Chapter 4 Habitats
4.2.3 Coldwater Systems 4.2.3.1 Ecosystem Description
Coldwater habitats can be found in different sized streams in the Mountain ecoregion, certain locations within the Piedmont ecoregion, and in springs or groundwater-fed systems found in all ecoregions of the state. Often the streams are headwaters in the Mountains, but the upper portions of some small- and medium-river systems can have coldwater habitats if they are influenced by cooling water discharges from hydropower facilities or effluent discharges from industrial processes. The coldwater designation is based upon two general principles: temperature regime and fish community structure. When used to classify coldwater streams, the temperature regimes of summer water temperatures typically do not exceed 20 degrees Celsius (°C) [68 degrees Fahrenheit (°F)]. This is a suggested temperature that will usually support a coldwater fish community structure that includes salmonid species (e.g., trout species) (USACE 2003) . For migrating salmonids in the Pacific northwest, the EPA recommends a 7-day average daily maximum water temperature of 20°C (USEPA 2012a) . McCullough et al. ( 2009 ) suggest 22°C–23°C as a threshold for juvenile salmonid species. A review of research literature seems to indicate the need for availability of a temperature gradient appropriate to support differing size, age, and possibly sex of the species. Whether the seasonal and daily variation of water temperature is natural or induced, the temperature will influence the distribution of aquatic species in this aquatic system ( Caissie 2006 ). Coldwater streams generally have a fish species composition that includes: Brook, Brown, and Rainbow trout, Mottled Sculpin, Longnose and Blacknose Dace, and Central Stoneroller. This list of species is not inclusive and is provided as general guidance on community structure. Table 4.2.3-1 lists the type of aquatic natural communities that may provide coldwater habitats and the ecoregion where they likely occur. Descriptions of these natural communities can be found in later sections of this chapter.
Table 4.2.3-1 Aquatic natural communities containing coldwater habitats Stream Size Ecoregions Springs/Groundwater/Cave Waters Statewide Headwaters/Small Creeks (< 40 sq.mi. DA) Mountain, Piedmont Large Creeks/Small Rivers (40–200 sq.mi. DA) Mountain, Piedmont Medium Rivers (200–3,800 sq.mi. DA) Mountain, Piedmont Reservoirs & Impoundments Mountain
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2025 NC Wildlife Action Plan
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