Port Clinton is a city in and the county seat of Ottawa County, Ohio, United States, located at the mouth of the Portage River on Lake Erie. The p…Port Clinton is a city in and the county seat of Ottawa County, Ohio, United States, located at the mouth of the Portage River on Lake Erie. The population was 6,025 at the 2020 census. It is the principal city of the Port Clinton micropolitan area, about 34 miles southeast of Toledo.