[2] Along with neighboring watersheds, the Hoquiam River flows through one of the most biomass-productive zones in the world and an important forestry region.

It flows generally south to Hoquiam, where it empties into Grays Harbor, an estuary of the Pacific Ocean.

The East, West, and Middle Forks all originate north of Grays Harbor and flow generally south.

[10][11] The Hoquiam River and its tributaries support runs of Chinook, chum and coho salmon, steelhead, and sea-run coastal cutthroat trout.

Barriers such as culverts have been removed or replaced in recent years, allowing fish to migrate upstream farther and more easily.