The outflows from two of the five Great Lakes (Lake Superior and Lake Ontario) are regulated by control structures. These outflows are varied in accordance with their respective regulation plans.

The outflows from Lakes Michigan-Huron and Erie are not regulated, but rather, are controlled exclusively by the hydraulic characteristics of their outlet rivers.

Lake Superior
Outflows from Lake Superior are regulated near the twin cities of Sault Ste. Marie, Michigan and Ontario. Outflows are controlled by three hydropower plants and a 16-gate control structure called the Compensating Works. The outflow is established on a monthly basis by the International Lake Superior Board of Control. The outflow is set in accordance with the current regulation plan, Plan 77A.

ILSBC: To access information on Lake Superiors current outflow and background information on the International Lake Superior Board of Control

Current News Release: To access the latest news release, which provides updated information on the Lake Superior Outflow.

Lake Ontario
Outflows from Lake Ontario are established on a weekly basis by the International St. Lawrence Board of Control. The principle control structure is the Moses Saunders Dam. The Lake Ontario outflow is set in accordance with the current regulation plan, Plan 1958-D.

ISLRBC: To access the latest information on the regulation of Lake Ontario and background information on the Board.

This Weeks Regulation Strategy: To access the Lake Ontario regulation strategy for the coming week.

Last Weeks Outflows: To access last weeks Lake Ontario outflow data.