Fox River Watershed Investigation – Stratton Dam to the Illinois River: Water Quality Issues and Data Report to the Fox River Study Group, Inc. Illinois State Water Survey Contract Report 2004-06

iii This report documents the development and application of two simulation models for the Fox River: a watershed hydrologic model using the Hydrological Simulation Program-FORTRAN (HSPF), and a receiving stream water quality model using QUAL2K. Both simulation models were calibrated with observed data and subsequently used to simulate the impacts of selected watershed management alternatives (scenarios) on water quality in the Fox River. The Fox River HSPF model simulates rainfall runoff processes for watersheds adjacent to the Fox River from Stratton Dam to the mouth of the Fox River at the Illinois River. Runoff is simulated using 31 separate tributary watershed models and two models of the Fox River mainstem. The tributary results are then utilized as an input to the mainstem model. Observed flows at Stratton Dam are used as the upstream boundary condition defining inflow from the Fox River watershed above Stratton Dam. The HSPF model hydrology was calibrated for water years 1991-1999 and validated for water years 2000-2003. The hydrology calibration was verifie