Wetlands provide some of the highest-valued ecosystem services and offer critical habitat to various species in the Greater Toronto Area (GTA). Despite their significance, their extent in the region has declined drastically and continues to diminish with pressures from urbanization. The associated change in the natural topography and impervious surface cover alters local hydrology, including transport pathways for pollutants such as chloride (Cl), a common component in road de-icing salts that can be toxic to freshwater aquatic organisms in elevated concentrations. Among such species, excess Cl has caused adverse, or lethal effects on amphibians that rely on shallow wetlands in the GTA to breed and lay eggs. Pool-breeding amphibians are at particular risk when they are in their aquatic larval stage, which for some, intersects with when Cl concentrations often peak in streams in the GTA. With little insight into Cl concentration dynamics in their breeding habitats during this period, weekly water samples were collected from April to September 2023 in wetlands suitable for amphibian breeding in the GTA. The study found that nearly one-third of sites exceeded the federal Cl guidelines for the protection of aquatic life at least once, with three above the chronic guidelines (120 mg/L) and one above the acute guidelines (640 mg/L) for the entire season. Continuous surface water connections and higher proportions of salted areas in catchments were generally associated with greater Cl concentrations, however, unique temporal patterns and responses to precipitation between wetlands with similar spatial characteristics suggest additional Cl sources and pathways.