OpenNSPECT (Nonpoint Source Pollution and Erosion Comparison Tool)

Posted on: 3/21/2010 - Updated on: 3/19/2021

Posted by

Jennie Hoffman


Use OpenNSPECT, the open-source version of the Nonpoint Source Pollution and Erosion Comparison Tool (more), to investigate potential water quality impacts from development, other land uses, and climate change. OpenNSPECT was designed to be broadly applicable. When applied to coastal and noncoastal areas alike, the tool simulates erosion, pollution, and their accumulation from overland flow.


  • Provides estimates and maps of surface water runoff volumes, pollutant loads, pollutant concentrations, and total sediment loads
  • Helps users identify areas that might benefit from changes to proposed development strategies
  • Processes digital elevation data quickly and easily
  • Provides a means to analyze "what if" land use change scenarios

OpenNSPECT estimates and maps how water quality (i.e., surface water runoff volume, pollutant loads and concentrations, and total sediment loads) may vary as a result of climate change, development, and other land use changes. OpenNSPECT integrates several different data types to generate maps of overland flow, pollutants, and erosion, including land use/land cover, elevation, soil types, rainfall factor, and precipitation. OpenNSPECT can be applied in a diversity of locales (i.e., coastal and non-coastal areas) and can be used by land managers, natural resource managers, local officials, planners, policymakers, and others as a comparative tool to inform planning processes and to help meet water quality objectives. For example, practitioners can compare tool outputs to national or state water quality standards, use the visual and numerical output components to identify best development options, or use outputs to guide the development of local watershed plans. OpenNSPECT can also be used to identify watershed areas that could be targeted for best management practices (BMP) development and pollution reduction activities. OpenNSPECT maps can also provide visual examples in proposals or presentations and/or be used as educational tools. Training is available for OpenNSPECT, and users can also register for and participate in an online community and user group where they can discuss real-time project applications of OpenNSPECT with other practitioners and access software updates.

Example in use: OpenNSPECT has been applied in diverse areas, including Saipan, Hawaii, Wisconsin, South Carolina, Alabama, and the Northeastern United States (see for a complete list of projects). Practitioners have utilized OpenNSPECT to improve their understanding of nonpoint source pollution patterns and to inform and enhance the management of different watersheds, coastal zones, and marine areas. For example, Weeks Bay National Estuarine Research Reserve (NERR) in Alabama used the private version of OpenNSPECT (N-SPECT) to analyze water quality issues and assist with achieving water quality objectives outlined in its Watershed Management Plan. Two freshwater rivers drain into Weeks Bay NERR, rivers that drain agricultural, construction, and urban sites, exposing the estuary to significant nonpoint source pollution. Of particular concern were high fecal coliform counts that can prevent harvest of several important oyster beds. In combination with local water quality data and other integrated modeling tools (e.g., NOAA’s Coastal Change Analysis Program (C-CAP) Land Cover Atlas, Impervious Surface Analysis Tool), Weeks Bay NERR staff used N-SPECT to identify potential sources of fecal coliform contamination within the watersheds draining to Weeks Bay and to test how hypothetical management and land use changes would affect future fecal coliform levels. Using the data gathered from N-SPECT, they were able to implement a three-tier strategy to address nonpoint source water pollution issues, which included natural resource-based planning (e.g., land use plans that prioritize natural resource protection), low-impact site design components (e.g., vegetation buffers, porous pavement), and development and implementation of best management practices in sub-watershed areas of highest pollution contribution.

Phase of Adaptation: Awareness, Assessment, Planning


Land managers, water utility managers, natural resource managers, local authorities, planners, policy makers

Managing Organizations

This organization was established in 2014 when NOAA combined two offices: the Coastal Services Center and the Office of Ocean and Coastal Resource Management. The basic missions of the two programs remain intact, but the new organizational structure is bringing value-added services to taxpayers.

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