Jump to main content.


Model Report

Enhanced Stream Water Quality

Last Revision Date: 11/16/2009 View as PDF
General Information Back to Top
Model Abbreviated Name:

Model Extended Name:

Enhanced Stream Water Quality
Model Overview/Abstract:
***QUAL2E is not included in the current version of BASINS***

QUAL2E is a steady state and quasi-dynamic water quality model for the simulation of point source impact on water quality including nitrogen and phosphorus cycling, dissolved oxygen and BOD, algae, fecal coliform, other conservative and non-conservative substances, and temperature and fecal coliform for steady mean or 7Q10 flow. In the BASINS system, reach flow, reach network, and point source data are extracted for user selected reach segments and automatically populated in the QUAL2E Windows interface.
As the QUAL2E water quality model is steady state flow and pollutant load model, the output it produces is pollutant concentration or flow as a function of distance downstream.

QUAL2E, which can be operated either as a steady-state or as a dynamic model, is intended for use as a water quality planning tool. The model can be used, for example, to study the impact of waste loads on instream water quality or to identify the magnitude and quality characteristics of nonpoint waste loads as part of a field sampling program. The user also can model effects of diurnal variations in meteorological data on water quality (primarily dissolved oxygen and temperature) or examine diurnal dissolved oxygen variations caused by algal growth and respiration.

QUAL2E can be used to calculate Waste Load Allocations (WLAs) and/or Total Maximum Daily Loads (TMDLs), ultimately resulting in permit limits. The Windows interface developed for the QUAL2E model helps users prepare input files more efficiently. Default values for constants are included in the interface to provide reasonable numbers with which to begin the modeling. Integrated data manipulation options, stream network graphics, and plotting capabilities are among the many useful features included in the QUAL2E Windows interface. Different screens or parts of screens will be active or inactive depending on the input. This feature reduces the potential for making mistakes during data entry.

Model Technical Contact Information:
Paul Cocca
Office of Water (OW)
Office of Science and Technology (OST)
U.S. EPA/OW/OST (Mail Code: 4305)

QUAL2E was developed by Linfield Brown and Thomas Barnwell of Tufts University, Medford, MA, Department of Civil Engineering with funding from EPA Office of Research and Development Environmental Research Lab in Athens, GA. It is maintained by Russell Kinerson (U.S. EPA, Office of Water (OW), Office of Science and Technology (OST)).

Model Homepage: http://www.epa.gov/ost/BASINS

User Information Back to Top
Technical Requirements
Computer Hardware
PC with 64 MB RAM (minimum)
Compatible Operating Systems
Windows 95, 98, or later
Other Software Required to Run the Model
Download Information
The model is publicly available from U.S. EPA, Office of Water (OW), Office of Science and Technology (OST).


Using the Model
Basic Model Inputs
Screening model with moderate input requirements.


Site-specific inputs include pollutant loading rates, meteorological data, and sediment oxygen demand.

User Support
User's Guide Available?
Calibration required in order to assess predictive accuracy of the model.

Documentation can be downloaded or obtained on disk/CD from:



Paper copies are available through NTIS (1-800-553-6847). Ask for the ?QUAL2E User Manaul? EPA/600/3-87/007 and/or the ?QUAL2E Windows Interface Manual? EPA/823/B/95/003.


Provides: (1) an abstract or abstract equivalent in the introduction, (2) schematic/diagram showing model structure and interaction of model components, (3) equations, equation solution methodologies, and related simplifying assumptions, (4) example input/output files, (5) input and output variable documentation including definitions, units, temporal/spatial dimensions, temporal/spatial resolution options, and (if applicable such as with FORTRAN) format, (6) guidance on selecting and/or estimating values and/or distributions for input variables (including guidance on calibration and selecting default values and/or distributions), and (8) description of sensitivity analysis, uncertainty analysis, and testing (validation) methodologies and results.

User Qualifications
The user needs only moderate level of technical education and/or modeling experience, e.g., an undergraduate or advanced degree in environmental modeling related fields such as environmental engineering.

Model Science Back to Top
Summary of Model Structure and Methods
Simulates formation and fate/transport of daughter products of primary pollutants.

The model uses mixed U.S. / S.I. units and flexible user-defined units.

The model provides mathematical guidance to assist the user when selecting modeling parameters.

Governing equations are solved numerically by Monte Carlo simulation.

Model Evaluation
Code verification has been performed.


Substantial model testing (evaluation), sensitivity analysis, and uncertainty analysis have been performed.


Model has been externally peer reviewed.

Local Navigation

Jump to main content.