Walnut Creek is a 22.6-mile tributary of Lake Erie in Erie County, Pennsylvania in the United States. It has a drainage basin of 38.1 square miles and is part of the Lake Erie Watershed. Walnut Creek is a popular location for steelhead fishing and is stocked with steelhead. A marina near the mouth of the creek, maintained by the Pennsylvania Fish and Bo…Walnut Creek is a 22.6-mile tributary of Lake Erie in Erie County, Pennsylvania in the United States. It has a drainage basin of 38.1 square miles and is part of the Lake Erie Watershed. Walnut Creek is a popular location for steelhead fishing and is stocked with steelhead. A marina near the mouth of the creek, maintained by the Pennsylvania Fish and Boat Commission, offers access for fishers as well as boat access to Lake Erie.