The Miami River Watershed

The Miami River watershed drains approximately 36.7 sq. miles (23,390 acres) of land and is the smallest watershed of the Tillamook Bay drainage. It is located near the town of Garibaldi. Mean Annual Precipitation is 122 inches. Elevations in the watershed range from sea level at the mouth to 2,780 ft in the headwaters. Vegetation in the watershed has changed greatly since pre-settlement. Historically, vegetation included a large amount of late-successional forest, with priairies, swamps, marshes and tidally-influenced forest in the lowlands. Uplands were mostly a mis of western hemlock, western red cedar, douglas fir, grand fir, noble fir and sitka spruce. Since then land has been cleared and harvested, wetlands drained and pastures created. A series of fires since the 1930's burned much of the remaining forest. The majority of the forested uplands have been replanted with douglas fir for timber production. The forest is currently dominated by closed canopy, even-aged conifer and hardwood stands between 25 and 47 years old. The lowlands are mostly used for pasture with rurual residential and urban areas. Riparian conditions almost uniformly demonstrate undesirable conditions, with all stream reaches surveyed lacking sufficient densities of conifers in the riparian zones Riparian conditions vary with land use. The tidal mainstem is in poor condition, laking riparian habitat with dominant vegetation consisting of blackberries and non-native grasses. Riparian areas which do exist are scattered and narrow and contain a mixture of brush and young hardwoods. Forested areas contain continuous riparian vegetation consisting of dense mature and young hardwoods. The upper watershed areas contain a varied mixture of mature conifer and hardwood stands and young dense hardwood stands. Stream shade is a limiting factor in some reaches, especially throughout the lower and middle mainstem reaches, with resulting summer mainstem temperatures often exceeding standards. Wetlands are an important landscape feature in the Miami River watershed, mainly in the lower watershed. The predominant wetland types are palustrine wetlands and a few tidal salt marshes. Unlike the rest of the Tillamook Bay rivers, the construction of dikes and levees has not been common in the Miami River watershed. Some palustrine wetlands in the Miami river watershed have been disconnected from the stream by ditching and flood protection efforts.