2 Sep 2025

Natural Gas Pipelines

The U.S. natural gas pipeline network is a highly integrated network that moves natural gas throughout the continental United States. The pipeline network has about 3 million miles of mainline and other pipelines that link natural gas production areas and storage facilities with consumers. In 2017, this natural gas transportation network delivered about 25 trillion cubic feet (Tcf) of natural gas to 75 million customers.

About half of the existing mainline natural gas transmission network and a large portion of the local distribution network were installed in the 1950s and 1960s because consumer demand for natural gas more than doubled following World War II. The distribution network has continued to expand to provide natural gas service to new commercial facilities and housing developments.

2 Sep 2025

Air Facility System Sites

This layer displays the locations of regulated facilities that discharge air pollutants in the United States. The Air Facility System (AFS) contains compliance and permit data for stationary sources of air pollution (such as electric power plants, steel mills, factories, and universities) regulated by EPA, state and local air pollution agencies. The information in AFS is used by the states to prepare State Implementation Plans (SIPs) and to track the compliance status of point sources with various regulatory programs under Clean Air Act. For more information, please visit the EPA Air Facility System web page.

2 Sep 2025

Oil and Natural Gas Fields

The layer represents Oil and Natural Gas Fields. Generally, Oil and Natural Gas “Fields” are defined as “a low in the Earth’s crust of tectonic origin in which sediments have accumulated.” This definition was originally defined by the Bureau of Land Management (BLM). Within the larger area of the basins this feature class also contains smaller geographic “plays” which are defined as “A set of known or postulated oil and gas accumulations sharing similar geologic, geographic, and temporal properties, such as source rock, migration, pathway, timing, trapping mechanism, and hydrocarbon type. A play differs from a basin; a basin can include one or more plays.” This definition was originally defined by the United States Geologic Survey (USGS) and was appropriated for use in the creation of this feature class. The geographic coverage of this layer is the Continental United States, Canada, and Mexico.

2 Sep 2025

Air Quality System Sites

This layer displays the locations of air quality monitoring stations in the United States. The Air Quality System (AQS) contains ambient air pollution data collected by EPA, state, Local, and tribal air pollution control agencies from thousands of monitoring stations. AQS also contains meteorological data, descriptive information about each monitoring station (including its geographic location and its operator), and data quality assurance/quality control information. For more information, please visit the EPA Air Quality System web page.

2 Sep 2025

Electric Bulk Power Transmission Lines

This layer represents electric power transmission lines. Transmission Lines are the system of structures, wires, insulators and associated hardware that carry electric energy from one point to another in an electric power system. Lines are operated at relatively high voltages varying from 69 kV up to 765 kV, and are capable of transmitting large quantities of electricity over long distances. Underground transmission lines are included where sources were available.

2 Sep 2025

Safe Drinking Water Information System Sites

This layer displays the locations of a subset of the Environmental Protection Agency (EPA) Safe Drinking Water Information System (SDWIS) sites. The SDWIS contains information about public water systems and their violations of EPA’s drinking water regulations. Data can be accessed through the EPA’s Clip N Ship map application. For more information, please visit the Safe Drinking Water Information System web page.

2 Sep 2025

Army Corps Floodwalls

This layer displays United States Army Core of Engineers surveyed Floodwalls. The USACE defines an Floodwall as a structure erected to protect areas from high river stages. For more information about USACE data, visit the National Levee Database.

2 Sep 2025

Emissions & Generation Resource Integrated Database (eGRID)

This layer displays the locations of the Environmental Protection Agency (EPA) Emissions & Generation Resource Integrated Database (eGRID) sites. The eGRID is a comprehensive source of data on the locations and environmental characteristics of almost all electric power generated in the United States. For more information, please visit the EPA eGRID web page.

2 Sep 2025

Army Corps Enbankments

This layer displays United States Army Core of Engineers surveyed Embankments. The USACE defines an Embankment as the area of a floodplain from which flood water is excluded by the levee system. For more information about USACE data, visit the National Levee Database.

2 Sep 2025

National Pollutant Discharge Elimination System (NPDES)

This layer displays the locations of regulated facilities that discharge pollutants into surface waters in the United States. Location and environmental characteristics about facilities requiring discharge permits is contained in the Environmental Protection Agency (EPA) National Pollutant Discharge Elimination System (NPDES). Facilities requiring permits include industrial, municipal, and other facilities must obtain permits if their discharges go directly to surface waters (via discrete conveyances such as pipes or man-made ditches). Individual homes that are connected to a municipal system are not reported to the EPA. For more information, please visit the EPA National Pollutant Discharge Elimination System web page.