South Puget Sound Model Nutrient Study
Entry ID:
wa_de_spasm
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Summary
Abstract:
Ecology's Southwest Regional Office (SWRO) is concerned about nonpoint and point source nutrient loading to the southern portion of Puget Sound (located south of The Narrows near Tacoma). Their major concern is that the past and future growth around this region may cause adverse effects on water quality due to increased eutrophication. The ... SWRO requested that the Environmental Investigations and Laboratory Services (EILS) Program evaluate the ability of the South Sound to assimilate nutrients, and if needed, recommend point source waste load allocations (WLAs) and nonpoint source load allocations (LAs) for controlling nutrients. Excessive nutrient inputs can accelerate the eutrophication process and affect water quality in the following ways: 1) increase the growth of algae and cause shifts in community structure, leading to the predominance of undesirable forms (e.g., toxic phytoplankton blooms); 2) alter the balance between phytoplankton, zooplankton, fish and shellfish that may result in an unusually high accumulation rate of organic matter on bottom sediments, which may depress bottom oxygen concentrations; 3) change the aerobic bacteria populations to anaerobic sulfate-reducing bacteria, that can poison the water column with hydrogen sulfide, which may lead to further community structure changes; and 4) affect recreational activities due to objectionable odors, and unsightly algal mats. The capacity of South Sound to assimilate pollutants from its drainage basins is presently not well understood. The major goal of this project is to develop a computer model that can be used to simulate hydrodynamics and water quality, characterize and evaluate pollutant loading, and identify specific point and nonpoint sources of pollutants to South Sound. If needed, another goal of the project will be to establish a total maximum daily load (TMDL) for waterbodies not meeting standards. The TMDL will be used to regulate pollutant loads and establish appropriate point source wasteload allocations (WLAs), and nonpoint source load allocations (LAs). Technical Approach Section 303(d) of the Clean Water Act, requires states to develop TMDLs for their waterbodies that are not meeting their designated uses under technology-based pollutant controls. However, Ecology has not adopted nutrient criteria or recommended procedures for protecting waterbodies from excessive nutrient loading. Since no site-specific or numeric nutrient criteria exist for the Puget Sound, criteria must be developed to protect the designated uses and water quality standards. For the South Sound, EILS is proposing to develop site-specific nutrient criteria based on linking measured nutrient concentrations (or loads) and an endpoint indicator--i.e., dissolved oxygen concentrations. The marine water quality standards for dissolved oxygen vary according to the classification of a waterbody. The waterbody Classes AA, A, and B are required to have dissolved oxygen concentrations which exceed 7.0, 6.0, and 5.0 mg/L, respectively, to meet state standards. In addition, the following applies to all of the Classes: "When natural conditions, such as upwelling, occur, causing the dissolved oxygen to be depressed near or below the criterion, natural dissolved oxygen levels may be degraded by up to 0.2 mg/L by human-caused activities." This last condition is likely to be the endpoint indicator to link changes in nutrient concentrations (loading) to water quality violations which may occur in South Sound. The reason the South Sound is considered a good candidate for linking the effects of nutrients to dissolved oxygen concentrations and the allowable 0.2 mg/L degradation is because many of the bays and inlets in the region have periods (primarily in late summer) when oxygen concentrations drop below the criteria. The natural dissolved oxygen concentrations in many of the South Sound waters are sometimes lower than the criteria because upwelled Pacific Ocean water flowing into the Puget Sound can have naturally low dissolved oxygen. Newton et al., (1997) assessed dissolved oxygen concentrations in Puget Sound and suggested that bottom dissolved oxygen concentrations can be exacerbated in areas that have strong density stratification (e.g., in areas with freshwater input), high production due to inhibited mixing, and oxidation of sunken organic material (i.e., dead phytoplankton.). Eutrophication will likely have the greatest impact in South Sound areas where flushing is low, where strong density stratification occurs, and where phytoplankton growth may be nutrient limited, such as in bays and inlets. The following factors control nutrient enrichment, eutrophication, and oxygen depletion: (1) nutrient loading rates from atmospheric deposition, tributary inflows, point source discharges, nonpoint source inputs (shorelands), and sediment-water exchange; (2) hydrodynamic characteristics such as tides, stratification, mixing, and freshwater inflow; and (3) photosynthetic characteristics and processes such as light availability (season, depth), temperature, growth, death, respiration, settling, and other phytoplankton kinetics. In order to determine the nutrient concentration that can be assimilated into the South Sound without causing violations of the endpoint target, EILS is proposing to model the waterbody. Model predictions will be used to establish the nutrient criteria by simulating estimated critical conditions and nutrient loading based on past, present, and future water quality scenarios. The central issues in calibrating the hydrodynamic or circulation model of the South Sound will be simulating the tides, currents, and salinity gradients. The pattern and motion of water in the South Sound influences the distribution of dissolved oxygen. For example, stratification established by light, fresh water inputs, and salty Pacific Ocean water inflows may limit the vertical exchange of dissolved oxygen and increase oxygen depletion in the bottom waters. Although much more complicated, the circulation may also affect algal productivity and the ultimate deposition and decomposition of the organic mater produced from algal blooms. The central issues in calibrating the water quality model will be simulating the primary production by algae, decomposition of oxygen containing material, and the concentration of dissolved oxygen. Understanding the planktonic organisms, the effects of nutrient enrichment, and the rates and pathways of organic matter production and decomposition will determine the precision and accuracy of the model to predict dissolved oxygen concentrations. In order to predict circulation and water quality with the EFDC model the suite of variables listed below will have to be determined by using a combination of historical and newly collected data. Circulation/Transport Stage (tide gauge data) Current (velocity and direction) Salinity Suspended Solids Tributary freshwater inflows Precipitation Wind (speed and direction) Atmospheric pressure/relative humidity/cloud cover Temperature (water and air) Eutrophication/Dissolved Oxygen Salinity Suspended solids Dissolved oxygen Nitrate-nitrite-N Total kjeldahl-N Total phosphorus Primary Production Metals (iron, manganese) Silica Zooplankton Temperature Biochemical Oxygen Demand (CBOD/NBOD) Total and dissolved organic carbon Ammonium-N Ortho-phosphate Solar Radiation Light Extinction Algal Composition/Biomass (diatoms, dinoflagellates, cyanobacteria, greens) Chlorophyll a/phaeopigments Tributary Loads (nutrients, BOD) Sediment Sedimentation Rate (lead 210/sediment cores) Sediment Oxygen Demand Resuspension Rates (percent solids, silica) Particulate Flux (nutrient transport and cycling, pigment transport and distribution) Information was obtained from http://www.ecy.wa.gov/ecyhome.html.
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Description:
Metadata in Biological Data Profile format.
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Geographic Coverage
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Spatial coordinates
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N: 49.39
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S: 45.15
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E: -116.53
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W: -125.15
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Data Set Citation
Dataset Originator/Creator:
Washington State Department of Ecology
Dataset Title:
South Puget Sound Model Nutrient Study
Dataset Release Place:
Olympia, Washington
Dataset Publisher:
Washington State Department of Ecology
Online Resource:
http://www.ecy.wa.gov/ecyhome.html
Quality
In order to improve the usefulness of the South Puget Sound Nutrient Study results and focus the planning process, a Quality Assurance Project Plan (QAPP) will be completed in FY99 (see Project Schedule). EILS guidelines and specifications for preparing a QAPP will be followed (Ecology, 1991). At a ... minimum, the QAPP will contain a review of the following elements: 1. Project description 2. Project objectives and goals 3. Study design 4. Data analysis and modeling 5. Project schedule and laboratory budget 6. Project organization 7. Data quality objectives and analytical procedures 8. Sampling procedures The QAPP will discuss the data needed to calibrate and confirm the EFDC model, and establish nutrient loading to the modeled area. The QAPP will also discuss in more detail how the model will be used to determine the potential to violate water quality criteria, and recommend waste load allocations (WLAs) for point sources and load allocations (LAs) for nonpoint sources of nutrients. However, developing a rough calibrated EFDC model (using historical data) of the South Sound will be pursued in parallel with preparing the QAPP. An important part of defining the data quality objectives for this project will be to identify what decisions and actions might be taken based on the proposed study. Ecology's regional office watershed managers (see Project Organization) will need to develop decision statements for addressing the results of the study. The decision statements should address what decisions and actions Ecology will make if specific parts of South Sound are estimated to have increased algal growth and reduced dissolved oxygen concentrations because of human caused contributions of nutrients. EPA (1997) has identified the following specific activities for developing decision statements: Define the alternative actions that could result from resolution of the principal study question. Combine the principal study question and the alternative actions into a decision statement. If applicable, organize multiple decisions to be made by priority. 
Access Constraints
None
Use Constraints
None
Data Set Progress
IN WORK
Data Center
Department of Ecology, Washington State
Data Center URL:
http://www.ecy.wa.gov/
| Data Center Personnel |
Name:
GREGORY
PELLETIER
Phone:
360.407.6485
Fax:
360.407.6884
Email:
gpel461 at ecy.wa.gov
Contact Address:
Washington State Department of Ecology
Environmental Investigations and Laboratory Services Program
Watershed Assessments Section
Post Office Box 47600
City:
Olympia
Province or State:
Washington
Postal Code:
98504-7600
Country:
USA
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Personnel
Role:
TECHNICAL CONTACT
Phone:
(360) 407-6000
Email:
bcus461 at ecy.wa.gov
Contact Address:
Washington State Department of Ecology
Environmental Investigations and Laboratory Services Program
P.O. Box 47710
City:
Olympia
Province or State:
WA
Postal Code:
98504-7710
Country:
USA
Role:
DIF AUTHOR
Phone:
(301) 614-6898
Fax:
301-614-5268
Email:
Tyler.B.Stevens at nasa.gov
Contact Address:
NASA Goddard Space Flight Center
Global Change Master Directory
City:
Greenbelt
Province or State:
MD
Postal Code:
20771
Country:
USA
Extended Metadata Properties
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Creation and Review Dates
DIF Creation Date:
2002-07-30
Last DIF Revision Date:
2012-12-12
Future DIF Review Date:
2003-07-30
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