The two primary objectives of WATERSHEDSS are to:
  1. transfer water quality and land treatment information to watershed managers in order to assist them in making appropriate land management and land treatment decisions to achieve water quality goals
  2. assess and evaluate sources, impacts, and potential management options for control of nonpoint source pollution in a watershed based on user-supplied information and decisions.


To adequately control nonpoint source pollution of a water resource, water quality managers must focus on minimizing the impacts of individual nonpoint source pollutants. The strategic choice and placement of best management practices (BMPs) in the watershed can successfully reduce the input of individual pollutants and may improve water quality. WATERSHEDSS (WATER, Soil, and Hydro- Environmental Decision Support System) was designed to help watershed managers and land treatment personnel identify their water quality problems and select appropriate best management practices.

WATERSHEDSS is comprised of three components:

  1. The watershed assessment and evaluation which includes a pollutant budget spreadsheet and an agricultural best management practice (BMP) database
  2. An educational component, containing detailed information and references on NPS pollutants and sources.
  3. An annotated bibliography of NPS literature

Watershed Assessment and Evaluation

The watershed assessment and evaluation part of WATERSHEDSS includes a hypertext expert-systems-like user interface, the agricultural BMP data base, and the pollutant budget spreadsheet.

To begin the assessment and evaluation portion of decision support system, click on Decision Support, located on the home page. You will then be asked a series of questions about your watershed, including information about the type of surface water resource, the designated uses of the water resource, the water use impairment, the source of the pollutant, and regional agricultural practices. Based on this and other information, alternative land treatment practices will be suggested and you will be able to choose the practice(s) that you believe will be most beneficial for reducing water pollution. The evaluation portion of the decision support system is designed as an interactive system that will require that you input information and make decisions.

Because of the computing environment, only one water resource, designated use, or water use impairment can be selected for each run. If you are trying to manage multiple water resources, designated uses, or impairments, you will have to go through the system again and then manually combine the lists of land treatment practices that are recommended.

If you are unsure of your pollutant source, an export coefficient spreadsheet is included. The spreadsheet can only be accessed after the pollutant, which has to be either nitrogen or phosphorus, is identified. To use the spreadsheet you will need land use data in number of acres, such as number of acres of corn, number of acres in residential use, etc. Because of the inexact nature of the export coefficients, the purpose of the pollutant budget spreadsheet is not to calculate an exact amount of nutrient reaching the water resource, but rather to estimate the relative importance of given land uses contributing to the identified water quality problem.

Educational Component

The Water Quality and Land Treatment Educational Component of WATERSHEDSS is comprised of text units covering diverse topics on water quality, water quality monitoring, land treatment, watershed management, and watershed projects. This information can be accessed directly from the home page of WATERSHEDSS or within the watershed evaluation section of the decision support system by clicking on the "?" icons.

Annotated Bibliography of NPS Literature

The Annotated Bibliography is a link to the North Carolina State University (NCSU) Water Quality Group Nonpoint Source (NPS) Library of literature focusing on nonpoint source pollution.  It contains over 6,000 annotated articles on NPS pollution and its control, with search capabilities by author, title, keyword, or topic.


The water quality standards used in WATERSHEDSS were gathered from various federal, state, and professional sources. When possible, published criteria were incorporated. When standards were not available for a given designated water use or water quality parameter, recommended limits from published literature were employed. Often, similar standards and recommended limits were located in all sources consulted. However, credible sources occasionally reported different standards or recommended limits for the same designated water use. In these cases, the limits employed by WATERSHEDSS represent either the mean or mode of the reported numbers, depending on what was deemed most appropriate for each designated water use.

The user is advised to check applicable water quality criteria, standards, or recommended limits for his/her specific jurisdiction.


WATERSHEDSS has been developed under a grant from the U.S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, Ecosystems Research Division, Athens, GA (EPA Project #CR822270/Grant Cooperative Agreement 818397011), Understanding the Role of Agricultural Landscape Feature Function and Position in Achieving Environmental Endpoints, which was granted to North Carolina State University. The EPA project officer is Dermont Bouchard. Principal Investigator and Project Manager is Judith A. Gale (NCSU).

The development of this decision support system is a cooperative effort between the NCSU Water Quality Group at North Carolina State University (prime contractor) and the Agricultural and Biological Engineering Department at The Pennsylvania State University (subcontractor). Personnel involved in the development of WATERSHEDSS include:

I. Conceptualization of the Decision Support System Framework - Deanna L. Osmond (NCSU)

II. Programming of WATERSHEDSS (other than the GRASS/AGNPS software) - Cary B. Knott, Ritchie Schacher, and Joe Walker (NCSU)

III. Educational Component

A. Water Quality Information - Kathryn A. Bartenhagen, Marjut H. Turner, and Deanna L. Osmond (NCSU)

B. Agricultural Nonpoint Source Pollution Control Concepts (RCWP Fact Sheets) - Judith A. Gale, Deanna L. Osmond, Daniel E. Line, Jean Spooner, and Steven W. Coffey (NCSU)

C. Wetlands Information - Marjut H. Turner and Richard Gannon (NCSU)

D. Non-Agricultural BMP Descriptions - Richard W. Gannon, Kathryn A. Bartenhagen, and Linda L. Hargrove (NCSU)

E. Case Studies - Judith A. Gale (NCSU) and David W. Lehning (PSU)

IV. Agricultural BMP Data Base - Mike A. Foster, Paul D. Robillard, David W. Lehning and R. Zhao (PSU). Additions of wetland and riparian area BMPs were made by Richard W. Gannon (NCSU) and data base management was handled by Joe R. Wells (NCSU).

V. AGNPS/GRASS Interface - Daniel E. Line, Dave Peterson, Trey Askew (NCSU) and Z. Li and Mike A. Foster (PSU)

VI. Pollutant Budget Spreadsheet - Steven W. Coffey, Deanna L. Osmond, and Cary B. Knott (NCSU)

This decision support system should be cited as follows: Osmond, D.L., D.E. Line, J.A. Gale, R.W. Gannon, C.B. Knott, K.A. Bartenhagen, M.H. Turner, S.W. Coffey, J. Spooner, J. Wells, J.C. Walker, L.L. Hargrove, M.A. Foster, P.D. Robillard, and D.W. Lehning. 1995. WATERSHEDSS: Water, Soil and Hydro-Environmental Decision Support System,

We would like to acknowledge the contribution of Don Meals (University of Vermont) in the very thorough and useful review he made of WATERSHEDSS.


The contents and views expressed in this document are those of the authors and do not necessarily reflect the policies or positions of the North Carolina Cooperative Extension Service, the USEPA, or other organizations named, nor does the mention of trade names for products or software constitute their endorsement. The North Carolina State University Water Quality Group is not responsible for any undesirable outcomes attributed to decisions made by users based on WATERSHEDSS recommendations.

The standards and recommended limits in WATERSHEDSS are designed to aid managers across the United States in defining their water quality problems. However, not all water bodies are capable of attaining water quality that meets published standards. Background water quality will fluctuate greatly in each region according to the average temperature, average rainfall, and regional geology. In addition, some of the standards and recommended limits employed by WATERSHEDSS may differ from those that are currently enforced in your state.

The water quality standards used in WATERSHEDSS have been gathered from various federal, state, and professional sources. When possible, published standards were incorporated. When standards were not available for a given designated water use or water quality parameter, recommended limits from published literature were employed. Not all limits are supported by extensive research in the literature. As a result, some recommended limits may not be completely accurate for your water body.