^EPA

United States

Environmental	Region 9 Ground Water

Protection Agency	Office (WTR-9)	JUNE 2000

Sole Source Aquifer Designations
in EPA, Region 9

The U.S. EPA's Sole Source Aquifer Program was established
under Section 1424(e) of the U.S. Safe Drinking Water Act
(SDWA.) Since 1977, it has been used by communities to
help prevent contamination of groundwater from federally-
funded projects. It has increased public awareness of the
vulnerability of groundwater resources.

How did this program start? SDWA regulations
implementing the sole source aquifer statute were first
proposed in 1977 for the Edwards Underground Reservoir in
San Antonio, Texas. These regulations guided U.S. EPA in
the subsequent designation of 64 sole source aquifers across
the United States.

What does the Sole Source Aquifer Program do? The

Sole Source Aquifer program allows for EPA environmental
review of any project which is financially assisted by federal
grants or federal loan guarantees. These projects are
evaluated to determine whether they have the potential to
contaminate a sole source aquifer. If there is such a potential,
the project should be modified to reduce or eliminate the risk,
or federal financial support may be withdrawn. This doesn't
mean that the Sole Source Aquifer program can delay or stop
development of landfills, roads, publicly owned wastewater
treatment works or other facilities. Nor can it impact any direct
federal environmental regulatory or remedial programs, such
as permit decisions.

The Sole Source Aquifer Program's review authority extends
only to projects funded with federal assistance that are to
be implemented in designated sole source aquifer areas. (For
regulations applicable to new private development, you should
consult with your local, county or state environmental health
agency.)

Typical projects reviewed by the U.S. EPA include housing
projects undertaken by Housing and Urban Development, and
highway construction and expansion projects undertaken by
the Federal Highway Administration. In 1991, the U.S. EPA
reviewed 152 federal assistance projects totaling $571 million;
of these projects, 25 had to be modified to prevent
contamination of sole source aquifers. Modifications included
the redesign of bridges and highways to prevent spills of
hazardous materials.

How do you designate an aquifer as a "Sole Source"
Aquifer? As the name implies, only a "sole source" aquifer
can qualify for the program. To be a sole source, the aquifer
must supply more than 50% of a community's drinking water.
Any individual, corporation, association, or federal, state or

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local agency may petition the U.S. EPA for sole source aquifer
designation, provided the petition includes sufficient
hydrogeologic information. An outline describing how such
petitions should be prepared is contained in The Sole Source
Aquifer Designation Petitioner Guidance, copies of which are
available at EPA Regional offices (see contact information
below.)

What about Boundaries? Determination of sole source
aquifer boundaries is a difficult aspect of the designation
process since the "designated area includes the surface area
above the aquifer and its recharge area." Thus, some sole
source aquifers extend across state boundaries. The 10,000
square-mile Eastern Snake River Aquifer, for example,
includes portions of Idaho, Nevada, Utah, and Wyoming.

In Region 9: nine sole source aquifers have been designated
in the following areas as shown on the map: Upper Santa
Cruz and Avra Basin Aquifer, covering parts of Pima, Pinal,
and Santa Cruz Counties, Arizona; Naco-Bisbee Aquifer,
Arizona; Ocotillo-Coyote Wells, Imperial County, California;
Fresno Aquifer, California; Scotts Valley Aquifer, Santa Cruz
County, California; Campo-Cottonwood Aquifer, San Diego
County, California; Northern Guam Aquifer, Guam; Southern
Oahu Aquifer, Hawaii; and Molokai Aquifer, Hawaii.

Region 9 SSA maps are on the web at www.epa.gov/safewater/
ssanp.html. For more information about SSA designation and
project reviews, please call David Albright, manager of the
Ground Water Office, at (415) 972-3971 or email
albriaht.david@epa.aov.

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