Total Maximum Daily Loads

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.

Local Stakeholder Advisory Committee

See the Local Stakeholder Advisory Committee web page for the meeting schedule and committee documents.

Basin description

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.


Implementation-ready TMDLs

DEQ committed to using a novel approach referred to as “implementation-ready TMDLs” for the Mid-Coast Basin that will identify detailed actions needed to meet TMDL goals and Oregon's water quality standards.



DEQ began working on the Mid-Coast TMDLs in 2005 but did not complete the project as scheduled. Since then, new information and legal developments affected the scope and schedule of the effort. In 2009, Northwest Environmental Advocates challenged EPA's and NOAA's conditional approval of Oregon's Coastal Nonpoint Pollution Control Plan under the Federal Coastal Zone Act Reauthorization Amendments.

As part of the settlement agreement between the litigants, DEQ made commitments to address outstanding management measures through issuance of implementation-ready TMDLs for the coastal zone management area, beginning with the Mid-Coast Basin. DEQ intends to issue the Mid-Coast TMDLs by June 2013, but has notified the federal agencies, state agency partners and Advisory Committee that date will not be met. The relationship between the CZARA requirements and Mid-Coast TMDLs is being re-assessed by DEQ, EPA and NOAA, and new project schedules are being developed and will be shared once they are ready. The public will have an opportunity to comment on the draft TMDLs in before they become effective.

Key documents and correspondence (not comprehensive list):



Mid-Coast Basin Coordinator
David Waltz 541-687-7345

Basin Coordinator List​