Rapid urban growth globally has been linked to worsening eutrophication of receiving lakes and ponds. Traditionally, eutrophication of freshwater ecosystems is attributed to the increased supply of the limiting nutrient phosphorus (P). Salinization is an additional stressor of urban lakes. In cold climate regions, it is often primarily driven by the runoff of road salt applied during the winter. While the ecological damages caused by P enrichment and salinization to freshwaters are well established, thus far their impacts on water quality have been considered separately. Despite strict controls that have curbed P emissions, many lakes in North America continue to exhibit eutrophication symptoms, including declining dissolved oxygen (DO) and rising dissolved inorganic P (DIP) concentrations in the hypolimnion. Our research on an urban lake in Southern Ontario showed that these eutrophication symptoms are linked to salinization associated with the expansion of urban land cover in the watershed, rather than excess external P loading. To determine how widespread this novel salinization-eutrophication link is, we examined water chemistry monitoring data from other urban lakes in North America. Trend analysis shows a progressive salinization coupled to increasing hypoxia and increasing DIP to total P ratios. Rising salinity strengthens water column stratification, in turn, reducing the oxygenation of the hypolimnion and enhancing P remobilization from the sediments. We conclude that stricter controls on salt emissions are needed to mitigate eutrophication symptoms in affected lakes.