Reference Sites


North Carolina streams have many sources of impact, such as private and public land development, point source dischargers, agricultural and urban runoff, as well as increasing climatological changes.  Despite this vast array of pressures, the natural environment of North Carolina retains many streams that, although not pristine, are essentially unimpacted.  This project was initiated to identify streams that have little to no stress from anthropogenic sources, or, for some ecoregions, are the least impacted streams. These identified streams will allow tracking of both human and climate induced impacts by DWR biologists.  Because geology, altitude and watershed size contribute to stream characteristics, existing sample sites in differing Level IV Ecoregions with varying watershed size were identified as suitable candidates for reference sampling. 


The process used to choose reference sites began with evaluation of existing benthos and fish community sample sites. For sites in potentially least-impacted areas, landuse in the watershed was determined (see here for details) using the following categories:

• Percent Forest/Water/Wetland
• Percent Agriculture/Cropland
• Percent Grass/Shrub
• Percent Suburban
• Percent Urban/Barren

 An attempt was made to obtain reference sites from a range of watershed areas in each ecoregion as follows  (detailed criteria are given here):

• One site from a small watershed of less than three square miles
• Two sites from medium sized watersheds of three to 25 square miles
• One site from a large watershed of more than 25 square miles in area

Sites with any of the following characteristics were not considered for reference conditions:

• Low “natural” landscape area 
• The presence of one or more NPDES permitted dischargers upstream for small and medium watersheds
• The presence of a potential local source of impact

List of Current NCDWR Biological Reference Sites


NCDWR Reference Site Locations (click site for details)