Click here for an up-to-date listing of current St. Marys River flow as determined by its monthly regulation plan and current St. Lawrence River flow as determined by its weekly regulation plan.
The Measurement of Flows in the Great Lakes Connecting Channels and the International Section of the St. Lawrence River
The discharge of a river is defined as the volume of water flowing past a particular point in unit time. The US Army Corps of Engineers Detroit District measures discharge on the Great Lakes Connecting Channels (St. Marys River, St. Clair River, Detroit River, Niagara River) and the international section of the St. Lawrence River. The measurements are used to develop and verify discharge ratings that reference water level gauges, to analyze hydraulic structures, and to calibrate hydraulic models. Discharge data are also used operationally in navigation, hydropower production, lake regulation, water level forecasting, water apportionment, monitoring of compliance with agreements and treaties and in a wide range of studies.
Click here to watch a short video describing flows on the Great Lakes Connecting Channels and how they are measured.
Detailed information regarding the collection and use of discharge data is available upon request at HHPM@USACE.ARMY.MIL.
Conveyance Change Monitoring
The St. Clair River is a naturally occurring dynamic river system which plays a role in conveying water from Lake Huron to Lake St. Clair and eventually Lake Erie. As such, any change in the shape of the river can have an effect on the level of the Great Lakes. Sediment entering the St. Clair River from Lake Huron, dredging the navigation channel, ice jams and other natural processes can all result in changes to the rivers ability to move water through the system. The US Army Corps of Engineers Detroit District monitors changes in the St. Clair River by measuring the shape, or bathymetry, of the river and computing how the changes affect the amount of water that can pass through the system.
Additional information is available upon request at HHPM@USACE.ARMY.MIL.