Does the plan keep Superior between 182.76 and 183.86 m?
- This is the first of nine Study Board decision criteria used in the evaluation of Lake Superior regulation plans. The IJC’s current Orders of Approval specifies these levels as desirable maximum and minimum levels for Lake Superior. These levels are close to historical records, and similar to the levels reached by Plan 1977A when simulated with the historical net basin supplies (NBS). The current Orders establish an absolute requirement to stay within the levels when tested with historical NBS adjusted for diversions (at least to 1979) and Lake Superior water levels must not exceed 183.86 m (603.2 ft) more often than under the 1955 Modification of the Rule of 1949 plan. The Orders include the statement “with the supplies of the past as adjusted and in such a manner as to not interfere with navigation”. For a plan to “pass” this criteria, it means that for the selected plan and NBS, this criterion was fully met; in other words, the maximum Lake Superior level was less than or equal to 183.86 m (603.2 ft) and the minimum was 182.76 m (599.6 ft) or more.