US Army Corps of Engineers
Engineer Research and Development Center Website


Published Nov. 12, 2014
Longitudinal view of temperature output for a riverine section,reservoir, and estuary from a CE‐QUAL‐W2 application.

Longitudinal view of temperature output for a riverine section,reservoir, and estuary from a CE‐QUAL‐W2 application.

CE‐QUAL‐W2 (W2) is a two‐dimensional, longitudinal/vertical, hydrodynamic and water quality (WQ) model. Since the model assumes lateral homogeneity, it is best suited for relatively long and narrow waterbodies exhibiting longitudinal and vertical water quality gradients. The model has been applied to rivers, lakes, reservoirs, estuaries and combinations thereof.  


  • Chosen as the reservoir WQ model of choice throughout the U.S. and many other countries
  • Chosen as the 2-D, longitudinal/vertical hydrodynamic and water quality model of choice for:
    • USACE
    • U.S. Geological Survey (USGS)
    • U.S. Department of the Interior, Bureau of Reclamation (USBR)
    • U.S. Environmental Protection Agency (U.S. EPA)
    • Tennessee Valley Authority (TVA)
  • More than 300 applications worldwide
  • Recent applications of W2 were developed for:
    • Minnesota River ‐ FY08
    • Cougar Reservoir ‐ FY12
    • Lost Creek Lake – FY13
    • Applegate Lake – FY14
    • Clarion Reservoir FY09
    • Lehigh River FY12
    • Tygart Reservoir and River FY13
  • Cited in more than 15 PhD dissertations, 50 Master’s theses, more than 100 presentations at scientific meetings by numerous researchers, and in more than 20 journal articles by various researchers worldwide

Specifications/Features/System Requirements

W2 includes variable density as affected by temperature, salinity, TDS and TSS to simulate stratified flow. There are 28 water quality constituent state variables. Any combination of constituents can be included or excluded from a simulation. The effects of salinity or total dissolved solids/salinity on density and thus hydrodynamics are included only if they are simulated in the water quality module. The water quality algorithm is modular, allowing constituents to be easily added as additional subroutines. New features and enhancements include:

  • W2 version 3.71 is being modified to allow a choice of modeling organic matter or organic carbon, organic nitrogen, and organic phosphorus as state variables and directly simulates aquatic carbon, nitrogen and phosphorus cycles.
  • DiToro’s benthic sediment diagenesis module was integrated into W2 version 3.71 to enable W2 to simulate dynamic interactions between bed sediments and water column.


The latest version of W2 is version 3.71, which features new algorithms that allow for dynamic port selection and fish habitat volume predictions, in addition to the water quality and hydrodynamic components. W2 version 3.8 beta is available from the Environmental Modeling Branch, formerly the Water Quality and Contaminant Modeling Branch.

Documentation, Training & Support

Cole, T. M., and S. A. Wells (2006). "CE‐QUAL‐W2: A two‐dimensional, laterally averaged, Hydrodynamic and Water Quality Model, Version 3.5," Instruction Report EL‐06‐1, US Army Engineering and Research Development Center, Vicksburg, MS

ERDC Points of Contact

Questions about W2?
Contact:  Dr. Dorothy Tillman
(601) 634‐2676   


Contact: Dr. Barry Bunch
(601) 634‐3617