Peterborough, Ont, City, population of 71 446 (2001c), 69 742 A (1996c), 68 379 (1991cA), 61 049 (1986c), area 58.61 km2, is situated on the Otonabee River, about 40 km north of Lake Ontario and 110 km northeast of Toronto. The seat of Peterborough County, it is the largest city on the TRENT-SEVERN WATERWAY and the regional centre for the KAWARTHA LAKES cottage country.