Lake Superior and Lake Michigan-Huron above chart datum 

#LSN_Shipping   high water levels in the upper Great Lakes

THUNDER BAY, ONATAIO  -  February 3, 2018  (LSN)  More seasonable conditions returned to the Lake Superior and Lake Michigan-Huron basins in January. Nonetheless, both lakes continue to see the effects of a wet spring and summer, and water levels of Lake Superior and Lake Michigan-Huron remain well above average as a result.

The monthly mean level of Lake Superior in January was 183.65 m (602.53 ft), the 2nd highest on record (1918 - present) and the highest since January 1986. Lake Michigan-Huron’s mean January level was 176.73 m (579.82 ft), the 15th highest on record and the highest since 1998. The high levels coupled with strong winds and waves have resulted in shoreline erosion and coastal damages across the upper Great Lakes system. Lake ice may provide a level of protection to some areas of the shoreline, but additional shoreline erosion and coastal damages may occur this winter should active weather continue.

In consideration of the continuing high water levels in the upper Great Lakes, the International Lake Superior Board of Control, under authority granted to it by the International Joint Commission (IJC), will continue to release outflows of up to 2,510 cubic meters per second (cms) (88,640 cubic feet per second (cfs)) through the winter months. This flow is 100 cms (3,530 cfs) more than the normal winter maximum prescribed by Regulation Plan 2012. Actual outflows may vary depending on hydrologic and ice conditions, as well as maintenance activities at the hydropower plants on the St. Marys River, all of which have been directed to flow at their maximum available capacity.

The gate setting of the control structure will be maintained at the current setting (eight gates open 26 cm each, which is equivalent to approximately one gate fully open) during the month of February. This setting is expected to continue
throughout the winter, as is typically the case when gates become frozen in ice. Likewise, there will be no change to the setting of Gate #1, which supplies a flow of about 15 cms (530 cfs) to the channel north of the Fishery Remedial Dike.

The net water supplies to Lake Superior were below average in January. The level of Lake Superior fell 9 cm (4 in) last month, while on average the lake declines 7 cm (3 in) in January. The Lake Superior level at the beginning-of- February is 32 cm (13 in) above average, 17 cm (7 in) above the level recorded a year ago at this time, and the 2nd
highest on record. The level of Lake Superior is expected to continue its seasonal decline in February.

The net water supplies to Lake Michigan-Huron were below average in January. The level of Lake Michigan-Huron remained stable last month, while on average the lake declines 2 cm (0.8 in) in January. The level of Lake Michigan-Huron is 46 cm (18 in) above its long-term average beginning-of-February level, 26 cm (10 in) higher than it was a year ago and the 125th highest on record. The level of Lake Michigan-Huron is expected to continue its seasonal
decline in February.