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Environmental Modeling Community of Practice

Water Quality Analysis Simulation Program (WASP)

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The Water Quality Analysis Simulation Program (WASP) is an enhancement of the original WASP (Di Toro et al., 1983; Connolly and Winfield, 1984; Ambrose, R.B. et al., 1988). This model helps users interpret and predict water quality responses to natural phenomena and manmade pollution for various pollution management decisions. WASP is a dynamic compartment-modeling program for aquatic systems, including both the water column and the underlying benthos.

WASP allows the user to investigate 1, 2, and 3 dimensional systems, and a variety of pollutant types. The state variables for the given modules are given in the table below. The time varying processes of advection, dispersion, point and diffuse mass loading and boundary exchange are represented in the model. WASP also can be linked with hydrodynamic and sediment transport models that can provide flows, depths velocities, temperature, salinity and sediment fluxes. This release of WASP contains the inclusion of the sediment diagenesis model linked to the Advanced Eutrophication sub model, which predicted sediment oxygen demand and nutrient fluxes from the underlying sediments.

WASP is one of the most widely used water quality models in the United States and throughout the world. Because of the models capabilities of handling multiple pollutant types it has been widely applied in the development of Total Maximum Daily Loads (TMDL). WASP has capabilities of linking with hydrodynamic and watershed models which allows for multi-year analysis under varying meteorological and environmental conditions. WASP has been applied to all of the major estuaries in Florida where it was linked with a hydrodynamic and watershed model simulating 12 continuous years to aid US EPA in the development of numeric nutrient criteria. Other examples of its use are:
  • eutrophication of Tampa Bay, FL;
  • phosphorus loading to Lake Okeechobee, FL;
  • eutrophication of the Neuse River Estuary, NC;
  • eutrophication Coosa River and Reservoirs, AL;
  • PCB pollution of the Great Lakes;
  • eutrophication of the Potomac Estuary;
  • kepone pollution of the James River Estuary;
  • volatile organic pollution of the Delaware Estuary; 
  • heavy metal pollution of the Deep River, North Carolina; and
  • mercury in the Savannah River, GA.

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WASP Preprocessor

The data preprocessor allows for the rapid development of input datasets. The ability to bring data into the model is as simple as cut and paste or queried from a database. The preprocessor provides detailed descriptions of all model parameters and kinetic constants. When linking WASP with hydrodynamic models it is as simple as pointing to the hydrodynamic linkage file.

  • Import time series from WRDB, Spreadsheet, Text Files
  • Automatically import hydrodynamic model interface information
  • Multi-session capable
  • Run time diagnosis

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Post Processor

The Post-Processor (MOVEM) provides an efficient method for reviewing model predictions and comparing them with field data for calibration. MOVEM has the ability to display results from all of the WASP models as well as others. MOVEM allows the modeler to displays the results in two graphical formats:

  1. Spatial Grid . a two dimensional rendition of the model network is displayed in a window where the model network is color shaded based upon the predicted concentration.
  2. x/y Plots -- generates an x/y line plot of predicted and/or observed model results in a window.

There is no limit on the number of x/y plots, spatial grids or even model result files the user can utilize in a session. Separate windows are created for each spatial grid or x/y plot created by the user.

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WASP Model Information

Current Version 8.32
Release Date April 2, 2019
Operating System Early versions of Windows, 64-bit Windows 7 or higher, Mac OSX, Linux Ubuntu
Intended Audience Environmental Engineers/Scientists, Regulatory Agencies
Key Words aquatic biology, assessment, compliance, discharge, environmental effects, hydrology, metals, NPS related, NPDES, point source(s), surface water, test/analysis, TMDL related
Media Surface Water
Pollutant Types Conventional Pollutants (Nitrogen, Phosphorus, Dissolved Oxygen, BOD, Sediment Oxygen Demand, Algae, Periphyton), Organic Chemicals, Metals, Mercury, Pathogens, Temperature

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File Type / Priority Filename / Format / Size File Description

File Download Information

Install / Required WASP8 Download  All of the WASP Installers are listed below. There is a 64 Bit Windows Installer, 64 Bit Mac OS X (Yosemite or Higher), 64 Bit Linux (Built on Ubuntu). You will need to have knowledge on how to install software on your target operating system.

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Contact information

Please contact Tim Wool ( with questions or comments on WASP.

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US EPA Region 4 and the National Water Quality Modeling Work Group is will post additional  5-day workshops on water quality principles / modeling using the Water Quality Analysis Simulation Program (WASP) in this section.

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