There are many factors that affect both inland lakes and Georgian Bay water levels and flow, including:
To measure water levels and flow, gauge readers or automatic recording devices can be used. Rate of flow needs multiple measurements of channel depth, width, and flow velocity. With enough measurements of flow over an assortment of water levels, a water level-discharge association is established. The discharge rate can then be processed from measured water levels.
Floods and droughts are a natural part of the ecosystem. Changes in surface water levels are natural. Some ecosystems even rely on these fluctuations. Because of the many lakes in Muskoka that act as flood reservoirs, flooding is not a major issues. The Ministry of Natural Resources manages water levels on the system to ensure that there is adequate flood storage during the spring freshet.
Minor to moderate droughts are also part of the normal environment. These droughts often result in forest fires, which can facilitate the reproduction of some plant and tree species, such as Jack pine and many prairie species.
A floodplain is an area capable of change due to high stream flow conditions. Greater streamflow conditions generally mean a larger area adjacent to the stream will be affected by floodwaters. Humans can sometimes induce flooding, through watershed alteration and land use changes. Floodplain regulations help make sure construction and building in or near floodplains is done responsibly.
Water levels on Georgian Bay in Lake Huron are always changing. They can change within a few hours (short-term changes) in response to a storm system, undergo seasonal changes in response to higher evaporation rates in the late fall, winter and spring, and higher precipitation and melting snow-pack in spring, to long-term changes that can see Lake Huron fluctuate within a range of about two metres between highs and lows.
The Georgian Bay Association has been instrumental in working with scientists and senior levels of government to identify water level issues and ensure the long-term consideration of the impact of water levels on the social, economic and environmental values of the Bay.
The Muskoka River Water Management Plan (MRWMP) was implemented in 2006 and takes an ecosystem-based approach to water management by considering the interests and concerns of all water users within the watershed, including fish, wildlife, navigation, hydro generation, recreation, flood control, etc.
Learn more about water management planning and the Muskoka River Water Management Plan.