WASP — The Complete Guide: Free Water-Quality Modelling for Rivers, Lakes and Estuaries

WASP (Water Quality Analysis Simulation Program) is a dynamic water-quality model from the US Environmental Protection Agency (EPA). It is in the public domain and completely free, and the physical and biological processes it simulates are the same everywhere — so you can run it on a stream, reservoir or estuary in any country, with local data. It is available for Windows, macOS and Linux.

WASP

US Environmental Protection Agency

A dynamic water-quality model for rivers, lakes and estuaries: nutrients, dissolved oxygen, eutrophication and toxic pollutants, from the US EPA.

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What you get

Water bodies — rivers, lakes, reservoirs and estuaries, divided into segments.
Eutrophication — nitrogen, phosphorus, algae and dissolved oxygen.
Toxic pollutants — organic chemicals and metals, including exchange between water and sediment.
Sediment and temperature — transport and settling of particles, and heat balance.
Scenarios — comparing the current state with reduced loads or a new treatment plant.

What to know

WASP computes the chemical and biological processes, but the flow must come from elsewhere: flows and volumes are entered as data or taken from a hydrodynamic model. Calibration requires field measurements of water quality, and the learning curve is steep. In return you get a widely accepted model.

Related tools

For pollution loads coming from an agricultural catchment — SWAT. For hydrodynamics and water quality in estuaries and coasts — Delft3D. For water chemistry and mineral reactions — PHREEQC.