Chapter 5 Threats
hydropower generation can significantly change flow regimes downstream of hydropower dams.
Large hydropower facilities are typically peaking operations: they generate electricity during peak demand periods. As a result, large volumes of water are released to generate electricity during peak energy demand periods and water releases diminish during low energy demand periods so that the available water supply can be replenished for future use. This results in a flow regime that can be vastly different from the natural flow regime in terms of magnitude, frequency, duration, timing, and rate of change (Poff et al. 1997) . These flow regime alterations can cause changes to the aquatic community, including local extirpation of species. Dams also fragment habitats and disrupt the movements and migrations of fish and other aquatic organisms. Diadromous fish are those that spend part of their life in the ocean and part of their life in freshwater. They include Striped Bass, American Shad, American Eel, and Shortnose Sturgeon. These species are particularly vulnerable to blockages imposed by dams. Upstream and downstream passage facilities and strategies are often required to reconnect populations of these species to their necessary habitats. The combined effects of barriers and altered flows can affect other important riverine processes, such as bedload and sediment transport, nutrient cycling, and woody debris transport. 5.5.5 Mining and Quarries – Anticipated Impacts North Carolina has mines and quarries throughout most of the state that supply sand, gravel, granite, minerals, and other materials used for various development projects. Sand and gravel can be mined from open pits or sometimes directly from rivers. Recently, some exhausted granite quarries have been considered as water supply sources to augment existing water supplies. Existing mines and quarries are expected to expand and new mines and quarries created to continue to supply demand into the future. North Carolina allows mines to operate in streams to dredge out sand and gold. Dredging in- stream incises the channel, which increases flow velocity and causes sedimentation downstream. In-stream mining also increases turbidity and stream temperatures through the loss of riparian vegetation that provides shade. These changes negatively impact aquatic species, often resulting in reduced reproductive success and survival. They can severely impact habitat and sedentary taxa like mussels at the mine site itself. Near-stream mining is also allowed in North Carolina and has similar, although often less severe impacts. Both types of mining operations can also degrade the surrounding riparian habitat and downstream wetland habitats. Fracking activities in other parts of the state will increase the demand for sand and water (NCAFS 2002) .
The primary direct impacts to wildlife resources from mining and quarries (not instream mining) relate to land conversion. Additional impacts can result if stormwater runoff is discharged
5 - 20
2025 NC Wildlife Action Plan
Made with FlippingBook Ebook Creator