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Rock River (Sturgeon River) Wikipedia
The Rock River is a 6.1-mile-long (9.8 km) stream in Baraga County on the Upper Peninsula of Michigan in the United States. It rises at the outlet of Worm Lake, east of Covington, and flows northwest to the Sturgeon River, which continues west, then north to Portage Lake and Lake Superior. The Rock River descends 350 feet (110 m) over its 6-mile (10 km) course, for an average rate of 58 feet per mile.