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Statistical modelling of in-stream phosphorus

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Title: Statistical modelling of in-stream phosphorus
Author: Fortin, M.; Demal, L.
Abstract: Phosphorus enrichment of the Avon River causes eutrophic conditions to prevail throughout the summer months both above and below the City of Stratford. The reduction of phosphorus inputs to the river system is being considered as one means of controlling this eutrophication. To this end, phosphorus inputs from a variety of urban and rural sources have been estimated, and remedial control measures have been assessed. Phosphorus inputs and in-stream transport are compared, and a black box approach is used to model in-stream processing of phosphorus. With this approach, in-stream concentrations are related to phosphorus inputs in order to predict improvements engendered by input reductions. Total phosphorus inputs over the May-to-September period were estimated to be 4763 kg. Of this amount, 1052 kg. are exported out of the river system. The remainder may be lost to seasonal or long-term in-stream sinks. The discrepancy may also be caused by a downward bias in the estimation of exports. Fifty percent (50%) of inputs are urban in origin, 44% are from rural agricultural activities and a further 6% are from background sources. The Stratford water pollution control plant is the largest and most concentrated source. Rural overland runoff and urban storm water are the next most significant sources. No single source predominates overall within the basin. Consequently, significant reductions can be made only if several sources are controlled. With maximum feasible reductions of inputs, in-stream concentrations of phosphorus along the Avon River are predicted to fall 10 to 51%. The greatest reductions are expected below the Stratford Water Pollution Control Plant. Concentrations above Stratford are affected only if rural measures are implemented.It is not clear that reductions of phosphorus inputs considered in this study will be sufficient to control eutrophic conditions in the Avon River. They will nevertheless lower in-stream concentrations towards the Provincial guideline for phosphorus and will contribute to the control of phosphorus loadings to the Thames River and Lake Erie.
Date: 1983
Rights: Queen's Printer for Ontario, Crown Copyright, Non-Commercial Use Permitted
Rights Holder: Queen's Printer for Ontario

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