A TMDL or Total Maximum Daily Load is a calculation of the maximum amount of a pollutant that a waterbody can receive and still meet water quality standards. Computer models are used extensively for water quality management and TMDLs. Models are used to predict the water quality in a water body in response to changes in pollutant loading and various allocation strategies.
QUAL2KW - A modeling framework for simulating river and stream water quality. The QUAL2KW framework has the following characteristics:
YASAIw - A Monte Carlo simulation add-in for Microsoft Excel. This add-in is a free open-source framework for Monte Carlo simulation in Excel. YASAIw is a modification of the original YASAI add-in that was developed by Rutgers University. The modified version (YASAIw) adds several new features including more distributions, correlated random variables, sensitivity analysis, and the ability to run user-defined macros during simulation. Also available is an example using YASAIw with QUAL2Kw.
Foodweb - A generalized modeling framework for bioaccumulation of hydrophobic organic chemicals in aquatic food webs. This Excel/VBA program is a generalized modeling framework 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 - A solar position and solar radiation calculator for Excel/VBA.
Sunrise/Sunset - An Excel workbook with seven VBA functions for sunrise/sunset and solar position: dawn, sunrise, solar noon, sunset, dusk, solar azimuth, solar elevation.
Shade - A tool for estimating shade from riparian vegetation written in Excel/VBA.
tTools for ArcGIS - An ArcGIS project with tools for sampling geospatial data to obtain input data for the calculator for shade from riparian vegetation and topography.
rTemp - 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) - The River Metabolism Analyzer (RMA) is an Excel workbook tool to apply four methods to analyze continuous monitoring data from a stream to analyze 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 predict response to parameter changes with the following methods:
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 the text text book by 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 5 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.
CO2SYS - A calculator for the CO2 system in seawater written in Excel/VBA. 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 Excel/VBA 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.
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.
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), waste load 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 - Guidance documents for TMDL modeling by the US Environmental Protection Agency
USEPA Models - Comprehensive list of models supported by the US Environmental Protection Agency
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 - A USEPA publication that is an essential reference for water quality model calibration.
USEPA Visual Plumes Model - Visual Plumes model system is a Windows-based software application for simulating surface water jets and plumes.
CORMIX - 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 - The USGS publishes a series of manuals for planning and conducting water resource investigations.
Oregon DEQ - Tools for analysis of water quality by the Oregon Department of Environmental Quality (e.g. HeatSource temperature model).
CE-QUAL-W2 - 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 firstname.lastname@example.org (inlcude your real name, affilitation, mailing address, phone number, and valid institutional, business or government email address).
GEMSS - Generalized Environmental Modeling System for Surfacewaters (GEMSS) is an integrated system of 3-D hydrodynamic and transport models developed by J.E. Edinger Associates Inc.
Ecology's Mixing Zone Guidance - Guidance for conducting mixing zone analyses
Ecology's Permit Writers Manual - Technical guidance and policy manual for NPDES permit writers in Washington State
Ecology's TMDL Technical Guidance - Guidelines for selected technical topics were prepared to ensure consistency in developing TMDL reports in Washington State
Ecology's TMDL Development Guidance - Guidance for Determination and Allocation of Total Maximum Daily Loads (TMDL) in Washington State
Office of the Washington State Climatologist - The function of the State Climatologist is to collect, disseminate, and interpret climate data. This new web site provides links to sources of climate data and seasonal forecasts for the state of Washington.
NOAA National Weather Service - The latest observations (up to 7 days of data) from NOAA's National Weather Service stations across the northwest (data provided by NOAA's National Weather Service forecast office in Missoula Montana).
University of Washington Live from Earth and Mars - Continuous weather data (1996 to present) from selected stations in Washington and Oregon from an educational Web site provided by the University of Washington.
AgWeatherhNet - Washington State University’s Washington Agricultural Weather Network.
NOAA National Weather Service - Seattle office (western Washington).
NOAA National Weather Service - Spokane office (eastern Washington).
NCDC Climate Data Inventories - Download any of 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 data set (1980 - 1997) of temperature, precipication, humidity and radiation has been produced as a continuous surface at a 1 km resolution.
USGS surface water data for Washington - Data from all USGS surface water stations in Washington.
Puget Sound Tide Model - The 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 subsequently updated by H. Mofjeld to include the full suite of standard tidal constituents.
Puget Sound Digital Elevation Model - Combined bathymetry and topography of Western Washington, including the Straits of Juan de Fuca, Puget Sound and Hood Canal.
Department of Ecology
P.O. Box 47600
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