The Municipality of Trent Hills is a township municipality in Northumberland County in Central Ontario, Canada. It is on the Tren…The Municipality of Trent Hills is a township municipality in Northumberland County in Central Ontario, Canada. It is on the Trent River and was created in 2001 through the amalgamation of the municipalities of Campbellford/Seymour, Percy Township, and Hastings Village. Thereafter it was known briefly as Campbellford/Seymour, Percy, Hastings.