The Corps of Engineers routinely monitors conditions at Federal navigation channels. This includes bathymetric surveys, which are detailed measurements of the elevation of the bottom of a channel relative to a fixed elevation datum. These surveys are conducted on an annual basis at most Federal channels. The information is used to identify shoaling, or areas where sediments have accumulated, as well as any other obstructions. When shoaling is identified, the Corps issues a notice to navigation users in cooperation with the Coast Guard.
Survey data is used to determine the need for maintenance dredging at Federal channels, and to estimate the quantity of sediments that will have to be removed by the dredging contractor. Sediments to be dredged are sampled and tested in order to determine the appropriate options for management of the dredged material.
Bathymetric surveys of Federal navigation channels are available in electronic form at one or more web sites maintained by the Corps of Engineers, including the following:
The Corps of Engineers no longer maintains or distributes nautical charts or maps of the Great Lakes. Charts developed by the National Oceanic & Atmospheric Administration can be obtained from a number of local distributors.