removal of dams and the creation of fish passage bypass in dams are projects designed to restore aquatic connectivity. Problems with contaminants can occur if fish passage projects take place in polluted ecosystems. This presentation will discuss the environmental risks associated with fish passage projects. A fish passage case study for a Wisconsin river will be presented describing the potential contaminant risks of upstream fish passage. A baseline risk assessment will be presented that numerically estimates risk to upstream wildlife from passing downstream lake sturgeon (Acipenser fulvescens) contaminated with polychlorinated biphenyls (PCBs). The bald eagle (Haliaeetus leucocephalus) is used as a bioindicator species for piscivorous wildlife in the baseline risk assessment.  The assessment determined that although risk does exist, it is likely below the level that adversely affects bald eagle reproductive success. The assumptions and uncertainties of the risk assessment and additional considerations for determining risk will also be discussed. Conducting baseline risk assessments and monitoring contaminants in wildlife should be used to determine potential environmental impacts of fish passage projects.