TRIHALOMETHANE PRECURSOR MODEL FOR LAKE YOUNGS, WASHINGTON

A mathematical model is developed to estimate trihalomethane formation potential (THMFP) in Lake Youngs, Wash. The model simulates both seas onal trends and spatial variations. The model kinetic framework includ es total organic carbon (TOC), THMFP, chlorophyll a, zooplankton, Secc hi disk depth, dissolved oxygen, dissolved TDP, and total phosphorus ( TP). Calculated THMFP concentrations are dependent on external watersh ed TOC loading, algal cell densities, and TOC associated with extracel lular products. Model performance is evaluated by comparison of calcul ated results with measured data from Lake Youngs. Analyses illustrate how THMFP concentrations in the raw water supply change as a function of watershed TP and TOC loading. A general assessment considers the ro le of watershed land-use control, reservoir management, alternative tr eatment technologies, and the operation of the water supply distributi on system in complying with finished drinking water standards for THM.