- The Brightwater Treatment Plant, which treats waste and storm waters for King County, opened in 2011. To ensure that the treatment plant would be an asset to its host community, the campus was designed to include an Environmental Education and Community Center and a 70-acre public open space with walking trails and natural wetland habitat. The Brightwater Center’s three miles of trails yield a fascinating, family-friendly hiking experience through wetlands and woodlands that serve as a protected enclave for native wildlife and plant species.