July 2018 State of the Wetlands in the Lake Simcoe Watershed Ontario Streams Technical Report No. 2018-01 Alexander Kissel, Habitat Technician & Alice Choi, GIS Technician, Ontario Streams ontariostreams.ca Summary Wetlands in the Lake Simcoe Watershed are critical to the health of the Lake and its surrounding ecosystem. They cover 18.4% of the surface area around the Lake or 52 847 hectares (ha). About 62.4% of these wetlands have been evaluated using the Ontario Wetland Evaluation System (OWES) Southern Manual. The distribution of wetlands vary with fewer and smaller wetlands on the Oak Ridges Moraine (7.1% of surface area), the Schomberg Clay Plains (5.5%) and the uplands west of the the Lake (10.9 to 12.7%), contrasting with the larger valley and shoreline wetlands in the lowlands around the Lake (25.7%). Small wetlands play an important role particularly in the landscapes where they make up a large portion of the wetlands. A high resolution (15 centimetre pixel) analysis of aerial imagery from 1999/2002 to 2013/2016 for the Lake Simcoe Watershed has shown that many small wetland losses, and the occasional larger ones, add up over this time period to a loss of almost eight square kilometres or 773 ha (1.5% of the total wetland area). This loss is higher than previous estimates using lower resolution (30-metre pixel) satellite imagery which cannot pick out the smaller losses that have a large cumulative impact. The highest losses have been from agriculture (46.4% of all losses), following in descending order by residential (10.5%), peat extraction (10.4%), canals (9.6%), highways/roads (6.6%), industrial/commercial (5.7%), fill (4.6%), dug-out ponds (4.3%), recreation (1.6%) and aggregates (0.3%). Another 88 ha of wetlands have also been degraded by clear-cutting, haying, grazing and ditching. In contrast, 60 ha of wetlands have expanded largely because of agricultural abandonment resulting in a net wetland loss for the Watershed of 713 ha. Relative losses vary greatly by municipality. Barrie had the highest, losing 10.2% of its Watershed wetlands, followed by East Gwillimbury (4.9%), Newmarket (4.4%), Innisfil (3.2%) and Bradford West Gwillimbury (3.1%). Much below the average, are Scugog and Kawartha Lakes, which had relative losses of only 0.2%. East Gwillimbury had the highest total loss of 257.3 ha, or 33.3% of all the wetland lost in the Watershed, followed by Georgina at 13.9%, Innisfil at 9.9%, Brock at 8.2% and Bradford West Gwillimbury at 8%. While losses have generally increased since 1999/2002 in the York Region and Simcoe County (including Barrie and Orillia) portions of the Watershed they have finally started to drop a small amount during the most recent sampling period. However, in the Durham Region portion of the Watershed, wetland losses have risen steadily over the three sampling periods. The losses have been highest in the municipalities being urbanised or with extensive market gardens. Rural areas have also experienced losses from agriculture, and particularly from peat extraction. The Province’s Conservation Wetland Strategy 2017-2030 provides a great opportunity to slow down or stop the continued losses and degradation of wetlands in the Watershed. Correspondingly, the relatively smaller wetland gains that have occurred should be encouraged. This should include increased outreach and incentives to landowners and the acquisition of more wetlands for public enjoyment and to protect those threatened. Existing protection measures also need to be more strongly enforced. i State of the Wetlands in the Lake Simcoe Watershed Ontario Streams July 2018 Acknowledgements This report is authored by Ontario Streams. Established in 1995, Ontario Streams is a non-profit environmental organisation dedicated to the conservation and rehabilitation of streams and wetlands, through education and community involvement. Since our inception, we have worked closely with numerous communities, landowners, and school groups to develop lasting partnerships in education and environmental stewardship. With over 20 years of experience, Ontario Streams has continued to demonstrate leadership in aquatic ecosystem rehabilitation. Many Ontario Streams' projects have occurred in and around the Greater Toronto Area (GTA), where the need for rehabilitation has been greatest. In addition to the restoration projects that Ontario Streams continues to champion, our organisation has also been involved in the development of several programs, studies, and information-sharing projects. Ontario Streams also coordinates our own Adopt-A-Stream program where we help groups become involved in community stewardship by adopting local streams or wetlands. The Ontario Ministry of Natural Resources and Forestry (OMNRF), Aurora District and their Geographic Information Services (GIS) and wetland experts provided imagery, technical advice and edited/verified the wetland change dataset. Environment Canada funded the project through the Lake Simcoe/Southeast Georgian Bay Clean-up Fund (LSGBCUF). Introduction Wetlands in the Lake Simcoe Watershed are critical to the health of the lake and its surrounding ecosystem. They harbour a number of species at risk and are critical to the life cycle of many plants and animals including fish, frogs, salamanders, turtles, waterfowl and sensitive forest bird species. They also provide important hydrological functions such as flood attenuation, improving water quality, contributing to groundwater discharge and recharge and serving as long-term nutrient traps. They are used by the public for nature enjoyment, outdoor education, fishing and hunting. The importance of wetlands to the ecological health of the lake has been recognised by the Province's Lake Simcoe Protection Plan which was approved in 2009. This report on the current state of wetlands in the watershed will hopefully contribute to discussions on the effectiveness of the Plan, and on its upcoming ten-year review in 2019. This report tracks the changes that have occurred to wetlands within the Lake Simcoe Watershed between the years 1999/2002 and 2013/2016. These include wetland losses and gains, as well as the degrading of wetlands by logging, ditching and other disturbances. The cause for each change is noted and is summarised for the Watershed's seven upper tier and 16 lower tier municipalities (see Figure 1) and by landscape type including its six physiographic regions and four ecodistricts (see Figure 2). Historic aerial photography back to 1946/1954 has also been used to further quantify wetland losses from peat extraction and the conversion of most of the Holland Marsh to market gardens. The Watershed’s seven upper tier municipalities vary in size with the largest being York Region, followed closely by Durham Region, Simcoe County and the City of Kawartha Lakes (see Figure 1). Much smaller in size are the City of Barrie and Orillia and a very small corner of Peel Region 1 represented by its local municipality of Caledon. The upper tier York, Durham and Simcoe have a total of 15 lower tier or local municipalities. The largest in the Watershed is Brock closely followed by Uxbridge, Georgina, East Gwillimbury, King, Ramara, Innisfil, Oro-Medonte and Bradford West Gwillimbury (see Figure 1). In contrast, only a small part of Richmond Hill is in the Watershed. Wetlands in the Watershed currently cover 18.4% of the landscape around Lake Simcoe (see Figure 3). The distribution of wetlands varies with fewer and smaller wetlands on the Oak Ridges Moraine and Oro Moraine, contrasting with the large valley wetlands around the Lake and lining its shores. This variation is a reflection of the terrain or physiography of the Watershed. Four ecodistricts, characterised by having similar physiography and climate, make up the Watershed (see Figure 2). It is dominated in the centre by the Simcoe Lowlands and Uplands Ecodistrict 6E6 which consists of four physiographic regions: Simcoe Lowlands, Simcoe Uplands, Schomberg Clay Plains and Peterborough Drumlin Field. Most of ecodistrict 6E6 encompasses the former lake bed and islands of Glacial Lake Algonquin. With the retreat of the continental ice sheet, about 12 000 to 10 400 years ago, this glacial lake covered today’s Lake Huron, Lake Simcoe and the intervening lowlands. In the northwest corner of the Watershed, an island (Simcoe Upland) in Lake Algonquin supports the thick sands of the Oro Moraine and a rolling till plain. West of Cooks Bay, there is another till plain with scattered tear-dropped shaped hills called drumlins that were left behind by the ice sheet. Finally, ecodistrict 6E6 includes, in the southwest, the former clay beds of Glacial Lake Schomberg created 12 000 years ago when meltwater built up between the ice sheet and the up to 125 meters high Oak Ridges Moraine Ecodistrict 6E7. Southern Ontario’s largest moraine, it demarcates the southern edge of the watershed, and its aquifers provide the headwater source for many of its watercourses. In the southeast, between the lake and the Moraine, is the Peterborough Drumlin Field Ecodistrict 6E8, consisting of thousands of these hills scattered on a till plain. In the northeast corner of the Watershed, where the limestone bedrock of southern Ontario comes close to the surface, you have the Carden Plain Ecodistrict 6E9. The wetlands on these diverse landscapes have been variously impacted by our agricultural and urban activities. A wetland conversion analysis by Ducks Unlimited from pre-settlement times (1800) to the year 2002 has estimated considerable wetland losses over the years (DU 2010). For municipalities, which largely or entirely reside in the Lake Simcoe Watershed, these losses have varied from a low of 22% of all the pre-settlement wetlands in Uxbridge to highs of 75.7% in King, 80.4% in Barrie and almost 100% in Newmarket. In the mid-range, are Aurora at 59.3% loss, Innisfil 50.4%, Bradford West Gwillimbury 50%, Georgina 49.8%, East Gwillimbury 47.5% and Brock 37.5%.