It drains a mountainous timber-producing area of the Northern Oregon Coast Range west of Portland into Tillamook Bay and the Pacific Ocean.

Over the next 4 miles (6.4 km) Burton, Blue Ridge, Hatchery, Trowbridge, Little Rock, and Panther creeks all enter from the right.

About 1 mile (1.6 km) later, the stream passes under U.S. Route 101 and flows around the southwestern edge of Tillamook.

Based on data collected from April 1996 through 2008, the average flow at this gauge is 985 cubic feet per second (27.9 m3/s).

This is from a drainage area of 156 square miles (404 km2), about 89 percent of the total Trask River watershed.