Groundwater Quality in North Carolina

About:

Groundwater Management Branch (GWMB) staff collect groundwater quality data throughout the state. Most of the groundwater quality data being collected is from the Division of Water Resources (DWR) Monitoring Well Network (MWN). The DWR MWN consists of 698 groundwater wells at 239 sites across North Carolina. These wells range in age from 50+ years to less than a year old. A typical well site in the Coastal Plain may have several wells, each screened in one of the different aquifers at that particular location, while most well sites in the Piedmont and Mountain regions of the state have only one well in the basement rock/saprolite aquifer system.

These wells are, in most cases, located in areas where influence by industry or other land-use practices on groundwater quality is unlikely. This, along with the MWN's broad geographic and geologic coverage, provides prime conditions and an excellent opportunity to conduct a detailed characterization of ambient, or background, groundwater quality from both deep and shallow aquifer systems throughout the state. Currently, a long-term sampling project is underway to collect water quality data from all wells in the network.

Goals:

• Collect chemical data that describes the overall condition of groundwater quality across the state based on the geologic environment, identifying areas where groundwater quality does not meet the NC 02L Standards
• Characterize groundwater quality in the different aquifers present in the NC Coastal Plain using the DWR MWN
• Monitor water quality trends and characterization of ambient groundwater quality within defined geologic environments
• Collect samples from all MWN wells initially, then re-sample on a regular basis. Surficial and first confined aquifer wells will be sampled every 1 to 3 years, and deeper aquifer wells will be sampled every 5 to 10 years.
• Make all GWMB-collected groundwater quality data publicly available for viewing and downloading in a user-friendly mapping application and various other formats

Groundwater Monitoring Equipment:

GWMB staff use a variety of groundwater monitoring equipment for data collection. Click here to learn more about our specialized equipment.

Water Quality Indicators:

Field parameters: temperature, pH, specific conductivity, dissolved oxygen (DO), oxidation-reduction potential (ORP), turbidity, salinity

Laboratory parameters: metals (total and dissolved), nutrients, wet chemistry, microbiological parameters, volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), pesticides, per- and polyfluoroalkyl Substances (PFAS)

Results:

The State uses comprehensive water quality monitoring and assessment information on environmental conditions and changes over time to support water quality management decisions. This information helps to set levels of protection in water quality standards and to identify problem areas that are emerging or that need additional regulatory and non-regulatory actions. Results from this project will yield valuable groundwater quality data throughout the state and inform decision making regarding the relationship of groundwater quality to environmental quality and public health. While the focus of this study was originally intended to identify potential agricultural influences on drinking water in the Coastal Plain, data from this project will support multiple programmatic areas such as nutrient management, coal ash management, groundwater as a source of surface water parameters of concern, and saltwater intrusion.

Data is available for viewing and downloading from our groundwater quality webpage or through our groundwater quality mapping interface.

Collaborations:

The GWMB has established collaborations with researchers and educators from NC State University, Duke University, and Virginia Tech. Collaborations typically consist of the GWMB providing the samples and relevant background data, while the participating collaborator provides sample bottles, lab analysis, data, and data analysis. We continue to seek collaborations, so if you are interested, please send an email to [email protected].

History of Groundwater Quality Monitoring in North Carolina:

The idea of a broad-scale baseline (or background) groundwater quality monitoring program is not a new one; various agencies in North Carolina have been monitoring groundwater quality for over 70 years.

The U.S. Geological Survey (USGS) began a formal program of groundwater quality monitoring in North Carolina in the 1940s. Systematic monitoring by the State began in 1964 with the establishment of the first regional field offices and with installing new monitoring wells to study groundwater quality and the effects of withdrawing significant amounts of groundwater. A field analysis and a laboratory analysis typically were performed on each well. Initially, laboratory efforts focused only on inorganic parameters -- mainly metals and wet chemistry.

Prior to 1974 State groundwater quality monitoring activities were mostly concerned with saltwater intrusion, periodic analysis of public water supply wells by USGS, and monitoring pollution or potential pollution at a few select sites like landfills, chemical waste lagoons, and toxic waste burial sites. Beginning in June of 1974 a more comprehensive groundwater quality monitoring program was implemented with several major goals. These included an inventory of the natural quality of the state's groundwater by area and aquifer, an inventory of existing and potential groundwater pollution sources, review of waste-disposal permit applications, establishment of an adequate water level and quality monitoring system, and development of groundwater quality standards, classification, and regulatory implementation. At that time, two monitoring networks were established, one for groundwater impacted by human activities and one for groundwater not impacted by human activities (for baseline groundwater data). By the early 1980s, approximately 15,000 groundwater analyses had been conducted by the State Groundwater Program.

In May 1985, a more formal Baseline Water Quality Network was established. The plan at that time was to sample 200 of the state monitoring well network's 380 wells in four aquifer systems and six hydrogeologic units. Organic parameters, including pesticides, herbicides, and volatiles, were added to the suite of analyses performed on each groundwater sample. However, between the mid-1980s and the late-1990s, little information has been located about the condition of the quality aspect of the groundwater monitoring network.

From the late-1990s through the early-2010s, the State conducted a cooperative study with the USGS to increase the knowledge base of crystalline rock hydrogeologic conditions at various locations in the Piedmont and Mountain regions in North Carolina. This study is referred to as the Piedmont-Mountains Resource Evaluation Program, or simply REP. Organizational restructuring in the early-2010s led to shifting of personnel, priorities, and funding. Many of the REP sites are no longer monitored, but most of the wells still exist. More information can be found on the REP webpage and water quality data can be found here.

From 2010 to 2012, a broadly-scoped study of isolated wetlands (IWs) was conducted in southeastern NC and northeastern South Carolina. The groundwater portion of this study included long-term groundwater quality monitoring of several dozen wells, three aquifer pumping tests, and water level measurements. Data from this project clearly demonstrated that IWs are hydrologically connected to nearby water bodies with a surface connection to regulated streams. A full report on the Isolated Wetlands study can be viewed here and water quality data can be found here. And if you’re interested, we have over 75 years of other groundwater publications available for your viewing here.

In 2015, the idea of sampling all the state-owned monitoring wells as a means to understand background groundwater quality resurfaced. Work on the latest version of this project began as a pilot study in late 2015 with sampling wells in Sampson and Duplin counties to establish methods, streamline procedures, and procure proper equipment. Since the Summer of 2016, sampling has continued beyond these two initial counties and now, as of Summer 2020, includes 31 counties.