09/04/2024 | Press release | Archived content
The Board expects the total St. Marys River flow in September to be 2,210 m3/s (78,000 cfs), as prescribed by Regulation Plan 2012. Actual hour-to-hour and day-to-day flows may vary depending on hydrologic conditions, as well as variations in flow from the hydropower plants. The average St. Marys Rapids flow in September is expected to be approximately 540 m3/s, to meet the Plan 2012-prescribed flow in September in consideration of the capacity restrictions at the hydropower plants. Gate #1 will remain at its typical setting which supplies a flow of about 15 m3/s to the channel north of the Fishery Remedial Dike.
Anglers and other users of the St. Marys Rapids need to be cautious of the flows and water levels that will be experienced in the rapids in September. On Monday, September 9, the gate setting of the Compensating Works will be decreased from the current setting equivalent to approximately four gates fully open (Gates #7 through #15 open 97 cm each) to a setting equivalent to approximately three gates fully open (Gates #7 through #15 open 76 cm each).
After the gate adjustments, the St. Marys Rapids flow will decrease from approximately 640 m3/s to approximately 500 m3/s. Concrete core sampling at two Compensating Works piers requires Gates #10 and #14 to be raised to 130 cm early on Monday, September 9. Upon completion of the coring work, on Monday, September 9 or Tuesday, September 10, Gates #10 and #14 will be lowered to their September setting of 76 cm.
Water level changes over the month of August
Water supply conditions were drier than average in the Lake Superior and Lake Michigan-Huron basins inAugust.
Water levels as of the beginning of September
Forecast outlook
The International Lake Superior Board of Control is responsible for managing the control works on the St. Marys River and regulating the outflow from Lake Superior into Lake Michigan-Huron. Under any outflow regulation plan, the ability to regulate the flow through the St. Marys River does not mean that full control of the water levels of Lake Superior and Lake Michigan-Huron is possible. This is because the major factors affecting water supply to the Great Lakes (i.e. precipitation, evaporation, and runoff) cannot be controlled, and are difficult to accurately predict. Outflow management cannot eliminate the risk of extreme water levels from occurring during periods of severe weather and water supply conditions. Additional information can be found at the Board's homepage: https://ijc.org/en/lsbc or on Facebook at: https://www.facebook.com/InternationalLakeSuperiorBoardOfControl