Where is Grand Lake St. Marys?

The Grand Lake St. Marys watershed consists of nearly 13,500 acres of lake and approximately 57,000 acres of land which primarily drains to the Ohio River. The watershed spans portions of Auglaize (10%), and Mercer (90%) counties and can be considered as a tributary to both the Ohio River drainage Basin and the Lake Erie drainage Basin. Outflow from Grand Lake St. Marys’ west spillway drains to Beaver Creek and then to the Wabash River. The outflow from the east embankment sluice gate drains to the St. Marys River via the Miami & Erie canal system. This outflow has been estimated at or below 20% thus, the Grand Lake St. Marys watershed is administered as a portion of the Wabash River Hydrologic Unit Code (HUC) 05120101 at both federal and state levels.

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