The Kilchis watershed is characterized by steep forested uplands and flat alluvial lowlands. The dominant land ownership in the Miami River watershed is state and private industrial forest, accounting for 60% and 33% of the total area respectively. Much of the higher elevations have been harvested for timber or were burned as a part of the Tillamook Burns and are now second growth forests. The lower Miami River drains agricultural and rural residential areas and enters Tillamook Bay adjacent to the City of Garibaldi.

The human population of the watershed is concentrated around the city of Tillamook and the town of Bay City, within the Lower Kilchis River. Remaining population presence consists of scattered farm residences and sparse settlement of lower and middle reaches of the mainstem. Most of the watershed is utilized for forest use (92%), with agricultural us as the next largest at 5.8%. The remaining 0.3% is a combination of rural residential and miscellaneous uses.