Plan 2012 helps Lake Superior during extreme dry conditions
- Although Lake Superior Regulation Plan 2012 will not change water levels much when net basin supplies (NBS) are similar to the historical NBS, it will preserve levels on Lake Superior if an NBS sequence becomes significantly drier, as is possible under climate change. For example, for one of the most extreme NBS sequences used to formulate and evaluate regulation plans, the extended dry trend sequence (which represents extremely severe conditions, i.e., a 25-year drought), the simulated outflows of Plan 1977A fails in the 91st year of the simulation, with simulated Lake Superior levels at 181.74 m (596.25 ft), a metre (3.28 ft) below the historical minimum, and below the natural sill level. That is, discharges from Lake Superior cease. At the same time, Lake Superior Regulation Plan 2012 produces a level of 182.00 m (597.1 ft), and continues outflows from Lake Superior – a significant improvement.