| The Niagara River connects Lake Erie to Lake Ontario, and provides a significant inflow to Lake Ontario. This inflow has historically been contaminated from upstream sources, including Lake Erie, tributaries and discharges to the Niagara River, and inactive hazardous waste sites lying along the river. As a result, Lake Ontario receives a significant loading of contaminants from the Niagara River, including polychlorinated biphenyls (PCBs). Section 303(d) of the Clean Water Act of 1972 requires that impaired waterbodies, or those unable to meet established water quality standards, be listed. In addition, the United States Environmental Protection Agency (EPA) requires that impaired waterbodies are ranked on levels of priority. Based on ranking, jurisdictions must develop total maximum daily load (TMDL) analyses for such waterbodies. Lake Ontario's position on New York State's list of impaired waterbodies has established a goal that a TMDL analysis for PCBs be completed by 2011. Development of the TMDL involves a stepwise approach that first includes collection of recent data and developing a Niagara River contaminant transport model for PCBs that can provide input datasets to Lake Ontario's mass balance and food chain bioaccumulation model, LOTOX2. The Niagara River model was developed using the EPA's Water Quality Analysis Simulation Program (WASP) framework with specific modeling adjustments to the code made by Limno-Tech, Inc. These model adjustments includes linkage to a hydrologic flow routing model of the Niagara River and specific volatilization functions in riverine segments and Niagara Falls. In addition, the Niagara River model incorporates transport processes such as dispersion, adsorption of PCBs to sediments governed by a sorption coefficient, adjustable point and non-point source loadings, and settling in power production reservoir segments. The model can predict various water quality scenarios for Lake Ontario to create the necessary information for developing a TMDL. |
