Assessment Working Group RENCI at UNCA, NC DENR Natural Heritage Program, Mars Hill College, Land-of-Sky Regional Council, NC Department of Community Assistance |
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| A Project of Land-of-Sky Regional Council 339 New Leicester Hwy. Asheville, NC 28806 ph: (828) 251-6622 fax: (828) 251-6353 |
| Linking Lands and Communities in the Land-of-Sky Region Creating a framework for conservation and development that respects community values and natural systems |
The Water Quality Assessment: Using a Watershed Approach
Assessment Purpose
The purpose of the Water Quality Assessment is to identify lands in the region that are valuable for producing
clean water. The Water Quality Assessment was developed using a watershed approach, where sub-basins
throughout the region were individually prioritized and ranked based on their land cover, stream quality,
elevation, and ownership & protection status.
Sub-Basins
Dataset: DEM (Digital Elevation Model)
A total of 3,525 sub-basin units were generated for the 5-county region. Each was generated using the DEM
(Digital Elevation Model) using ArcHydro toolsets for ArcMap. This dataset classifies basin into smaller units
than the typical 14-digit hydrologic unit codes. The model prioritizes high elevation and forested sub-basins
that contain a stream or network of streams known to have good-to-excellent water quality.
Land Characteristics
Datasets: NCLD, 2006, DEM,SAHC and CMLC Protected Lands, Boundaries of US National Forest and NC
State forest lands; Boundaries of National Park Service lands; Parks and recreation resources from counties
and municipalities.
Lands adjacent to streams and other waterways have a significant impact on the region’s water quality. For
this reason, the dominant land cover in each sub-basin was used to assign initial rankings. Three categories
of land cover were deciphered using the National Land Cover Dataset (NCLD, 2006), including:
cropland received a medium-low ranking of 4; and sub-basins that are mostly developed lands received a low
ranking, between 1 and 3.
Within forested sub-basins, additional datasets and attributes were used to assign final rankings. Since
higher elevation areas are known to contain many headwater streams, these sub-basins received either an 8
or a 10, depending on the known water quality within the sub-basin. Land ownership was also taken into
consideration, where protected lands and sub-basins with conservation easements received a either an 6 or
an 8, depending on the dominant land cover in the sub-basin.
Stream Water Quality
Datasets: Water Supply Watersheds, High Quality Waters (HQW), Outstanding Resource Waters (ORW),
Stream Bioclassification; Native Trout Streams
A variety of datasets were used to assess the water quality in streams across the region. From these, two
categories of water quality were developed: moderate to high quality waters and high quality streams. Sub-
basins containing one or more high quality streams received a ranking of 9 or 10 depending on the area’s
elevation. Sub-basins containing one or more moderate –high quality streams received a ranking of 7 or 8,
depending on other factors present (including elevation and protection/ownership status).
Assessment Purpose
The purpose of the Water Quality Assessment is to identify lands in the region that are valuable for producing
clean water. The Water Quality Assessment was developed using a watershed approach, where sub-basins
throughout the region were individually prioritized and ranked based on their land cover, stream quality,
elevation, and ownership & protection status.
Sub-Basins
Dataset: DEM (Digital Elevation Model)
A total of 3,525 sub-basin units were generated for the 5-county region. Each was generated using the DEM
(Digital Elevation Model) using ArcHydro toolsets for ArcMap. This dataset classifies basin into smaller units
than the typical 14-digit hydrologic unit codes. The model prioritizes high elevation and forested sub-basins
that contain a stream or network of streams known to have good-to-excellent water quality.
Land Characteristics
Datasets: NCLD, 2006, DEM,SAHC and CMLC Protected Lands, Boundaries of US National Forest and NC
State forest lands; Boundaries of National Park Service lands; Parks and recreation resources from counties
and municipalities.
Lands adjacent to streams and other waterways have a significant impact on the region’s water quality. For
this reason, the dominant land cover in each sub-basin was used to assign initial rankings. Three categories
of land cover were deciphered using the National Land Cover Dataset (NCLD, 2006), including:
- • Developed lands (including Low, Medium, and High intensity Developed Lands)
• Cropland (including Grassland/Herbaceous, Pasture/Hay; Cultivated Crops)
• Forested Lands (including Deciduous, Evergreen, and Mixed Forests and Shrub/Scrub)
cropland received a medium-low ranking of 4; and sub-basins that are mostly developed lands received a low
ranking, between 1 and 3.
Within forested sub-basins, additional datasets and attributes were used to assign final rankings. Since
higher elevation areas are known to contain many headwater streams, these sub-basins received either an 8
or a 10, depending on the known water quality within the sub-basin. Land ownership was also taken into
consideration, where protected lands and sub-basins with conservation easements received a either an 6 or
an 8, depending on the dominant land cover in the sub-basin.
Stream Water Quality
Datasets: Water Supply Watersheds, High Quality Waters (HQW), Outstanding Resource Waters (ORW),
Stream Bioclassification; Native Trout Streams
A variety of datasets were used to assess the water quality in streams across the region. From these, two
categories of water quality were developed: moderate to high quality waters and high quality streams. Sub-
basins containing one or more high quality streams received a ranking of 9 or 10 depending on the area’s
elevation. Sub-basins containing one or more moderate –high quality streams received a ranking of 7 or 8,
depending on other factors present (including elevation and protection/ownership status).
- • Moderate to high quality streams include streams protected for Class C uses by NC Department of
Water Quality (WS III-V) OR rated “Good” through benthos (aquatic bugs) sampling. Class C waters
are protected for uses such as secondary recreation, fishing, wildlife, fish consumption, aquatic life
including propagation, survival and maintenance of biological integrity, and agriculture. Secondary
recreation includes wading, boating and other uses involving human body contact with water.
• High quality streams include streams designated as HQW (High Quality Waters) or ORW
(Outstanding Resource Waters) by NC Department of Water Quality; and streams with known naturally
and reproducing strains of brook trout, and/or ratings of “Excellent” through Benthos (aquatic bugs)
sampling.
| The following documents and maps are available here: Water Quality and Conceptual Model Data Sources and Descriptions Water Quality Assessment Map Water Quality Map Legend Water Quality Assessment Fact Sheet |