Lake Superior rose 9 inches in May, the second highest increase since 1918.
The boost was "a result of snowmelt and above-average precipitation received in the Superior basin during the past month," reports the International Lake Superior Board of Control.
Lake Superior rose to 2 cm (1 inch) above its chart datum level last month. The level of Lake Superior is expected to rise during June. Currently, the Lake Superior level is about 18 cm (7 inches) below its long-term average beginning-of-June level, and is 8 cm (3 inches) above the level recorded a year ago. This past month the level of Lake Superior rose an estimated 24 cm (9 inches), while on average it rises 9 cm (4 inches) in May.