Cape Fear River Basin 1,4-Dioxane Wastewater Discharge Data
1,4-Dioxane Background
EPA has identified 1,4-dioxane as a likely human carcinogen. See EPA’s Risk Evaluation for 1,4-dioxane.1,4-Dioxane is used for a variety of industrial purposes.
The U.S. Environmental Protection Agency's Third Unregulated Contaminant Monitoring Rule (UCMR 3) required public water supply systems throughout the United States to monitor for the presence of contaminants, including 1,4-dioxane, in drinking water in 2013-2015. Results of UCMR 3 monitoring indicated the presence of 1,4-dioxane in North Carolina was most prevalent within the Cape Fear River Basin.
Beginning in 2014, NCDEQ's Division of Water Resources (DWR) has conducted sampling studies to further quantify the in-stream concentrations of 1,4-dioxane and their potential sources within the basin. DEQ also required direct dischargers to sample their discharge for 1,4-dioxane. For details on monitoring, studies and additional actions taken by DWR, see the information below.
Overview
DWR continues to sample municipal wastewater treatment plants and surface waters across the Cape Fear River Basin. In addition, DWR continues to assist municipalities to minimize or reduce 1,4-dioxane coming from industrial wastewater. Significant reductions have occurred at some wastewater treatment plants through a collaborative effort with the Environmental Management Commission and DEQ. DEQ will continue to work with the EMC to seek further reductions in 1,4-dioxane discharges. DEQ is also exploring other avenues for protecting drinking water. To read more about specific actions taken to manage 1,4-dioxane in wastewater discharge in the Cape Fear River Basin, see the final report delivered to the N.C. Environmental Management Commission Water Quality Committee in November 2024 and the 2nd Annual 1,4-dioxane Progress Report in January 2024.
In August 2023, DWR included 1,4-dioxane permit limits in Asheboro’s National Pollutant Discharge Elimination System (NPDES) permit. In September 2024, the North Carolina Office of Administrative Hearings issued an order striking these limits. DEQ has appealed that ruling and EPA has objected to the ruling’s removal of the 1,4-dioxane limits from the permit. Because 1,4-dioxane has been determined to be a likely human carcinogen, DEQ agrees with the EPA that limits are necessary to protect North Carolinians’ drinking water.
1,4-Dioxane Detections in Municipal Wastewater Discharges
DWR has conducted monitoring at select wastewater treatment plants identified to have elevated levels of 1,4-dioxane in their discharge to the Cape Fear River Basin, including Asheboro, Burlington, Greensboro, High Point and Reidsville. The concentrations detected in the wastewater discharge of those plants since the beginning of 2024 are shown below. The data include concentrations of 1,4-dioxane measured in "grab samples," or wastewater samples taken at a single point in time by the facility. For 1,4-dioxane, the grab samples are performed using an EPA-certified test method. In addition, the data also display "composite" data collected by DWR staff. Composite data measure the concentrations of 1,4-dioxane in combined samples collected across a period of time. The composite samples are taken for informational purposes to understand levels of 1,4-dioxane traveling through the wastewater treatment plant in a week.
Asheboro Wastewater Treatment Plant
The Asheboro Wastewater Treatment Plant submits grab sample data for 1,4-dioxane to DWR. The 2024 and January 2025 data are shown in the graph below. In addition, you can also view the data displayed in a table: Asheboro WWTP 2024-25 Grab Sample Data. A graph showing the facility grab sample monthly average is also available: Asheboro WWTP Monthly Average Grab Samples 2024-25.
The graph below shows 1,4-dioxane detections in data collected by DWR. The graph shows concentrations of 1,4-dioxane found in weekly composite samples, meaning the level of 1,4-dioxane measured in a collection of multiple wastewater samples drawn on multiple days. In addition, you can also view the data displayed in a table: Asheboro 2024-25 Composite Data.
South Burlington Wastewater Treatment Plant
South Burlington WWTP submits grab sample data for 1,4-dioxane to DWR. The 2024 data are shown in the graph below. In addition, you can also view the data displayed in a table: South Burlington WWTP facility grab data 2024.
The graph below shows 1,4-dioxane detections in data collected by DWR for the South Burlington WWTP. The graph shows concentrations of 1,4-dioxane found in weekly composite samples, meaning the level of 1,4-dioxane measured in a collection of multiple wastewater samples drawn on separate days across a week. In addition, you can also view the data displayed in a table: Burlington South WWTP Composite Data 2024.
High Point Eastside Wastewater Treatment Plant
The High Point Eastside WWTP submits grab sample data for 1,4-dioxane to DWR. The 2024 data are shown in the graph below. In addition, you can also view the data displayed in a table: High Point Eastside Facility Grab Sample Data 2024.
The graph below shows 1,4-dioxane detections in data collected by DWR for the High Point Eastside WWTP. The graph shows concentrations of 1,4-dioxane found in weekly composite samples, meaning the level of 1,4-dioxane measured in a collection of multiple wastewater samples drawn on separate days across a week. In addition, you can also view the data displayed in a table: High Point Eastside WWTP DWR Composite Data 2024.
Greensboro T.Z. Osborne Wastewater Treatment Plant
Greensboro's T.Z. Osborne WWTP submits grab sample data for 1,4-dioxane to DWR. The 2024 data are shown in the graph below. In addition, you can also view the data displayed in a table: Greensboro WWTP Grab Sample Data 2024.
East Burlington Wastewater Treatment Plant
The East Burlington WWTP submits grab sample data for 1,4-dioxane to DWR. The 2024 data are shown in the graph below. In addition, you can also view the data displayed in a table: East Burlington 2024 Grab Sample Data.
Reidsville Wastewater Treatment Plant
The Reidsville WWTP submits grab sample data for 1,4-dioxane to DWR. The 2024 data are shown in the graph below. In addition, you can also view the data displayed in a table: Reidsville WWTP Grab Sample Data 2024.
