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Center for Spatial Information and Research

Application of NOAA's Non-Point Source Pollution Tool

Evaluation Document:

Workshop Presentations:


NOAA developed the Nonpoint Source Pollution and Erosion Comparison Tool (N-SPECT) to help land managers and local planners to predict potential water quality impacts to rivers and streams from nonpoint source pollution and erosion. Input data includes information about the area of interest (land cover, elevation, precipitation, and soil characteristics). Different land cover change scenarios (such as a development) can then be added to get information about potential changes in surface water runoff, nonpoint pollution, and erosion. The tool was built as an extension to ESRI's ArcView 8.3 or ArcView 9.x and can be freely downloaded from the web. Implementation of the tool provides the following output:

  • Accumulated runoff, pollutant, and sediment load grids
  • Pollutant and sediment concentration grids
  • Pollutant assessment grid, which compares the resulting concentrations in receiving waters to user-specified water quality standards
  • Ability to simulate land cover changes, such as developments

We will test N-SPECT in at least one jurisdiction that is anticipating conversion of land cover. We will assess the ease of application and train local planners on how to interpret the output for resource management purposes.

This research effort focused on evaluating the ease of implementation of the N-SPECT model. RGIS-PN selected the McLane Creek watershed located near Olympia , WA to apply the model. Required datasets were collected or in some cases developed (e.g. R-factor grid) and the model was parameterized and run. Proposed development scenarios were then incorporated to observe model's ability to reasonably anticipate future runoff and non-point pollution impacts. An important aspect of this objective was to develop an evaluation regarding the ease of implementation of N-SPECT. A model assessment was developed using a comprehensive set of criteria to evaluate N-SPECT regarding its ease of implementation, ability to generate reasonably accurate data estimates, and its utility to resource decision making processes at the watershed scale. This assessment was exported to a web document that is publicly available on RGIS-PN's website. A final aspect of this objective was to inform and train local planners concerning the implementation and interpretation of output data generated by the N-SPECT model. RGIS-PN developed a half day technical workshop that exposed participants to the theory, concepts, and assumptions embedded within N-SPECT, and provided hands-on training regarding the implementation of the model. Participants of the workshop included local members of the Washington Department of Ecology, U.S. Forest Service, and Yakima County 's Surface Water Department.