Hide Alert

Welcome to our new website. Learn more about what's new.

Models and tools for water quality improvement

Computer models are used extensively for water quality management and Total Maximum Daily Load studies.

Models are tools used to predict how a water body will respond to changes in the amount of "pollution loading" a river or stream receives. This helps us identify specific strategies and numerical loading requirements in our effort to meet clean water standards across the state.

Models and tools we support

  • QUAL2KW is a modeling framework for simulating river and stream water quality.
    • Version 6 - Non-steady, non-uniform flow using kinematic wave flow routing. Continuous simulation with time-varying boundary conditions for periods of up to one year with option to use repeating diel conditions similar to Version 5 but with either steady or non-steady flows. Has optional transient storage zones (surface and hyporheic transient storage zones).
    • Version 5 - Steady flows with repeating diel boundary conditions.
    • One dimensional. The channel is well-mixed vertically and laterally. Also includes up to two optional transient storage zones connected to each main channel reach (surface and hyporheic transient storage zones).
    • Dynamic heat budget. The heat budget and temperature are simulated as a function of meteorology on a continuously varying or repeating diel time scale.
    • Dynamic water quality kinetics. All water quality state variables are simulated on a continuously varying or repeating diel time scale for biogeochemical processes.
    • Heat and mass inputs. Point and nonpoint loads and abstractions are simulated.
    • Phytoplankton and bottom algae in the water column, as well as sediment diagenesis, and heterotrophic metabolism in the hyporheic zone are simulated.
    • Variable stoichiometry. Luxury uptake of nutrients by the bottom algae (periphyton) is simulated with variable stoichiometry of N and P.
    • Automatic calibration. Includes a genetic algorithm to automatically calibrate the kinetic rate parameters.
    • Monte Carlo simulation. Ready-to-run simulations with either the YASAIw add-in or Crystal Ball, including an example using YASAIw.
  • YASAIw is a Monte Carlo simulation add-in for Microsoft Excel. This add-in is a free open-source framework for Monte Carlo simulation. YASAIw is a modification of the original YASAI add-in that was developed by Rutgers University. The modified version adds several new features, including more distributions, correlated random variables, sensitivity analysis, and the ability to run user-defined macros during simulation. See an example using YASAIw with QUAL2Kw .
  • PIKAIA is a general purpose function optimization subroutine based on a genetic algorithm written in Excel/VBA. PIKAIA was originally developed in fortran by Charbonneau and Knapp.
  • Foodweb is a generalized modeling framework for bioaccumulation of hydrophobic organic chemicals in aquatic food webs. This Excel/VBA program is based on the model theory of Arnot and Gobas (2004) (PDF). The present version builds on the model application that was developed by Condon (2007) (PDF) for the Strait of Georgia, British Columbia.
  • SolRad is a solar position and solar radiation calculator for Excel/VBA.
  • Sunrise/Sunset is an Excel workbook with seven VBA functions for sunrise/sunset and solar position: dawn, sunrise, solar noon, sunset, dusk, solar azimuth, solar elevation.
  • Shade is an Excel/VBA tool for estimating shade from riparian vegetation.
  • tTools for ArcGIS is an ArcMap Python add-in with tools that analyze stream-channel attributes and near-stream topography and vegetation to estimate effective shade inputs for use in temperature modeling programs. An older version of tTools for ArcGIS 9.x (Build 7.5.3) is also available for download.
  • rTemp is a simple model written in Excel/VBA to predict a time-series of water temperatures in response to heat fluxes determined by meteorological data, groundwater inflow, hyporheic exchange, and conduction between the water and sediment.
  • River Metabolism Analyzer (RMA) is an Excel workbook tool to apply four methods to analyze continuous monitoring data from a stream for stream metabolism and reaeration. This tool can be used to solve for gross primary production, respiration, reaeration, and limitation due to light, temperature, nutrients, and to predict response to parameter changes with the following methods:
    • delta method to solve for reaeration, gross primary production, and respiration
    • night-time regression to solve for reaeration and respiration
    • inverse modeling to solve for gross primary production, respiration, reaeration, light limitation, and temperature limitation
    • predictive modeling to evaluate model response to changes in any model parameters, including nutrient limitation
    The "Delta method" was developed by Chapra and DiToro (1991) as a way to estimate stream reaeration, primary production, and respiration from diel dissolved oxygen data. The Delta method is described in detail in Chapra (1997). This Excel/VBA program uses the algorithms of McBride and Chapra (2005) to calculate the parameters of the Delta method. The nighttime regression method for estimation of reaeration and respiration is described by Grace and Imberger (2006). The inverse modeling method solves for up to five parameters of a simple model for dissolved oxygen and/or total inorganic carbon: maximum gross primary production, ecosystem respiration, reaeration, light limitation, and temperature limitation.
  • SedFlux is an Excel/VBA model of sediment nutrient fluxes and sediment oxygen demand from diagenesis based on a method that was originally developed by Dominic DiToro.
  • CO2SYS is an Excel/VBA calculator for the CO2 system in seawater. This program takes any two parameters of the CO2 system in seawater (alkalinity, total inorganic carbon, pH, and fugacity or partial pressure of CO2) and calculates the other two parameters for given input and output conditions of temperature and pressure. Calcium solubility is also calculated for both calcite and aragonite. This application is based on the original DOS program named CO2SYS by Lewis and Wallace (1998). Dr. Christopher Sabine from NOAA has an online lecture on the use of CO2SYS. The following versions, starting with the current version, are available for immediate download. Contact Greg Pelletier if you need a copy of an earlier version.
  • COARE - Coupled Ocean Atmosphere Response Experiment. Bulk air-sea heat flux algorithm, version 3.0b (Excel/VBA translation of Fortran 77 program from Chris Fairall's FTP site at NOAA) .
  • Seawater properties - Properties of water (and seawater) for Excel/VBA, using the UNESCO equation of state. VBA functions include potential temperature (theta), in-situ density (rho), sigma-t, sigma-theta, thermal expansion coefficient (alpha), saline contraction coefficient (beta), compressibility, freezing temperature, and specific heat.
  • Manning's n calculator is an Excel/VBA program to calculate Manning's n (or depth) from cross-section data for trapezoidal or rectangular channels based on equation 14.32 in Chapra's Surface water quality modeling textbook.
  • Centroid calculator is an Excel/VBA program to calculate the centroid of a time-concentration series or any x-y series of data.

Other models and resources

  • USEPA Center for Exposure Assessment Modeling - Models supported by the US Environmental Protection Agency, inlcuding WASP, QUAL2E, SMPTOX3, and others.
  • USEPA DFLOW tool for low flow analysis - DFLOW is a Windows-based tool developed to estimate user selected design stream flows for low flow analysis
  • USEPA Ecosystems Research Division Watershed/Water Quality Modeling Technical Support Center - Tools and approaches that can be used in the development of Total Maximum Daily Loads (TMDL), wasteload allocations, and watershed protection plans. Includes: water quality models (QUAL2K, WASP,EPD-RIV1, AQUATOX), watershed tools and/or models (BASINS, Watershed Characterization System, Loading Simulation Program, HSPF, WAMView), and hydrodynamic models (EFDC, EPD-RIV1).
  • USEPA Guidance for TMDL Modeling
  • USEPA Models - Comprehensive list of models
  • USEPA OWOW Guidance - Guidance documents for TMDL modeling by the US Environmental Protection Agency Office of Wetlands, Oceans, and Watersheds
  • USEPA Quality System Guidance - Agency-wide quality system guidance documents that apply to internal USEPA organizations
  • USEPA Rates, Constants, and Kinetics Formulations Manual is an essential reference for water quality model calibration.
  • USEPA Environmental Fate Database (Envirofate) identifies persistent chemical classes, as well as physical or chemical properties that may correlate to particular behavior in the environment. The EFDB is comprised of several interrelated files, including DATALOG, CHEMFATE, BIOLOG, and BIODEG. These databases share a CAS# file containing over 20,000 chemicals with a preferred name and formula and a bibliographic file containing full references on over 36,000 articles cited. The EFDB is maintained by Syracuse Research Corporation under the sponsorship of the USEPA.
  • USEPA Visual Plumes Model is a Windows-based application for simulating surfacewater jets and plumes.
  • CORMIX is a mixing zone model and decision support system for environmental impact assessment of regulatory mixing zones resulting from continuous point-source discharges.
  • USGS techniques for water resource investigations is a series of manuals for planning and conducting water resource investigations.
  • Oregon DEQ has tools for analysis of water quality (e.g. HeatSource temperature model).
  • CE-QUAL-W2 has information about the CE-QUAL-W2 model from Portland State University
  • EFDC - For information on obtaining or using the current public version of the Environmental Fluid Dynamics Code (EFDC) and supporting documentation and auxiliary software tools, contact John Hamrick at TetraTech at 703-385-6000 or john.hamrick@tetratech-ffx.com (inlcude your real name, affilitation, mailing address, phone number, and valid institutional, business or government email address).
  • GEMSS, Generalized Environmental Modeling System for Surfacewaters, is an integrated system of 3-D hydrodynamic and transport models developed by J.E. Edinger Associates Inc.
  • Our Permit Writers Manual offers technical guidance for NPDES permit writers in Washington state. Mixing Zone Guidance is Appendix C.
  • Ecology's TMDL Technical Guidance has selected technical topics to ensure consistency in developing TMDL reports in Washington state
  • Ecology's TMDL Development Guidance for Determination and Allocation of Total Maximum Daily Loads in Washington state
  • Pesticide Properties Database (PPDB) is maintained by Dr. Kathleen Lewis at the University of Hertfordshire, UK.

Meteorological data

  • Office of the Washington State Climatologist collects, disseminates, and interprets climate data. Find links to sources of climate data and seasonal forecasts for the state of Washington.
  • NOAA National Weather Service - The latest observations (up to seven days) from NOAA's National Weather Service stations across the northwest from the forecast office in Missoula, Montana.
  • University of Washington Live from Earth and Mars shows continuous weather data (1996 - present) from selected stations in Washington and Oregon.
  • AgWeatherhNet is Washington State University’s Agricultural Weather Network.
  • NOAA National Weather Service - Seattle (western Washington).
  • NOAA National Weather Service - Spokane (eastern Washington).
  • NCDC Climate Data Inventories - Download any NOAA/NCDC weather data.
  • DAYMET GIS data for daily meteorology summaries - DAYMET is a model by the University of Montana. Using a digital elevation model and daily observations of minimum and maximum temperatures and precipitation from ground-based meteorological stations, an 18-year daily dataset (1980 - 1997) of temperature, precipication, humidity, and radiation has been produced as a continuous surface at a 1 km resolution.
  • NCAR GIS data for climate change scenarios provides access to global datasets of climate change scenarios by National Center for Atmospheric Research.
  • NOAA climate maps are full-color maps of climatic elements such as monthly and annual temperature, precipitation, snow, wind, pressure, etc., chosen to portray the climate of the U.S. The period of record for most of the maps is 1961-1990. Most of the maps can be downloaded in a high-resolution PDF format or as ESRI Shape Files.

Streamflow data

Tide and bathymetry data and tools

  • Puget Sound Tide Channel Model is a research tool programmed in Python by David Finlayson for predicting the tides of the Sound. The model was originally developed by Lavelle et al. (1988) at NOAA PMEL and was updated by H. Mofjeld to include the full suite of standard tidal constituents.
  • Puget Sound Digital Elevation Model combines bathymetry and topography of Western Washington, including the Straits of Juan de Fuca, Puget Sound, and Hood Canal.
  • NOAA VDatum transformation tool transforms coastal elevations between 28 different vertical datums consisting of tidal, orthometric, and ellipsoidal (3-D, three dimensional) datums.