Proposed Abstract Title

Instream Attenuation of Nitrogen and Phosphorus in the Puget Sound Basin

Presenter/Author Information

Richard Sheibley, U.S. Geological SurveyFollow

Type of Presentation

Poster

Session Title

General Pollution Topics

Location

2016SSEC

Description

Delivery of nutrients from major rivers in the Puget Sound basin to the marine environment can be large. Therefore, it is important to understand how nutrients are retained, or attenuated, within streams and rivers in the Puget Sound basin. Using a review of the scientific literature and multiple empirical modeling approaches for estimating nutrient attenuation in streams and rivers we estimated potential instream nutrient attenuation for the major river basins in Puget Sound. Instream nutrient attenuation was explained in terms of four primary factors: sinuosity, channel slope, specific discharge, and uptake velocity (vf) of the reach. A scoring procedure based on these factors showed that reaches where attenuation scores were high, we saw higher relative attenuation of nutrients. From a management perspective, preservation and improvement of instream nutrient attenuation should focus on two goals, (1) increasing the travel time through a reach and contact time of water sediment (reactive) surfaces and (2) lowering nutrient concentrations (and loads) to avoid saturation of instream attenuation. These goals can be reached by (1) maintaining and restoring channel-floodplain connectivity, (2) maintaining and restoring healthy riparian zones along streams, (3) managing point and nonpoint nutrient loads to streams and rivers, and (4) restoration of channel features such as woody debris and maintaining pool-riffle morphologies. Fortunately, many of these management approaches are already being undertaken during projects aimed to restore quality salmon habitat. Therefore we believe there is a dual benefit to these projects that may also lead to enhanced potential for nitrogen and phosphorus attenuation.

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Instream Attenuation of Nitrogen and Phosphorus in the Puget Sound Basin

2016SSEC

Delivery of nutrients from major rivers in the Puget Sound basin to the marine environment can be large. Therefore, it is important to understand how nutrients are retained, or attenuated, within streams and rivers in the Puget Sound basin. Using a review of the scientific literature and multiple empirical modeling approaches for estimating nutrient attenuation in streams and rivers we estimated potential instream nutrient attenuation for the major river basins in Puget Sound. Instream nutrient attenuation was explained in terms of four primary factors: sinuosity, channel slope, specific discharge, and uptake velocity (vf) of the reach. A scoring procedure based on these factors showed that reaches where attenuation scores were high, we saw higher relative attenuation of nutrients. From a management perspective, preservation and improvement of instream nutrient attenuation should focus on two goals, (1) increasing the travel time through a reach and contact time of water sediment (reactive) surfaces and (2) lowering nutrient concentrations (and loads) to avoid saturation of instream attenuation. These goals can be reached by (1) maintaining and restoring channel-floodplain connectivity, (2) maintaining and restoring healthy riparian zones along streams, (3) managing point and nonpoint nutrient loads to streams and rivers, and (4) restoration of channel features such as woody debris and maintaining pool-riffle morphologies. Fortunately, many of these management approaches are already being undertaken during projects aimed to restore quality salmon habitat. Therefore we believe there is a dual benefit to these projects that may also lead to enhanced potential for nitrogen and phosphorus attenuation.