SPA 910/W8-188
United States
Environmental Protection
Agency
Region 10
1200 Sixth Avenue
Seattle WA 98101
April 1988
Office of Ground Water
Resource Document
For Consideration of the
Tulalip Aquifer as a
Sole Source Aquifer
StiUaguamish River
Puget
SOUT,J
South Fork
Stillaguamish River
Tulalip Indian
Reservation
Everett
Lake
Stevens
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FOR THE CONSIDERATION OF THE TULALIP AQUIFER
AS A SOLE SOURCE AQUIFER
Office of Ground Water
U.S. Environmental Protection Agency
Region 10
Seattle, Washington 98101
May 1988
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TABLE OF CONTENTS
Page
LIST OF TABLES
LIST OF FIGURES
INTRODUCTION 1
Sole Source Aquifer Program 1
Purpose and Scope 1
AQUIFER AREA DESCRIPTION AND PHYSICAL CHARACTERISTICS 2
Geographic Setting 2
CH mate 2
Population 2
Geology 3
Bedrock Uni ts 3
Unconsol 1 dated Deposits 4
AQUIFER AREA BOUNDARIES 5
DRINKING WATER SUPPLY 7
Surface-Water Use 7
Ground-Water Use 8
GROUND-WATER QUALITY 9
POTENTIAL FOR AQUIFER CONTAMINATION 10
ALTERNATIVE DRINKING WATER SOURCES 10
SUMMARY 12
REFERENCES 13
APPENDIX 1: TABLES
APPENDIX 2: FIGURES
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LIST OF TABLES
1. Public Ground-Water Systems: Locations,
Populations Served, and Well Depths Appendix 1
2. Tulalip Aquifer Area Census Tracts
and Tract Populations Appendix 1
3. Summary of Drinking Water Use in the
Tulalip Aquifer Service Area Appendix 1
LIST OF FIGURES
1. Tulalip Sole Source Aquifer Area;
Proposed Boundaries Appendix 2
2. Tulalip Sole Source Aquifer Area,
Petitioned and Proposed Boundaries Appendix 2
3. Tulalip Sole Source Aquifer Area,
Population Density Appendix 2
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In April of 1984 the U.S. Environmental Protection Agency (EPA) received a
petition, from the Seven Lakes Water Association (SLWA), requesting sole
source aquifer (SSA) designation for the Association's service area in west
central Snohomish County, Washington. The SLWA intends to utilize sole source
aquifer designation as one means of protecting their ground water resource.
The petitioned aquifer was formerly unnamed. It is referred to, in this
report, as the "Tulalip Aquifer."
The Administrator published a notice of receipt of the SLWA petition and a
request for public comment in the Federal Register on July 17, 1984. At that
time, EPA determined that the area proposed by the petitioners did not cover
the entire aquifer and, therefore, had to be expanded. Preparation of this
report was delayed until essential data were made available by the U.S.
Geological Survey for use in defining the appropriate aquifer boundaries.
Sole Source Aquifer Program
The Safe Drinking Water Act, Public Law 93—523, was signed into law on
December 16, 1974. This act provides the statutory basis for designation of
sole source aquifers by the Environmental Protection Agency. Section 1424(e)
of the Act states:
"If the Administrator determines, on his own initiative or upon petition,
that an area has an aquifer which is the sole or principal drinking water
source for the area and which, if contaminated, would create a
significant hazard to public health, he shall publish notice of that
determination in the Federal Register. After the publication of any such
notice, no commitment for Federal financial assistance (through a grant,
contract, loan guarantee, or otherwise) may be entered into for any
project which the Administrator determines may contaminate such aquifer
through a recharge zone so as to create a significant hazard to public
health, but a commitment for Federal assistance may, if authorized
underanother provision of law, be entered into to plan or design the
project to assure that it will not so contaminate the aquifer."
To qualify as a sole source aquifer, an aquifer must supply at least 50 per
cent of the area's drinking water, and there must be no physically, legally,
or economically feasible alternative sources that can substitute for the total
drinking water supplied by the aquifer (EPA, 1987).
Purpose and Scope
The purpose of this report is to describe the characteristics of the aquifer
area and to evaluate the area against criteria for sole source aquifer
designation. Specific topics discussed are: (1) the boundaries of the
aquifer area as proposed by EPA; (2) hydrogeologic characteristics; (3) ground
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water and surface water consumption; (4) water quality, (5) potential for
contamination, and (6) the availability of economically feasible alternative
sources of drinking water. This report summarizes information available to
EPA as of April, 1988; no additional field studies were conducted by EPA.
AQUIFER AREA DESCRIPTION AND PHYSICAL CHARACTERISTICS
Geographic Setting
The Tulalip aquifer, as proposed by EPA, covers approximately 180 square miles
of west central Snohomish County (Fig. 1). It extends over most of the area
between Puget Sound and Granite Falls, and between the South Fork
Stillaguamish River and Lake Stevens. The Newberg Area sole source aquifer is
also immediately east of the new proposed aquifer. These boundaries represent
a considerable expansion of the area originally petitioned by the SLWA
(Fig. 2).
The expansion of the boundaries of the sole source area beyond those
petitioned is based on EPA's assessment of hydrogeologic characteristics of
western Snohomish County, and on EPA guidelines for sole source aquifer
designation. By definition, an aquifer is a geological formation, group of
formations, or part of a formation capable of yielding a significant amount of
water to a well or spring (EPA, 198.7). A petitioner can .petition for part of
an aquifer if that portion is hydrogeologically separated from the rest of the
aquifer; the petitioner might also petition an aquifer system to the extent
that all aquifers in the system are hydrogeologically connected (EPA, 1987).
EPA has determined that the area petitioned by SLWA is hydrogeologically
connected to surrounding aquifer materials both laterally and vertically, and
thus constitutes an aquifer system. These considerations are discussed in
detail in the section of this report entitled "Aquifer Boundaries".
The climate of the Tulalip Aquifer area is characteristic of the Puget Sound
lowland area, with heavy precipitation in winter and a dry period in summer.
For example, the average annual precipitation is 46 inches, at Arlington,
which occurs predominantly as rain, with occasional periods of light snowfall
during the winter (Lee Krogh, National Weather Service, oral communication,
February 1988 ). Temperatures range from an average high in July of 72.7
degrees to an average low in January of 32.6 degrees.
Population
Much of the proposed aquifer area is sparsely populated and predominantly
rural, with the towns of Marysville and Arlington containing the highest
population densities. EPA estimates that approximately 47,150 people live
within the proposed sole source aquifer area. This estimate was arrived at by
totaling 1986 U.S. Census Bureau tract population estimates (Table 2).
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Fractions of census tracts 526 and 535.02 were used because only portions of
the tracts are contained within the aquifer area. A 50 percent population
Increase 1s predicted through the year 2002, with an additional increase of 88
percent over the subsequent 35 year period (Rasmussen and Huse, 1987).
Geology
The availability and movement of ground water in western Snohomlsh County is
governed largely by the nature and distribution of subsurface geologic
materials. Therefore, understanding the geology of the Tulalip Aquifer is
critical in determining the type and extent of aquifer materials that are
capable of yielding significant amounts of water when saturated. The Tulalip
Aquifer materials consist of accumulations of unconsolidated glacial and other
surflcial deposits overlying, at depth, consolidated sandstone and igneous and
metamorphic bedrock (Fig. 3). Local alluvial deposits occur along rivers,
streams, and Puget Sound. The sandstones and bedrock units outcrop along, and
form part of, the eastern boundary of the proposed sole source aquifer area.
The following detailed discussion of the varied geologic materials of the
proposed area are based on recent geologic maps produced by Minard
<1985a,b,c,d,e,f,g) and Booth (1985).
BEDROCK UNITS
Two types of bedrock units occur below unconsol1 dated deposits near the
eastern boundary of the Tulalip Aquifer area. The older of these two types is
a pre-Tert1ary age (Paleozoic and Mesozoic) "melange" or group of metamorphic
and igneous rocks. The other type of bedrock present is a Tertiary
sedimentary rock, consisting of conglomerate, sandstone, siltstone, and shale
(Minard, 1985c; Booth, 1985). Outcrops of these rock types constitute a
portion of the eastern boundary of the proposed sole source aquifer area.
Metamorphic and igneous rocks outcrop in much of the area east of the South
Fork Stillaguamish River valley, beyond the Tulalip Aquifer boundary (Minard,
1985c; Booth, 1985). Only a very small outcrop actually occurs within the
aquifer area, near the community of Hyland, located along the west bank of the
Pilchuck River (Minard, 1985f). These rocks consist largely of low grade
metamorphic rocks, including metamorphosed pillow basalt, argil lite,
recrystallized limestone, and sections of meta-basalt (greenstone). Clasts
from this rock unit are common 1n much of the glacial deposits of the region.
Outcrops of the igneous sections of this rock unit do not occur within the
proposed area.
The sedimentary rocks outcrop along the South Fork of the Stillaguamish
River. They consist of sections of conglomerate, sandstone, siltstone, and
shale, with lenses of coal interbedded within the different sections. The
rocks range in color from dark gray and olive gray to reddish brown and tan.
Bedding ranges from thick and massive to thin and shaly, and induration from
well indurated to loose and crumbly (Minard, 1985b,c,f; Booth, 1985).
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UNCONSOLIDATED DEPOSITS
Several different types of unconsolldated units exist within the TuTalip
Aquifer area. Non-glacial units include younger alluvial and estuarine
deposits, and beach deposits. Unconsolidated glacial and other surficial
deposits occur in thicknesses of up to approximately 600 feet within the
proposed sole source area (Minard, 1985a,c). Most glacial units were
deposited approximately 15,000 years ago during what has been termed the
Vashon Stade of the Fraser Glaciation. They consist of recessional outwash,
till, and advance outwash, which are all units of the Vashon drift, and
separate, older units known as transitional beds, Olympia gravels, marine
glacial drift, undivided till, and sedimentary deposits. The glacial deposits
provide the primary drinking water source for the area.
The younger alluvial and estuarine deposits He in and along present streams.
These sediments consist mostly of stream-deposited stratified sand and gravel,
with silt, clay, and organic matter present in the floodplain. These deposits
may be at least 30 meters thick near the mouth of the Stillaguamish River.
The beach deposit sediments form beaches along Puget Sound and consist mainly
of sand, but locally contain abundant gravel. Thickness of the deposits vary
according to tidal action.
Recessional outwash of the Vashon drift is the youngest glacial unit of the
proposed area. It occurs in terraces and upland valleys, and on hilltops and
slopes, throughout the proposed area. It consists mostly of stratified sand
and gravel with silt and clay layers common locally. The thickness of the
deposit ranges from 1 to-7 meters.
Till occurs at the surface in much of the proposed area. It underlies the
recessional outwash, where that unit is present. This till is mostly a
non-sorted mixture of clay and silt, sand, pebbles, cobbles, and boulders, but
includes some lenses of stratified material. It is generally compact and
often referred to as hardpan. Till thickness ranges from 1 to 30 meters.
Advance outwash sediments underlie the till throughout the proposed area.
They consist of mostly gray, pebbly sand with increasing amounts of gravel
higher in the section. Fine-grained sand and silt are common in the lower
section. The advance outwash can be as much as 90 meters thick, and is known
as being capable of yielding some of the largest amounts of water in the
region.
The transitional beds outcrop in places beneath the advance outwash deposits,
and consist mostly of thick beds of gray clay, silt, and very fine to fine
sand. It outcrops near the bases of the bluffs bordering the Sti1laguamish
River Valley and along Puget Sound. Thickness usually ranges from 10 to 12
meters.
The Olympia gravel underlies the advance outwash and transitional beds, and
outcrops at the bases of bluffs along the south side of the Stil laguamish
River near its mouth and at Kayak Point on Puget Sound. They consist of
massive sandy, pebbly gravel, alternating with beds and lenses of coarse sand
and gravel. Thicknesses between 6 and 8 meters are exposed at the surface
but the total thickness of the deposit is unknown.
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The marine glacial drift underlies the recessional outwash and crops out In
the bluff along the Stillaguamish River near Sllvana Terraces. It consists of
1 to 2 meters of fossilIferous gray clay, silt, and sand with sparse to
abundant pebbles.
A pre-Vashon age till unit, referred to as "till—undivided" by Mlnard
<1985a). lies beneath the marine glacial drift at the eastern end of that
drift's outcrop area. It consists of hard clay material similar to the Vashon
till.
The unit termed "sedimentary deposits-undivided" lies beneath the marine
glacial drift at the western end of that drift's outcrop area. They consist
of 8 to 10 meters of firm, medium gray, very fine sand, silt, and clay.
AQUIFER AREA BOUNDARIES
The proposed sole source aquifer area is considerably larger than the area
originally petitioned for designation by the Seven Lakes Hater Association.
This expansion was based on review by EPA of available information on
ground-water resources of western Snohomish County, and on regional
ground-water flow modeling of the Tulalip Plateau area, conducted by the U.S.
Geological Survey (Lum and Alvord, in press).
The originally petitioned area consisted of only a portion of the Tulalip
Plateau area (Fig. 1). The Tulalip Plateau is a upland area bounded by the
Stillaguamish River Valley on the north, the Marysville Trough on the east,
and Possession Sound and Ebey Slough on the south. Previous investigations
have indicated that aquifer materials of the Tulalip Plateau area are largely
continuous, through the plateau, and therefore constitute a single aquifer
system, larger than the petitioned area (see Newcomb, 1952; Drost, 1983;
Parametrix, 1983; Hart Croswer, 1978; Shannon and Wilson, 1981; and Sweet,
Edwards, 1984). On the basis of this available information, EPA initially
determined that the aquifer area should be at least as large as the Tulalip
Plateau area.
EPA then consulted U.S. Geological Survey staff engaged in numerical
ground-water flow modeling of the Tulalip Plateau area and vicinity.
Preliminary results of this modeling suggest that deeper aquifer zones of the
Tulalip Plateau area (i.e., zones greater than approximately 200 feet in
depth), below the elevation of the surface of the Marysville trough, are
recharged by ground water moving westward from central Snohomish County. On
this basis, EPA determined that the aquifer boundaries should be extended
beyond the area of the Tulalip Plateau, to incorporate all areas with aquifer
materials in hydrologic connection with deep zones beneath the Tulalip
Plateau. Accordingly, EPA is now proposing to designate an area extending
eastward from the Tulalip Plateau to Granite Falls, the Pilchuck River and the
South Fork Stillaguamish River.
Therefore, the rationale for enlarging the originally petitioned area is to
conform to EPA sole source aquifer Petitioner Guidance requirements regarding
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designation of hydrogeologically connected aquifer materials. The area was
also enlarged to assure adequate protection to areas that might contribute or
convey recharge to materials in hydrogeologlc connection with"deep wells in
the petitioned area and vicinity. The Petitioner Guidance states that "a
petitioner can petition for part of an aquifer if that portion is
hydrogeologically separated from the rest of the aquifer, or, the petitioner
can petition for an aquifer system to the extent that all aquifers in the
system are hydrogeologically connected". Available information Indicates that
the originally petitioned area is hydrogeologically connected to surrounding
aquifer materials, both laterally and vertically. In addition, deep wells
(greater than about 200 feet) in and near the petitioned area are recharged by
water migrating at depth from the east. (Table 1 lists depths of public
ground-water system wells.) The proposed sole source aquifer area consists of
all aquifer material that EPA considers to be hydrogeologically connected with
the originally petitioned area, or consists of unconsolidated material that
extends to regional discharge areas such as rivers or Puget Sound.
The proposed sole source aquifer area, the Tulallp Aquifer, consists largely
of an accumulation of unconsolidated glacial and other surficial deposits in
west central Snohomish County (Fig. 1). It is approximately 180 square miles
in area. It is an aquifer system which extends from Puget Sound eastward to
bedrock outcrops in the Cascade Mountains foothills. The boundaries were
formulated by EPA by assessing available geologic and other maps (e.g. Booth,
1985; Minard, 1985a,b,c,d,e,f,g), to ascertain the extent of unconsolidated
materials, and to Identify regional discharge areas that would serve to bound
the aquifer materials. It 1s bordered on the west by Puget Sound; on the
north by the Stlllaguamish River; on the east by the South Fork Stillaguamish
River, outcrops of bedrock, and the Pllchuck River; and on the south by Lake
Stevens and a tributary of Steamboat Slough. The Newberg Area sole source
aquifer is also immediately east of the new proposed aquifer.
Ground water flows from the east to the west through the Tulalip Aquifer, with
local ground-water flow systems present in the upper deposits located on
topographic highs. Recharge to the aquifer occurs mainly in the form of
direct percolation of precipitation. Other forms of recharge include
percolation from lakes and streams located on topographic highs, and deep
regional recharge flowing from the Cascade Mountains towards the west (Lum, in
press). Recharge from the adjacent Newberg Sole Source Aquifer may also be
contributing to the aquifer, along the eastern boundary near Granite Falls.
Discharge from the aquifer occurs mainly as direct inflow into the
Stlllaguamish River, Steamboat Slough, Puget Sound, lakes located below the
water table (Lum, in press), and other minor streams, creeks, and springs in
the area. Discharge also occurs in the form of evapotranspiration from
vegetation covering the area.
The portion of the Tulalip Aquifer boundaries that are contiguous with the
Newberg Area sole source aquifer, along the Pilchuck River, represents an area
where the Tulalip Aquifer may be in hydrogeologlc connection with
unconsolidated material outside of the proposed aquifer area. This boundary
is assumed to be adequate for meeting the purposes of sole source aquifer
designations since the adjacent material has been designated as another Sole
Source Aquifer area. The Stillaguamish River, South Fork Stillaguamish River,
Pilchuck River, Lake Stevens, and Steamboat Slough are assumed to be
ground-water discharge areas. The western edge of the sedimentary rock unit
outcrops (in the South Fork Stillaguamish River valley) were used as part of
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the eastern boundary of the Tulallp Aquifer area because of their consolidated
nature and probable low water-yielding characteristics as compared to the
unconsolidated glacial deposits. The bedrock boundary represents the extent
of geologically similar aquifer material. The base of the Tulallp Aquifer is
likewise defined as being coincident with the bottom of the unconsolidated
glacial deposits (see Geology section).
DRINKING WATER SUPPLY
Drinking water for residents of, and visitors to, the proposed Tulalip Sole
Source Aquifer area 1s supplied by ground-water and surface water sources.
One criterion that must be met for an area to be considered a sole source
aquifer area is that at least 50 percent of its drinking water must be
obtained from the aquifer. Available data on drinking water consumption in
the proposed area shows that this criterion is met. This evaluation is based
on currently known drinking water consumption data.
Alternative sources of water supply, both within and outside the aquifer area,
were also considered. Plans are being formulated to transport water from the
city of Everett's surface water supply to densly populated towns located
within the Tulalip Aquifer area (Claire Olivers, city of Everett, oral comm.,
March 1988). If implemented, Imported surface water from Everett could
potentially affect the qualification, of the Tulallp Aquifer as a sole source
of drinking water. However, no contracts or legally binding agreements have
been signed, and future projections of factors such as area population and
total area water use are considered speculative. Therefore, in accordance
with EPA guidelines, this water source from outside of the proposed aquifer
area, was not considered when evaluating the aquifer qualifications for sole
source designation (EPA, 1987).
The following discussion presents an analysis of the available drinking water
data, and the assumptions made to obtain estimates of total ground water and
surface water used for drinking water purposes. Public water supply
consumption values represent drinking water distributed to densly populated
areas such as cities and towns, plus drinking water distributed to small,
localized areas such as neighborhoods. Private consumption values represent
drinking water consumed by individual households. Spring-water use is
considered to be ground water and is included in the ground-water use
calculations.
Surface-Hater Use
Surface water used in the area for drinking water supply is obtained from
lakes and streams. Most of the surface water is used by private households,
with only one public surface water system in operation.
According to the Washington Department of Social and Health Services (DSHS)
Water Facilities Inventory data base, the only public surface water system in
the area is Lakeview Water Users located near Lake Stevens. The system serves
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approximately 50 people. The total surface water use by this system is
estimated to be 6,450 gallons per day based on the maximum consumption rate of
129 gallons per day per person. This rate was obtained from the Seven Lakes
Water Association Inc. daily pumping records which show a maximum usage of 325
gallons per day per connection. This value was divided by an assumed average
household population of 2.52 persons (U.S. Census Bureau, 1986 estimate) to
obtain the per capita use figure.
Private surface water use was estimated by determining the number of users in
the aquifer service area who have Washington Department of Ecology (WDOE)
water rights. This number of households was then multiplied by 150 gallons
per day per connection. This usage rate is the same used in the Newberg Area
Sole Source Aquifer determination, and is consistent with individual household
usage figures presented in other publications (U.S. Dept. of Health, Education
and Welfare, 1963). According to the WDOE water rights data base, a total of
65 private systems have surface water rights. This results is a private
surface water use of approximately 9,750 gallons per day.
Combined public and private surface water use within the aquifer service area
1s estimated to be 16,200 gallons per day (Table 3). This value represents
0.3 per cent of the total drinking water used in the area.
Ground-Hater Use
Total ground water usage by public systems using ground water sources is
estimated to be approximately 5,999,661' gallons per day (Table 3). This value
was obtained by multiplying the total population served by public ground-water
systems in the aquifer service area by the per capita water usage rate for
public water supply systems (129 gallons per capita per day).
Public System
Ground-Water Use = Ppub x RPub
where PPub = Population served by public
ground-water systems
(= 46,509)
and RPub
therefore,
Per capita water usage for public
supplies (129 gallons per day).
Public System
Ground-Water Use = 5,999,661 gallons per day
The population served by public systems using ground water, 46,509 persons
was obtained from the DSHS database. Table 1 lists the 158 systems that serve
the Tulalip Aquifer area.
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Ground-water usage from private wells, 25,680 gallons per day, was estimated
by multiplying the population using private wells by the usage rate for
Individual wells (60 gallons per capita per day).
Private Ground-Water Use
Pr1
where:
pn
and RPr1
therefore,
Private Ground-Water Use
Population served by individual wells
within the aquifer service area;
(Total Aquifer Area Population,
47,151) - (Population served by public
systems, 46,559) - (Population served
by private surface water systems, 164)
= 428
Per capita usage for individual water
supplies (60 gallons per day).
25,680 gallons per day.
The total drinking water consumed from ground water (public plus private
supplies) is thereby estimated to be 6,025,341 gallons per day ("Table 3).
This represents 99.7 percent of the total drinking water consumed in the area.
Therefore, the requirement that an area obtain more than 50 percent of its
drinking water from ground water for sole source aquifer designation is met.
GROUND-WATER DUALITY
Ground water used for drinking water in the proposed sole source aquifer area
is generally of good quality. Water from a small number of wells throughout
the area is treated to remove chloride, iron,
sediment. A small amount is also floridated.
largest provider, treats to remove chloride.
arsenic in the drinking water has shown up at
private wells completed in consolidated bedrock near the Newburg Area Sole
Source Aquifer boundary. These wells are not currently being used for
drinking water purposes.
maganese, and suspended
Marysville Utilities, the
Recently, naturally occurring
elevated levels in several
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10
POTENTIAL FOR AQUIFER CONTAMINATION
The unconsolidated, permeable nature of the glacial deposits that comprise the
Tulalip Aquifer indicate that the aquifer is vulnerable to contamination.
Contamination originating from the surface would most likely quickly penetrate
downward through the upper unconsolidated deposits, and possibly move
laterally along the Vashon till surface, or penetrate to greater depths.
Wells which obtain water from these deposits are considered vulnerable to
leaching contaminants.
The Tulalip Aquifer is vulnerable to contamination from a wide variety of
sources, such as pesticide application, leaking fuel, or chemical storage
tanks, agricultural runoff, animal wastes, septic systems, landfill leachate,
and accidental spills of hazardous materials. If ground water were to be
contaminated, its usefulness as a source of drinking water could be impaired
or destroyed. Assuming that the technology to remove the contaminant, or
contaminants, exists and is readily available, an increased expenditure of
energy and funds would still be required to make the water usable again. If
the technology is not available, or if the expense for decontamination is too
high, the contaminated aquifer could become practically useless as a drinking
water source, and Its usefulIness for other purposes could be greatly impaired.
ALTERNATIVE DRINKING HATER SOURCES
An analysis of alternative sources of drinking water supplies in and near the
Tulalip Aquifer area indicates that there are no sources that can provide an
economically feasible alternative. Although there is sufficient unallocated
surface water from the Stillaguamish River, and potentially available imported
water from the city of Everett, the cost of construction for diversion,
treatment, storage, and distribution systems make these alternatives
economically prohibitive to serve the entire aquifer service area.
The city of Everett is considering an expanded water supply service area that
would encompass portions of the proposed Tulalip Sole Source Aquifer area.
The city currently has an excess supply of water that exceeds the quantity of
drinking water currently extracted from the aquifer. However, the city of
Everett has determined that it is economically feasible to supply only those
areas that have population densities greater than 400 people per square mile
(C. Oliver, city of Everett, oral comm., March 1988). Much of the area
proposed for sole source aquifer designation does not meet this density
(Fig. 3). Therefore, water from the city of Everett cannot be considered an
economically feasible alternative source of drinking water supply for the
Tulalip Aquifer.
In addition to prohibitive costs of distribution, treatment, etc., of
Stillaguamish River water, fisheries protection measures for the river require
restrictions on water allocations. These restrictions would make it highly
unlikely that the river could replace TOO percent of the drinking water
consumed from the Tulalip Aquifer. A volume of 75,619,080 gallons per day
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11
(117 cubic feet per second) was measured as the 57-year low flow at the U.S.
Geological Survey stream gage at Arlington. The total amount of drinking
water used from the aquifer (more than six million gallons per day) represents
eight percent of this low flow. However, withdrawal of this amount of water
from the river could have detrimental effects on fish, and, in fact, water is
available for allocation only 50 percent of the time during of the year (K.
Slatter, WDOE, oral comm.., March 1988) - Therefore, the Sti 1 laguamish River
cannot be considered a reliable source of drinking water for residents in the
Tulalip Aquifer area.
An assessment of surface water as an alternative source of water for the North
Snohomish County area was made by the North Snohomish County Regional Water
Association (Rasmussen and Huse, 1987). They found that surface water, in
general, In the area can not be considered viable alternatives to providing
water to the region. They state:
"The Impoundment of surface water on the Tulalip
Reservation has been Investigated by others, as a
source of water and was found not to be cost
effective. Treatment of the supply would certainly be
required. Surface waters from the Plateau area have
been observed to contain high concentrations of total
phosphorus and total coll form bacteria. The
concentration of nutrients appears to be related to
flow conditions. Nitrates and total nitrogen are
greater 1n the wet run off season while total
phosphorus shows the inverse relationship. Total
phosphorus and ammonia concentrations are greatest in
the dry season storm run off.
Two additional subbasins with possible potential for
water supply are the Stillaguamish River and Pilchuck
Creek, a tributary to the Stillaguamish River.
Development of either of these streams is not likely
because of the importance of the Stillaguamish River
to the management of fisheries resources in the Puget
Sound area.
In summary, the limitations to the development of
surface water as a significant potable water supply
would be:
1. Quality as previously mentioned (treatment would
be required).
2. Water rights.
3. Reservoir sites are not available.
4. Lack of control over watershed uses (land use
control for contamination prevention)-
Because of these limitations, the surface waters in
northwestern Snohomish County do not appear to be a
viable candidate for development as a regional water
supply."
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12
Deepening and/or drilling new wells to bedrock units beneath the aquifer would
not be a viable method of obtaining safe drinking water should the aquifer
become contaminated, because bedrock wells would probably not produce
sufficient quantities of ground water, due to lower porosity and
permeability. In addition, arsenic may be encountered in bedrock wells where
ground water has passed through mineralized veins, as has occurred near
Granite Falls.
The proposed Tulalip Sole Source Aquifer area Is located in northwest
Snohomish County, Washington and covers approximately 180 square miles. The
area originally petitioned by the Seven Lakes Water Association Inc. has been
expanded to include the entire aquifer area. The aquifer is composed of
mostly unconsolidated glacial deposits overlying consolidated sandstone*
metamorphic, and Igneous bedrock units. Ground water flows generally from
east to west, with local systems present in topographically high areas.
To qualify as a sole source aquifer, an aquifer must supply at least 50
percent of the area's drinking water, and there must be no economically
feasible alternative sources that can substitute for the total drinking water
supplied by the aquifer (EPA, 1987). An analysis of available data Indicates
that the proposed area meets these criteria and qualifies for designation as a
sole source aquifer area. Approximately 99.7 percent of drinking water in the
area comes from the aquifer, compared to 0.3 percent from surface water
sources. There are also no economically feasible alternative drinking water
sources to supply the area should the aquifer become contaminated. Potential
surface water sources are considered to be too costly when treatment,
transportation, and fisheries habitat losses are considered, and deepening or
drilling additional wells provides no assurance that uncontaminated water
would be obtained because of the nature of the aquifer materials.
Designation of the area as a sole source aquifer would establish a process
whereby EPA would review federal financially assisted projects proposed in the
area. These reviews would be conducted by EPA to assure that proper design,
construction, and operational controls are in place to protect the aquifer
from contamination that may cause a significant adverse effect on the public
health.
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13
REFERENCES
Booth, D.B., 1985, Surfldal geology of the Granite Falls 15-Minute Quadrangle,
Snohomish County, Washington, U.S. Geological Survey Open File Report
85-504.
Drost, B.W., 1983, Water resources of the Tulallp Indian Reservation,
Washington, U.S. Geological Survey Water-Resources Investigations
Open-File Report 82-648, 153 p.
Hart Crowser and Associates Inc., 1978, Groundwater investigation for the
Seven Lakes Water Association, Snohomish County, Washington, 11 p.
Lum, W.E., and Alvord, R.C., in press. Quantitative evaluation of the water
resources of the TuTalip Indian Reservation and certain adjacent areas,
Washington, U.S. Geological Survey Water Resources Investigations Report.
Minard, J.P-, 1985a, Geologic map of the Stanwood Quadrangle, Snohomish
County, Washington, U.S. Geological Survey Miscellaneous Field Studies
Map MF-1741.
Minard, J.P., 1985b, Geologic map of the Arlington West 7.5 Minute Quadrangle,
Snohomish County, Washington, U.S. Geological Survey Miscellaneous Field
Studies Map MF-1740.
Minard, J.P., 1985c, Geologic map of the Arlington East Quadrangle, Snohomish
County, Washington, U.S. Geological Survey Miscellaneous Field Studies
Map MF-1739.
Minard, J.P., 1985d, Geologic map of the Tulalip Quadrangle, Island and
Snohomish Counties, Washington, U.S. Geological Survey Miscellaneous
Field Studies Map MF-1744.
Minard, J.P., 1985e, Geologic map of the Marysville Quadrangle, Snohomish
County, Washington, U.S. Geological Survey Miscellaneous Field Studies
Map MF-1743.
Minard, J.P., 1985f, Geologic map of the Lake Stevens Quadrangle, Snohomish
County, Washington, U.S. Geological Survey Miscellaneous Field Studies
Map MF-1742.
Minard, J.P., 1985g, Geologic map of the Snohomish Quadrangle, Snohomish
County, Washington, U.S. Geological Survey Miscellaneous Field Studies
Map MF-1745.
Newcomb, R.C., 1952, Ground-water resources of Snohomish County, Washington,
U.S. Geological Survey Water-Supply Paper 1135, 133p.
Parametrix, Inc., 1983, Recommended candidate site areas, Snohomish County
landfill site selection study phase 1-3 — technical report. Snohomish
County Department of Public Works, Solid Waste Division, 72 p.
Rasmussen and Huse Engineering, 1987, North Snohomish County regional water
study and preliminary assessment.
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14
Reid, Mlddleton and Associates, Inc., 1984, Water system plan for Seven Lakes
Water Association, Inc., 56 p.
Shannon and Wilson, Inc., 1981, Groundwater supply potential, Kayak Point
residential development, Snohomish County, Washington, Prepared for
Atlantic Richfield Company, 23 p.
Sweet, Edwards and Associates, Inc., 1984, Site area B geotechnical
feasibility study, Snohomish County landfill site selection study
phase 1-4, Geotechnical Report, 16 p.
U.S. Department of Health, Education, and Welfare, 1963, Manual of individual
water supply.
U.S. Environmental Protection Agency, 1987, Sole source aquifer designation
petitioner guidance, 30 p.
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APPENDIX
TABLES
-------
TABLE
LOCATIONS AND NAMES OF PUBLIC WATER SUPPLY SYSTEMS USING GROUND WATER FOR
DRINKING WATER, RESPECTIVE POPULATIONS SERVED, AND WELL DEPTHS.
(Multiple well depths indicate more than one well in use.)
Location
(Township-Range)
T29N, R5E
T29N, R6E
T30N, R4E
System Name
Bigsby-Willson Water System
Meadow Vista
Lonnle Serrano Well
Ivan Elsele
Goodsell Community Well
Musgrove Plat
44th St. NE Pump Station
Engels-Noff singer Water System
Happy Hill Community Club
Kayak Ridge Water System
Tulare Beach Water Association
Tulalip Water System
Sunny Shores Community Club
Sam Lake Improvement Association
Indian Lake Improvement Association
Hoi turn Water System
Doleshal & Olivera Water
McCauley Water System
Roland Lyons
Kathann Estates
Guertin, Raymond Water System
Hinton Estates #7
Knowles - Bodeen Water System
Hinton Estates #6
Hanson, Leonard Water System
Santi , Ernie Well
Spee-B1-Dah
Tulalip Shores Water Association
Miller - Garitee Water System
Ness Water System
Tulalip Wood Water System
Arcadia Water Supply
Upper Tulalip
Marysville Estates - Aqua Hills
Wooding Bert Water System
Olson, Vera Water System
Potlatch Beach Community
Population
Served
18
24
6
6
9
9
6
6
69
18
141
3,150
60
75
105
8
4
9
12
126
9
6
6
6
3
6
31
114
6
20
39
30
24
40
6
6
15
Well Depth
(feet)
162
195
165
43
150
65
175
354
220; 121
46
65; 65
95;102;95
195
420; 276
267
146
170
167
168
170
15
180
175
118
140
142
497
496; 137
228
411
241
247
380
73; 128
140
unknown
171
continued
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Table 1, continued
Location
(Township-Range)
T30N, R5E
T30, R6E
System Name
South View Water System
Brade Carroll Well
Milt Hutchinson Well
Short Plat 231-79
Seg, 51-84
Chealco Water Supply
Snug Harbor Mobile Home Park
Kahm Water System
Short Plat 224-81
Boggs, James Water System
Glunt Kenneth Water System
Garner OL Well
Sands Mobile Home Park
Cross Water System
Mobi le Manor
Barkly Manor
Country Mobile Estates
Marysville Highlands
Allendale Community Water
Grace Water Association
Marysville Highlands East Comm. Water
Private Water District Association
Lauck Road Association
Raab, Sherrill Water System
Schmidt Water System
Indian Creek Water System
John Duncan Community Well
Cobian, Eitelberg, Stover Well
Grannis Tracts Duplex
Grannis Tracts Lot 13
Grannis Tracts Triplex
Carl A. Southard
McBee, Molly Water System
Costa, Manual Water System
Kent Boyd Water System
Lake Cassidy Estates
Paradise Resort
Miner, Jerry Water System
Murphy, Donald Water System
Keister Water System
Hoffman Duplex
Short Plat 398-70
Vanbeek, Clarance Water Sytem
Sunken Acres Water System
Cedar Lane Water Association
L & B Water System
Perrigoue Farm
Nel son-Moberg
Waites Apartment
Jehova Witness Church
Population
Served
24
9
6
15
6
78
71
9
6
9
6
15
52
9
276
36
65
6
45
9
12
12
12
9
3
21-
6
9
6
6
9
8
6
6
6
42
2
6
6
6
6
12
9
18
290
9
9
6
21
3
Well Depth
(feet)
175
162
11
139
160
191
153; 153
no
63
25
42
33
24; 23
25
50; 50; 50
27
45
182
90
100
98
80
48
80
30
45
32
37
unknown
65
unknown
unknown
20
75
unknown
105
30
165
16
15
150
83
unknown
100
17; 17; 17
120
unknown
unknown
20; 200
116
continued
- 2 -
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Table 1, continued
Location
(Township-Range)
T31N, R4E
T31N, R5E
System Name
Poeshel and Schultz #4
Taklo-Wilhelm Water System
Driscoll Water System
Rodeo Downs Water System
Angerbauer Water System
Schlndler Water System
Short Plat 565-70 and 566-70
Wicklund Builders
Getchell Park Community Water
Cedar Springs Camp
Cascade Forest Products
Marysville Utilities
ii ii
Tony Dimak
Anderson Roger Water System
Ford, Louis Spring
Summerset Water System
Ridgecrest Water System
Lakeside Shores Improvement Assoc.
Lakewood West Water Association
Poeschel and Schults System 3
Orchard Beach Community
Lake Goodwin Resort
Glonek Water System
Loch-0-Rama
Lake Ki Sunrise Water
Mt. View Assembly of God
45 Road Water System
Kingston Water District
McAllister & Braaten Water System
Seven Lakes Water Association
H ii
H n
Aeschlima, Foster Water System
Cedar Grove Resort
Tall Firs Assessors Plat
Lake Goodwin, Short Plat 41-84
Camp KI 1 loqua
Bartlett Tract
Cascade Crest Estates Water System
Cascade View Water System
Fire Trail Acres
Warm Beach
Hinton Acres
Fletcher, Loren Water System
Arlington Water Dept.
ii ii
Eagle Ridge Water System
Grove, John Water System
Burnhill Mobile Home Water System
Population
Served
15
6
6
6
6
12
9
14
120
11
6
31,000
90
6
12
9
9
105
45
90
90
2
6
63
96
3
9
30
6
3000
6
9
75
4
3
12
9
18
15
900
6
15
4200
146
9
9
Well Depth
(feet)
75
60
90
55
80
110
unknown
300
42
unknown
25
328,40,450
200
unknown
16
unknown
90
155
231; 349
280
220; 160
47
140
220
200
154; 155
62
216
302
272
272; 24
176; 470
180; 25
320
65
unknown
80
155
178
220
220
169
unknown
114
18
40; 40; 40
185
38
40
398
continued
- 3 -
-------
Table 1, continued
Location
(Township-Range)
T31N, R6E
System Name
-
Arlington Terrace
Poeschel and Schultz #5
Cedar Stump Tavern
Smokey Point Mobile Park
Webber, Leroy Water System
Airway Mobile Park
Watson, James Water System
Bartle Water System
Davis Chris Water System
McPherson Hills Water System
Top of the Hill Homeowner's Assoc.
Edgecomb Landowners Assoc.
McKeown Acres
Short Plat
Forest Grove Mobile Home Park
Bertilson Water System
Hinton Estates
Glasgow Water System
John Klein Spring
Stilli Ridge Estates
Elmer Klein Dairy Farm
River Meadows County Park
Hammer Water Association
Short Plat 37-79
Tobias Water System
Total
Population
Served
29
48
3
80
6
90
9
4
6
20
78
21
12
9
78
6
6
18
30
33
9
4
21
6
9
46,509
Well Depth
(feet)
76
70
40
17
30
64
235
215
-?-
250
50; 182
173
43
165
35
80
100
85
unknown
30; 40
22
71
334
unknown
299
- 4 -
-------
TABLE 2
TULALIP AQUIFER AREA CENSUS TRACTS AND TRACT POPULATIONS
CENSUS TRACT
532
531
535.01
530
528.02
529.01
529.02
527
1/2 of 526
1/8 of 535.02
TOTAL
POPULATION
3857
3604
6158
5416
6224
5299
5356
5712
4824
701
47,151
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TABLE 3
SUMMARY OF ESTIMATED DRINKING WATER USE
TULALIP AQUIFER SERVICE AREA
DRINKING WATER
TYPE AND USE
Ground Water
Public1
Private
Total Ground Water
Surface Water
Public1
Private
Total Surface Water
TOTAL DRINKING WATER
POPULATION
SERVED
46,509
428
46.937
50
164
214
47,151
MAXIMUM USE
(gallons per day)
5,999,661
25,680
6,025,341
6,450
9,750
16,200
6,041,541
PERCENT
WATER USED
99.7
0.3
100.0
from Washington Dept. of Social and Health Services data base.
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APPENDIX 2
FIGURES
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PROPOSED FOR DESIGNATION UNDER THE
AUTHORITY OF SECTION 1424(e) OF THE
SAFE DRINKING WATER ACT (PL-93-5231
Aquifer Area
Explanation
Tulalip Sole Source Aquifer boundary
proposed by EPA
WASHINGTON
Figure l.-Map showing.Tulalip Sole Source Aquifer boundary as proposed by EPA.
Base map is modified from U.S.G.S. Port Townsend Quadrangle, 1975.
Scale 1:100,000
Contour Interval 50 Meters
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Tulalip Sole Source Aquifer boundary
proposed by EPA
Sole Source Aquifer boundary petitione
by Seven Lakes Water Association Inc.
kilometers
1 0123
i i i.t t
-,
miles
Figure 2.-Map showing Sole Source Aquifer boundary petitioned by Seven Lakes Water
Association Inc., and boundary proposed by EPA.
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Tulalip'Sole Source Aquifer boundary
proposed by EPA
Section blocks with.RQflulation.denailis
greater than 400 persons per square mil
kilometers
_ 1 o 1 23
Figure 3.-Map showing section blocks located within the proposed Tulalip Sole
Source Aquifer area that have population densities greater than
400 persons per square mile (City of Everett, 1982).
miles
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