Introduction

Cantley's shoreline clay

One of the distinguishing features of Cantley's shoreline are the pockets of leda clay, remnants of the ancient Champlain Sea, that can have a significant erosion and landslide impact on the river and the littoral zone's aquatic life. The attached map shows the most vulnerable areas where clay should be carefully monitored for soil or vegetation disturbance.

In general the Gatineau River and the 3 year-round streams flowing into it all have good quality water but much of the littoral zone in the river has been degraded with deposits of leda clay sediment. The most degraded area comes from an abandoned lane alongside Cascades Creek where clay sediment has destroyed approx. 200-300 m of littoral zone biodiversity. Gone is the ecosystem necessary for supporting fish, plants and macroinvertebrates such as mussels - each mussel is capable of filtering 50+ liters of water per day.

Sediment from abandoned Mont Cascades Creek lane

Cantley's shoreline leda clay zones

Cantley's 2005 Master Plan "Orientation 1.4 (page 3)" recognizes the importance of protecting the quality of riverbanks and waterfront areas but lacks direction on how to assess the risks associated with shoreline modification, especially in areas of leda clay where heavy sedimentation and mini-landslides can significantly degrade wetlands and waterways. The 2017 Conservation of Wetlands and Waterways Act in part is intended to prevent such degradation.

The ecosystem benefits of protecting wetlands and littoral zones are numerous (pp 6-7) some of which are:

• • acting as a pollution filter, controlling erosion and retaining sediments by, among other things, preventing and reducing surface water and groundwater pollution and sediment input;

  • acting as a regulator of water levels by retaining meteoric water and meltwater and allowing part of it to evaporate, thereby reducing the risk of flooding and erosion and promoting groundwater recharge;

  • conserving the biological diversity that enables the wetlands and bodies of water or the ecosystems to provide living species with habitats in which to feed, find cover and reproduce;

  • acting as a sun screen and natural wind-shield by maintaining vegetation, which prevents excessive warming of water and protects soils and crops from wind damage;

• sequestering carbon and mitigating the impacts of climate change; and

  • protecting the quality of the landscape by preserving the natural character of a site and the attributes of the countryside associated with it, thus enhancing the value of adjacent land.

Questions

1. Who monitors the potential impact of shoreline modification?

2. Who defines and regulates development activities in hazardous shoreline sensitive clay land?

3. Who determines technical guidelines pertaining to floods and natural hazards based on current science and climate change research so there is sufficient freeboard to minimize the risk of landslides in areas of hazardous sensitive clay?

4. How to communicate to property, or prospective, property owners of high risk landslide potential of their shoreline?

5. How to support municipalities that wish to restore badly eroded leda clay shorelines? .