Source Water Assessment Program (SWAP) Additional Data Information

Welcome to the NC SWAPInfo website. The following is a description of information pertaining to the data and methodology of North Carolina’s Source Water Assessment Program (SWAP) model.

Source Water vs. Treated Water

Source water is the untreated water from a stream, river, lake, or groundwater aquifer that is used to supply public drinking water. SWAP assessments highlight factors that could potentially influence the quality of source water. SWAP assessments do not reflect the quality of water that is ultimately provided for public consumption because source water is treated and monitored before it reaches the consumer. The quality of treated public drinking water is regulated through the federal Safe Drinking Water Act and the North Carolina Rules Governing Public Water Systems.

Assessment Methodology

The methodology developed to assess the susceptibility of public drinking water sources to potential contamination is based on expert opinion concerning the relative importance of factors that can impact water quality, not scientific experimentation. The methodology is also based on United States Environmental Protection Agency (USEPA) guidance and input provided by a Technical and Citizen (TAC) Advisory Committee.

A source water’s final susceptibility rating is a function of the following two parameters: the contaminant rating and the inherent vulnerability rating. The contaminant rating is determined from an inventory of the potential contaminant sources (PCS) that occur in the source water’s assessment area.  To complete this analysis each PCS type has an assigned risk category of higher, moderate, or lower. These risk catagories can differ depending on the source water type. The risk categories were assigned to each PCS type using input from the TAC Advisory Committee. A higher risk category represents a relatively higher risk for source contamination.

PCS types and their associated risk category

PCS Type Risk Category for Surface Water Sources Risk Category for Groundwater Sources
Animal Operations Higher Higher
CERCLA-Fed. Remediation Higher Higher
Hazardous Waste Sites Higher Higher
Inactive Hazardous Waste Sites Higher Higher
Non-Discharge Permits Lower Moderate
NPDES Permits Higher Lower
PCB Sites Higher Higher
Pollution Incidents Higher Higher
Septage Disposal Sites Higher Higher
Soil Remediation Sites Higher Higher
Solid Waste Facilities Moderate Moderate
Tier II Sites Higher Higher
Old Landfill Sites Higher Higher
UIC Permits Lower Moderate
UST Permits Moderate Higher

Disclaimer: Proximity of known potential contaminant sources to public drinking water sources is intended to provide a starting point for local communities to assess conditions that may adversely impact drinking water quality. The Public Water Supply Section is not responsible for any errors in any data displayed or in its corresponding metadata. Decision-making related to sensitive, urgent or legal issues should include due diligence beyond the information provided by this application.

Statewide Data and Automated Analysis

Considering fiscal and schedule constraints, the North Carolina Public Water Supply Section and the TAC Advisory Committee determined that the assessments for approximately 8,000 sources of drinking water must be based on established state-wide data. Also, it was determined that analysis of the data and creation of the assessment reports would need to be an automated process utilizing a Geographic Information System (GIS). Therefore, it must be recognized that the assessment results are based on data for which there is state-wide coverage.

NC Public Water Supply Sources Information

A public water system provides water for human consumption through pipes or other constructed conveyances to at least 15 service connections or serves an average of at least 25 people for at least 60 days a year. There are four main types:

  • Community – A public water system that supplies water to the same population year-round.
  • Transient Non-Community – A public water system that provides water in a place such as a gas station or campground where people do not remain for long periods of time.
  • Non-Transient Non-Community – A public water system that regularly supplies water to at least 25 of the same people at least six months per year, e.g., schools, office buildings and hospitals which have their own water systems.
  • Adjacent - Two or more water systems that are adjacent and are owned or operated by the same supplier of water and that together serve 15 or more service connections or 25 or more persons. An example of an adjacent water system is adjoining mobile home parks that together meet the community water system definition.

The Public Water Supply (PWS) sources data was created from a data extraction from the Safe Drinking Water Information System database in May of 2020. This database contains all the active drinking water sources in North Carolina. These sources include surface water intakes where the water is pumped and treated from a river, lake or reservoir, and groundwater wells where the water is pumped and treated from underground aquifers - natural reservoirs below the earth's surface. These sources were mapped using various methods, primarily mapping grade Global Positioning System units (GPS) with differential correction. You may download a copy of this data at the following website: https://www.nconemap.gov/. For additional information about this data, contact the Drinking Water Protection staff at the following website: https://deq.nc.gov/about/divisions/water-resources/drinking-water/drinking-water-protection-program/contact.

Potential Contamination Source Data

As stated above, to maintain a common basis for assessing sources of public drinking water in North Carolina, only regulatory agency databases with state-wide coverage were used to develop the inventory of PCSs. Within these databases, only those PCSs with available location data could be used. All PCS datasets were provided to the Public Water Supply Section "as is"; therefore, the accuracy of the location data is unverified. It is recognized that some problems exist with respect to the accuracy, reliability, quality and completeness of the data obtained from regulatory agency databases. The Public Water Supply Section makes no claim or guarantee of data quality, correctness, completeness, or validity and does not warranty or assure this data in any way.

Unless otherwise noted, all data containing latitude and longitude was included in the assessments. Records that did not have location information were not used. A GIS shapefile was created using the latitude and longitude in decimal degrees.

Animal Operations

This data set represents permitted animal facilities consisting of swine, cattle, poultry and horse farms that are required to have Certified Animal Waste Management Plans (CAWMP). Animal facilities are defined by General Statute 143-215.10B as feedlots involving 250 or more swine, 100 or more confined cattle, 75 or more horses, 1,000 or more sheep, or 30,000 or more confined poultry with a liquid waste management system.

The Division of Water Resources’ (DWR) rules mandated that all animal facilities in operation prior to January 1, 1994 register with the division. Since January 1, 1994, any new animal facilities were required to obtain a CAWMP before starting their animal operation. In addition, any animal facilities in operation prior to January 1, 1994 were required to obtain a CAWMP by December 31, 1997. As of January 1, 1997, all new animal facilities were required to obtain a permit from DWR prior to construction and be certified prior to startup, and all existing animal facilities were to be permitted by DWR over the next 5 years.

The data set was obtained from the DWR, Water Quality Regional Operations, Animal Feeding Operations Branch in February of 2019. For additional information about this data, contact the Animal Feeding Operations staff by phone at 919-707-9129 or visit their website at: https://deq.nc.gov/about/divisions/water-resources/water-quality-permitting/animal-feeding-operations.

CERCLA-Fed. Remediation

This data set was provided by the Federal Remediation Branch (FRB), which is part of the Superfund Section within the N.C. Division of Waste Management. It represents sites where the FRB is working with USEPA, and in some cases the Department of Defense, to investigate, assess, remediate, or monitor hazardous waste contamination. These sites are regulated under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), which established authority for the government to respond to the release/threat of release of hazardous waste, including cleanup and enforcement actions. Some of these sites, which meet specific criteria set out in the USEPA's Hazard Ranking System (HRS), are included on the National Priorities List (NPL). The NPL identifies sites that appear to warrent cleanup measures. The NPL sites are eligible for remedial action financed by a federal trust fund with a state cost share or by potential responsible parties (PRP).

The data set was downloaded from the NC Department of Environmental Quality Online GIS website at: https://data-ncdenr.opendata.arcgis.com/datasets/federal-remediation-branch. It was dated May 23, 2019. For additional information about this data, contact the Division of Waste Management, Federal Remediation Branch by phone at 919-707-8213 or visit their website at: https://deq.nc.gov/about/divisions/waste-management/superfund-section/federal-remediation-branch.

Hazardous Waste Sites

This data set represents the location of sites within North Carolina that are regulated by the hazardous waste portions of the Resource Conservation and Recovery Act (RCRA). This includes large quantity generators, small quantity generators, transporters of hazardous waste, permitted treatment, storage, or disposal (TSD) facilities and TSD facilities that are under an Order or a Consent Agreement. (Note: facilities that are conditionally exempt small quantity generators may also be included if they are also a transporter or TSD facility.) The data is extracted from the USEPA RCRAInfo database.

The data set was downloaded from the NC Department of Environmental Quality Online GIS website at: https://data-ncdenr.opendata.arcgis.com/datasets/hazardous-waste-sites. It was dated March 19, 2019. For additional information about this data, contact the Division of Waste Management, Hazardous Waste Section staff by phone at 919-707-8202 or visit their website at: https://deq.nc.gov/about/divisions/waste-management/hw.

Inactive Hazardous Waste Sites

This data set represents hazardous substance spill and disposal sites and includes active and inactive facilities and a variety of property types. Some of the sites are regulated under the CERCLA and are included because they do not fall under the responsibility of other environmental programs. The term "inactive" refers to the fact that cleanup was inactive at large numbers of sites at the time of program enactment. This data set includes closed remediation sites that have land use restrictions recorded as part of the remedy.

The data set was downloaded from the NC Department of Environmental Quality Online GIS website at: https://data-ncdenr.opendata.arcgis.com/datasets/inactive-hazardous-sites-1?geometry=-90.11%2C33.656%2C-69.379%2C36.796. It was dated November 26, 2019. For additional information about this data, contact the Division of Waste Management, Inactive Hazardous Sites Branch by phone at 919-707-8327 or visit their website at: https://deq.nc.gov/about/divisions/waste-management/superfund-section/inactive-hazardous-sites-program.

Non-Discharge Permits

The non-discharge database identifies domestic, industrial, and municipal facilities that are permitted to apply treated wastewater effluent, reclaimed water, and residuals to the land surface.

Data was obtained from the DWR, Water Quality Permitting Section, Non-Discharge Branch in April of 2019. For additional information about this data, contact the program staff by phone at 919-707-3654 or visit their website at: http://deq.nc.gov/about/divisions/water-resources/water-resources-permits/wastewater-branch/non-discharge-permitting.

NPDES Permits

The National Pollutant Discharge Elimination System (NPDES) PCS category consists of multiple data sets identifying facilities permitted for the operation of point source discharges to surface waters in accordance with the requirements of Section 402 of the Federal Water Pollution Control Act. Point sources are discrete conveyances such as pipes or man-made ditches. The NPDES Permit Program controls water pollution by regulating point sources that discharge pollutants into public waters. This category also include facilities with active and expired State Stormwater Permits. The individual data sets that comprise this category include the following

  • NPDES Stormwater Permits

This data set represents the location of facilities with active or expired NPDES Stormwater Permits and facilities with No Exposure Certifications. The goal of the NPDES Stormwater Permitting Program is to prevent stormwater runoff from washing harmful pollutants into surface waters. Both individual and general permits are included. 

Data was obtained from the Division of Energy, Mineral, and Land Resources, Stormwater Permitting Program in February of 2019. For additional information about this data, contact the program staff by phone at 919-707-3639 or visit their website at:  https://deq.nc.gov/about/divisions/energy-mineral-land-resources/stormwater.

  • NPDES Wastewater General Permits

This data set represents the location of active wastewater treatment facilities that are permitted under the NPDES Permit Program. The listed facilities are covered by a general NPDES permit, which is written to cover multiple dischargers with similar operations and types of discharges.    

Data was obtained from the DWR, Water Quality Permitting Section, NPDES Wastewater Permitting Program in February of 2019. For additional information about this data, contact the program staff by phone at 919-707-3601 or visit their website at:  https://deq.nc.gov/about/divisions/water-resources/water-resources-permits/wastewater-branch/npdes-wastewater-permits.

  • NPDES Wastewater Individual Permits

This data set represents the location of active wastewater treatment facilities that are permitted under the NPDES Permit Program. Each listed facility is covered by an individual NPDES permit that is written to reflect the site-specific conditions of the facility based on submitted information. The individual NPDES permit is unique to the facility.     

Data was obtained from the DWR, Water Quality Permitting Section, NPDES Wastewater Permitting Program in February of 2019. For additional information about this data, contact the program staff by phone at 919-707-3601 or visit their website at:  https://deq.nc.gov/about/divisions/water-resources/water-resources-permits/wastewater-branch/npdes-wastewater-permits.

  • State Stormwater Permits

This data set contains the locations of facilities with active and expired State Stormwater Post-Construction Permits. The Post-Construction Permit Program requires subject new developments to install and maintain permanent stormwater management measures that are designed to protect surface waters from the impacts of the development’s stormwater runoff after the construction process is complete. 

Data was obtained from the Division of Energy, Mineral, and Land Resources, Stormwater Permitting Program in March of 2019. For additional information about this data, contact the program staff by phone at 919-707-3639 or visit their website at:  https://deq.nc.gov/about/divisions/energy-mineral-land-resources/stormwater.

PCB Sites

This data set identifies generators, transporters, commercial storers and/or brokers and disposers of Polychlorinated Biphenyls (PCBs). Concern over the toxicity and environmental persistence of PCBs resulted in the Toxic Substances Control Act (TSCA). This act prohibits the manufacture, processing, and distribution in commerce of PCBs. Thus, TSCA legislates true "cradle to grave" (from manufacture to disposal) management of PCBs in the United States. PCBs are mixtures of synthetic organic chemicals with the same basic chemical structure and similar physical properties ranging from oily liquids to waxy solids. Due to their non-flammability, chemical stability, high boiling point and electrical insulating properties, PCBs were used in hundreds of industrial and commercial applications. These included electrical applications, heat transfer materials, hydraulic equipment, plastics, rubber, and many others.

The data set was obtained from the USEPA, Office of Pollution Prevention and Toxics in February of 2019. For additional information about this data, contact the PCB staff at 404-562-8512 or visit their website at: https://www.epa.gov/pcbs/learn-about-polychlorinated-biphenyls-pcbs.

Each record that contained a physical address that could be address matched was included in the data set. Public Water Supply Section staff performed the address matching.

Pollution Incidents

The Pollution Incidents PCS category consists of multiple data sets containing information regarding the release of pollutants into the environment that have, or are likely to have, impact on the groundwater resources of the State. The initial information regarding these releases is usually obtained from responsible parties or concerned citizens, who report a release to the NC Department of Environmental Quality. After an incident is reported, regional office staff investigate the reported incident and enter the results of their investigation into a state-wide database. The individual data sets that comprise this category include the following:

  • AST Incidents

This data set represents sites where there has been a discharge of petroleum to the soil and/or groundwater, from a source other than an Underground Storage Tank (UST) system, e.g., Aboveground Storage Tank (AST) system, spills, dumping, etc. All included records have an incident number and have not been closed out.

This data set was downloaded from the NC Department of Environmental Quality Online GIS website at: https://data-ncdenr.opendata.arcgis.com/datasets/ast-incidents. It was dated June 13, 2019. For additional information about this data, contact the Division of Waste Management, Underground Storage Tank Section staff by phone at 919-707-8171 or visit their website at: https://deq.nc.gov/about/divisions/waste-management/ust/ast-program.

  • Dry-Cleaning Sites - Contaminated

This data set contains an inventory of reported incidents from sites contaminated with dry-cleaning solvents. Substances released into the environment include solvents used in the dry-cleaning process. 

This data set was downloaded from the NC Department of Environmental Quality Online GIS website at: https://data-ncdenr.opendata.arcgis.com/datasets/dry-cleaning-sites-contaminated-1. It was dated May 23, 2019. For additional information contact the Division of Waste Management, Dry-Cleaning Solvent Cleanup Act Program staff by phone at 919-707-8365 or visit their website at: https://deq.nc.gov/about/divisions/waste-management/dry-cleaning-solvent-cleanup-act-program.

  • UST Incidents

This data set represents sites where there has been a release of petroleum to the soil and/or groundwater, from an UST system. All included records have an incident number and have not been closed out.

The data set was downloaded from the NC Department of Environmental Quality Online GIS website at: https://data-ncdenr.opendata.arcgis.com/datasets/ust-incidents?geometry=-166.201%2C-29.535%2C168.311%2C29.229. It was dated June 13, 2019. For additional information about this data, contact the Division of Waste Management, Underground Storage Tank Section staff by phone at 919-707-8171 or visit their website at: https://deq.nc.gov/about/divisions/waste-management/ust.

Septage Disposal Sites

This data set represents all active and permitted Septage Land Application Site (SLAS) and Septage Detention and Treatment Facility (SDTF) sites in North Carolina. The Septage Management Program assures that septage (a fluid mixture of untreated and partially treated sewage solids, liquids, and sludge of human or domestic origin that is removed from a septic tank system) is managed in a responsible, safe and consistent manner across the state.

The data set was obtained from the Division of Waste Management, Solid Waste Section in May of 2019. For additional information about this data, contact the Septage Management Program staff by phone at 919-707-8283 or visit their website at: https://deq.nc.gov/about/divisions/waste-management/waste-management-rules/septage.

Soil Remediation Sites

This data set represents sites that have received a permit from the NC Underground Storage Tank Section, under the Petroleum Contaminated Soil Remediation Permit Program. These sites are used to bioremediate soil that has been contaminated by leaking petroleum storage tanks. Bioremediation is a treatment process that uses naturally occurring microorganisms (yeast, fungi, or bacteria) to break down, or degrade, hazardous substances. These microorganisms break down organic compounds, such as petroleum products that are hazardous to humans, into harmless products (mainly carbon dioxide and water). Sites that have been "closed out" were excluded.

The data set was obtained from the Division of Waste Management, Underground Storage Tank Section in February of 2019. For additional information about this data, contact the Underground Storage Tank Section staff by phone at 919-707-8171 or visit their website at: https://deq.nc.gov/about/divisions/waste-management/ust.

Solid Waste Facilities

This data set represents all the permitted Municipal Solid Waste (MSW), Construction and Demolition (CDLF), Land-Clearing and Inert Debris (LCID) and Demolition (older facilities) landfill facilities. Coal Ash landfills and Tire landfills are also included. These facility types undergo inspections and groundwater monitoring as part of facility management. This data set also includes active solid waste facility types that are not designated as landfills, such as compost, household hazardous waste, incinerators, medical waste, tire processing and transfer stations.   

The data set was obtained from the Division of Waste Management, Solid Waste Section in May of 2019. For additional information about this data, contact the Solid Waste Section staff by phone at 919-707-8247 or visit their website at: https://deq.nc.gov/about/divisions/waste-management/solid-waste-section.

Tier II Sites

This data set contains an inventory of facilities that store hazardous materials and are subject to the reporting requirements of the Emergency Planning and Community Right to Know Act (EPCRA). EPCRA was authorized by Title III of the Superfund Amendments and Reauthorization Act (SARA). Tier II forms require basic facility identification information, employee contact information for both emergencies and non-emergencies, and information about chemicals stored or used at the facility including:

  • The chemical name or the common name as indicated on the Safety Data Sheet (SDS);
  • an estimate of the maximum amount of the chemical present at any time during the preceding calendar year and the average daily amount;
  • a brief description of the manner of storage of the chemical;
  • the location of the chemical at the facility; and
  • an indication of whether the owner of the facility elects to withhold location information from disclosure to the public.

Data, from the 2018 reporting year, was obtained from the Department of Public Safety, Division of Emergency Management. For additional information about this data contact the Division of Emergency Management staff at 919-436-2746 or visit their website at: http://www.ncdps.gov/Emergency-Management/Hazardous-Materials/EPCRA-Tier-2.

Old Landfill Sites

This data set contains the locations of non-permitted landfills that closed prior to January 1, 1983, when waste disposal permitting regulations commenced. These sites are not currently in operation.

The data set was downloaded from the NC Department of Environmental Quality Online GIS website at: http://data-ncdenr.opendata.arcgis.com/datasets/pre-regulatory-landfill-sites-1. It was dated November 14, 2018. For additional information about this data, contact the Division of Waste Management, Pre-regulatory Landfill Program staff by phone at 919-707-8327 or visit their website at: https://deq.nc.gov/about/divisions/waste-management/superfund-section/pre-regulatory-landfill-program.

UIC Permits

The Underground Injection Control (UIC) Program protects groundwater quality by preventing illegal waste disposal and by regulating the construction and operation of wells used for injecting approved substances, aquifer recharge, and other activities. The most common types of injection wells in North Carolina are used for:

  • Aquifer Storage and Recovery (ASR)
  • Geothermal Heating and Cooling
  • In-Situ Groundwater Remediation
  • Stormwater Infiltration - effective May 1, 2012

The data set was obtained from the DWR, Groundwater Protection Program in March of 2019. For additional information about this data, contact the UIC Program staff by phone at 919-807-6496 or visit their website at: https://deq.nc.gov/about/divisions/water-resources/water-resources-permits/wastewater-branch/ground-water-protection/injection-wells.

UST Permits

A UST system is a tank and any underground piping connected to the tank that has at least 10 percent of its combined volume underground. The federal UST regulations apply only to underground tanks and piping storing either petroleum or certain hazardous substances. These facilities are regulated under Subtitle I of RCRA and must be registered with the state and receive an operating permit annually. Until the mid-1980s, most USTs were made of bare steel, which is likely to corrode over time and allow UST contents to leak into the environment. Faulty installation or inadequate operating and maintenance procedures also can cause USTs to release their contents into the environment. The greatest potential hazard from a leaking UST is that the petroleum or other hazardous substance can seep into the soil and contaminate groundwater. A leaking UST can also present other health and environmental risks, including the potential for fire and explosion. The facilities included in this data set have active Underground Storage Tank systems registered with the UST Section.

Data was obtained from the Division of Waste Management, Underground Storage Tank Section in May of 2019. For additional information about this data, contact the Underground Storage Tank Section staff by phone at 919-707-8171 or visit their website at: https://deq.nc.gov/about/divisions/waste-management/ust.