Announcements / Science

Lake Memphremagog and South Bay Depth Chart Now Available!

The Vermont Watershed Management Division is pleased to announce the publication of a precise online depth chart for the Vermont portions of Lake Memphremagog and South Bay available at the following link – Vermont Depth Charts.

This map is a culmination of years of work by the Vermont Watershed Management Division with support from partnering agencies.  The US Environmental Protection Agency that spent a week collecting depth soundings of the lake in the fall of 2013 and then another two days surveying South Bay in the fall of 2014.  Also in 2013, the Quebec Ministry of Sustainable Development, Environment and the Fight against Climate Change completed depth soundings covering the central portions of the lake.  Finally, in the late fall of 2014 staff from the Vermont Watershed Management Division manually collected nearly 700 depths in the section of the lake between South Bay and Lake Memphremagog between bridges where larger boats could not reach which allowed for a complete depth chart to be created.  The depth data on the main lake was shared with the Canadian Hydrographic Service who published a new navigational chart for Lake Memphremagog covering both Vermont and Quebec portions in 2014.

The new Vermont Lake Memphremagog and South Bay depth chart.

The new Vermont Lake Memphremagog and South Bay depth chart.

The process involved technical steps that ensures the utility of the resulting depth information for many uses.  The Canadian Hydrographic Service compiled the data sets from the main lake and, with the support from Agency of Natural Resources Geographic Information Service (GIS) staff, created a computer-based datasets including a digital elevation model and isobaths.  These datasets were then used to estimate lake segment volumes and cross sectional areas, to support water quality modeling Lake Memphremagog. This modeling work is an important component in the development of a phosphorus pollution control plan (or Total Maximum Daily Load) for Lake Memphremagog.

These datasets were also used to create a new depth chart for Lake Memphremagog and South Bay for use by the general public.  This new depth chart includes depths for South Bay and the waters near Newport, and also provides greater detail about depths on the Vermont Portions of Lake Memphremagog than previously available.  This chart would not have been possible without the support of the US Environmental Protection Agency, Quebec Ministry of Sustainable Development, Environment and the Fight against Climate Change, and Canadian Hydrographic Service.