WLRD Science Seminar Sammamish River Water Quality Model Status Report November 19, 2002

Sammamish-Washington Analysis and Modeling Program

Sammamish River Model

Sammamish River Basins

CE-QUAL-W2 Model 2-D model Laterally averaged No zooplankton, macrophytes, sediment diagenesis Epiphyton and riparian shade model added recently

Background Initially developed by Seattle Corps Corps contractor updated model Corps transferred model to King County

Model State Variables Indicator Bacteria Inorganic Suspended Solids Nutrients (N,P,Si) Labile and Refractory Organic Matter Dissolved Oxygen Algae Alkalinity/Inorganic Carbon

Model Derived Variables Total, Particulate, and Dissolved Org. C Analytical nutrient forms (e.g., TP, TKN) Total Suspended Solids Chlorophyll a Dissolved Oxygen Saturation pH

Hydrodynamic Output Temperature Horizontal and Vertical Velocity Density

Model Calibration Steps Water Balance/Hydraulics Temperature Water Quality Conservative constituents Nutrients DO/pH Light penetration Phytoplankton Start

Model Data Needs Bathymetry Meteorology Gaged tributary quantity and quality Ungaged inflow quantity and quality Calibration data (quantity/quality)

Data Sources Bathymetry (HEC model cross sections) Meteorology (Sea-Tac, UW, Sand Point NOAA) Hydrology and stream temperature (WLRD, USGS, Snohomish Co., USACOE) Water quality data (WLRD, Ecology) Water surface elevations (USACOE, Reuse study)

Sammamish River X-Sections

Meteorological Data Sources

Stream Gaging Locations

Lake Washington Water Surface Elevation Kenmore

ACOE 1999 Temperature Study Stations

King County Temperature Stations

Forward-Looking Infrared Study - September 2, March 23, 2000

Forward-Looking Infrared Study September 2, 1999

Model Setup

Model Grid

Model Calibration

Sammamish River Recon August 30, 2001

Ongoing Temperature Monitoring

Ongoing Water Surface Profiling

Shade Inputs

Water Quality Model Development

Water Quality Locators Prior to Year 2000

Ecology Sampling Locations 08B070 08B110

Water Quality Locators >=Year 2000

Water Quality Model Boundary Conditions

Water Quality Model Results

Water Quality Model Diurnal DO and pH Fluctuations

Recommendations Groundwater data collection Ungaged tributary input refinement River water surface elevations/travel time studies Mainstem river temperature data collection Additional mainstem water quality stations including storm sampling and chl a meas. Tributary organic carbon monitoring Continuous DO/pH monitoring

Model Calibration Steps Water Balance/Hydraulics Temperature Water quality –Conservative constituents –Nutrients –DO/pH –Light penetration –Phytoplankton Revisit temperature and repeat water quality

Model State Variables Total dissolved solids Multiple arbitrary constituents –Conservative tracer –Residence time –Indicator bacteria Ammonium Nitrate Dissolved inorganic P Dissolved silica Particulate biogenic silica Multiple inorganic suspended solids Total iron Labile DOM Refractory DOM Labile POM Refractory POM Multiple CBOD groups Multiple algal groups Dissolved oxygen Total inorganic carbon Alkalinity

Model Derived Variables Total, dissolved, and particulate organic carbon Total, dissolved, and particulate organic nitrogen Total Kjedahl nitrogen Total nitrogen Total, dissolved, and particulate organic P Total suspended solids Total inorganic suspended solids Dissolved oxygen saturation Algal production Chlorophyll a Total algal biomass pH Carbon dioxide Bicarbonate Carbonate

Hydrodynamic Output Horizontal and vertical velocity Temperature Density Vertical eddy viscosity Vertical shear stress Advection of vertical momentum Advection of longitudinal momentum Longitudinal momentum Horizontal density gradient Horizontal pressure gradient Shear at top of layer Shear at the bottom of layer Gravity term due to channel slope

Model Data Needs Channel cross sections/bathymetry Meteorology (air temp, dew point, wind, clouds, observed solar radiation) Measured tributary inflow quantity and quality Unmeasured (including gw?) inflow quantity and quality Calibration data (quantity/quality)

Water Quality Boundary Conditions TDS = 0.55 x Spec. Cond. Dissolved silica = 7.2 mg/L Particulate biogenic silica = 2.0 mg/L Ammonium, nitrate, diss. P from observations TIC from pH and alkalinity measurements Inorganic suspended solids = TSS - POM* *POM = Particulate organic matter …but organic carbon concentration not measured

Water Quality Boundary Conditions Assume tributary TOC = 5 mg/L Assume 40 % of organic matter is carbon Assume 90 % of TOC is dissolved Assume 30 % of TOC is labile Therefore: –LDOM = TOC x 2.5 x 0.9 x 0.3 –RDOM = TOC x 2.5 x 0.9 x 0.7 –LPOM = TOC x 2.5 x 0.1 x 0.3 –RPOM = TOC x 2.5 x 0.1 x 0.7

Water Quality Boundary Conditions Assume three algal groups (diatoms, greens, blue-greens) for initial modeling Assume algae contributed only at the upstream boundary with Lake Sammamish Assume conversion of chlorophyll a to algal biomass (mg/L) = chl a (µg/L) x Assume fraction of influent algal biomass that is: Diatoms = 0.5 Greens = 0.3 Blue-greens = 0.2