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HAWQS (Hydrologic and Water Quality System)

Basic Information

The Hydrologic and Water Quality System (HAWQS) Exit Version 1.0 is a web-based interactive water quantity and water quality modeling system that can assist states, local governments, and others with water quality protection decision-making. The system employs as its core modeling engine the Soil and Water Assessment Tool (SWAT) Exit, an internationally-recognized public domain model.

HAWQS provides users with interactive web interfaces and maps; pre-loaded input data; outputs that include tables, charts, and graphs; a user’s guide, and online development, execution, and storage of a user’s modeling projects.

With support from Texas A&M University Spatial Sciences Laboratory and USDA Agriculture Research Service, EPA developed and released the Hydrologic and Water Quality System (HAWQS) Beta version in June 2016. The beta webcast and associated slides are provided below. Future webcasts will be announced on this site and via other communication channels.

Download HAWQS Version 1.0 Flyer

HAWQS Webcast and Slides

  • August 16, 2016 HAWQS Beta Webcast.
  • Webcast Slides (PDF)
  • If you need assistance, please email us at

Learn More

HAWQS substantially enhances the usability of SWAT to simulate the effects of management practices based on an extensive array of crops, soils, natural vegetation types, land uses, and other scenarios for hydrology and the following water quality parameters:

  • Sediment
  • Dissolved oxygen
  • Pathogens
  • Pesticides
  • Nutrients
  • Water temperature
  • Biological oxygen demand

HAWQS users can select from three watershed scales, or hydrologic unit codes (HUCs) — 8-digit ~700mi2, 10-digit ~227 mi2, 12-digit ~40mi2 — to run simulations. HAWQS allows for further aggregation and scalability of daily, monthly, and annual estimates of water quality across large geographic areas up to and including the continental United States.

How HAWQS Works

  • The user creates a project for a modeling scenario and changes the variables and inputs using web interfaces.
  • To run the simulation, HAWQS connects with the latest version of SWAT Model to process the inputs, data and other information for the scenario.
  • SWAT finishes processing and generates outputs; HAWQS stores outputs centrally.
  • Users can view results through a web interface, save results, and run additional scenarios.

Why Use HAWQS?

  • HAWQS is seamlessly integrated with the latest version of the SWAT Model. SWAT, with more than 2,500 peer-reviewed publications, has been in use for more than 25 years.
  • HAWQS integrates SWAT check to identify potential model problems.
  • Scenarios can be run at three different watershed scales.
  • HAWQS deploys pre-loaded input data — no need to prepare input data such as point source, land use, and/or agricultural practices. Users can also load custom input data when necessary.
  • Modeling projects are performed through a web browser and projects, scenarios, input data, and output data are centrally stored, reducing users' computing requirements.
  • Users can download results in commonly used tabular and chart formats (csv, txt, jpg, png).

HAWQS Data Sources

Watershed Boundary

USGS, HUC 8,10, and 12

Livestock and Crops


Aerial Deposition

National Atmospheric Deposition Program


USACE National Inventory of Dams



Land Use



PRISM (1981-2015)

NCDC NWS/NOAA (1961-2010)

NEXRAD (2005-2015)


USGS National Elevation Dataset

Management Data

NRCS CDL – Cropland Management Dataset