INTERNATIONAL LAKE SUPERIOR BOARD OF CONTROL
Update on Lake Superior outflow
The International Lake Superior Board of Control, under authority granted to it by the International Joint Commission, has set the Lake Superior outflow to 1,560 cubic meters per second (m3/s) (55.1 thousand cubic feet per second (tcfs)) for the month of April, effective April 3, 2012.
This is an increase from the March outflow, which was 1,500 m3/s (53.0 tcfs).
This outflow is as prescribed by Plan 1977-A.
The April outflow will be released by discharging about 1,456 m3/s (51.4 tcfs) through the three hydropower plants and passing most of the remaining flow through the control structure at the head of the St. Marys rapids.
The gate setting of the control structure will be maintained at the existing setting equivalent to one-half gate open (four gates open 20 centimeters (cm), or about eight inches each).
There will be no change to the setting of Gate No. 1 that supplies the Fishery Remedial Works.
This past month the water supplies to the lakes Superior and Michigan-Huron basins were above normal.
Lake Superior is currently 22 cm (nine inches) below chart datum level.
The level of Lake Superior is expected to rise in April.
Currently, the Lake Superior level is about 25 cm (10 inches) below its long-term average beginning-of-April level, and is 12 cm (five inches) higher than the level recorded a year ago.
This past month the level of Lake Superior rose six cm (two inches), while on average it falls one cm (zero inches) in March.
The level of Lakes Michigan-Huron rose 10 cm (four inches) this March, while on average it rises four cm (two inches) in March.
The level of Lakes Michigan-Huron is now about 28 cm (11 inches) below its long-term average beginning-of-April level, and is 20 cm (eight inches) higher than it was a year ago.
Currently, Lakes Michigan-Huron is four cm (two inches) above its chart datum level.
The level of Lakes Michigan-Huron is expected to rise in April.
The board continues to monitor conditions both on Lake Superior and downstream and will advise the International Joint Commission accordingly on those conditions.
BG Margaret Burcham is the United States board member.