The Meramec River (local pronunciation: /ˈmɛrɨmæk/) is one of the longest free-flowing waterways in Missouri, draining 3,980 square miles (10,300 km2) while wandering 218 miles (351 km) from headwaters near Salem to where it empties into the Mississippi River near St. Louis at Arnold and Oakville. The Meramec watershed coverssix Missouri Ozark Highland counties—Dent, Phelps, Crawford, Franklin, Jefferson, and St.