Development and Application of a Water Quality Management Model of Eutrophic Onondaga Lake, NY

The water quality of Onondaga Lake, NY has been compromised by a 100-year history of municipal and industrial pollution. A state-of-the-science water quality model was developed for the system to facilitate contemporary water quality management which includes: 1) development of total phosphorus and ammonia TMDLs and 2) assessing the feasibility of diverting a large point source discharge out of the Lake and into an adjacent river system. The OLWQM consists of a number of submodels representing the major hydrodynamic, water column nutrient cycling, and sediment processes controlling water quality in the lake. The water column submodel describes nitrification, organic matter decomposition, algal photosynthesis, respiration, and nutrient uptake, and zooplankton and zebra mussel grazing and respiration. The sediment flux submodel simulates the conversion of particulate organic material settling from the water column to dissolved nutrients and the concurrent consumption of oxidized compounds from the overlying water column. The model was calibrated over the period from 1994 to 2003 and successfully simulated the major water quality dynamics observed within the system. Additionally, the model simulated the gross patterns in chlorophyll-a in the epilimnion as well as phosphorus retention within the lake sediments. Finally, the model was able to simulate compliance-based measures of important water quality standards and guidance values developed for the lake. The next step of model development includes linkage of the Lake model with a model of the adjacent river system and validation of the linked models.