Update on Lake Superior outflow conditions

NEWS RELEASE

INTERNATIONAL LAKE SUPERIOR BOARD OF CONTROL

*************************
The International Lake Superior Board of Control, under authority granted to it by the International Joint Commission (IJC), has set the Lake Superior outflow to 2,800 cubic meters per second (m3/s) (98.9 thousand cubic feet per second (tcfs)) for the month of September, effective September 3.

The September outflow is expected to exceed the combined capacities of the hydropower plants on the St. Marys River, which will be approximately 2,030 m3/s (71.7 tcfs) in September, and most of the excess flow will be released through the control structure at the head of the St. Marys Rapids.

The gate setting of the control structure in September will remain at the existing setting equivalent to approximately five gates open, and anglers should continue to be cautious of the potentially hazardous flow and water level conditions in the St. Marys Rapids that will be experienced throughout the month.

The five-gate equivalent setting will be achieved by maintaining Gates #2 to #13 and #15 partially opened a total of 76 cm (30 in) each.

There will be no change to the setting of Gate #1, which supplies a flow of about 15 m3/s to the channel north of the Fishery Remedial Dike.

Furthermore, Gate #14 will continue to remain closed to facilitate collection of field data measurements, and Gate #16, which was opened 5 cm (2 in) to facilitate sea lamprey trapping through June and July, will remain at this setting until a later date.

The September outflow of 2,800 m3/s (98.9 tcfs) is 30 m3/s (1 tcfs) less than that prescribed by Regulation Plan 2012, in accordance with the Board’s approved deviation strategy.

The Board continues to adjust the outflow of Lake Superior to accomodate expected maintenance at the hydropower plants and reduce the potential for adverse consequences of high and fluctuating flows and water levels in the St. Marys Rapids.

Flows less than the Plan 2012 were released in May and June of this year, and this was followed by flows greater than Plan 2012 being released in July and August.

The Board expects to release flows somewhat less than Plan 2012 again in September through November.

The monthly mean water level of Lake Superior in August was 183.68 m (602.63 ft).

This is 15 cm (6 in) above the long-term (1918-2014) August average and the highest August level since 1997.

The net water supplies to Lake Superior were above average in August.

The level of Lake Superior remained about the same last month, while on average the lake rises 1 cm (0.4 in).

The Lake Superior level at the beginning-of-September is 16 cm (6 in) above average, 1 cm (0.4 in) above the level recorded a year ago at this time, and 49 cm (19 in) above its chart datum level.

The monthly mean water level of Lake Michigan-Huron in August was 176.72 m (579.81 ft). This is 17 cm (7 in) above the long-term (1918-2014) August average - the highest August level since 1998.

The net water supplies to Lake Michigan-Huron were above average in August.

The level of Lake Michigan-Huron declined 2 cm (1 in) last month, while on average the lake falls 4 cm (2 in) in August.

The level of Lake Michigan-Huron is 18 cm (7 in) above its long-term average beginning-of- September level, 20 cm (8 in) higher than it was a year ago, and 70 cm (28 in) above its chart datum level.

The levels of Lake Superior and Lake Michigan-Huron are both expected to continue their seasonal declines in September.

Brigadier General Richard Kaiser is the United States Board Member. Mr. Jaymie Gadal is the Board Member for Canada.

For further information please contact Ms. Cynthia Jarema, Watershed Hydrology Branch, U.S. Army Corps of Engineers – Detroit District, at (313) 226-6127 or [email protected].

Additional information can be found here on the Board’s homepage, Facebook or the U.S. Army Corps of Engineers, Detroit District Superior Regulation webpage.