In the past few years, five separate studies have been undertaken at AECL's Chalk River Laboratories to determine the levels of tritium in the environment due to routine releases from an experimental heavy water reactor. Data from these studies are presented in terms of the ratios of the long-term average tritium concentrations in precipitation, soil and plants to the long-term average HTO concentration in air moisture. The data are used to assess the performance of models that predict long-term average tritium concentrations in the environment.