The 1972 Great Lakes Water Quality Agreement between the United States and Canada concerning improvement of the water quality of the Great Lakes has led to a study of the probable effects of nuclear power generation on radioactivity levels in the lakes. A simplified physical model of the Great Lakes system has been employed which assumes thorough annual mixing but allows for the perturbations in dilution volume required by the periodic establishment of thermoclines. Corrections are made, where necessary, for removal of radionuclides by sedimentation and equilibration. The results are given in terms of the concentration of radionuclides in each lake and the dose rates resulting from continuous, long-term ingestion of system waters. Dose calculations are performed using equations promulgated by the ICRP in Report 10. Using the model described, it is possible to obtain analytical solutions for the coupled differential equations describing these quantities. A Fortran computer program, GLA-1, has been employed to reduce calculational effort.