Hydrologic and Water Quality System (HAWQS)

Posted on: 10/17/2017 - Updated on: 2/27/2020

Posted by



The Hydrologic and Water Quality System (HAWQS) is a web-based interactive water quantity and quality modeling system that employs as its core modeling engine the Soil and Water Assessment Tool (SWAT), 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 raw output data; a user guide, and online development, execution, and storage of a user's modeling projects.

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

HAWQS users can select from three watershed scales or hydrologic unit codes (HUCS) – 8-digit ~700mi2; 10-digit ~227 mi2; and 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.

The United States Environmental Protection Agency (USEPA) Office of Water supports and provides project management and funding for HAWQS. The Texas A&M University Spatial Sciences Laboratory and EPA subject matter experts provide ongoing technical support including system design, modeling, and software development. The United States Department of Agriculture (USDA) and Texas A&M University jointly developed SWAT and have actively supported the model for more than 25 years.

View the HAWQS brochure.

Managing Organizations

The Environmental Protection Agency is an independent executive agency of the United States federal government tasked with environmental protection matters. The Environmental Protection Agency has ten Regional offices, each of which is responsible for the execution of the Agency's programs within several states and territories.


Type of Tool
Target Climate Changes and Impacts