By Peter Sale
In a previous article, Kevin Trimble proposed using watershed hydrology to help manage floods. How do we do this?
The Muskoka Watershed Council recommends integrated watershed management if we want long-term success. Integrated watershed management is widely used in North America and overseas, but not yet in Muskoka.
Nature is interconnected; every organism, every physical feature, every process. What happens in the forest ends up in the lake, upstream ends up downstream, and what happens downstream can even affect what happens upstream. A watershed is a natural management unit which captures precipitation, filters and stores water, and regulates its release as river flow.
The Muskoka River Watershed, stretching from the Algonquin Highlands to the outlets of the Moon and Musquash Rivers at Georgian Bay, includes nearly all the District Municipality of Muskoka, as well as portions of Algonquin Highlands and Seguin Townships, a total of 4,660 kilometres squared. Over half the precipitation arriving in this watershed never gets to Georgian Bay; it is trapped in soils, trees and groundwater or evaporated back to the sky. The rest sometimes causes floods.
Integrated watershed management begins by recognizing that water quality as well as quantity or flow are strongly dependent on the nature of the watershed: its topography, its natural infrastructure of soils, forest types, ground cover, wetlands, rivers and lakes, and its human infrastructure of roads, parking lots, buildings, bridges, channels and dams. Built infrastructure for managing river flow plays an important, but minor, role in how water moves through our watershed. Even if it were possible, it would be far more costly to attempt to manage flow entirely using built infrastructure; we must also use natural infrastructure. In addition, nutrients and pollutants move with the water, playing major roles in determining environmental quality of both the land and water. Flow management is far more than engineering of some river channels; it’s a central part of integrated environmental management.
To implement integrated watershed management in Muskoka, all levels of government, economic sectors and the community must have seats at the planning table, and regulatory agencies and municipalities must ensure their individual actions become part of a seamless, watershed management process.
Muskoka’s long experience with co-operative approaches to environmental management makes integrated watershed management a particularly good fit, and provincial funding promised in 2018 for Muskoka’s environment permits an immediate start. A GIS-based inventory of man-made and natural infrastructure is the first step for modelling the watershed’s hydrology and its capacity to store and move water. Developing a fully interactive hydrological model for use in guiding management decisions is the next step. Such a model provides managers with a vital tool to ask the “what if” questions around the consequences of any planned actions. The model also reveals consequences of events beyond our control such as those caused by global climate change. If we want to minimize future flooding and sustain Muskoka’s environment, we have to take an integrated watershed management approach.
The good news is that much of the needed environmental inventory and some records of precipitation and river flow are already available. Data need to be brought together and augmented as needed to commence the comprehensive hydrological study that will deliver the interactive model. These initial steps require a targeted research effort that could best be met by engaging university-based researchers in collaboration with relevant management agencies.
With integrated watershed management in place, managers will better understand the factors driving water flow, and be able to incorporate that knowledge into all planning decisions, including decisions for any future flow control infrastructure. Integrated watershed management will help ensure nature is thriving alongside a robust Muskoka economy and lifestyle, plus cost-effective management and fewer unpleasant surprises when spring comes around each year.