Predicting Phosphorus Levels in a Future Reservoir

The concentration of total phosphorus at spring turnover in a proposed flow-augmentation reservoir is predicted, with a steady-state and two dynamic models, for a wide, but representative, range of reservoir operation. Simulations were performed utilizing hypothetical data sets which correspond to the hydraulic regime of the Delaware River from 1929 through 1970. The level of total phosphorus to be expected in the reservoir is shown to be highly dependent on its hydraulic operation. Phosphorus enrichment of the reservoir watercolumn will be coupled to the reservoir's primary function of augmentation of Delaware River flows during low runoff periods. The best estimate simulations of the dynamic system with the dynamic models indicate the total phosphorus concentrations at spring turnover will equal or exceed 0.020 mg/1 continuously; levels which are generally associated with a eutrophic condition. There are some indications that mesotrophy may prevail for years when augmentation releases to the Delaware River are not made.