Disappearance of the Black River after the Lake Washington Ship Canal

Before construction of the Lake Washington Ship Canal and the Hiram M. Chittenden (Ballard) Locks, Lake Washington drained south via the Black River into the Duwamish River. Completion of the canal and locks lowered Lake Washington and caused the Black River to cease flowing, permanently eliminating that historical outlet. The loss of the Black River altered local hydrology and wetland areas south of Seattle and is documented in engineering and historical records from the canal project. The change is directly tied to the canal and locks built at the Ballard Locks site.