Our Wetlands
Wetlands in the Nottawasaga Watershed
The Nottawasaga Watershed contains more than 4,000 individual wetlands that are greater than 0.1 hectares. To many people, wetlands are great spots for fishing, hunting, paddling, hiking, bird-watching, and are valuable outdoor “classrooms” for people of all ages.
The Nottawasaga Watershed is home to diverse and ecologically significant wetlands. These wetlands play a crucial role in the local ecosystem, supporting a variety of wildlife and plant species. They serve as important habitats for birds, amphibians, and other wildlife, particularly during migration periods. The wetlands also help filter pollutants from the water, improve water quality, and provide flood control by absorbing excess rainwater. Additionally, they contribute to the overall health of the river system by maintaining hydrological balance.
In Ontario and many places around the world, wetlands are evaluated and “graded” by significance. Ontario uses the Ontario Wetland Evaluation System, which is a provincially-approved protocol that sets standardized scoring metrics to assess biological, social, hydrologic and special features of the wetland. A provincially significant wetland is identified by the province as the most valuable.
In the Nottawasaga Watershed, these wetlands are the internationally significant Minesing Wetlands and 36 provincially significant wetlands as well as 35 important but non-provincially significant wetlands. There are thousands of smaller unevaluated wetlands in the watershed.
Unevaluated wetlands provide similar ecosystem and natural hazard mitigation services at local level. Regardless of evaluation status, all wetlands contribute to a healthy watershed and provide valuable ecosystem services including flood control and providing clean drinking water.
What are wetlands, and why are they so amazing?
Wetlands are also very important for flood control, water filtering, groundwater recharge and discharge and wildlife habitat.
Like rivers, groundwater and lakes, wetlands are part of the water cycle. They are areas that have very wet soils that can flood seasonally. Wetlands can support vegetation that are adapted to seasonally or permanently high-water table.
Wetlands absorb water like a sponge. They can quickly trap water from storms or snowmelt and slowly release it. When there is a lot of rain or snowmelt, wetlands absorb and slow floodwaters, which helps to alleviate property damage and can even save lives. In the face of climate change, these wetlands are ever more important as we experience more extreme storm events.
Water in wetlands can come from different sources such as rain and snow, rivers, lakes and groundwater. The amount of water stored in a wetland depends on the temperature, daylight, snowmelt and rainfall amounts, soil and vegetation as well as characteristics of the individual wetland. Water levels in wetlands have natural cycles (called a hydroperiod), and in our region, are typically higher in the spring and lower in the summer.
In the Nottawasaga Watershed, wetlands contain the most water during and after the spring snowmelt and are typically drier during summer and early fall. They may refill later in the late fall with heavy rain. Water levels in groundwater-fed wetlands are relatively stable, but still rise in the early spring.
Depending how water in wetlands connect with other natural features, they are classified differently. There are four general types of wetlands: bog, fen, marsh, and swamp. In the Nottawasaga Watershed, swamps and marshes are the most common, while fens are relatively rare and no bogs have been found. All wetlands contain hydric (moist) soil formed by the abundance of water and water-tolerant plants.
A marsh is a type of wetland characterized by plants like grasses, sedges, and reeds adapted to saturated soil conditions. Water flows in and out of marshes continuously. Marshes are often flooded with shallow water; either seasonally or year-round, from surface or groundwater sources.
Too wet to support trees or shrubs, they often have recognizable plants like cattails, bulrushes and water lilies and have almost no shrub or tree coverage. Abandoned fields in low-lying areas often regenerate into marshes where there is enough water. In the Nottawasaga Watershed, marshes are often connected to large rivers and lake shorelines.
Swamps are similar to forests but are adapted to seasonal flooding. Woody plants like trees and shrubs, such as silver maple, willow, and black ash are found in swamps. These areas typically have standing water in the spring or are frequently flooded. Water levels in floodplain swamps, including parts of Minesing Wetlands, can rise and fall by more than 2 metres over the course of the year!
The soil in swamps often lacks oxygen due to saturation, leading to the buildup of organic matter. Swamps support a rich biodiversity, providing habitat for various wildlife, including birds, amphibians, reptiles, and insects, all of which thrive in the dense vegetation and abundant water.
Swamps are vulnerable to changes in moisture – if they become too wet or too dry, the trees will not be able to tolerate these changes. For instance, if too wet, it may convert to a marsh or thicket swamp. Pressures like land use conversion and climate change can change the patterns in wetland water levels at a local level (Georgian College Wetland) or watershed level (Minesing Wetlands) by altering natural drainage patterns that reduce or increase water flows to wetlands.
In the Minesing Wetlands, the floodplain swamps have significantly died back due to historic and recent changes in land use across the wetland catchment. These changes include clearing natural areas for agricultural expansion and urban development.
Fens are generally always wet and support unique plant communities, such as shrubs, grasses, sedges and herbs with occasional trees such as black spruce and tamarack.
This type of wetland is usually fed by groundwater, which gives them a distinct chemistry compared to other wetlands, like marshes or swamps. Water flow out of fens is very slow, leading to nutrient-poor conditions for plant growth. Fens often have a neutral to alkaline pH and support specialized plant species that are adapted to these conditions like mosses, sedges, grasses, and some flowering plants.
Who to Contact
Watershed Science Team
705-424-1479 x 234
iockenden@nvca.on.ca
Conservation Areas