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| Title | Snohomish River Estuary Dry Season TMDL Study Phase I - Water Quality Model Calibration | |||
| Month-Year Published | July 1995 | |||
| Online Availability |
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| Short Description |
A psuedodynamic model of dissolved oxygen in the Snohomish River Estuary system from Possession Sound to river mile 20 was developed using the model WASP5 to simulate hydrodynamics and water quality. The model was calibrated using data collected in August and September 1993. The model predicted that natural conditions in a large portion of the estuary would be below dissolved oxygen standards under critical conditions. In addition, part of the lower mainstem is projected to display oxygen deficits in exceedance of the 0.2 mg/L allowed by the standards when natural conditions are below the standard. (Also see abstract below) | |||
| Publication Number | 95-338 | |||
| Author(s) | Cusimano, B. | |||
| Print Availability | ||||
| Number of pages | 56 pp. + app. (160 total) | |||
| Keywords | copper, dissolved oxygen, effluent, fecal coliform, model, pH, point source, river, Snohomish River, study, survey, TMDL, Total Maximum Daily Load, waste, wastewater treatment plant, water, Water Quality | |||
| Subject Waterbodies |
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| Abstract | Long Description |
A psuedodynamic model of dissolved oxygen in the Snohomish River Estuary system from Possession Sound to river mile 20 was developed using the model WASP5 to simulate hydrodynamics and water quality. The model was calibrated using data collected in August and September 1993. The model predicted that natural conditions in a large portion of the estuary would be below dissolved oxygen standards under critical conditions. In addition, part of the lower mainstem is projected to display oxygen deficits in exceedance of the 0.2 mg/L allowed by the standards when natural conditions are below the standard. Eighty-nine percent of this deficit is predicted to be caused by discharges from the two City of Everett wastewater treatment plants. Analysis of the Monroe and Sultan wastewater treatment plant effluents indicate they would have a minimal effect on dissolved oxygen in the Skykomish and Snohomish Rivers. Pending verification of the water quality model, a total maximum daily load (TMDL) will likely be needed to control the discharge of oxygen-depleting substances to the lower river and estuary. Survey and historical data show that the water quality of tributaries in the study area is poor due to high fecal coliform, high nutrients, and low dissolved oxygen concentrations. It is recommended that TMDLs be developed to address these problems. Class II inspection results suggest that point source loading of copper also may need to be controlled through the development of a TMDL. |
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