Monitoring water-quality and geomorphology in the French Broad River during I-26 construction

Science Center Objects

The North Carolina Department of Transportation (NCDOT) has partnered with the U.S. Geological Survey (USGS) to assess the water-quality and geomorphologic impacts resulting from the I-26 construction projects in western North Carolina. Streamflow, precipitation, and water-quality monitoring data, coupled with periodic assessments of geomorphology, will support the NCDOT construction-site inspections by allowing adaptive responses to potential construction impacts and provide the public with readily accessible, objective information regarding conditions in the French Broad River corridor.

Introduction:

Asheville area monitoring stations

Asheville area monitoring stations.

The North Carolina Department of Transportation (NCDOT) has begun a series of transportation improvement projects (I-26 Connector and I-26 Widening) in western North Carolina. The I-26 Widening project widens a 22-mile stretch of interstate from Hendersonville to Asheville. The I-26 Connector project redesigns a 7-mile stretch of interstate freeway from southwest to northwest Asheville. Construction of the I-26 Connector and I-26 Widening projects will occur within the French Broad River corridor, an area of environmental and cultural significance. The environmental impact assessment identified two endangered species, the Appalachian Elktoe and the Gray Bat, with a possible presence within the bounds of these projects. Construction will also take place in recreational areas that provide opportunities for kayaking, rafting, and fishing. The NCDOT has committed to minimizing environmental impacts resulting from the I-26 Connector and Widening projects and aims to become a steward of the French Broad River corridor.

Water-quality monitoring:

Six continuous water-quality monitoring stations were installed in summer 2019 to collect turbidity, specific conductance, dissolved oxygen, pH, and temperature. Locations were selected based on their proximity to construction areas in an effort to capture upstream-downstream differences in water-quality. Find water-quality data online through the USGS National Water Information System:

Geomorphologic monitoring:

Geomorphologic Survey in the French Broad River

Geomorphologic Survey in the French Broad River. (Dan Wagner and Amanda Whaling)

Two reaches of the French Broad River will be surveyed throughout construction to monitor sediment erosion and/or deposition resulting from bridge construction. Bathymetric surveys will be conducted approximately twice per year to map the river bed and calculate changes to bed form between surveys. LiDAR surveys of the river banks will be conducted approximately once per year to identify potential areas of bank erosion or instability. 

Additional monitoring:

Streamflow monitoring is occurring at the following four stations:

 

Water-quality and discharge monitoring equipment at Hominey Creek, near West Asheville, NC

Water-quality and discharge monitoring equipment at Hominy Creek, near West Asheville, NC.

Precipitation monitoring is occurring at the following three stations:

 

A River WebCam located at station 03448050 is posting photos of the French Broad River and is refreshed every 5 minutes. A second River WebCam will be located at 03451500 (near future). See the viewing area for 03448050 below, or explore all River WebCams in the South Atlantic Water Science Center.