Chloride in Toronto Area Streams


StreamWQinTorontoRegion_pagepicToronto and Region Conservation Authority (TRCA) is responsible for stream water quality monitoring throughout the Toronto region as part of its Regional Watershed Monitoring Program. Every month, surface water quality is sampled at 38 locations from a wide range of catchment areas that are subject to different sources and levels of contamination. Samples are analyzed for a standard suite of conventional water quality parameters, heavy metals, nutrients, and bacteria.

Although some contaminants have decreased over the assessment period, the concentration of chloride in streams has shown an increasing trend. Increases in peak winter concentrations as well as summer baseline concentrations of chloride have been observed. This may be attributed to increases in road salt application on existing roads as well as the expansion of the road network. At present, the level of chloride in some urban waterways is sufficient to cause negative effects to some species of plants and animals. Principal sources of chloride contamination in streams include road salt applied to roadways, parking lots, and driveways.