Bacteria, total organic carbon (TOC), organic matter that may contribute to sediment oxygen demand (SOD), total phosphorus (TP) and solar radiation inputs are the main pollution concerns for the North Fork Coquille River. These parameters are being addressed within the Coquille River Subbasin through the bacteria, dissolved oxygen and temperature TMDLs for the North Fork Coquille River from the confluence with the South Fork Coquille River up to river mile 52.3.
Primary areas of concern
Temperature: Applies to eight subwatersheds that includes the North and East Fork Coquille River mainstems and sections of Woodward, Moon, Alder, Elk and Middle Creek tributaries. The Temperature TMDL is being developed in a manner consistent with addressing known anthropogenic, background, and unidentified heat load sources, applying surrogate measures (site potential shade) and implicit margin of safety within the modeling.
Bacteria: Applies to the North Fork Coquille River subwatershed, river mile 0 to 19 that has a higher proportion of rural urban and agricultural land uses. The North Fork Coquille experiences higher bacteria concentrations than any of the other major tributaries of the Coquille River Subbasin, and so the highest peak flow nonpoint source load reductions are needed to meet shellfish harvesting criteria in the lower Coquille River.
Dissolved oxygen: Applies to two reaches within the North Fork Coquille River subwatershed, river mile 0 to 27.9. The dissolved oxygen TMDL addresses the pollutants of total organic carbon, organic matter that may contribute to sediment oxygen demand, total phosphorus and solar radiation inputs which limits the oxygen carry capacity of waterbodies. Based on regression modeling, if temperature is reduced 3oC, the mean of the measured DO concentrations will increase 0.6-0.7 mg/L and no more than 10% of individual measurements will be less than 8.0 mg/L.
Total number of North Fork Coquille River miles listed for temperature impairments: 123.8 miles; 8 Temperature TMDLs
Total number of North Fork Coquille River miles listed for bacteria Impairments: 38 miles; 2 Bacteria TMDLs
Total number of North Fork Coquille River miles listed for dissolved oxygen Impairments: 27.9 miles; 2 dissolved oxygen TMDLs