There is a growing interest in assessing risk to non-human biota following exposure to radionuclides . However, before dose to aquatic biota can be determined, it is critical to have a solid understanding of radionuclide concentrations in key environmental phases due to their importance in determining external and internal dose. Further understanding of a system can be reached by monitoring temporal changes in radionuclide levels in these phases, especially if assessing the success of remediation activities. The current study has focused on estimating inputs of 90 Sr, 137 Cs and 60 Co to the sediments of a small, Canadian Shield lake located downstream of two Waste Management Areas at AECL's, Chalk River Laboratories site over a 40-year period. Overall, it was found that 137 Cs and 60 Co inputs have declined in the lake over the last 40 years, which resulted in a net depletion of these radionuclides from the sediments over time. Strontium-90 inputs have remained fairly constant over this time period with 90 Sr retention in lake sediments of approximately 15%. It is expected that benthic biota will receive approximately a 2- to 6-fold higher radionuclide dose than pelagic organisms, on average, particularly when feeding in the depositional zone of the lake.