Salt vulnerability assessment methodology for urban streams

•A new methodology is developed to identify Salt Vulnerable Areas (SVAs) for urban streams.•The stream chloride concentration equation uses readily available spatial data.•The vulnerability assessment is performed on seven sites in four watersheds.•The approach prioritizes implementation of best management practices to SVAs.•The highest contribution to stream chloride concentration was due to parking lots. De-icing agents such as road salts while used for winter road maintenance can cause negative effects on urban stream water quality and drinking water supplies. A new methodology using readily available spatial data to identify Salt Vulnerable Areas (SVAs) for urban streams is used to prioritize implementation of best management practices. The methodology calculates the probable chloride concentration statistics at specified points in the urban stream network and compares the results with known aquatic species exposure tolerance limits to characterize the vulnerability scores. The approach prioritizes implementation of best management practices to areas identified as vulnerable to road salt. The vulnerability assessment is performed on seven sites in four watersheds in the Greater Toronto Area and validated using the Hanlon Creek watershed in Guelph. The mean annual in-stream chloride concentration equation uses readily available spatial data – with province-wide coverage – that can be easily used in any urban watershed.