St. Johns River

The Ocklawaha River flows north and joins the St. Johns as the largest tributary, and one of significant historical importance. The Ocklawaha (also printed as Oklawaha) drainage basin expands through Orange, Lake, Marion, and Alachua Counties, comprising a total of 2,769 square miles (7,170 km). Ocala, Gainesville, and the northern suburbs of the Orlando metropolitan area are included in this basin. There are two headwaters for the Ocklawaha: a chain of lakes, the largest of which is Lake Apopka in Lake County, and the Green Swamp near Haines City in Polk County, drained by the Palatlakaha River. The Silver River, fed by one of Florida's most productive springs expelling 54,000,000 US gallons (200,000,000 L) daily, is located about midway along the 96-mile (154 km) Ocklawaha.

Question: is the st johns river the only river that flows north
Answer: no