Nutrient Loads and Budgets in the Bay of Quinte, Lake Ontario, 1972 to 2001
Description:... The Bay of Quinte became highly eutrophic in the 1960s and 1970s. In the late 1970s a long-term program began to replace and upgrade sewage treatment facilities releasing effluents directly into the bay. This report describes the assembly and analysis of data for nutrient loads and budgets for the Bay of Quinte covering the period 1972 to 2001. The methods closely follow those used by Minns et al. (1986b) in an earlier study of the Bay covering the period 1965 to 1981. Changes in the frequency and spatial cover of sampling made some simplifications of the methods necessary. Loads and budgets were estimated by month and by bay section (upper, middle, and lower) for total phosphorus (P), total nitrogen (N), and chloride (C1). Point source loading of P have declined dramatically with decreases continuing to the present. Point source N loads are unchanged while C1 loads have increased. Analyses of whole Bay and sectional budgets showed there have been shefts in retention and estimated sediment P reflux in line with expectated declines in reflux after point source load reductions were implemented. The colonization of dreissenid mussels in themid-1990s and the associated increases in macrophyte cover and dinsity have altered the nutrient budgets thereby increasing upper bay concentrations. Recommendations for the future include more rigorous collection of nutrient and flow data for the major rivers and point sources, allowing refinement of certain components of the Bay of Quinte nutrient budgets. The budget results provide a basis for future development of a model simulating P dynamics over the period 1972 to 2001 and predicting future conditions under alternate hydrologic regimes, ecosystem conditions, and P management in the Bay of Quinte.
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