Future Nitrogen Loading to the Salish Sea: Population Growth, Land Use Change, and Climate Change
Presentation Abstract
Estimates of future nitrogen loading to the Salish Sea from watershed inflows and marine point sources were developed for 2020, 2040 and 2070. This is the first compilation of future nitrogen loads to the Salish Sea, taking into account population growth, land use change, and climate change. Future nitrogen loading estimates were used as forcings for a three-dimensional circulation and dissolved oxygen model developed by Pacific Northwest National Laboratories and the Washington State Department of Ecology. Future nitrogen loads from watershed inflows are estimated to increase due to a general shift in land use across the region in the form of decreasing forested and agricultural land and increasing developed land. Future watershed nitrogen loads will also be influenced by changes in streamflows due to the effects of climate change on regional hydrology. These changes include increases in peak streamflow and decreases in summer baseflow for some rivers, resulting in changes in the magnitude and timing of nitrogen delivery to the Salish Sea. Future nitrogen loads from marine point sources, primarily wastewater treatment plants, are expected to double by 2070 due to regional population growth. The adoption of biological nutrient removal treatment technologies has the potential to more than offset this increase in loading by reducing effluent nitrogen concentrations. Limited long-term historic data suggests declining oxygen and increasing nitrogen levels in the Pacific Ocean near the open boundary. Since future estimates of Pacific Ocean conditions do not exist, we extrapolated these historic trends into the future to estimate future conditions at the open boundary, but this estimate remains highly uncertain. When applied to model scenarios, these future loading estimates allowed us to evaluate the relative effects of future human nutrient loads, climate influences, and Pacific Ocean conditions on the occurrence of low dissolved oxygen levels throughout the Salish Sea.
Session Title
Session S-02A: Future Salish Sea Water Quality
Conference Track
Marine Water Quality
Conference Name
Salish Sea Ecosystem Conference (2014 : Seattle, Wash.)
Document Type
Event
Start Date
30-4-2014 1:30 PM
End Date
30-4-2014 3:00 PM
Location
Room 615-616-617
Genre/Form
conference proceedings; presentations (communicative events)
Contributing Repository
Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.
Subjects – Topical (LCSH)
Water--Nitrogen content--Salish Sea (B.C. and Wash.); Nutrient pollution of water--Salish Sea (B.C. and Wash.); Watershed management--Salish Sea (B.C. and Wash.)
Geographic Coverage
Salish Sea (B.C. and Wash.)
Rights
This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.
Type
Text
Language
English
Format
application/pdf
Future Nitrogen Loading to the Salish Sea: Population Growth, Land Use Change, and Climate Change
Room 615-616-617
Estimates of future nitrogen loading to the Salish Sea from watershed inflows and marine point sources were developed for 2020, 2040 and 2070. This is the first compilation of future nitrogen loads to the Salish Sea, taking into account population growth, land use change, and climate change. Future nitrogen loading estimates were used as forcings for a three-dimensional circulation and dissolved oxygen model developed by Pacific Northwest National Laboratories and the Washington State Department of Ecology. Future nitrogen loads from watershed inflows are estimated to increase due to a general shift in land use across the region in the form of decreasing forested and agricultural land and increasing developed land. Future watershed nitrogen loads will also be influenced by changes in streamflows due to the effects of climate change on regional hydrology. These changes include increases in peak streamflow and decreases in summer baseflow for some rivers, resulting in changes in the magnitude and timing of nitrogen delivery to the Salish Sea. Future nitrogen loads from marine point sources, primarily wastewater treatment plants, are expected to double by 2070 due to regional population growth. The adoption of biological nutrient removal treatment technologies has the potential to more than offset this increase in loading by reducing effluent nitrogen concentrations. Limited long-term historic data suggests declining oxygen and increasing nitrogen levels in the Pacific Ocean near the open boundary. Since future estimates of Pacific Ocean conditions do not exist, we extrapolated these historic trends into the future to estimate future conditions at the open boundary, but this estimate remains highly uncertain. When applied to model scenarios, these future loading estimates allowed us to evaluate the relative effects of future human nutrient loads, climate influences, and Pacific Ocean conditions on the occurrence of low dissolved oxygen levels throughout the Salish Sea.
