A dynamic river basin water quality model, EXPLORE was developed to simulate the dynamics of water flow and quality in rivers, estuaries, shallow lakes and impoundments. The model will handle several boundary conditions such as weirs, dams, loops, diversions and discharges in addition to tidal flows and the occurrence of tidal flats. The water quality module consists of a multiparameter transport submodel with various other submodels which describe the chemical-biological kinetics of the system. A total of 16 water quality parameters can be modeled simultaneously. Testing and verification of the EXPLORE river basin model was conducted on the Willamette River Basin in Oregon. This basin was chosen because the Willamette is a large river with a tidally influenced reach, several major tributaries and considerable flow regulation, thereby encompassing a wide range of hydraulic conditions. The following appendicies were also prepared: A-Literature Review, B - User's Manual, C - Programmer's manual.