Tumwater Creek is a relatively small independent drainage to salt water, entering salt water near the western end of Port Angeles harbor. It has been heavily impacted by development throughout the watershed. Urban and rural developments have had substantial impact in Tumwater Creek. The lower one-quarter mile is culverted under waterfront industrial and city street properties, and the following half-mile is confined and channelized between a high valley wall and the Tumwater Truck Route. The upper watershed has experienced extensive rural conversion, with associated animal and stormwater effects. As noted by Haring (1999), of particular concern is the very large, active slide area, initially caused by altered stormwater drainage. Fine sediment generated from this massive stormwater-related gully headcutting to the west of Black Diamond Road (just north of Alice Road) is a continuing source of excessive sediment input into Tumwater Creek. At this location, stormwater from Black Diamond, Alice, and Hoar roads has been routed into a small draw that historically had a very small drainage area. In addition, these road cuts have intercepted very large volumes of groundwater that can be seen percolating into ditch lines. With these additional flows, the gully walls have collapsed due to increased undercutting by the consolidated stormwater runoff. Steady headcutting continues towards Black Diamond Road, delivering large amounts of sediment to Tumwater Creek.