Carolina-Terwilliger Subwatershed Facts
The Carolina-Terwilliger subwatershed covers about 854 acres of southwest Portland.
- About 500 feet of natural riverbank remain on the Willamette River in this subwatershed.
- Cottonwood Bay is used as stop-over habitat for osprey, hawks, herons, and other birds.
- The subwatershed has 28,770 (5.4 miles) feet of open stream channels.
- Parks and open space make up 234 acres of the subwatershed; 190 acres of land are in public ownership.
- The central portion is extremely steep and has not been developed.
- 420 acres of the subwatershed are forested.
31 acres of the subwatershed have woodland type tree canopy.
- Three streams that originate in Marquam Nature Park and Terwilliger Wildlands flow to a combined sanitary and stormwater pipe near Barbur Boulevard.
- About half of this subwatershed is impervious area, mostly streets.
- The forested areas and streams of the subwatershed provide an important link between the West Hills and the Ross Island-Oaks Bottom ecosystem complex to the east, and between Marquam Nature Park to the north and Tryon Creek State Natural Area to the south.