Hydrologic and Water Quality System: A Modeling Tool for Evaluating Effects to Water Quantity and Quality

A web-based interactive water quantity and water quality modeling system that can assist federal agencies, states, local governments, and others with water quality protection decision-making and policy evaluation in the contiguous United States.

On this page:

• About the Program
• Types of Assistance
• How This Program Helps Build Resilience
• Connections to Other EPA, Federal, or Non-Governmental Efforts

About the Program

The Hydrologic and Water Quality System (HAWQS) is a web-based interactive water quantity and water quality modeling system that employs the Soil and Water Assessment Tool (SWAT) public domain model as its core modeling engine.

HAWQS enables the use of SWAT to simulate the effects of different water management practices, policy changes, and climate change scenarios based on a variety of crops, soils, natural vegetation types, and land uses on hydrology and many different water quality parameters (sediment, pathogens, nutrients, biological oxygen demand, dissolved oxygen, pesticides, water temperature).

To simulate multiple climate futures, and the respective impacts to water quality and quantity, HAWQS includes 12 Global Circulation Models from the Coupled Model Intercomparison Project version 5 as weather options, in addition to historical weather. For customized future simulation, HAWQS also includes the option to vary precipitation and temperature values by a user-defined percentage or amount, respectively, applied over a specified time. Additionally, modelers may adjust various climate variables to generate climate scenarios using the built-in weather generator. Scenario comparison features in the HAWQS interface allow users to compare impacts to water resources under alternate futures. For example, HAWQS was used to model water quality (temperature, dissolved oxygen, nitrogen, and phosphorus) under multiple climate futures, in the technical report under the Climate Change Impacts and Risk Analysis project to inform the fourth National Climate Assessment of the U.S. Global Change Research Program.

Types of Assistance

The EPA’s Office of Water supports and provides project management and funding for HAWQS. More specifically, HAWQS offers state, local, and the public the following types of assistance:

Technical Assistance

HAWQS provides users with:

• Interactive web interfaces and maps.
• Pre-loaded national input data.
• Output data (including tables, charts, graphs, and raw data).
• User documentation including a user guide, use cases covering typical modeling scenarios, and HAWQS-relevant climate change data and resources.
• Online development, execution, and storage for users modeling projects.

HAWQS administrators maintain an outward-facing email (HAWQS@epa.gov) to help answer training and usage questions from HAWQS users and a separate email (eco.web@tamu.edu) to provide assistance with account settings and system errors.

Outreach and Education Assistance

The program helps to coordinate and support webinars and outreach activities with various partners.

How This Program Helps Build Resilience

The HAWQS modeling system can allow states, local governments, and others to prepare, adapt, and build resilience by modeling different agricultural conservation practices, point and nonpoint source pollution control scenarios, and watershed management alternatives. The tool can also help these users assess the effectiveness of national and regional policy or programs.

Connections to Other EPA, Federal, or Non-Governmental Efforts

In addition to providing support for EPA regulatory actions under the Clean Water Act, HAWQS has been used to advance several projects in other EPA programs, including an atmospheric nitrogen deposition analysis in the Upper Mississippi River Basin performed by the EPA’s Office of Research and Development, as well as water quality case studies in the EPA’s Office of Air and Radiation.

HAWQS has also been used in other governmental efforts:

• A Government Accountability Office report on irrigation technology options.
• A U.S. Department of Agriculture Conservation Effects Assessment Project land management study.
• The Alabama Department of Environmental Management’s watershed planning.
• The Texas State Soil and Water Conservation Board development of the Texas HAWQS.
• The Oklahoma Conservation Commission, Oklahoma State University, and Oklahoma Water Resources Center development of an Oklahoma HAWQS platform.
• The Clemson University development of a HAWQS platform for the state of South Carolina.
• The Meskwaki Nation (Sac and Fox Tribe) development of a reservation specific HAWQS platform.

Several universities around the country are also using HAWQS as a research tool, as well as a teaching tool for graduate courses on watershed modeling and management.