Chapter 4 Habitats
Five western basins in the state are part of the Interior Basin and drain to the Mississippi River and the Gulf of Mexico (Hiwassee, Little Tennessee, French Broad, Watauga, and New). North Carolina boundaries for these five river basins, along with the Savannah River Basin, are entirely within the Mountain ecoregion, which dominates the western third of the state. Generally, streams in the Mountain ecoregion are relatively high gradient with cool waters, have boulder and cobble-gravel bottoms, and are of low-to-moderate fertility. Larger streams and rivers have historically supported exceptionally diverse warmwater communities. The other 12 basins of the state are part of the Atlantic Slope and flow to the Atlantic Ocean. The headwaters of the Broad, Catawba, and Yadkin-Pee Dee River basins drain the eastern slopes of the Mountains. These river systems drain toward the ocean through the rolling topography of the Piedmont, where all but three of the remaining river basins originate. The Piedmont is a mosaic of broad valleys interspersed with highlands of varying topography and geology. Streams in the Piedmont are generally warmwater systems, have cobble-gravel and sand bottoms, and are of intermediate gradient and fertility. The fall line marks a change in topography from the Piedmont to the flat terrain of the Coastal Plain. The North Carolina basins of the White Oak, Chowan, and Pasquotank rivers are entirely within the Coastal Plain ecoregion and are characterized by low gradient warmwater streams with sand and mud bottoms and high fertility. Natural lakes and extensive wetlands are important aquatic habitats found only in North Carolina’s Coastal Plain ecoregion. A method developed by the US Geological Survey (USGS) spatially organizes drainage areas (DAs) by dividing watersheds into successively smaller hydrologic units based on four levels: regions, subregions, accounting units, and cataloging units (Seaber et al. 1987) . The hydrologic units are arranged or nested within each other, from the largest geographic area (regions) to the smallest geographic area (cataloging units). Regional hydrologic units are identified by a unique two-digit hydrologic unit code (HUC), but smaller units may represent the most useful planning unit. The HUCs and associated maps have undergone extensive review by principle federal, regional, and state water-resource agencies and are widely accepted for use in planning and data sharing (Seaber et al. 1987) . In North Carolina, 12-digit HUCs are commonly used for sharing aquatic resource data. Surface water classifications are another tool used in North Carolina to manage and protect state waters. The NCDWR assigns primary classifications to freshwaters to designate the highest and best uses (e.g., drinking water supplies, recreation) for conservation within the surface waters. Each classification has an associated set of water quality standards to protect those uses. All waters must at least meet the standards for Class C (fishable/swimmable) waters. The other primary classifications provide additional levels of protection for water contact recreation (Class B) and drinking water (Water Supply Classes I through V). Streams, rivers, and lakes may have several classifications applied to the same area because they protect different uses or special characteristics of the waterbody (NCDEQ 2025f,g) .
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2025 NC Wildlife Action Plan
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