Brentwood Lake is an unincorporated community in far eastern Carlisle Township, Lorain County, Ohio, United States. It lies at the intersection of State Routes 57 and 82 midway between Elyria and Grafton. Located at the center of the community was a small lake, compliments of an earthen dam from which a small stream flows to the East Branch Black River that runs just to the west of the community. The earthen dam was dismantled for safety reasons and today there is only a small stream without a lake. When there was a lake, Mr.