LAUSR

Abstract Since the establishment of the Toronto and Region Area of Concern in 1985 there have been marked improvements in water quality and sediments. These improvements have led to the re-designation of five beneficial use impairments as unimpaired. For the remaining six beneficial use impairments (five listed as impaired and one requiring further assessment), efforts are underway to assess their status and identify actions that could lead towards their re-designation. Here we introduce a series of nine articles that establish benchmarks of current conditions, provide critical supporting information to undertake an assessment, or directly assess (or re-confirm) the status of a beneficial use impairments.