Science Inventory

Applying the index of watershed integrity to the Matanuska–Susitna basin


Aho, K., J. Flotemersch, S. Leibowitz, M. LaCroix, AND M. Weber. Applying the index of watershed integrity to the Matanuska–Susitna basin. Arctic, Antarctic, and Alpine Research. Taylor & Francis Group, London, Uk, 52(1):435-449, (2020).


Our first objective was to pilot application of the ICI and IWI at a more regional scale that would facilitate the incorporation of local and regional anthropogenic stressors into the ICI and IWI. Incorporation of local stressors would allow for consideration of stressors critical to, and actionable by, watershed managers of the study area. Our second objective was to use the newly developed regional-scale model to demonstrate how information provided by the IWI could be used to create a practical scenario of value to decision-makers and environmental planners of the study area.


The Matanuska–Susitna Borough is the fastest growing region in the State of Alaska and is impacted by a number of human activities. We conducted a multiscale assessment of the stressors facing the borough by developing and mapping the Index of Watershed Integrity (IWI) and Index of Catchment Integrity (the latter considers stressors in areas surrounding individual stream segments exclusive of upstream areas). The assessment coincided with the borough’s stormwater management planning. We adapted the list of anthropogenic stressors used in the original conterminous United States IWI application to reflect the borough’s geography, human activity, and data availability. This analysis also represents an early application of the NHDPlus High Resolution geospatial framework and the first use of the framework in an IWI study. We also explored how remediation of one important stressor, culverts, could impact watershed integrity at the catchment and watershed scales. Overall, we found that the integrity scores for the Matanuska–Susitna basin were high compared to the conterminous United States. Low integrity scores did occur in the rapidly developing Wasilla–Palmer core area. We also found that culvert remediation had a larger proportional impact in catchments with fewer stressors.

Record Details:

Product Published Date: 08/27/2020
Record Last Revised: 10/06/2020
OMB Category: Other
Record ID: 349822