On behalf of the Onondaga County Department of Water Environment Protection (OCDWEP), Anchor QEA developed of a state-of-the-science water quality model of the Three Rivers System (containing portions of the Seneca, Oneida, and Oswego Rivers in New York).  The Seneca River is on New York State’s 303(d) list of impaired water bodies and receives flows from Onondaga Lake through its outlet.  Onondaga Lake and the 26-kilometer segment of the Seneca River from Cross Lake to the Onondaga Lake outlet are two of the State of New York’s highest water quality management priorities.  Under a consent judgment, Onondaga County is required to evaluate the feasibility of diverting the 85 MGD Syracuse Metropolitan Treatment Plant (Metro) effluent from Onondaga Lake, New York, to the Seneca River to mitigate Onondaga Lake’s water quality problems.

To guide decisions regarding the Metro diversion and to assess the water quality impairments of the Seneca River, Anchor QEA developed a water quality model describing the oxygen dynamics of the river system.  The model includes mechanistic descriptions of nutrient and phytoplankton dynamics, sediment oxygen demand and nutrient flux, and bioenergetics-based zebra mussel respiration.  The water quality model was calibrated using 6 years of monitoring data.  The performance of the model was favorably reviewed by an independent peer review panel under the authority of the Onondaga Lake Partnership (a consortium of local, state, and federal agencies).  In addition to the successful peer review, the sediment flux submodel developed by Anchor QEA has undergone an independent evaluation by the U.S. Environmental Protection Agency and has been adapted into its Water Quality Analysis Simulation Program modeling framework.  The Three Rivers Model is currently being integrated with a model of Onondaga Lake water quality to facilitate future management of the lake and river system.