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Preface—Restoring Toronto’s waters: Progress toward delisting the Toronto and Region Area of Concern

2018; Taylor & Francis; Volume: 21; Issue: 3 Linguagem: Inglês

10.1080/14634988.2018.1491759

1539-4077

S. C. Dahmer, Laud Matos, A. W. Morley,

Urban Stormwater Management Solutions

In 1987, Toronto and Region (formerly Metro Toronto) was recognized as one of 43 Great Lakes Areas of Concern (AOCs) under the amended Great Lakes Water Quality Agreement (GLWQA). AOCs are locations where water quality and ecosystem health are considered to be severely degraded as a result of local sources of pollution caused by human activities that may affect the wider Great Lakes system. Under the GLWQA, the governments of Canada and the United States committed to restoring ecosystem health in the Great Lakes (IJC, 1987).Toronto and Region was identified as an AOC as a result of complex environmental challenges from several centuries of agriculture, industrialization and urban development that have dramatically reshaped the terrestrial and aquatic environments. The health of the waterfront is linked to conditions and activities in local watersheds, which provide a conduit to Lake Ontario by way of the rivers and creeks – as well as storm and sanitary sewer systems – that run through local communities.The boundary of the Toronto and Region AOC encompasses 42 km of waterfront together the north shore of Lake Ontario, along with the six watersheds from Etobicoke Creek in the west to the Rouge River in the east that drain into Lake Ontario (Figure 1). The watersheds of the AOC, which drain an area of approximately 2000 km2, originate from the southern slopes of the Oak Ridges Moraine (north of the City of Toronto), and are composed of more than 40% rural landuse, and contain Rouge National Urban Park, one of the world's largest national urban parks. At the same time, more than three million people live in the AOC drainage area and the City of Toronto is at the centre of one of the most densely urbanized and fastest growing areas in the Great Lakes.Historically within the AOC, a vast number of habitats have been degraded: wetlands have been drained and filled (e.g. Ashbridges Bay Marsh); forests and riverbank vegetation were removed; creeks were buried, channelized or concreted; shorelines were hardened; and dams and weirs were built that obstructed fish movement in rivers. Contaminants associated with runoff from stormwater and snow melt from local watersheds, and direct discharge of industrial and domestic wastewater, have created serious water quality impacts in local rivers, and along the waterfront. Spills, road runoff and historically unregulated chemical inputs to sewers from industries and residences contributed to a highly degraded aquatic environment.These multiple stressors polluted the local environment, impacted fish and wildlife habitats and populations (both directly and indirectly) and degraded water quality at beaches, leading to the impairment of several beneficial uses in the Toronto region, and forming the basis for the AOC designation.A Remedial Action Plan (RAP) was developed for each AOC to guide restoration and protection efforts with the goal of restoring impaired beneficial uses (i.e. Beneficial Use Impairments, or BUIs) and ultimately having the area removed from the list of AOCs.For the Toronto and Region AOC, the Stage 1 RAP report Environmental Conditions and Problem Definition (RAP, 1989) identified the nature and scope of issues related to water quality, fish, wildlife, and habitats within the AOC, with an emphasis on conditions along the Toronto waterfront. Of the 14 possible BUIs identified in the GLWQA, 8 were considered impaired, 3 required further assessment, and 3 were considered not impaired within the Toronto and Region AOC (Table 1). Restoration targets developed for each BUI were laid out in the Stage 2 RAP report Clean Waters, Clear Choice: Recommendations for Action (RAP, 1994), along with 53 key actions to restore Toronto's waters, fish, wildlife, and habitats.The RAP process is currently in the implementation phase (Stage 3). RAP partners are completing remedial actions and monitoring the recovery of environmental conditions throughout the AOC. Over the past 17 years, three major interim progress reports: Clean Waters, Healthy Habitats: 2001 RAP Progress Report (RAP, 2001); Moving Forward: 2007 RAP Progress Report (RAP, 2009); and Within Reach: 2015 RAP Progress Report (RAP, 2016) have detailed environmental monitoring results, achievements in remediation initiatives, and assessed how conditions in the Toronto and Region AOC compare against the BUI re-designation criteria.Over the past 30 years, implementation of remedial and management actions have led to significant and demonstrable improvements in the quality of water and sediment, the amount and condition of terrestrial and aquatic habitats, and the health of fish and wildlife, including: Phosphorus levels along the waterfront meet the mesotrophic target set for the RAP, however, continued work on critical wet weather flow infrastructure projects is needed (RAP, 2015; Howell et al., 2018);There has been a substantial reduction in E. coli loadings to the waterfront, resulting in a steady decline in beach closings (e.g. Edge et al., 2018). Eight of Toronto's 11 waterfront beaches are now Blue Flag beaches;Aesthetic condition of local watersheds and the Toronto waterfront are generally excellent or good, and AOC waters are free of substances that produce persistent objectionable deposits, unnatural colour or turbidity, or unnatural odours (Dahmer et al., 2018);Bottom sediments along the waterfront are getting cleaner and the health of benthic communities have improved (RAP, 2013, 2014);Levels of contaminants in fish continue to decline and there are no restrictions on consumption of many resident fish (Bhavsar et al., 2018);Aquatic habitat improvements, including the creation and restoration of habitat for migration, spawning, nursery, feeding, shelter and overwintering support an increased diversity of fish species along the waterfront (Hoyle et al., 2018; Veilleux et al., 2018; Choy et al., 2018).Four of the original eleven beneficial uses that were identified as impaired in 1987 have been re-designated as not impaired (Table 1), and progress on the remaining BUIs is well advanced (RAP, 2016). The articles presented in this special issue on Ecosystem Recovery in the Toronto and Region AOC summarize restoration actions and monitoring conducted by RAP partners that will contribute to the re-designation of the remaining beneficial use impairments to a status of 'not impaired'.Despite the considerable progress that has been made, work remains to be done. Moving forward the Toronto and Region RAP will focus on actions to address the remaining impaired beneficial uses, including: Eutrophication or undesirable algae;Beach closings;Degradation of fish and wildlife populations;Loss of fish and wildlife habitat; andRestrictions on fish consumptionCritical to delisting the Toronto and Region AOC are two major infrastructure projects: the Don River and Central Waterfront project (discussed in Snodgrass et al., 2018), which will address wet weather flow controls, combined sewer overflows (CSOs) and sanitary servicing needs in one complete system; and the Don Mouth Naturalization, which will create 29 hectares of new naturalized area in the river mouth and valley, including a new 1 km river mouth, 14 hectares of aquatic habitat and wetlands and 16 hectares of new parkland to enhance biodiversity and help clean our water and improve habitat conditions. These projects are integral to reducing bacteria, nutrients and suspended sediment to the nearshore, which will support continued water quality improvement, reduce the risk of developing eutrophic conditions, and improve aquatic habitat and ecosystem health along the waterfront.Toronto and Region RAP partners have set a goal of completing restoration actions by 2025 in order to move toward delisting Toronto and Region as an AOC. This goal will be challenging to meet but, as we hope to illustrate through this special issue, we believe it is indeed within reach.S. C. Dahmer1, L. Matos2, and A. Morley31Toronto and Region Conservation Authority, Toronto, Ontario, Canada2Environment and Climate Change Canada, Toronto, Ontario, Canada3Ontario Ministry of the Environment, Conservation and Parks, Toronto, Ontario, Canada