SOLE SOURCE AQUIFER BACKGROUND STUDY:
CROSS-PROGRAM ANALYSIS
Office of Ground-Water Protection
Office of Water
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
November 1987
U.S. Environmental Protection Agency
Begion 5, Library (5PL-16)
230 S. Dearborn St-eet, Boom 1*670
Chicago, IL 60604
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TABLE OF CONTENTS
Page
Number
TABLE OF CONTENTS i
LIST OF EXHIBITS iii
FOREWORD v
ACKNOWLEDGEMENT vi
EXECUTIVE SUMMARY vii
I. INTRODUCTION 1
1. Information Collection Methodology 4
2. Report Organization 4
II. OVERVIEW OF REGIONAL DESIGNATION PROCESS 7
1. Implementation Strategies 7
2. Petitions 7
3. Project Reviews 7
4. The Designation Process 7
III. CROSS-PROGRAM ANALYSIS 12
1. Institutional/Policy Review 12
(1) Review Of SSA Petitions 13
(2) Review Of Regional Response 18
(3) Review Of The Use Of
Designation Criteria 20
(4) Review Of Projects Receiving
Federal Financial Assistance 21
2. Review of Hydrogeologic Data 23
(1) Level Of Technical Information 24
(2) Basis Of Agiiifer Boundary
Delineation 26
(3) Aquifer Size 37
(4) Lithology 37
(5) Hydrologic Complexity 37
(6) Vulnerability to Contamination 42
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Summary Of Cross Program Analysis 43
(1) Institutional/Policy
Characteristics 43
(2) Hydrogeologic Characteristics 44
11
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LIST OF EXHIBITS
Page
Exhibit Number
1-1 List Of Sole Source Aquifers 2
1-2 Location Of Designated and Pending SSAs 3
1-3 Type Of Information Reviewed And Extracted 5
From Regional Files For Each SSA
II-l Petition Content Requirements Under Old
Designation Process 9
I1-2 New Sole Source Aquifer Designation
Decision Process 11
III-l Year Of Petition Submittal 14
III-2 Distribution Of Petitioner Types 16
II1-3 Concerns Of Petitioners 17
III-4 Distribution Of Regional Review Efforts 19
II1-5 Population Served By SSA 22
III-6 Percentage Of Population Using SSA 22
III-7 Percentage Comparison Between Petitioners
Map Scale And Associated Land Area 25
III-8 Technical Data Presented In Petitions 25
III-9a Principal Criteria Used By Petitioners To
Delineate SSA Boundaries 27
III-9b Principal Criteria Used By EPA Regions To
Delineate SSA Boundaries 27
111-10 Relationship Between Petitioner's Proposed
SSA And That Approved By EPA 28
I11-11 Metes And Bounds For The Boundary
Delineation Of The Spokane Valley-Rathdrum
Prairie Aquifer 29
111
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Exhibit *T
Number
111-12 Aquifer Relationships, Seven Valleys
Aquifer, Pennsylvania 31
II1-13 Aquifer Relationships, New Rockford
Aquifer, North Dakota 32
111-14 Aquifer Relationships, Biscayne
Aquifer, Florida 34
II1-15 Areas Included in SSA Approved or
Recommended for Designation 35
111-16 Aquifer Relationships, Theoretical
Artesian System 36
111-17 Aquifer Size 38
111-18 Lithology 38
111-19 Aquifer Complexity 39
II1-20 Generalized Ground-Water Flow, Guam 40
111-21 Location and Directions of Ground-Water
Flow At or Near the Top of the Zone of
Saturation 41
IV
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FOREWORD
This document is one in a series of documents that
summarize the designated and pending Sole Source Aquifers
(SSAs) in eight of the ten U.S. Environmental Protection
Agency (EPA) Regions. These documents resulted from an
EPA study that assessed the status of the Sole Source
Aquifer Program. In addition, the information obtained
from this study was used to (1) assist in the streamlining
of the SSA designation process and (2) assist in
establishing criteria for identifying critical aquifer
protection areas in response to the 1986 amendments to the
Safe Drinking Water Act (SDWA).
Additional information on the Sole Source Aquifer
Program can be obtained from the Office of Ground-Water
Protection in Washington, D.C., and from the ten EPA
Regions.
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ACKNOWLEDGEMENT
This report was prepared by the Office of Ground-Water
Protection (OGWP), U.S. Environmental Protection Agency
(EPA), Washington, D.C. Mr. William G. Stelz of OGWP served
as the Project Manager for EPA, assisted by Mr. Paul
Violette. Booz, Allen & Hamilton Inc. and Dames & Moore
under Contract No. 68-03-3304 assisted in the preparation of
this report. EPA Regional OGWP representatives deserve
thanks for their cooperation in the review of this document.
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EXECUTIVE SUMMARY
The Sole Source Aquifer (SSA) Program was established
under Section 1424(e) of the Safe Drinking Water Act (SDWA)
of 1974. This section authorizes the EPA Administrator to
determine that an aquifer is the "sole or principal" source
of drinking water for an area. The program also provides
for EPA review of Federal financially assisted projects
planned for the area to determine their potential for
contaminating the aquifer. Based on this review, no
commitment of Federal financial assistance may be made for
projects "which the Administrator determines may contaminate
such aquifer," although Federal funds may be used to modify
projects to ensure that they will not contaminate the
aquifer.
On September 23, 1986, EPA's Office of Drinking Water
(ODW) officially transferred its responsibilities for
administering the Sole Source Aquifer Designation Program to
the Office of Ground-Water Protection (OGWP). In an effort
to smooth the transition of responsibilities and help OGWP
identify ways to administer the SSA designation program
provisions efficiently, OGWP undertook this study of the SSA
designation process.
This report represents an historical account of the past
SSA program. New guidance released by EPA in February 1987,
"Sole Source Aquifer Designation Petitioner Guidance," will
be the basis of the SSA program henceforth. As part of this
SSA Background Study, EPA has published separate Regional
reports describing the individual SSAs within each
respective Region.
The overall objectives of the background study were to:
Identify SSAs that have been designated and
petitions that are pending
Characterize the similarities and differences
between SSAs
Understand what information sources and analyses
are needed to designate an aquifer
Collect information on the designation process and
procedures so that EPA may develop a more
streamlined designation process.
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To collect information on the SSA program, a project
team interviewed EPA Regional staff and reviewed Regional
files on both designated and pending SSAs. Three-person
teams consisting of an EPA representative, a senior
policy/institutional analyst, and a senior hydroqeoloaist
conducted the Regional visits.
The project team's information gathering indicates that
to date, 23 aquifers have received SSA designation, 19
others have petitions pending designation, and eight
petitions are considered to be inactive. The following is a
summary of cross-program analysis of the institutional and
policy characteristics of the petitions received and the
hydrogeologic characteristics of the petitioned aquifers as
determined by the team's investigation.
(1) Institutional/Policy Characteristics
EPA Regions have received petitions rather consistently
over the past 11 years, with a peak in submissions in the
early 1980s. Environmental groups represent the largest
petition groups, although petitions were submitted by local
governments, citizens, and local water suppliers as well
About one-half of the petitions were submitted in an attempt
to stop or affect a specific project. Landfills and
publicly owned treatment works (POTWs) were the two types of
facilities most likely to cause petitioners to submit SSA
applications. The other half of the petitions was submitted
to protect ground-water resources.
Once the Regions received the petitions, they either
collected additional data or contacted the USGS and outside
consultants. To provide public participation, the Regions
held public hearings and accepted written public comments.
State and local governmental agencies often provided written
comments as well.
The Regions largely used three criteria to determine
whether an aquifer should be designated. They were: (1) at
least 50 percent population dependency on ground water, (2)
the existence of alternative water supplies, and (3) the
vulnerability to ground-water contamination. Two-thirds of
the petitions providing such information indicated over 90
percent dependency of the population on ground water. In
fact, almost half of the petitioned aquifers have been
characterized as providing 100 percent of the drinking water
supply.
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The second criterion, alternative water supplies, was
interpreted differently by various Regions. Some Regions
addressed only available, existing sources as
alternatives, while other Regions considered undeveloped,
potential sources as well. The Regions used no formal
approach or methodology to measure the third criterion,
vulnerability. Typically, the Region reviewed real
hydrogeologic characteristics and declared the aquifer to
be vulnerable.
For designated SSAs, most Federal financially assisted
projects reviewed by the Regions were approved without
modification. For a few projects, modifications were made
in order to be approved for the SSA area.
(2) Hydrogeologic Characteristics
Petitions contained up to nine different types of
hydrogeologic information. Ground-water use and pollution
source data were most commonly included in the petitions.
Lithologic and formation nomenclature were usually
presented as excerpts from geologic reports. Ground-water
flow, water table depth, and other hydrologic data were
generally not included in the petitions. Taken as a
whole, the petitions alone were not adequate for making a
delineation determination.
Petitioners and the Regions were approximately equally
likely to use hydrogeologic criteria as a basis for
delineating SSAs. Worth noting, however, is that the
Regions frequently revised the petitioners' original
boundaries once more comprehensive and sophisticated
technical information had been reviewed. In many cases,
these revisions were the result of the Region including
the recharge area and/or streamflow source zone in the
delineated area. In fact, all delineated SSAs included
the aquifer recharge area and 70 percent included the
streamflow source zone.
In terms of size, over two-thirds of the aquifers were
less than 1,000 square miles while several were larger
than 12,000 square miles. Over half of the aquifers were
in unconsolidated deposits. Most aquifers behaved as
single hydrologic units (i.e., 25 of 42 aquifers or 60
percent). The remaining 40 percent were multilayered,
containing several definable water-bearing zones. The
Regions in all cases treated multiple and confined aquifer
systems as "leaky," assuming that unconfined, overlying
units would contribute pollutants to the underlying units.
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For ground-water flow characteristics, the petitioners
generally based the analysis on surface topography and
rarely used ground-water models. The depth to ground
water was less than 30 feet in almost two-thirds of the
cases. Shallow depths were often considered to represent
susceptibility to contamination. The petitions often
listed pollution sources that contributed to making the
aquifers more vulnerable to contamination.
More detailed information on individual SSAs is
available in the individual Regional reports, which are
intended to complement this cross-program analysis.
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I. INTRODUCTION
The Sole Source Aquifer (SSA) Program was established
under Section 1424(e) of the Safe Drinking Water Act
(SDWA) of 1974. This section authorized the Administrator
of the Environmental Protection Agency (EPA) to determine
that an aquifer is the "sole or principal" source of
drinking water for an area. The program also provided for
EPA review of Federal financially assisted projects
planned for the area to determine their potential for
contaminating the aquifer. Based on this review, no
commitment of Federal financial assistance may be made for
projects "which the Administrator determines may
contaminate such aquifer," although Federal funds may be
used to modify projects to ensure that they will not
contaminate the aquifer. As of August 1987, there have
been 23 designated SSAs nationwide; 19 remain in some
stage of review. These SSAs are listed in Exhibit 1-1 and
depicted on a map of the U.S. in Exhibit 1-2.
On September 23, 1986, the Office of Drinking Water
(ODW) officially transferred its responsibilities for
administering the SSA designation program to the Office of
Ground-Water Protection (OGWP). As an initial step in
developing its program implementation strategy, OGWP
issued guidance (Sole Source Aquifer Designation
Petitioner Guidance, February 1987, hereafter referred to
as the SSA Designation Guidance) that has streamlined the
SSA designation process. This guidance has been designed
to ensure that the SSA designation time frame will be
consistent with the eligibility criteria of the SSA
demonstration program authorized by 1986 amendments to
SDWA. Also, additional information and definitions with
respect to the SSA program can be obtained from this
document.
To develop the SSA Designation Guidance and to
effectively administer the SSA program, OGWP conducted a
review of the 12-year old SSA program. The purpose of the
review was to collect background historical information
about the SSA designation process. This background
information consisted of both hydrogeologic data on each
designated and pending SSA and policy/administrative
information on the designation process itself. The study
involved three separate and distinct tasks. Task 1
included the preparation of a directory/listing of the key
documents supporting each designated or pending SSA and
the production of a map of the designated and pending
SSAs. Task 2 involved development of a profile of each
SSA. In addition, information gained on the SSA
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EXHIBIT 1-1
List Of Sole Source Aquifers*
DESIGNATED
PENDING
NJ
I
1. Edwards Aquifer, TX
2. Spokane-Rathdrum Prairie, WA-ID
3. Northern Guam
4. Long Island, NY
5. Fresno Co., CA
6. Biscayne Aquifer, FL
7. Buried Valley, NJ
8. Maryland Piedmont, MD
9. Whidbey Island, WA
10. Camano Island, WA
11. Cape Cod, MA
12. Ridgewood, NJ
13. Upper Rockaway Basin, NJ
14. Brooklyn-Queens, NY
15. Nantucket Island, MA
16. Block Island, RI
17. Upper Santa Cruz 8.
Avra-Altar Basin, AZ
18. Schenectady-Niskayuna, NY
19. Scotts.Valley, CA
20. Clinton Street-Ballpark, NY
21. Seven Valleys, PA
22. Cross Valley, WA
23. Clarke Co., VA
24. Quaboag River Valley, MA
25. New Jersey Coastal Plain, NJ
26. State of New Jersey
27. Cattaraugus Creek-Sardinia, NY
28. Mt. Olive, NJ
29. Volusia-Floridan, FL
30. Pleasant City, OH
31. Catawba Island, OH
32. Delaware Basin, TX-NM
33. Capital Area-Baton Rouge, LA
34. WiIcox-Shreveport, LA
35. Edwards Aquifer-Barton
Springs, TX
36. New Rockford, ND
37. Pearl Harbor-Honolulu, HI
38. Naco-Bisbee, AZ
39. Snake Plain, ID
40. Newberg Area, WA
41. Seven Lakes, WA
42. North Florence Dunal, OR
INACTIVE
South Kingstown, RI
North Kingstown, RI
Highland (Ramapo
Valley), NJ
New Castle, DE
Oakland Co., MI
Carrizo-Wilcox,
Bastrop Co., TX
DeSoto Parish, LA
East Helena, MT
*As of August 1987
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As of August 1987"
EXHIBIT 12
LOCATION OF DESIGNATED AND PENDING SSA's
(NUMBERS REFER TO EXHIBIT 1-1)
NOT TO SCALE
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designation process supported ongoing development of the
SSA Designation Petition Guidance. Task 3 encompassed
generation of this report including the Region-by-Region
summaries and creation of a dBase III data file to access,
compare, and manipulate data on the characteristics of
aquifers and petition review process. This data file may
be accessed by EPA Regional personnel through OGWP.
1- Information Collection Methodology
On this assignment, EPA and its consultants visited
eight of the ten EPA Regions. These visits entailed
interviews with Regional staff and a review of Regional
files on both designated and pending SSAs. Three-person
teams consisting of one EPA representative, one senior
policy/institutional analyst and one senior hydrogeologist
conducted the visits. The teams did not visit Regions V
and vn because of their low level of SSA petition activity,
The teams reviewed documents that significantly
contributed to the designation process. The analysts used
data from these notes and files for further assessment of
the process. Exhibit 1-3 lists the types of information
reviewed in the Regional files.
Typically, the teams interviewed Regional EPA staff
using a protocol consisting of general Questions about the
process. The questions primarily dealt with the
designation process, hydrogeologic and policy issues, the
draft guidance on SSA designation, petition
characteristics, and review of projects receiving Federal
financial assistance.
2. Report Organization
This report presents the results of the cross-program
analysis. It also summarizes the key characteristics of
all the aquifers and analyzes similarities and differences
among Regional programs as well as among individual
aquifers. Its focus is on both the administrative and
technical aspects of the historical SSA designation
process.
Published separately are eight Regional volumes that
contain data on SSAs in the respective Regions. These
documents include information about the hydrogeologic
characteristics of the SSAs and the institutional
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EXHIBIT 1-3
Type Of Information Reviewed And Extracted From
Regional Files For Each SSA
Name and type of petitioner
Reason(s) for petition submittal
Contents of the petition
Federal Register announcements regarding
receipt of the petition and request for public
comment
Response to Federal Register announcements
(i.e., written or verbal comments)
Public hearings records
Hydrogeologic data and reports
Ground-water use information
Pollution sources and vulnerability records
Population data
Alternative source studies
Existing contamination
Current treatment practices
Schedule of designation
Memoranda of Understanding (MOU) with other
Federal agencies
Role of local/State governments in the process
Projects receiving Federal financial
assistance reviewed
Other relevant and appropriate information.
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functioning of the review and designation process. The
information describes what was in the petition, how it was
handled by the Agency, the supplemental studies undertaken,
and the criteria used in the Regional decision-making
process.
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II. OVERVIEW OF REGIONAL DESIGNATION PROCESS
l. Implementation Strategies
Some Regions have used different approaches in
implementing the SSA Program. These implementation
differences resulted to some extent from differences in
Regional interpretation of the SSA program regulations
proposed in September 1977, but also from differences in
Regional and State hydrogeology and regulatory
philosophies. For example, some Regions encouraged public
hearings and workshops to increase community awareness of
possible ground-water contamination within the SSA. In
order to address technical concerns, many Regions responded
by contracting for a more extensive hydrogeologic assessment
of the proposed aquifer(s). The U.S. Geological Survey
(USGS) was often used in order to obtain the necessary data.
2. Petitions
EPA received SSA petitions from individual citizens,
environmental groups, local governments, and public water
suppliers. The technical detail provided in each petition
was highly variable, and the Regional staff often requested
more information.
As a rule, the petitions were submitted either to
provide for aquifer protection or as a perceived method to
inhibit the siting of an unwelcomed project. In many cases,
the Regions faced simultaneous support and opposition to SSA
designation from the petitioners, other interested parties,
and local and State governments affected.
3. Project Reviews
After an aquifer is designated as an SSA, all Federal
financially assisted projects are subject to review by EPA
before final approval is granted. To carry out this review
function, each Region signed a Memorandum of Understanding
(MOU) with Federal agencies that provide project funds.
This process allows EPA to assess the environmental impact
of Federal financially assisted projects and to offer
modifications where necessary. As a result of this review,
some projects have been-modified, but the SSA program has
not resulted in cancellation of any projects.
4. The Designation Process
Pursuant to the draft SSA regulations, all EPA Regions
followed the same general steps in performing the review of
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petitions and designation of SSAs. These steps are briefly
described below.
Review Petition for Adecruacv When a petition was
submitted to a Region, the initial step was to review the
contents of the petition to ascertain its completeness. A
complete_petition was expected to contain all the
information and maps described in the proposed SSA
regulations. The petition content requirements from these
regulations are contained in Exhibit II-l. The Regions
generally did not request additional data from the
petitioner. The Regions formally requested the petitioner
to submit more information in only six cases.
Acceptance of Petition Following the review for
completeness and submittal of any additional requested data,
the Region formally accepted the petition and began its
technical review.
Technical Review of Petition The Regions performed
independent reviews of the petition's data to ascertain
whether the aquifer met the criteria for an SSA. These
reviews often involved collection of additional data and
review of citations of technical documents listed in the
petition. In many cases, the Regions contracted with the
USGS to perform additional studies of the aquifer. The
collected information served as the basis for the findings
of the Region.
Public Comments and Hearings The Regions published
Federal Register notices indicating receipt of the petition,
specifying the time and location of any public hearings, and
requesting public comments.
Findings and Designation Determination The data in
the petition, subsequent studies, and information developed
in the comments provided the basis for the Regional
designation decision. The data were evaluated in terms of
the criteria listed In the proposed regulations.
Submittal of Action Memorandum to EPA Headquarters
The Regions submitted an action memorandum to EPA
Headquarters explaining their findings and providing a
recommendation on the designation decision. The details in
the action memorandum varied according to the specific
nature of each SSA.
Designation Time Frame In general, the rime frame for
this designation process varied depending on local needs,
hydrogeologic factors, and administrative constraints. In
many cases, the designation time directly reflected the
level of technical detail required by the Regional staff.
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EXHIBIT II-l
Petition Content Requirements
Under Old Designation Process
Per the Proposed Regulations (42 FR 51620, September 29,
1977), Section 148.10, Petition Submission Requirements:
(a) Name, address, and telephone number of the petitioner
(b) Statement of the requesting person's interest in the
Administrator's determination
(c) Statement of why contamination would result in a
significant hazard to public health
(d) All pertinent information regarding
(1) The aquifer and its location
(2) The location of the aquifer area the petitioner
alleges is the sole or principal source of drinking
water
(3) The population in the area described in (2)
(4) Alternative sources of drinking water for the area
(5) The recharge and streamflow source zone(s) for the
aquifer
(6) The sources of recharge to the aquifer and their
location
(7) Projects which might contaminate the aquifer
through the recharge zone
(8) The public water systems utilizing water from the
aquifer, the number of people served by each
system, and the water treatment provided by each
system
(e) Maps showing, to the best of the petitioner's knowledge
(I) The location and boundaries of the aquifer
(2) The location and boundaries of the recharge zone(s)
(3) The location of the source(s) of recharge to the
aquifer
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The SSA Designation Guidance released by OGWP has
established a uniform time frame for designation as well as
established a new process. (See Exhibit II-2.)
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EXHIBIT 11-2
NEW SOLE SOURCE AQUIFER DESIGNATION DECISION PROCESS
L PHE-SUBMBSION ACTIVITIES
IV. DESIGNATION DETERMMATION
PETITIONER
H. INITIAL REVIEW/
COMPLETENESS DETERMINATION
ML DETAILED REVEMOTECHNICAL VERIFICATION
EPA
TMIEFRAME
V
HOBTMUWEO
v
til DM1
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III. CROSS-PROGRAM ANALYSIS
A major objective of this report was to summarize the
SSA designation process based upon data reviewed during
visits to eight EPA Regions and discussions with Regional
personnel. This chapter presents that summary in two parts:
Review of the institutional/policy characteristics
of the SSA program
Review of the hydrogeologic characteristics of the
aguifers.
Information collected on all aguifers that are either
designated (i.e., 23 SSAs) or pending designation (i e 19
petitions currently under consideration) formed the basis
for these analyses.
Petitions withdrawn from the process by the petitioner
or not considered by the Region typically had insufficient
information for the purposes of this cross-program
analysis. Generally, no information was collected from the
States, petitioners or other sources not in the Regional
files.
1 Institutional/Policy Review
The institutional/policy review addressed four topics:
Petition and petitioner characteristics
Regional response to petitions
Use of designation criteria
Review of projects receiving Federal financial
assistance.
In reviewing petitions and petitioner characteristics
three areas were assessed: the type of petitioner, the
reason for the petitioner's actions, and the content of the
petition. This also included looking at trends in who
submitted the petition and why.
Review of the Regional response to receipt of a petition
consisted of an evaluation of how the Region acted on a
petition, including the reliance upon the petitioner's data
and the extent of independent Regional data collection and
analysis. The role of the USGS in providing additional
information was specifically noted.
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Review of the Region's use of designation criteria was
based on the criteria contained in the regulations EPA
proposed for the SSA designation process (42 FR 51620) on
September 29, 1977. The five criteria proposed for SSA
designation were:
Availability of alternative sources of drinking
water
Size of the area and population served by the
aquifer
Susceptibility of the aquifer to contamination
through the recharge zone (i.e., vulnerability)
Location of the aquifer
Number of public water systems utilizing water from
the aquifer, the number of people served by such
systems, and the treatment provided by such systems.
The review documented which criteria the Regions used in
their decision-making and how these criteria were addressed
by both the petition and each respective Region.
Finally, a review was performed of the effectiveness of
the project reviews following designation. Because only a
few Regions had discrete records of the results of these
reviews, the analyses are general in nature with few
specific examples of Regional activity.
(1) Review Of SSA Petitions
Review of the petitions revealed information that may be
divided into three distinct areas: the year of petition
submittal, the types of petitioners, and the rationale for
petition submittal.
Petition Submittal Date Petitions were submitted to
the EPA Regions rather consistently over the past 12 years.
Exhibit III-l breaks out the years of submittal of petitions
since 1975. There was no obvious reason for the peaking of
submittals in the early 1980s.
Several possible explanations include:
Increased public and regional awareness of the
process
Belief that the resulting designation can provide
protection of ground-water resources
General increasing concern for ground-water
protection aside from the SSA process.
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EXHIBIT 111-1
YEAR OF PETITION SUBMITTAL
16-f
75-77
78-79
'81-'83
'84-Present
Year
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Type of Petitioner A total of 45 original petitioners
were identified. The term original petitioners was used
because in many cases additional petitioners submitted
documents in support of the original submission and declared
themselves to be petitioners. For the most part, these
additional petitioners were national environmental groups
and local officials.
As Exhibit II1-2 indicates, environmental groups, both
local and national, comprised the largest petitioner group
(40 percent). These petitioners often sought to protect a
local source of drinking water from a variety of general or
specific threats. The next largest group, local
governments, represented about one-third of the
petitioners. These local governments also demonstrated
concern about the preservation of local area ground-water
resources. Almost 20 percent of the petitioners were
individual citizens, many of whom were concerned about a
local project or development that might affect their
drinking water. The smallest group was the local water
suppliers (nine percent), who realized that contamination of
the ground water could represent considerable costs to them.
Concerns of Petitioners In about half the cases, the
petitioners identified aquifer protection as their principal
concern. In the remainder, the petitioners were attempting
to stop or influence a specific project through the aquifer
designation process. Exhibit III-3 shows that 20 petitions
could be identified as attempts to stop or influence a
specific project. This was determined through the petition
information itself or petitioner correspondence with the
Region. Such projects included landfills, publicly owned
treatment works (POTWs), pipelines, and government
installations. In fact, the first SSA designation petition
(the Edwards Aquifer) was submitted in response to
environmental concerns about the effects of two housing
projects on recharge to the ground-water supply in the San
Antonio, Texas, area. Landfills triggered more petitions
than any other specific project. In Region X alone county
landfill planning was responsible for three different
petitions.
Half the petitions identified overall improvement or
protection of ground-water resources as their principal
concern. These petitions usually cited previous examples of
ground-water contamination that forced treatment or the
closing of wells. The petitioner typically stated that it
would be nearly impossible to provide large populations with
alternative water supplies if the ground water were to
become contaminated; however, socioeconomic analyses which
would asses the impact of alternative water supplies were
generally lacking in the petitions.
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EXHIBIT 111-2
DISTRIBUTION OF PETITIONER TYPES
Environ. Groups
40%
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EXHIBIT 111-3
CONCERNS OF PETITIONERS
Housing Development
Water Project (CoE)
Nuclear Waste Repository (DOE)
Sewer Pipes
Landfill (Hazardous and Solid Waste)
POTW (Siting and Waste Disposal)
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(2) Review Of Regional Response
The Regions normally accepted SSA petitions when they
were first submitted. In fact, Regions have returned only
six petitions to the original petitioner, requesting further
information before accepting them. In a number of cases,
the Regions requested additional data. The petitioner
submitted the data as an addendum to the petition without
having to resubmit the entire petition.
Petition Completeness Many petitions were incomplete
upon submission. In many cases, the petitions lacked basic
information on population served by the aquifer and on
alternative sources of drinking water. The petitions often
contained inadequate technical documentation to describe the
boundaries of the aquifer, the aquifer service area, or the
recharge area and streamflow source zone.
The type of petitioner was not indicative of the kind
and amount of data provided. Petitions submitted by
citizens groups were as likely to be as complete as those
prepared by local governments or water suppliers. The
Biscayne aquifer petition, which was submitted by a group of
citizens, was complete in the information provided.
Petitions submitted by local governments varied in quality.
The Guam petition, submitted by the Governor, was complete,
while a petition from four local governments in
Massachusetts lacked important information.
The completeness of the petition seemed to be dependent
on the available resources. Where extensive hydrogeologic
investigations already had been completed by either the USGS
or a State agency, the petitions contained substantial
technical data. The extent of local public support also
appeared to affect the completeness of the petitions.
Petitions submitted by well-supported local groups generally
were the best petitions in terms of the depth and breadth of
information provided.
Technical Review Once the petition was accepted, the
Regions took a variety of steps in performing the technical
review of the documents. These generally fell into several
identifiable categories, as shown in Exhibit II1-4.
In about one-third of the cases, the Regions asked the
USGS to perform a study of the hydrogeologic conditions of
the aquifer. In the mid-1970s, the EPA and USGS negotiated
a Memorandum of Understanding (MOU) that funded USGS
hydrogeologic studies of 12 aquifers. Several of the
Regions used this MOU mechanism to provide supplementary
technical documentation. Although thorough, USGS studies
typically took a year or more to complete. For this reason,
some Regions chose to do their own technical documentation.
-18-
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EXHIBIT 111-4
DISTRIBUTION OF REGIONAL REVIEW EFFORTS
USGS After Receipt 34%
Private Contractor 21°/c
Existing USGS 27%
-19-
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In about one-quarter of the cases, a USGS study had
already been completed in the area and was included in the
petition as a reference or direct citation. Such was the
case with the Edwards Aquifer, where technical studies had
been performed for several years prior to petition
submission. The petitions for several aquifers, most
notably Cape Cod, were submitted on the basis of the data
and conclusions provided in an existing USGS study.
In about 20 percent of the cases, the Regions used
outside consultants' studies as the basis for their
technical review. This was often the petitioner's
contractor and funding was provided by the petitioner.
For the remaining 18 percent of the petitions, the
Regions performed an in-house review of the petitioner's
data without outside support. In most cases this resulted
in the development of a technical support document. In
every case, it resulted in an independent assessment of the
petition's data and an evaluation based on the designation
criteria. ^
Public Comments And Hearings A final aspect of the
Regional response to petitions involved public participation
in the decision-making process through public comments and
hearings. In every case, the Regions published notice of
the receipt of a petition and invited public comment on the
proposed designation. Depending on the public interest
expressed or adverse comments received, the Regions held one
or more public hearings in or near the designated area
specified in the petition. In this way, the Regions hoped
to achieve maximum public involvement in the designation
process.
The public comment period is also the point at which
State and local government agencies often voice their
support or opposition to the proposed designation. Strong
opposition has generally delayed the designation process.
(3) Review Of The Use Of Designation Criteria
The 1977 proposed regulations identified criteria for
making a determination with respect to SSA designation. The
Regions, for the most part, used three of these criteria to
determine whether an aquifer should be designated:
Percent of population dependent upon the proposed
aquifer for drinking water
The existence of alternative water supplies
The vulnerability of the ground water to
contamination.
-20-
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Population Dependency Exhibit II1-5 shows the large
range and distribution of populations served by the aquifer
in the designated SSA areas. As shown, the range extends
from less than 1,000 persons to well over several million
persons. The distribution approximates a bell-shaped curve
with the mean in the range of 10,000 to 100,000 people.
In contrast, the distribution of the percentage of the
population dependent on the aquifers is skewed markedly. Of
27 aquifers for which population data were available,
two-thirds were more than 90 percent dependent on the
aquifer for drinking water (see Exhibit III-6). In fact,
most of these aquifers were characterized as providing 100
percent of the drinking water supply. These included a
number of islands that depend entirely on ground water for
drinking water.
Alternative Water Supplies A second, related
criterion the Regions considered in making designation
determinations was the existence of alternative sources of
drinking water. In some instances, Regional staff performed
capacity calculations under drought conditions to determine
the ability of the alternative to meet the demand. These
studies were only capacity based; no Region performed formal
economic feasibility studies of potential alternative water
supplies.
Those Regions that did not attempt a capacity study
considered only existing ground-water supply systems as
feasible alternatives. As a rule, development of nearby
streams, lakes, or aquifers as viable alternatives to the
proposed aquifer was not considered.
Vulnerability of Ground Water The Regions used no
formal mechanism or approach for measuring vulnerability. A
review of the site's hydrogeologic characteristics based on
conventional vulnerability concepts produced recommenda-
tions. Many petitions cited well contamination as proof of
vulnerability. The State of Louisiana however, developed a
"Quantitative Pollution Index" under a Section 208 grant to
study the Capital Area Aquifer. The State mapped geology,
land use, soils, and risk levels, and used these to develop
a measure of vulnerability related to recharge and
permeability. No real use has yet been made of findings
other than to raise concern over the high levels of risk in
the study area.
(4) Review Of Projects Receiving Federal Financial
Assistance
Under the Safe Drinking Water Act, aquifer designation
requires the Regions to review all Federal financially
assisted projects within the designated area. Such projects
-21-
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EXHIBIT 111-5
Population Served by SSA
Number
of SSAs 6 -I
<1K 1K-10K 10K-100K 100K-500K 500K-1M
POPULATION
EXHIBIT 111-6
Percentage of Population Using SSA
20
Number
of SSAs 10
0 -
50%
18
60% 70% 80% 90%
PERCENTAGE OF DEPENDENCY
100%
-22-
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included new housing developments financed through Federal
mortgage instruments, Federal highway system modifications
and additions, funds for improvements on POTWs, airport
renovations, and economic development grants, among others.
Direct Federal actions, such as DoD activities, did not
require a review. In order to be informed of such projects,
each Region signed an MOU with each Federal agency that
provides project funds. Almost all Regions have MOUs with
the Farmers Home Administration (FmHA), the Federal Highway
Administration (FHA), the Veterans Administration (VA), and
the Federal Aviation Administration (FAA). In all, there
are 11 Federal Administrations or Departments that have
signed MOUs with EPA Regions.
The information on project reviews indicated that over
90 percent of the projects reviewed were preliminary reviews
followed by an in-depth review if necessary. Community
Development Block Grants and Federal mortgages to housing
developers were typical of this kind of project. For
example, on Long Island, between 1978 and 1981, 127 projects
were cited as requiring review. Initial screening indicated
only 12 of the projects needed an analysis to determine if
they affected the SSA. The types of projects that most
often required review were airport modifications, large
housing developments proposing to use septic systems instead
of an available sewer system, and highway construction.
Most projects that were subjected to a review of
possible environment impact were approved without
modification. No project was ever cancelled or stopped as a
result of an SSA impact review. However, there were
projects that required modifications:
Regions I and II both required several proposed
housing developments to connect to the available
sewer system or lose their Federal funds.
A Region II analysis required a Federal highway
route to be changed. Region IV required design
modifications for highway interchanges due to
possible effect on the SSA.
Region I required the removal of on-site hazardous
wastes and old underground storage tanks at an
airport. FAA funds could not be used in the
cleanup effort.
2. Review Of Hydrogeologic Data
Hydrogeologic information was necessary to define the
spatial limits and the vulnerability of SSAs. The technical
-23-
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hydrogeologic information included in each accepted petition
varied with petition, but as the SSA program matured, each
Region required similar kinds of information. This section
examines the hydrogeologic features of SSA petitions as
defined by the:
level of technical information
basis of aquifer boundary delineation
aquifer size
lithology
hydrologic complexity
vulnerability to contamination.
(1) Level Of Technical Information
SSA petitions usually provided limited technical
information. In most cases, the petitions contained
excerpts from or references to published technical reports
developed by the USGS, State agencies, water companies, or
universities. There were, however, exceptions. For
example, Guam provided a well-organized, technically
complete petition that required little additional technical
support.
In most cases, the petitioners used maps to define the
spatial limits of the proposed aquifers. These maps
commonly consisted of topographic or geologic maps that had
been enlarged or reduced to fit on an 8-1/2 x 11-inch piece
of paper. In general, petitioners requesting protection for
larger areas were more likely to submit small-scale maps,
while those wishing to protect smaller areas more frequently
submitted medium-scale maps. For 15 percent of the
petitions no map was provided that depicted the designated
area. Map scale information is summarized in Exhibit III-7.
Nine different types of hydrogeologic information
commonly included in the petitions were identified. Exhibit
II1-8 presents the frequency of occurrence of these data in
the petitions. This exhibit indicates the availability of
information rather than its quality or adequacy.
In general, the common concern among petitioners was the
degradation of ground water. Exhibit II1-8 indicates that
ground-water use and pollution source data were most
commonly included in the petitions. The ground-water use
information generally considered population usage estimates
and lists of public water supplies or annual yields. In
most cases, the proposed development project was presented
as the primary source of contamination even though it may
not have been constructed yet.
Lithologic and formation nomenclature were presented
most frequently in excerpts from geologic reports.
-24-
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EXHIBIT III-7
Percentage Comparison Between Petitioners' Map Scale
And Associated Land Area
Land
Area Size (mi scr. )
0-50
50-100
100-1,000
1,000-10,000
10,000+
Map Scale (1 inch equals)
Large Medium
(0 - .38 mi) ( .39 - 3.9 mi)
10%
20%
70%
33%
13%
47%
7%
Small
(4.0+)
100%*
*1 site only.
EXHIBIT III-8
Technical Data Presented In Petitions
.. , ,
Hydrogeologic Data
Ground-Water Use
Pollution Sources
Lithology
Vulnerability
SW/GW Relationships
Ground-Water Quality
Ground-Water Flow
Water Table Depths
Hydrologic Data
Occurrence in Petition
_______ by Percentage
90%
59%
56%
24%
15%
-25-
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Generally, no attempt was made by the petitioner to describe
or characterize the physical properties of the geological
environment.
SSA petitions generally did not include ground-water
flow, water table, and other hydrologic data. Most
hydrologic assessments discussed ground-water/surface-water
relationships such as whether streams were gaining or
losing. Water quality was generally referred to as being
"good." Discussions of specific parameters were rare.
For the most part, the extent of technical information
presented by petitioners did not provide sufficient basis
for a determination. Many petitioners did not supply maps
or inadequately defined the boundaries of the proposed SSA.
Data that were submitted generally did not define the
specific hydrogeologic conditions that exist and the Regions
often requested the petitioners to submit more data. In
addition, the Regions at times developed their own
supplementary data bases to define the boundaries when
necessary.
(2) Basis Of Aquifer Boundary Delineation
Where the original petitions employed maps to delineate
the SSA boundaries, these boundaries were determined by any
of a number of hydrologic, lithologic, and political/
cultural features. In some cases, a combination of features
was used to define the aquifers. Exhibit III-9a displays
the principal delineation criteria used by petitioners and
the associated numbers of petitions. Exhibit III-9b in
contrast presents the principal delineation criteria that
EPA Regions used for the same set of aquifers.
Comparing Exhibits III-9a and III-9b indicates that both
petitioners and the Regions were most likely to use
hydrologic criteria to delineate SSA boundaries. Although
petitioners and Regions relied on hydrologic features
approximately equally often, it is important to note that
for around 50 percent of petitions received, EPA
subsequently revised the SSA boundaries proposed by
petitioners. The frequency of these revisions is due to EPA
often modifying or expanding the proposed boundaries based
on more extensive information collected in the review
process or through public hearings. An example of an EPA
boundary modification is given in Exhibit .111-10.
Though the Regions did not completely define any areas
by political and cultural features, they did use metes and
bounds as a legal accommodation to define SSA boundaries.
Exhibit III-ll is the first of nine pages listing turning
points that enclose the Spokane Valley-Rathdrum Prairie
-26-
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EXHIBIT III-9a
Principal Criteria Used by Petitioners to
Delineate SSA Boundaries
Number of
Criteria Petitions % of Total
Hydrologic 24 60
Political/Cultural 4 10
Lithologic 3 7.5
Combinations 8 20
Not Determined 1 2.5
Total 40 Total 100%
EXHIBIT III-9b
Principal Criteria Used by EPA Regions to
Delineate SSA Boundaries
Number of
Criteria Petitions % of Total
Hydrologic 23 57.5
Political/Cultural 2 5
Lithologic 2 5
Combinations 10 25
Not Determined 3 7.5
Total 40 Total 100%
-27-
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CROSS VALLEY AQUIFER
Snohomish/King Counties, Washington
PETITIONER'S
PROPOSED AREA
ii
EPA PROPOSED
AREA
EXHIBIT HMO
RELATIONSHIP BETWEEN PETITIONER'S
PROPOSED SSA AND THAT APPROVED BY EPA
-28-
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Beginning at the mouth of the Little Spokane
River in Section 32, T.27N., R.42E.W.M. and fol-
lowing the channel of the Little Spokane River
upstream to the mouth of Oeadman Creek in Sec-
tion 33, T.27N., R.43E.W.M.; thence up the chan-
nel of Oeadman Creek to the section line between
Sections 2 and 3, T.26N., R.43E.W.M.; thence
south along the section line to the northeast
corner Section 22. T.26N., R.43E.W.N.; thence
east % mile along the north line of Section 23
to the northeast corner of the NVfc NWH Section
23. T.26N., R.43E.W.M.; thence south % mile to
the southeast corner of the NVfc NWH Section 23,
T.26N., R.43E.H.M.; thence east about 3/4 mile
to the section line between Sections 23 and 24,
T.26N., R.43E.H.M.; thence south % mile along
the section line to the west quarter corner Sec-
tion 24; thence east about 1% miles to the
northeast corner NWH SW\ Section 19, T.26N.,
R.44E.W.M.; thence south about 3/4 mile to the
southeast corner Mfc NVfc Section 30, T.26N.,
R.44E.W.H.; thence east about 1% miles to the
southwest corner NE% NE% Section 29, T.26N.,
R.44E.W.M.; thence south % mile to the southwest
corner SEH NE% of Section 29; thence east about
3/4 mile to the center of Section 28, T.26N.,
R.44E.U.M.; thence north % mile to the north
quarter corner Section 28; thence east about 2%
miles to the northeast corner Section 26, T.26N.,
R.44E.U.M.; thence south % mile to the east
quarter corner Section 26; thence east 1 mile .to
the east quarter comer Section 25, T.26N.,
R.44E.W.M.; thence in a northeasterly direction
to the north quarter corner Section 30, T.26N.,
R.45E.W.H.; thence north about 1% miles to the
center of Section 18, T.26N., R.45E.H.M.; thence
in a north-northeasterly direction about 4 mile
to the northwest corner NE% NE% Section 18;
thence north 1 mile to the northwest corner N0»
HP* Section 7, T.26N., R.45E.W.M.; thence west h
mile to the south quarter corner Section 6,
T.26N., R.45E.W.M.; thence north 1 mile to the
north quarter corner Section 6; thence east k
mile to the southwest corner SPj SP» Section 31,
T.27N., R.45E.W.M.; thence north 2 miles to the
northwest corner, NE% XEH Section 30, T.27N.,
EXHIBIT IIM1
METES AND BOUNDS FOR THE BOUNDARY DELINEATION
OF THE SPOKANE VALLEY - RATHDRUM PRAIRIE AQUIFER
-29-
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Aquifer. Similar approaches were used for several other
aquifers, including the Biscayne Aquifer in Florida and the
Cross Valley Aquifer in the State of Washington.
Topographic divides were often used to define the areas
where recharge and surface water flow were directly related
to ground water in the area of concern. In some cases,
abrupt changes in water quality were also used for
definition purposes.
As mentioned above, many SSA boundaries were formed by
both hydrological and political/cultural criteria. For
example, the SSA boundaries of the New Castle, Delaware,
Aquifer were extended by the Region to the Maryland-Delaware
State line. Conversely, many of the potential areas based
on solely political/cultural features were modified by the
Regions to conform to hydrological criteria.
Hydrogeologic Considerations in Boundary Delineations
Three major areas were considered in the delineation of an
SSA: the aquifer, its recharge area, and its streamflow
source zone. The relationships among these areas must be
understood in order to delineate an SSA properly.
An aquifer is defined as a geologic formation, a group
of formations or a part of a formation that yields water to
wells and springs. Examples of single formation aquifers
are the Conestoga formation of the Seven Valleys Aquifer in
Pennsylvania (Exhibit 111-12), and the glacio-fluvial valley
fill deposits in the New Rockford Aquifer in North Dakota
(Exhibit 111-13). Examples of aquifers that include many
geologic units are the limestone formations of the Edwards
Formation in Texas or the volcanic flows of the Snake River
Aquifer in Idaho.
An aquifer recharge area was generally interpreted as
the land surface over which water infiltrates to the aquifer
or where ground water discharges to streams that flow to the
aquifer. In some settings, the recharge area may coincide
with the aquifer. However, in many instances, the recharge
area extends beyond the aquifer. For example, the Seven
Valleys SSA was expanded by the Region to include the entire
ground-water basin (see Exhibit 111-12). Here, the
Wissahicken and Marburg Formations were included in the SSA,
since they were in the recharge area of the Conestoga
formation. Similarly, the New Rockford Aquifer is currently
undergoing further study to determine the extent to which
the till deposits recharge the underlying valley fill
deposits, which serve as the primary aquifer material. (See
Exhibit 111-13.)
-30-
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YORK 7mi.
\
AQUIFER
(CONESTOGA
LIMESTONE)
STREAM FLOW
SOURCE ZONE
1-83
PENNSLYVANIA
MARYLAND"
EXHIBIT 111-12
AQUIFER RELATIONSHIPS, SEVEN VALLEYS
AQUIFER, PENNSYLVANIA
-31-
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-' ^
»»ROil«CMEN«Y ^Vs
i V
JAMES
RIVER.
HEIMDAL
AQUIFER.
1500 -
> 02> ra o oo; £, 5 *
^gsfegr^?.
L°.^s^O.?^A^^
1200
EXHIBIT IH-13
AQUIFER RELATIONSHIPS, NEW ROCKFORD
AQUIFER, NORTH DAKOTA
-32-
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It is likely that SSA designation ultimately would include
some of the overlying till as its recharge area.
A streamflow source zone is defined as the land area
from which runoff contributes to streams and lakes that
drain or recharge an aquifer. Often the recharge area and
streamflow source area coincide, but this was not always
the case. The most notable examples were the Biscayne
(Exhibit 111-14), Spokane Valley-Rathdrum Prairie, and
Edwards Aquifers. In each case, a we11-developed surface
water system existed outside the SSA and transported water
into it. In the case of the Biscayne Aguifer, Lake
Okeechobee and its drainage system are connected to a
canal network within the aguifer. Water recharges the
ground water from these canals during the drier months of
the year. Similarly, a small percentage of water is
supplied to the Spokane Valley-Rathdrum Prairie Aquifer
from a lake which lies outside the designated area.
Regional recommendations always included the recharge
zone as part of the SSA delineation. Seventy percent of
Regional recommendations also included the streamflow
source zone as part of the SSA (see Exhibit II1-15). The
streamflow source zone was generally excluded from a
designation if it either provided low volumes of water to
the aquifer or would produce a significantly larger
management area. For example, the Snake River Plain
Aquifer would be increased from 9,600 square miles to
36,000 square miles if the entire streamflow source zone
were included in the SSA.
It should also be noted that Regional designation
recommendations for confined aquifers have always been
extended to include the recharge zone (Exhibit 111-16).
In addition, all Regions that evaluated confined aquifers
included the recharge areas in the delineated area.
The ability to easily define an aquifer in the field
is important to water resource planning, facility siting,
and protection. Thirty-five percent of the aquifers can
be easily identified by metes and bounds, roadways,
municipal jurisdictional lines, rivers, shorelines, and
other rather obvious, permanent features. Thirty-eight
percent utilize such features as topographic divides and
prominent outcroppings, which are moderately obvious.
Twenty-seven percent have boundaries that are very
difficult to determine without extensive study. These use
quality concentration criteria, such as the "badwater
line" of the Edwards Aquifer, are determined through
models or are especially obscure, as in the New Rockford
Aquifer.
-33-
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DAY TON A
BEACH
ST.
PETERSBURG
MELBOURNE
Recharge Area
Boundary
WEST
PALM
BEACH
FT.
LAUDERDALE
MIAMI
SSA Boundary
EXHIBIT IIH 4
AQUIFER RELATIONSHIPS, BISCAYNE AQUIFER, FLORIDA
-34-
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Exhibit Ill-is
Areas Included In SSA Approved Or
Recommended For Designation
Percent
UNCONFINED AQUIFERS (39)
Aquifer And Recharge 14
Aquifer, Recharge, And Streamflow 64
CONFINED AQUIFERS (11)
Aquifer And Recharge 27
Aquifer, Recharge, And Streamflow 73
-35-
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I
OJ
CTi
I
Confined Portion of Aquifer
Potentiometric Surface
" " r f * T i __
- i r '- . . _, _ .1
EXHIBIT IIH6
AQUIFER RELATIONSHIPS, THEORETICAL ARTESIAN SYSTEM
-------
(3) Aquifer Size
Over two-thirds of the aquifers were less than 1,000
square miles. The smallest area was Block Island, Rhode
Island, which is seven square miles. The largest was the
Delaware Basin in Texas, which is 12,000 square miles.
Exhibit 111-17 summarizes the size of the aquifers.
(4) Lithology
Exhibit 111-18 summarizes the major rock types that
exist in the aquifers. Over half the aquifers were in
unconsolidated deposits. A small percentage was in
crystalline rocks.
Lithologic complexity and the extent of confinement
were two factors significant in the delineation of SSAs
and their water-bearing characteristics. Sixty percent of
the aquifers essentially behaved as a single hydrologic
unit, even though certain zones may have been more
productive than others. Multilayered aquifers comprised
the remaining 40 percent. These aquifers generally had
several definable water-bearing zones associated with the
specific lithologic units. Exhibit 111-19 lists aquifers
according to their hydrologic complexity.
Though multiple systems contained isolated or
semi-isolated water-bearing units, they were not
necessarily artesian. Only 14 percent of the areas
designated or under consideration contained artesian
units. In all cases, however, the Regions treated
multiple and confined artesian systems as "leaky,"
assuming that the overlying, unconfined units would
contribute pollutants to the "confined" units beneath them.
(5) Hydroloqic Complexity
Reconstruction of ground-water flow in SSA studies was
not clearly defined, even in USGS reports. Often general
cross-sectional flow patterns were included such as in
Kings and Queens Counties, New Jersey Coastal Plain
Aquifers, State of New Jersey, or in Guam
(Exhibit 111-20). In cases where basin morphology was
used to delineate aquifer boundaries, flow was
characterized by surface topography. The best examples of
relatively detailed reconstruction were the New Rockford
and Seven Valleys Aquifers (Exhibit 111-21) where
illustrations depicted local flow conditions. In the
former case, these directions were critical to the
selection of which areas were included if designation was
made.
-37-
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EXHIBIT 111-17
Aquifer Size
Avq. Size (mi sq.)
Size Range (mi sg.) Percentage in Range
0-50 29 31
50 - 100 8 83
100 - 1,000 31 204
1,000 - 10,000 29 4,424
Over 10,000 3 12,000
EXHIBIT 111-18
Lithology
Major Rock Types Percentage
Unconsolidated Deposits 53
Carbonate Sedimentary Rocks 15
Clastic Sedimentary Rocks 12
Igneous Rocks 5
Metamorphic Rocks 3
Multiple Lithologic 12
-38-
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EXHIBIT 111-19
Aquifer Complexity
Single
Cape Cod, MA
Nantucket Island, MA
Quaboag River Valley, MA
Block Island, RI
Buried Valley, NJ
Ridgewood, NJ
Mt. Olive, NJ
Upper Rockaway Basin, NJ
Seven Valleys, PA
Maryland Piedmont, MD
New Castle, DE
Biscayne Aquifer, FL
Capital Area-Baton
Rouge, LA
Carrizo-Wilcox-
Bastrop County, TX
Wilcox-Shreveport, LA
New Rockford, ND
Northern Guam
Scotts Valley, CA
Pearl Harbor-Honolulu, HI
Spokane-Rathdrum
Prairie, ID-WA
Snake Plain, ID
Camano Island, WA
Whidbey Island, WA
Cross Valley, WA
North Florence Dunal, OR
Multiple
Long Island, NY*
Brooklyn-Queens, NY
Clinton Street-Ballpark, NY
Schenectady/Niskayuna, NY
Cattaraugus Creek-Sardinia, NY
New Jersey Coastal Plain, NJ
State of New Jersey
Volusia-Floridan, FL*
Edwards Aquifer, TX*
Edwards Aquifer-Barton
Springs, TX*
Naco-Bisbee, AZ
Upper Santa Cruz &
Avra-Altar Basin, AZ
Fresno Co., CA*
Seven Lakes, WA
Newberg Area, WA
Contains Artesian Systems.
-39-
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Water
Water
Table
o
I
EXHIBIT 111-20
GENERALIZED GROUND WATER FLOW, GUAM
-------
77'QQ'
76*45'
7 G
Ground-water Divide
Direction of Shallow
Ground-water Flow
- 40*00'
7 I
SSA Boundary
Drainage to Chesepeake Bay
Below Mouth of Susquehanna
M D.
39*45'
5 Miles
EXHIBIT 111-21
LOCATION AND DIRECTIONS OF GROUND-WATER FLOW AT
OR NEAR THE TOP OF THE ZONE OF SATURATION
-41-
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Ground-water models were rarely used to delineate
boundaries or reconstruct ground-water flow. Thus far,
the Seven Lakes and Tulalip Reservation Aquifer in
Region X is the only case in which a model was used to
define the extent of the aquifer. A major USGS study had
been conducted in the area for purposes other than SSA
designation prior to petition submission. A
three-dimensional, finite difference model defined the
aquifer boundary and ground-water flow systems. Model
results, when available, have been considered by Region X
for delineating the aquifer and recharge area boundaries.
References in the Regional files to model use in
designating SSA boundaries also exist for the Biscayne,
the Volusia-Floridan, the Barton Springs, and the Camano
Island Aquifers. For instance, in the late 1960s, an
electrical analog model was used in the Biscayne Aquifer
to evaluate a hydrologic relationship between canal and
ground-water recharge. Since designation in 1979, other
model usage has been known to have occurred for this
aquifer, but this information was not in the Regional
files. The other three aquifers contained references to
two- and three-dimensional, USGS finite difference models
by Trescott, et al., which defined the hydrologic
properties of various formations. These studies were
conducted independently of SSA considerations.
For most aquifers, ground-water quality was considered
good. Ground-water quality data were usually general in
content, and summary data were often presented in
association with water use and ground-water pollution
discussions. Most file data presented information on
total dissolved solids (TDS), iron, sulfates, and
chlorides as they related to salt-water intrusion.
(6) Vulnerability to Contamination
In 64 percent of the aquifers investigated, water
tables were within approximately 30 feet of the land
surface. The approximate depth to the water table was
greater than 60 feet in 30 percent of the aquifers. The
remaining 6 percent have water tables that are moderately
deep, between 30 and 60 feet. Water table data were
commonly related to vulnerability in unconfined aquifers.
Locations with a shallow water table depth were considered
especially susceptible to contamination.
In most cases, the petitions identified potential
pollution sources that were a cause of concern. These
sources were offered as evidence of aquifer vulnerability
and potential impact on the quality of drinking water.
The typical petitioner's approach was to list a number of
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pollution sources, some of which may have caused
documented water quality problems. Normally, such lists
included underground storage tanks, sanitary landfills,
surface-water runoff, agricultural practices, on-lot
disposal, and sewage treatment plants. Additions were
generally related to local concerns associated with
specific locations, e.g., salt-water intrusion, canals,
underground injection wells, and oil and gas activities.
Rarely were actual pollution incidents identified by name
and location. Only in the Maryland Piedmont Aquifer was a
list of specific, Federally-supported potential
contamination or pollution sources identified by the
petitioner.
3. Summary Of Cross-Program Analysis
The following is a summary of the institutional and
policy characteristics of the petitions received and the
hydrogeologic characteristics of the petitioned aquifers.
(1) Institutional/Policy Characteristics
EPA Regions have received petitions rather
consistently over the past 11 years, with a peak in
submissions in the early 1980s. Environmental groups
represent the largest petition groups, although petitions
were submitted by local governments, citizens, and local
water suppliers as well. About one-half of the petitions
were submitted in an attempt to stop or affect a specific
project. Landfills and publicly owned treatment works
(POTWs) were the two types of facilities most likely to
cause petitioners to submit SSA applications. The other
half of the petitions was submitted to protect
ground-water resources.
Once the Regions received the petitions, they either
collected additional data or contacted the USGS and
outside consultants. To provide public participation, the
Regions held public hearings and accepted written public
comments. State and local governmental agencies often
provided written comments as well.
The Regions largely used three criteria to determine
whether an aquifer should be designated. They were: (1)
at least 50 percent population dependency on ground water,
(2) the existence of alternative water supplies, and (3)
the vulnerability to ground-water contamination.
Two-thirds of the petitions providing such information
indicated over 90 percent dependency of the population on
ground water. In fact, almost half of the petitioned
aquifers have been characterized as providing 100 percent
of the drinking water supply. The second criterion,
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alternative water supplies, was interpreted differently by
various Regions. Some Regions addressed only available,
existing sources as alternatives, while other Regions
considered undeveloped, potential sources as well. The
Regions used no formal approach or methodology to measure
the third criterion, vulnerability. Typically, the Region
reviewed hydrogeologic parameters of the aquifer and
declared it to be vulnerable.
For designated SSAs, most Federal financially assisted
projects reviewed by the Regions were approved without
modification. For a few projects, modifications were made
in order to be approved for the SSA area.
(2) Hydroqeoloqic Characteristics
Petitions contained up to nine different types of
hydrogeologic information. Ground-water use and pollution
source data were most commonly included in the petitions.
Lithologic and formation nomenclature were usually
presented as excerpts from geologic reports. Ground-water
flow, water table depth, and other hydrologic data were
generally not included in the petitions. Taken as a
whole, the petitions alone were not adequate for making a
delineation determination.
Both petitioners and the Regions most often used
hydrologic criteria as a basis for delineating SSAs, and
they were approximately likely to rely on these
delineation criteria. Worth noting, however, is that the
Regions frequently revised the petitioners' original
boundaries once more comprehensive and sophisticated
technical information had been reviewed. In many cases,
these revisions were the result of the Region including
the recharge area and/or streamflow source zone in the
delineated area. In fact all delineated SSAs included the
aquifer recharge area and 70 percent included the
streamflow source zone.
In terms of size, over two-thirds of the aquifers were
less than 1,000 square miles while several were larger
than 12,000 square miles. Over half of the aquifers were
in unconsolidated deposits. Most aquifers behaved as
single hydrologic units (i.e., 25 of 42 aquifers or 60
percent). The remaining 40 percent were multilayered,
containing several definable water-bearing zones. The
Regions in all cases treated multiple and confined aquifer
systems as "leaky," assuming that unconfined, overlying
units would contribute pollutants to the underlying units.
For ground-water flow characteristics, the petitioners
generally based the analysis on surface topography and
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rarely used ground-water models. The depth to ground
water was less than 30 feet in almost two-thirds of the
cases. Shallow depths were often considered to represent
susceptibility to contamination. The petitions often
listed pollution sources that contributed to making the
aquifers more vulnerable to contamination.
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