Muskoka River Siltation Project

The Muskoka River Watershed (MRW) originates in the northeast section of Algonquin Park and travels approximately 210 km southwesterly to its terminus in Georgian Bay an approximate area covered by the watershed of 5,100 km². The MRW contains fifteen (15) sub-watersheds, two (2) of which is the North and South Branch of the Muskoka River that converge into the Muskoka River at the Town of Bracebridge (Town) prior to depositing into Lake Muskoka. Originating from the 2013 Flood, the Town has taken an active role in raising awareness to other levels of government on the concerns with flooding and the siltation of the Muskoka River at the delta with Lake Muskoka.

The erosion of shoreline throughout the MRW is a naturally occurring process, but human activity has compounded the significance of erosion in many areas, particularly on the open lakes. The recent flooding events of 2013, 2016 and 2019, have manifested new areas of concern in relation to erosion and siltation. In response, the Town of Bracebridge held public open house events in 2015 to allow property owners, commercial operators, and others who utilize the Muskoka River to provide any additional background information. In the area of the Muskoka River delta at Bracebridge, exceptionally high-water levels and flow volumes resulted in substantial erosion, damage to the built infrastructure and silt deposits. The silt deposit has created navigational concerns for both recreational and commercial operators on the Muskoka River.

In subsequent years, the Town identified the following for potential concerns from sediments that have accumulated at the mouth of the Muskoka River:

• The navigational channel is no longer defined and the mouth of the Muskoka River is approximately 0.3 m deep at its deepest point and shallows to nothing in some areas where sandbars continue to form.
• Historically, the channel is typically 2.74 to 3.65 m deep at this location.
• The navigation channel is 375 m long by 52 m wide with approximately 39,000 m³ of sand and sediments that have accumulated near the western shoreline off of Caisses Island.

A bathymetry study was completed in 2017 for the Muskoka River delta consisting of the part of the Muskoka River from a point at Sandpit Island on Lake Muskoka easterly for approximately 1900 m including a portion of Alport Bay and from a point at Peninsula Island on Lake Muskoka southerly for approximately 1200 m.

While there has been some research and public discussion in the past, the need to fully understand the sedimentation of the river delta, river bank erosion and the effects of these problems on the environment and the community, as well as the options available to address these issues, are critical to deciding on a path forward for the Muskoka River.