Multiple waterbodies in the Mid-Coast Basin are identified as "impaired" through DEQ's Water Quality Assessment and 303(d) list for temperature, bacteria, sedimentation, dissolved oxygen and weeds/algae. Various parties are working on cooperative projects and taking positive actions to protect and improve water quality in the basin's rivers, tributaries and lakes.
The Mid-Coast Basin encompasses four subbasins: the Alsea, Siletz-Yaquina, Siltcoos and Siuslaw subbasins. This geographic area contains a wide variety of ecosystems and habitats, including high elevation Coast Range temperate forests, low elevation valleys, coastal wetlands, shallow lakes, estuaries and beaches.
Major land uses in the basin include private and federal forests, livestock grazing, rural residential development, with urban development concentrated along the Highway 101 corridor.
The rivers, lakes and estuaries of the Mid-Coast Basin are historically rich in native fish and other wildlife. In particular, salmonids including the Oregon Coast Coho are key fish species which are both culturally and economically important in Oregon's coastal basins. Certain salmonid populations are threatened or at risk due to a variety of factors documented elsewhere. Water quality in the Mid-Coast Basin is one factor that affects fish and other aquatic life.