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The Watershed Treatment Model (WTM) is a spreadsheet-based model that assists in watershed treatment management in three steps: calculating an initial pollutant load, estimating load reduction from management practice implementation, and then scaling the result in terms of future development and growth.

The WTM is offered in two versions, an “off the shelf” version more user-friendly and simpler for rapid assessment, and a “custom” version that allows the user to have complete control over equations and input, designed for advanced quantification. Both versions of the WTM allow watershed managers of all levels to effectively model their watershed treatment options.

Intended User: WTM is intended for use by any public user.

Geographic Focus: Model is designed to simulate any watershed, provided the user selects or enters the appropriate input information.

Scale: Watershed

Developer: Center for Watershed Protection, contact Deb Caraco at

  • How are source contributions estimated?
  • How is pollutant load removal estimated?
  • What does the user need to input?
  • What can the user expect as outputs?
  • Considerations
  • Additional Features