£EPA
User Guide for Aquifer Exemption Data
Aquifer Exemption Data
EPA's Aquifer Exemption map allows users to view aquifers that have been approved for exemption by EPA under the
Safe Drinking Water Act Underground Injection Control regulations. This interactive map brings together data
previously available only in paper form or at the Regional and state level. The map and accompanying data can be used
by states, businesses, communities, and others to view exempted aquifers in the United States, see accompanying
aquifer exemption data like depth of injection, local geology, and injected fluid characteristics, and can assist with
Underground Injection Control permit applications and approvals.
Background on Aquifer Exemptions
An aquifer is an underground body of rock that contains or can transmit groundwater. The Underground Injection
Control regulations allow EPA to exempt aquifers that do not currently serve as a source of drinking water and will not
serve as a source of drinking water in the future, based on certain criteria. Aquifer exemptions allow these underground
sources of water to be used by energy and mining companies for oil or mineral extraction or disposal purposes in
compliance with EPA's Underground Injection
Control requirements under the Safe Drinking
Water Act. Figure 1 shows simplified scenarios
where a well owner/operator or a state might
request EPA to approve an aquifer exemption.
The process begins when EPA receives information
about the aquifer proposed for exemption from a
state agency or well owner or operator. EPA
approves the aquifer exemption request if it meets
the necessary criteria. Injection of fluids can begin
only after EPA approves an aquifer exemption and
an underground injection control permit is
granted.
Aquifer Exemption Data Initiative
The EPA developed an interactive Aquifer
Exemption Map that allows users to find locations
of aquifers approved for exemption under the Safe
Drinking Water Act. The website also provides
geospatial files and data in a Microsoft Excel
spreadsheet with this accompanying user guide.
The map shows the approved aquifer exemption
boundaries, when available, in two dimensions and
information such as the depth of injection, local
geology, and injected fluid characteristics. The
Excel spreadsheet provides descriptive information
from the geospatial file without geospatial data.
Users may download the datasets, a fact sheet,
and this user guide from the website.
The map and accompanying data can be used by
Simplified Schematic Showing Scenarios Where
Aquifer Exemptions Might be Requested
An aquifer exemption may be required
to produce oil, natural gas, or minerals
from an aquifer
Aquifer mixed
with oil, natural
gas, or minerals
The EPA developed the aquifer exemption
process to protect drinking water aquifers and
meet industry needs. An aquifer exemption
allows fluid that might otherwise endanger a
drinking water source to be placed into a specific
portion of an aquifer. The EPA evaluates the
boundaries of the aquifer exemption proposed
by the well owner/operator or state so that
nearby drinking water sources remain protected.
The boundaries are shown for illustration
purposes as yellow dashed lines in this figure.
Rock layers that
protect overlying
aquifers from
contamination
An aquifer exemption may be required to
place wastes from industrial processes into
portions of aquifers.
Figure 1. Simplified schematic showing scenarios where aquifer
exemptions might be requested. The EPA evaluates proposed aquifer
exemption boundaries where fluids maybe injected while continuing
to protect nearby drinking water sources. The boundaries are shown
for illustration purposes as yellow dashed lines.

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£EPA
User Guide for Aquifer Exemption Data
polygons. The polygons represent the two-dimensional aquifer exemption boundaries. For example, locations described
by a radius around a specific latitude and longitude, as shown in Figure 3, appear as a circle. Some aquifer exemptions
are defined by one or more grids in the Public Land Survey System and have a square or rectangular appearance, shown
in Figure 3. The Public Land Survey System describes an area using a grid system with numbered townships, ranges, and
sections. Map scale may be changed by clicking on the scale adjustment tool represented by the following image on the
Aquifer Exemption Map,
Tabs display different
information about
the aquifer
exemptions
The geospatial file, a table of
attributes, user guide for the
data, and fact sheet are available
for download on the Further
Information tab
Artuifer exemptions Map
Underground Injection Control (UIC) Program
&EPA
About the Data
This website provides an interactive map that allows users to find
locations of aquifers approved for exemption under the Safe
Drinking Water Act Underground Injection Control Regulations.
The website also provides geospatial files and Excel data with an
accompanying user guide. The map shows the approved aquifer
exemption boundaries, when available, in two dimensions, and
information such as the depth of injection, local geology, and
injected fluid characteristics. The Excel spreadsheet provides
descriptive information from the geospatial file without geospatial
data. Users may download the datasets, a fact sheet and a user
guide from the "Further information" tab.
The map and accompanying data can be used by states,
businesses, communities, and others to view exempted aquifers in
the United States, see accompanying aquifer exemption data like
depth of injection, local geology, and injected fluid characteristics,
and can assist with Underground Injection Control (UIC) permit
Depth
Data Quality
Further Information
Text panels
on each tab
explain the
information
About Aquifer Exemptions
An aquifer is an underground body of rock that contains and can
transmit groundwater. The EPA exempts aquifers if the aquifer
%oes not currently serve as a source of drinking water and will not
Jerve as a source of drinking water in the future, based on certain
criteria. Aquifer exemptions allow these underground sources of
water to be used by energy and mining companies for oil or
mineral extraction or disposal purposes in compliance with EPA's
requirements.
Figure 2. Tabs at the top of the Aquifer Exemption Map allow users to view different information about the exemptions.
Users may download data, this user guide, and the fact sheet on the Further Information tab. Text panels on each tab
give the user context about the data presented on each tab.
Injection Well Classes Associated with Aquifer Exemptions
There are six classes of injection wells under the EPA's regulations. Class I wells are for the injection of industrial and
municipal waste fluids. Class II wells are for the injection of fluids related to oil and gas operations, such as enhanced
recovery (Class MR) or disposal of production wastes (Class 11D). Class III wells inject fluids that assist in extraction of
minerals such as uranium and salts. Class IV wells for certain hazardous or radioactive waste injection are banned except
under limited circumstances as part of an EPA or state-authorized ground water clean-up. Class V wells are for injection
activities not covered by the other well classes. Class VI wells inject carbon dioxide into deep rock formations for the
purpose of long-term storage.
EPA 810-F-16-010 June 2019

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£EPA
User Guide for Aquifer Exemption Data
Operators or states typically describe the injection
activity proposed for an aquifer when requesting an
exemption from the EPA. Aquifer exemptions requested
as of November 2017 are usually associated with three
of the six classes of injection wells regulated by the EPA
Underground Injection Control program. Most aquifer
exemptions (about 95 percent) are associated with Class
II wells. Almost two-thirds of aquifer exemptions
associated with Class II wells are for enhanced oil or gas
recovery (Class 11R) and one-third are for disposal of
wastewater (Class IID), A small percentage of the
aquifer exemptions are not associated with specific
Class II activities such as enhanced recovery or disposal;
those aquifer exemptions are designated as Class II
rather than Class IID or Class MR. About two percent are
associated with Class III mining wells. The remainder are
associated with Class I wells used to inject
nonhazardous industrial wastes and other fluids.
Aquifer Exemption Depth Mop
The aquifer exemption depth map shows the depth, in
feet, to the exempted aquifer from the land surface or
its elevation below mean sea level. Some aquifer
exemptions are shallow, while others are thousands of
feet below the surface (far below drinking water
aquifers). About two percent of aquifer exemptions are 500 feet or less below the surface; most are between 1,000 and
9,000 feet deep. Some are over 10,000 feet deep. In some cases, there is more than one exempted aquifer at the same
location, but at different depths and in different geologic formations. The aquifer exemptions may have overlapping
two-dimensional boundaries but they are separate aquifer exemptions. Information on overlapping aquifer exemption
boundaries is listed in the pop-up boxes by clicking the left and right arrows at the top of the box, as shown in
Depths of the aquifer exemptions are measured as feet below ground surface in the majority of exemptions. In some
aquifer exemptions located in California, Louisiana, Oklahoma, and Texas, depth is measured as feet mean sea level.
Feet mean sea level can either be positive or negative depending on whether the elevation is above mean sea level
(positive) or below mean sea level (negative). The two scales for measuring depth are shown separately in the legend.
Data Quality Map
The EPA continues to assess the quality of the aquifer exemption records. Many of the records are relatively complete.
Some aquifer exemption information is incomplete or aquifer Iocational information is imprecise. The incomplete or
imprecise information is a result of different methods of documenting the data over the more than three decades that
the EPA approved exemptions.
Because the EPA seeks to make as much information as possible available to the public, the aquifer exemption polygons
are color-coded to reflect the varying levels of certainty in the Iocational data. The EPA continues to collect information
about these aquifer exemptions, and new information will be added to the geospatial file as it becomes available.
•
(1 of 13) * X I
8_689
¦
L
Region: 8
Exemption IO; 8_689

¦
1 State or Tribe:
County: Converse
1 Well Class Type: I

Exemption Area: 4 square miles
Exemption Depth: 9,137 feet BGS

Injection Zone: Teapot
Lithology: sandstone
Injectate Characteristics:
Figure 3. Aquifer exemption locations described by a radius
around a specific latitude and longitude appear as a circle.
Aquifer exemption locations described by one or more grids in the
Public Land Survey System appear as square or rectangle shapes.
Pop-up boxes identify attribute information for each aquifer
exemption. Where there are overlapping polygons, the user can
click on the left and right arrows at the top of the pop-up box to
view information about each aquifer exemption.
EPA 810-F-16-010 June 2019

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