Public Comments – Final Report - Lake Champlain-Richelieu River Study Board

The International Joint Commission (IJC) is welcoming public input on the final report from the International Lake Champlain-Richelieu River Study Board (LCRRSB).  

The Report investigated the causes, impacts, risks and potential solutions to flooding in the Lake Champlain-Richelieu River basin shared between Quebec, Vermont and New York.

The comment period is open from August 19 to October 14, 2022.

Background

The Lake Champlain-Richelieu River basin forms in the United States between New York and Vermont, with much of Lake Champlain forming a border between the two states. The northern part of Lake Champlain crosses into Quebec, where it flows into the Richelieu River. The Richelieu River in turn joins with the St. Lawrence River near Montréal and continues flowing north into the Hudson Bay.

The IJC established the LCRRSB in 2016 to undertake a study of the causes, impacts, risks and potential solutions to flooding in the basin as per the Reference received from the U.S. and Canadian governments. As part of this reference, the IJC was asked to evaluate the causes and impacts of the 2011 flooding, and to make recommendations to mitigate future flood risks in the basin.

Study Report

The LCRRSB study report findings and recommendations cover four key themes:

1. Reduction in water levels via structural mitigation measures
2. Effects on impeding flows during floods of existing and additional wetlands in the basin
3. Enhancements to flood forecasting and flood response in the basin
4. Floodplain management best practices and lessons learned in other watersheds

The main study recommendations include:

• That selective excavation of the riverbed near Saint-Jean-sur-Richelieu, Quebec combined with the construction of a submerged weir would reduce high water levels during floods and would have the added benefit of raising water levels on Lake Champlain during dry years. A moderate diversion of high flows through the Chambly Canal could also be considered for additional flood-reduction benefits.
• The preservation of existing wetland areas, which can minimize water levels during floods while also stabilizing water levels during droughts in the basin.
• The governments are encouraged to operationalize the improved modeling and forecasting tools and coherent risk assessment systems and support/maintain them after the Study. The agencies responsible for flood forecasting in the basin continue collaboration and make available forecasting data so that forecasts on both sides of the border are of the highest possible quality and are accompanied by a concerted and consistent cross-border interpretation.
• Improving floodplain mapping for the use of emergency managers and enhancing communication campaigns around flood risk in the basin. The Board also recommended that jurisdictions in the basin reviews their floodplain management policies through the lens of making these areas more resilient for possible future floods.

Read the LCRRSB’s highlights report and full report.