Grass Lake Nature Park is a part of Olympia’s park and public access, open space inventory. This park contains the headwaters of Green Cove Creek and one of the most environmentally intact wetland systems in northern Thurston County. Over 100 bird species and 200 plant species have been recorded in the park. Grass Lake Nature Park’s primary functions are wildlife protection, wildlife viewing, and environmental education. Amenities include a 1.3-mile (2.1 km) hiking trail.