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Management of the historically contaminated waterfront at Cornwall, ON, relies on natural processes to isolate sedimentary contaminants. Determining the efficacy of this strategy in reducing risk to benthic invertebrates is complex as pollution impacts within the waterfront are spatially heterogeneous and modern-day climate warming may interact with contamination impacts and/or confound recovery signals. Long-term biological data from sites with unique stressor combinations are required to disentangle effects and assess whether benthic recovery has occurred. We compare long-term records of subfossil chironomid (Diptera: Chironomidae) assemblages among sediment cores from two contaminated Cornwall sites as well as a downstream reference site. Cornwall sediment cores show a functional absence of chironomids that co- occurs with high contaminant concentrations during the period of historic industrial activity. As contaminant concentrations decrease over time, chironomid abundance and the relative abundance of pollution-sensitive taxa increase. Recent intervals in all three sediment cores display increased relative abundance of warm-water, macrophyte-associated taxa. We conclude that recovery has occurred in both waterfront sites and that climate warming is affecting chironomid assemblages at a regional scale. [ABSTRACT FROM AUTHOR]