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

Figures & data

Figure 1. Map of the Matanuska–Susitna basin

Table 1. Functional Components and Stressors of the Index of Catchment Integrity (ICI) and Index of Watershed Integrity (IWI). The stressors used for the ICI are accumulated at the catchment (CM) scale while the stressors used for the IWI are accumulated at the watershed (WS) scale. A ‘+’ denotes a stressor is included in a functional component, while a blank signifies it is absent

		Functional Components
		Hydrologic Regulation	Regulation of Water Chemistry	Sediment Regulation	Hydrologic Connectivity	Temperature Regulation	Habitat Provision
Stressors	DenCDP	+			+
	DenCulv	+	+	+	+
	DenHouseRp						+
	DenMat		+	+
	DenMine		+	+
	DenPoll		+			+
	DenResvr	+	+	+	+	+	+
	DenSepSew		+		+	+
	DenSubd				+
	DenTransp			+
	DenTranspRp						+
	DenTranspStCrs						+
	PctAg	+	+			+	+
	PctAgRp				+
	PctImp	+
	PctUrb		+
	PctUrbRp				+	+	+
	SlopeTranspStCrs				+

Key (an asterisk, ‘*’, denotes stressors identified by the Mat-Su Basin Salmon Habitat Partnership):

DenCDP - Density of Canals, Ditches, and Pipelines

DenCulv - *Density of Culverts

DenHouseRp - Density of Housing within the Riparian Zone

DenMat - *Density of Conditional Use Permits for Gravel, *Parcels with Material Sales, *Timber Sales

DenMine - Density of Mines, *Historical Mining Disturbance, *State Prospecting Sites

DenPoll - Density of Contaminated Sites, Wastewater Treatment Facilities, Industrial Facilities

DenResvr - Density of Reservoirs

DenSepSew - *Density of Septic and Sewer

DenSubd - *Density of Cadastral Subdivisions

DenTransp - Density of Transportation (*Airports, Roads, Railroads, Trails)

DenTranspRp - Density of Transportation (*Airports, Railroads, Roads, Trails) in the Riparian Zones

DenTranspStCrs - Density of Transportation (Railroad, Road, Trail)-Stream Intersections

PctAg - Percent of Agricultural Land Cover

PctAgRp - Percent of Agricultural Land Cover in the Riparian Zone

PctImp - Percent Imperviousness of Human-Related Landscapes

PctUrb - Percent of Urban Land Cover

PctUrbRp - Percent of Urban Land Cover in the Riparian Zone

SlopeTranspStCrs - Density of Transportation (Railroad, Road, Trail)-Stream Intersections Weighted by the Slope of the Stream Reach

Figure 2. Maps of the ICI results (top) and the IWI results (bottom)

Figure 3. Map of the changes to ICI values caused by scenario 1 (top) and map of the changes to IWI values caused by scenario 1 (bottom) where A_c highlights large changes to ICI scores in catchments with high integrity along the Denali Highway; B_c highlights large changes to ICI scores in catchments with high integrity along the Petersville Road, and B_W highlights large downstream changes to IWI scores in watersheds with high integrity; C_c highlights the relatively small changes to ICI scores in the highly developed core area compared to C_W, which highlights larger changes to the IWI scores or the accumulated downstream impact of scenario 1