Notice to use caution in shoreline bluff areas
Conservation authorities issue notice to advise public to use caution near shoreline bluff areas
Ausable Bayfield Conservation Authority (ABCA) and Maitland Valley Conservation Authority (MVCA) are cautioning that shoreline bluffs continue to be at a high risk of collapse. They advise the public to continue to be cautious near these shoreline areas.
Erosion hazards are always present along shoreline bluffs but the conservation authorities want to remind the public the current risk of collapse remains higher than normal. This is because there can be a delay between erosion at the toe (bottom) of the bluff and subsequent bluff failure.
Lake Huron water levels reached an all-time high in 1986 and lake levels were near that record high in 2020. Those high lake levels and associated wave action resulted in extensive toe erosion. Although the Lake Huron water level has declined since then, many portions of the bluffs were left over-steepened and may still be unstable as a result.
The high risk of bluff failure will continue as the slope adjusts to the recent impacts of toe erosion and bluff oversteepening. This makes some areas along Lake Huron’s shoreline prone to collapse. This is a risk that can be further heightened due to seasonal rainfall and snowmelt that can saturate the ground and soften the bluffs. In this area, these are seasonal conditions that we typically experience during autumn and winter thaws and in the spring.
ABCA and MVCA continue to encourage landowners, the public, and municipal employees to stay away from the top of the lake bluff, especially where there have been signs of over-steepening or slope movement. Areas along the beach below these bluffs should also be avoided. Injury or loss of life could occur if a bluff collapses and beach users are caught in the deposition zone. The ABCA and MVCA continue to encourage landowners to monitor their property for signs of movement.
Unlike flood messages and low water advisories, that are issued and then expire as circumstances change, caution around shoreline bluff areas should always be practised as the risk of failure and collapse is inherent in a shoreline bluff system.
ABCA has created a fact sheet to help shoreline residents recognize signs of erosion. It also offers best management practices. A PDF file of the fact sheet is found on the Lake Huron web page on the abca.ca website.