U.S. Department of the Interior

U.S. Geological Survey

Hydrology and Water Quality of the Grand 

Portage Reservation, Northeastern 

Minnesota, 1991-2000

By T.A. Winterstein

Water-Resources Investigations Report 02-4156

Prepared in cooperation with the Grand Portage Band of Chippewa
U.S. DEPARTMENT OF THE INTERIOR

Gale A. Norton, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

Use of trade, product or firm names in this report is for identification purposes only and does not 

constitute endorsement by the U.S. Geological Survey.

Mound View, Minnesota, 2002

For additional information write to:

U.S. Geological Survey

District Chief

2280 Woodale Drive

Mounds View, MN 55112

Copies of this report can be purchased from:

U.S. Geological Survey

Branch of Information Services

Box 25286, MS 517

Federal Center

Denver, CO 80225

Information regarding the USGS is available on the Internet via the World Wide Web. 

You may connect to the USGS Home Page using the Universal Resource Locator (URL) at http://www.rvares.er.usgs.gov 

You may also connect to the Minnesota District Home Page at http://mn.water.usgs.gov/

For more information on all USGS reports and products (including maps, images, and computerized data), call 1-888-ASK-USGS

Water-Resources Investigations Report 02-4156
iii

CONTENTS

Abstract................................................................................................................................................................................. 1

Introduction........................................................................................................................................................................... 1

Purpose and scope..........................................................................................................................................................3

Description of the Grand Portage Reservation ..............................................................................................................3

Hydrology of the Grand Portage Reservation....................................................................................................................... 5

Water-quality in the Grand Portage Reservation .................................................................................................................. 5

Determining the recharge age of water from the Grand Portage Reservation.................................................................... 15

Tritium concentrations and sources .............................................................................................................................15

Sulfur hexafluoride sources and concentrations ..........................................................................................................17

Recharge ages of sampled water..................................................................................................................................23

Summary............................................................................................................................................................................. 26

References........................................................................................................................................................................... 26

Supplemental information................................................................................................................................................... 28

ILLUSTRATIONS

Figures 1–3. Maps showing:

1. Location of the study area, Grand Portage Reservation, Minnesota ...................................................................2

2. Bedrock geology of the Grand Portage Reservation, Minnesota ........................................................................4

3. Watersheds in the Grand Portage Reservation, Minnesota.................................................................................7

Figures 4–8. Graphs showing:

4. Discharge and runoff from Reservation River, and Grand Portage Creek, Grand Portage Reservation, 

and rainfall at Grand Portage Ranger Station, 1991 and 1992 ...........................................................................8

5. Daily precipitation at Grand Portage Ranger Station, cumulative departure from the mean of daily

 rainfall, and lake stages of Loon and Cuffs Lakes, Grand Portage Reservation, Minnesota, March 1998

 through December 2000 ....................................................................................................................................9

6. Concentrations of cations and anions in water sampled from wells in the Grand Portage Reservation, 

Minnesota, 1992–99 .........................................................................................................................................13

7. Concentrations of cations and anions in water sampled from springs in the Grand Portage Reservation, 

Minnesota, 1992–99 .........................................................................................................................................14

8. Concentration of cations and anions in water sampled from lakes and streams in the Grand Portage 

Reservation, Minnesota, 1992–99 ....................................................................................................................17

Figure 9. Trilinear diagran showing percentage distribution of major ion concentrations in water samples from 

ground water, springs, lakes, and streams in the Grand Portage Reservation, Minnesota, 1992–99 .................. 19

Figures 10–11. Graphs showing:

10. Temperature and dissolved oxygen profiles for Taylor and Center Lakes, Grand Portage Reservation, 

Minnesota, 1999–2000 .....................................................................................................................................22

11. Tritium concentrations in wells and springs and estimated recharge age of water in one well and two 

springs by sulfur hexafluoride dating in the Grand Portage Reservation, Minnesota, August 1999 ...............24

TABLES

Table 1. Wells, springs, streams and lakes sampled in the Grand Portage Reservation, Minnesota, 1992–2001 ..............10

Table 2. Ranges of pH, alkalinity, specific conductance, and ionic concentrations of water sampled in the Grand 

Portage Reservation, Minnesota, 1992–99 ...........................................................................................................12

Table 3. Hydrogeologic characteristics and well data for selected wells in the Grand Portage Reservation,

 Minnesota, 1992–2000..........................................................................................................................................18

Table 4. Field measurements at seven lakes in Grand Portage Reservation, Minnesota, 1997–2000................................20

Table 5. U.S. Environmental Protection Agency drinking-water standards and health advisories ....................................23

Table 6. Tritium data collected from wells and springs in the Grand Portage Reservation, Minnesota, 

August 16–24, 1999 ...............................................................................................................................................25
iv

TABLES—CONTINUED

Table 7. Estimated recharge age of water by sulfur hexafluoride analysis in wells and springs in the Grand Portage 

Reservation, Minnesota, sampled August and October 2000 ................................................................................25

Table S-1. Water-quality data collected from wells in the Grand Portage Reservation, Minnesota, August 1999 ............30

Table S-2. Water-quality data collected from springs in the Grand Portage Reservation, Minnesota, 1999......................32

Table S-3. Quality-assurance samples from the Grand Portage Reservation, Minnesota, August 1999 ...........................34

Table S-4. Percent difference between concentrations in field samples and replicate samples from well GW-4, 

Grand Portage Reservation, Minnesota, August 16, 1999.....................................................................................35

CONVERSION FACTORS

Multiply By To obtain

inch (in.) 2.54 centimeter

Foot (ft) 0.3048 meter

Mile 1.609 kilometer

Square foot per day (ft2/d) 0.09290 square meter per day

Square mile (mi2) 2.590 square kilometer (km2)

Gallon per minute (gal/min) 6.390 x 10-5 cubic meter per second

Degrees Fahrenheit (°F) (temperature °F –32)/1.8 degrees Celsius (°C)

Chemical concentrations are given in metric units. Chemical concentrations of substances in water are given in milligrams 

per liter (mg/L) or micrograms per liter (ug/L). Milligrams per liter are a unit expressing the concentration of chemical constituents in solution as mass (milligrams) of solute per unit volume (liter) of water. Micrograms per liter is a unit expressing 

the concentration of chemical constituents in solution as mass (micrograms) of solute per unit volume (liter) of water. One 

thousand micrograms per liter is equivalent to one milligram per liter.
1

Hydrology and Water Quality of the Grand 

Portage Reservation, Northeastern 

Minnesota, 1991–2000

by T.A. Winterstein

ABSTRACT

The Grand Portage Reservation is located in northeastern Cook County, Minnesota at the boundary between Minnesota, USA, and Ontario, Canada. Between 1991 and 2000 the U.S. Geological Survey conducted a series of studies, with

the cooperation with Grand Portage Band of Chippewa, to describe the water resources of the Grand Portage Reservation. 

Ground water moves primarily through fractures in the bedrock, probably in three ground-water systems: local,

regional, and deep. Lake Superior is thought to be the discharge point for brines in the deep ground-water flow system. 

The watersheds in the Grand Portage Reservation are small and steep; consequently streams in the Grand Portage Reservation tend to be flashy. Lake stages rise and fall with rainfall. 

The pH of water in the Reservation is generally alkaline (pH greater than 7.0). The alkalinity of water in the Reservation is low. Concentrations of major ions are much greater in ground water than in spring water and surface water.

The ionic composition of water in the Reservation differs depending upon the source of the water. Water from 11 of the

20 wells sampled are a calcium-sodium-chloride type. Water from wells GW-2, GW-7, and GW-11 had much greater specific conductance concentrations of major ions compared to the other wells. Some spring water (SP-1, SP-3, SP-4, SP-6,

and SP-8) is calcium-bicarbonate type like surface water, whereas other spring water (SP-5 and SP-7) is similar to the calcium-sodium-chloride type occurring in samples from about one-half the wells. The major chemical constituents in surface water are bicarbonate, calcium, and magnesium. 

Measured tritium and sulfur hexafluoride (SF6) concentrations in water samples from springs and wells were used to

determine the recharge age of the sampled water. The recharge ages of two of the wells sampled for tritium are before

1953. The recharge ages of the remaining 10 samples for tritium are probably after 1970. The recharge ages of seven SF6

samples were between 1973 and 1998.

INTRODUCTION

The Grand Portage Reservation is

located in northeastern Cook County,

Minnesota at the boundary between

Minnesota, USA and Ontario, Canada

(fig. 1). The Reservation is about 88

mi2 in area and located within the

Northern Lakes and Forests Ecoregion (Omernick, 1987), which contains numerous hills, small valleys,

streams, lakes, and wetlands.

Although some areas of the Reservation have been recently logged and

logging continues, the majority of the

forest is second growth forest and

undisturbed (the entire area was

logged during the late 1800’s and

early 1900’s). Most homes, businesses, and tourist and historical

attractions are located in the community of Grand Portage, along Highway

61, and along Highway 17 east of

Mineral Center. 

During 1991–2000, the U.S. Geological Survey (USGS) conducted a

series of studies, in cooperation with

Grand Portage Band of Chippewa, to

describe the water resources of the

Grand Portage Reservation (Ruhl,

1995 and 1997; Winterstein, 2000).

The purpose of these studies was to

provide the Reservation Tribal Council (1) information about the ground

water beneath the Reservation that

would help the Council in the efficient development of ground-water

supplies for commercial and residential use, (2) water-quality information

about Grand Portage and

Wauswaugoning Bays, which have

important aesthetic, fishery, and
2T. 63

N.

R. 5 E.

R. 6 E.

R. 7 E.

T.

64

N.

T.

62

N.

89°52'30" 89°45' 89°37'30" 89°30'

48°

47°52'30"

R. 4 E.

61

61

36

31

1

6

36 31

1 6

36 31

1 6

36 31

Base from U.S. Geological Survey

Digital data, 1:100,000, 1985,

Universal Transverse

Mercator projection,

Zone 15

CANADA

Pigeon Point

MINNESOTA

MICHIGAN

Hat Point

Grand

Portage

Mineral

Center

EXPLANATION

MINNESOTA

Reservation

Grand Portage Indian Reservation

Swamp

Lake

Wauswaugoning

Bay

Grand Portage

Bay

1717

1717

Pigeon

Red

Rock

Reservation River

Creek

River

Reservation Boundary

Hollow

Rock

Creek

Loon

Lake

Speckled

Trout

Lake

Center

Lake

Dutchman

Lake

Cuffs

Lake

Teal

Lake

L a k e S u p e r i o r

Suzie Island

Lucille Island

0

0

1 2

1 2 3 Kilometers

3 Miles

Grand Portage Creek

Eagle Marsh

North

Lake

Taylor

Lake

Chevans

Lake

Mt. Maude

Lake

Poplar

Creek

Little

Lake

Grand

Portage

Island

Raspberry Point

Grand

Portage

National

Monument

Turtle

Lake

Former Finland

Air Force Station

Cook County

Ely

Circle containing spring sampling sites and site numbers

Surface-water sampling site and site number

Ground-water sampling site and site number

SP-1

SW-1

GW-1

Monitoring well (Letters indicate

well identification)

RR

Location of the study area, Grand Portage Reservation, Minnesota. Figure 1.

GW-21

GW-20

GW-22

GW-14

GW-18

GW-17

GW-16

SP-7

SP-5, SP-6

SW-16

SW-14

SW-8

SW-9

SW-13

SW-11

SW-12 SW-7 GW-12

GW-13

GW-11

GW-10

SW-5

SW-4

GW-9

GW-8 SW-3

GW-6

SW-1

SP-1

SW-2

GW-5 GW-4

GW-2

GW-1

GW-7

SW-10 SP-3,SP-4

SW-6

SW-15

SP-8

GW-15

GW-3

GW-19

RR

HRC

SP-2
3

water-supply values to the Reservation, and (3) to collect the data needed

to improve our knowledge of the

source and water-quality of ground

water beneath the Reservation, to

manage the flow and protect the water

quality of several streams in the Reservation, and to protect the water

quality of lakes and wetlands within

the Reservation.

The three reports that have been

written as a result of the studies (Ruhl,

1995 and 1997; Winterstein, 2000)

contain information about (1) streamflow characteristics of Reservation

River, Grand Portage Creek, and

Pigeon River; (2) estimated transmissivities of aquifers beneath the Reservation; (3) well yields and the effects

of hydrofracturing on well yields; (4)

general physical and chemical properties of ground water from 10 wells

within the Reservation; (5) general

physical and chemical properties of

water and bottom sediment collected

from Grand Portage and

Wauswaugoning Bays of Lake Superior; (6) general physical and chemical properties of water collected from

two streams, two wetlands, and four

lakes within the Reservation; and (7)

analyses of trace metals and selected

organic constituents in lake sediments

from two lakes. Water quality and

recharge-age data that was collected

during 1999–2000 from wells and

springs in the Reservation has not

been published. 

Although parts of the hydrology

of the Grand Portage Reservation

have been described in the three

reports, the hydrology of the surface

and ground waters of the entire Reservation has not been described. The

water quality of ground water has not

been compared to the water quality of

surface waters, and the water-quality

data collected since 1997 has not been

compared to the water-quality data

collected during 1991–1996.

PURPOSE AND SCOPE

The purpose of this report is to:

(1) describe the ground- and surfacewater hydrology of the entire Reservation; (2) describe the water-quality

of lakes, streams, springs, and wells in

the Reservation using the data collected during 1991–2000; and (3)

present the results of ground-water

recharge-age dating using tritium and

sulfur hexafluoride data collected

during 1999–2000. Data collected

during 1999–2000 and the methods

used to collect it are presented in the

Supplemental Information Section. 

DESCRIPTION OF THE GRAND 

PORTAGE RESERVATION

The climate of the Grand Portage

Reservation is continental. Average

monthly temperature ranges from

about 8° F during January to about

62° F during July (Baker and others,

1985). Average annual precipitation is

about 29 in. based on a period of

record from 1941 to 1970 (Baker and

Kuehnast, 1978). About two-thirds of

precipitation is rain during April

through November. The other onethird is snowfall during December

through March. 

The hydrology of the Grand Portage Reservation is greatly influenced

by the geology of the Reservation

(fig. 2). In the Grand Portage Reservation, Early to Middle Proterozoic bedrock is covered by thin glacial

deposits of Pleistocene age. The oldest rocks are the Early Proterozoic

Rove Formation of the Animikie

Group, nearly flat-lying argillites,

slates, and greywackes. The Rove

Formation covers most of the northern

part of the Reservation and is truncated in the south by younger rocks of

the Middle Proterozoic Keweenawan

Supergroup (Green, 1982). The earliest Middle Proterozoic rocks are clastic sandstone of the Punkwunge

Formation that crop out along a narrow east-west strip through the center

of the Reservation. Overlying the

Punkwunge Formation and covering

much of the southwestern one-half of

the Reservation are igneous rocks of

the North Shore Volcanic Group.

Rocks of the North Shore Volcanic

Group include the Grand Portage

lavas, the Hovland lavas and the

Brule/Hovland-Reservation River diabase (Green, 1982; and Laurel Woodruff, U.S. Geological Survey,

personal commun., 2002). All rock

units in the Reservation are cut by

several generations of Middle Proterozoic diabase dikes. The dikes have

variable strikes, including east-west,

northeast-southwest, and northwestsoutheast, and may represent a single

intrusion or may be more complex

multiple intrusions, such as the dike

that forms Hat Point.

Bedrock structure controlled the

formation of the major slopes, ridges,

and valleys. Glaciation, weathering,

stream erosion, and wave action of

Lake Superior have resulted in the

formation and deposition of unconsolidated materials on top of the bedrock

(Ruhl, 1995). The unconsolidated

materials consist mainly of glacial

deposits, but include post-glacial alluvium, beach deposits, and peat. The

thickness of the unconsolidated materials generally is less than 50 ft, but

can be as great as 100 ft. 

The land surface of the Grand

Portage Reservation rises from Lake

Superior to highlands in the center of

the Reservation and then declines to

the Pigeon River, the northern boundary of the Reservation. The highest

elevation in the Reservation is near
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++++++++++++++ +++ +++ +++ +++ +++

T.

63

N.

R. 6 E.

R. 7 E.

T.

64

N.

89°45' 89°37'30" 89°30'

61

61

36 31

1 6

36 31

CANADA

Pigeon Point

MINNESOTA MICHIGAN

Hat Point

Grand

Portage

Mineral

Center

Wauswaugoning Bay

Grand Portage Bay

1717

Pigeon

River

Hollow

Rock Creek

Center

Lake

Dutchman

Lake

Cuffs

Lake

Teal

Lake

L a k e S u p e r i o r

Suzie Island

Lucille Island

0

0

1 2

1 2 3 Kilometers

3 Miles

Grand Portage Creek

Mt. Maude

Lake

Poplar

Creek

Little

Lake

Grand

Portage

Island

Raspberry Point

National

Monument

R. 5 E.

48°

47°52'30"

Swamp

Lake

17 Red

Rock

Reservation River Creek

Loon

Lake

Speckled

Trout

Lake

North

Lake

Taylor

Lake

Chevans

Lake

Portage

T.

62

N.

48°

R. 4 E.

36

31

1

6

36 31

1 6

Base from U.S. Geological Survey

Digital data, 1:100,000, 1985,

Universal Transverse

Mercator projection,

Zone 15

17

Reservation River

Reservation Boundary Eagle Marsh

Taylor

Lake

Grand

Bedrock geology of the Grand Portage Reservation, Minnesota.

Turtle

Lake

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

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-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-----

+

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+++

Middle Proterozoic diabase dikes

Logan intrusion

North Shore Volcanic Group

Puckwunge Formation

Rove Formation

Ground-water sampling site

and site number

EXPLANATION

GW-1

Geology modified from Green, 1982

Figure 2.

GW-21

GW-20

GW-22

GW-14

GW-18

GW-17

GW-16

GW-12

GW-13

GW-11

GW-10

GW-9 GW-8

GW-6

GW-5 GW-4

GW-2 GW-1

GW-7

GW-15

GW-3

GW-19
5

Swamp, Speckled Trout, and Loon

Lakes (figs. 1 and 2). 

Rivers and streams in the Grand

Portage Reservation flow either to the

Pigeon River or to Lake Superior (fig.

1). The courses of rivers and streams

and the boundaries of their watersheds

are influenced by the underlying bedrock geology of the Reservation. The

diabase dikes form ridges in the Reservation. Several lakes lie between or

alongside the following: Teal, Dutchman, Cuffs, Center, Speckled Trout,

Swamp, and Loon Lakes. The ridges

determine the course of several

creeks—for example, the upstream

portion of Grand Portage Creek flows

parallel to the ridges. The contact

between the North Shore Volcanic

Group and the Puckwunge Formation

is marked by a steep 200 ft drop to

Eagle Marsh Wetland north of Loon

and Swamp Lakes. This contact also

forms the southwestern boundary of

the watersheds for Dutchman Lake

and the headwaters of Grand Portage

Creek. 

HYDROLOGY OF THE GRAND 

PORTAGE RESERVATION

Ground water moves primarily

through fractures in the bedrock

beneath the Grand Portage Reservation because the glacial sediments that

overlie the bedrock are thin, generally

less than 50 ft thick. Not much is

known about the bedrock fractures

under most of the Reservation. They

have not been mapped because almost

all the wells in the Reservation are

located within 2 miles of Lake Superior. The fractures in two wells, RR

and HRC in figure 1, were mapped by

Paillet and Olson (1994) as part of a

study on increasing well yield using

hydrofracturing techniques. 

The intersecting diabase dikes

that cut all other bedrock units in the

Reservation may strongly influence

fracture flow of water. The dikes are

often crosscutting and may have deep

vertical root zones that extend well

below the surface, possibly creating

barriers to shallow ground-water

flow. The flat-lying Rove Formation

is variably metamorphosed near dike

margins and in some areas has been

transformed into an impermeable

hornfel rock. The dikes themselves

may have intruded along large

regional fractures and in turn may

have created additional fractures during intrusion into other rock units.

Insight into the hydrogeology of

the Grand Portage Reservation can be

gained from a study of the former Finland Air Force Station, which is

located about 75 miles southwest of

the Reservation (U.S. Army Corps of

Engineers, 1999) (fig. 1). The geology

of the area surrounding the station is

similar to the geology of the Reservation—thin unconsolidated material

overlying the North Shore Volcanic

Group intersected by diabase dikes

(Green, 1982; U.S. Army corps of

Engineers, 1999). A fracture analysis

conducted for the former Finland Air

Force Station study determined that

greater than 50 percent of fractures in

boreholes are typically encountered in

the first 150 ft of depth (Natural

Resources Engineering Co., written

commun., 2000). The station is underlain by two primary ground-water systems—a local system and a regional

system. The local system is present

primarily in the upper 100 ft of bedrock, where fractures occur at a relative high density. This system

receives recharge solely from infiltration of precipitation. Ground-water

flow occurs within the fracture network and discharges to the surface at

seeps, wetlands, and ponds (U.S.

Army Corps of Engineers, 1999). The

regional system is below the local

system. Recharge to the regional system is from infiltration of precipitation, subsurface flow from upgradient

lands, and leakage from the local system. Outside the immediate area of

the station the regional system is shallow, at or near the land surface, and

discharges to lowland lakes and rivers

(U.S. Army Corps of Engineers,

1999). Fracture density in the regional

system is controlled by geologic

structures and is high near faults,

dikes, and rock contacts. 

Other studies have reported relatively well-connected, high-density

fracture systems in the uppermost

100–200 ft of layered Paleozoic sedimentary bedrock including the Paleozoic bedrocks of southeastern

Minnesota (A. Runkel, Minnesota

Geological Survey, written commun.,

2001). Wyrick and Borchers (1981)

reported that in Appalachian valleys

stress relief, the removal of compressional stress on underlying rocks by

erosion of overlying rocks, results in

predictable fracture patterns in valleys. The fractures are generally horizontal under valley floors and vertical

along valley walls. 

A local ground-water system may

exist in the upper fracture zone of the

bedrock beneath the Grand Portage

Reservation if the hydrogeology is

similar to that of the former Finland

Air Force Station. This system would

receive water from precipitation and

discharge to seeps, springs, wetlands,

ponds, and small creeks. Beneath this

system would be a regional groundwater system that receives water that

seeps from the local system. This system probably would discharge to Lake

Superior, Pigeon River, and large rivers and creeks such as the Reservation

River. 

Regionally, the land surface

descends from the interior of Minnesota and Canada to Lake Superior. As

a result, water in the deepest ground-
6

water system probably flows from the

interior of Minnesota and Canada,

and discharges to Lake Superior.

Lake Superior may be the discharge

area for brines in the deepest ground

water (Shepard Miller, Inc., 1995, p.

5–8).

Ruhl (1995) estimated the storage

coefficient (S) of the bedrock aquifers

that discharge ground water to the

Reservation River to be 1 x 10-4,

which is typical of aquifers under

confined conditions (Ruhl, 1995).

The storage coefficient for these aquifers is small compared to the transmissivity (T). The hydraulic

diffusivity (T/S) was estimated to be

9.0 x 105 ft2

/d (Ruhl, 1995). The high

estimated hydraulic diffusivity indicates that effects from hydrologic

stresses, such as ground-water withdrawals or recharge from rainstorms,

are propagated rapidly in these aquifers (Ruhl, 1995). 

The transmissivity of the bedrock aquifers around 17 wells completed in the aquifers ranged from 3 to

500 ft2

/d and had a median value of

20 ft2/d (Ruhl, 1995). The transmissivities could not be predicted from

the depth of bedrock penetration by

wells. The reported well yield for 19

wells in Ruhl’s study ranged from 1

to 100 gal/min. The median well yield

was 7 gal/min. The well yield was

greater in wells completed in the

North Shore Volcanic Group than in

wells completed in the diabase dikes

and in the Rove Formation. The water

level in 11 of 21 wells completed in

the bedrock was above the top of the

bedrock indicating that the aquifer

was confined at these well locations

(Ruhl, 1995).

Many of the springs in the Grand

Portage Reservation go dry during

summer. These springs probably are

fed by discharge from the local system. However, several springs (SP-2,

3, and 6; fig. 1) flow year round and

provide enough water to be used as a

domestic water source. These springs

likely are fed by the discharge from

the regional system. 

The watersheds of the streams in

the Grand Portage Reservation are

small (fig. 3) and stream slopes are

steep. Ground-water quantities feeding the streams are not large because

the unconsolidated material above the

bedrock is thin. As a result, streams in

the Reservation tend to be flashy—

sharp rises during rainstorms and

rapid declines afterwards. Stream discharges fall to zero or near-zero flow

during periods of low rainfall. Generally, the greatest periods of runoff are

in the spring, early summer, and fall

because of spring snowmelt and rain,

and early summer and fall rain.

Streamflow decreases to base flow

during the winter and during the summer when evapotranspiration exceeds

rainfall. These patterns are illustrated

by hydrographs for the Reservation

River near Hovland, Minnesota, and

Grand Portage Creek at Grand Portage, Minnesota (fig. 4). 

The percent of precipitation at the

Grand Portage Ranger Station that

became runoff in the Grand Portage

River and Reservation River watersheds from May 1991 through September 1992 was 40 and 45 percent,

respectively. The percentage of precipitation at the Grand Marais

weather station that became runoff in

the Pigeon River from 1921–99 was

44 percent. 

Lakes rise and fall with rainfall in

the Grand Portage Reservation. This

relation is illustrated by the lake

stages of Loon and Cuffs Lakes (fig.

1), which were continuously measured during the ice free part of the

year from June 1998 through November 2000. Lake levels in Loon and

Cuffs Lakes decline when rainfall is

below average and increase when rainfall is above average (fig. 5). The mean

precipitation in figure 5 is the average

of the daily precipitation from March

1, 1998, through December 31, 2000.

The cumulative departure declines

when precipitation is less than the

mean for the period; it rises when the

precipitation is greater than the mean

and is level if the precipitation is equal

to the mean. 

WATER QUALITY IN THE 

GRAND PORTAGE 

RESERVATION

The data collected during 1991–98

and the methods used to collect the

data are presented in Ruhl (1995 and

1997) and Winterstein (2000). The data

collected during 1999–2000 and the

methods used to collect the data are

described in the Supplemental Information Section of this report. The sampling sites are shown in figure 1 and

listed in table 1.

The pH of water in the Reservation

is generally alkaline (pH greater than

7.0) (table 2). Only two wells (GW-15

and GW-22) had a pH of less than 7.0

(6.8). pH less than 7.0 was measured in

two streams flowing from wetlands

(sites SW-4 and SW-10) and in Center

Lake and Cuffs Lake. The alkalinity, or

acid neutralizing capability, of water in

the Reservation is generally low, less

than 100 mg/L as CaCO3 (table 2).

The concentrations of the major

ions are much greater in ground water

than in spring water and surface water

in the Reservation. This difference is

reflected in the measured specific conductance of the sampled wells, springs,

and surface water (lakes and streams)

(table 2). The concentrations of the

major ions in the sampled water in

meq/L are shown in figures 6–8. Some

of the wells and surface-water sites
7

T.

63

N.

R. 5 E.

R. 6 E.

R. 7 E.

T.

64

N.

T.

62

N.

89°52'30" 89°45' 89°37'30" 89°30'

48°

47°52'30"

R. 4 E.

61

61

36

31

1

6

36 31

1 6

36 31

1 6

36 31

Base from U.S. Geological Survey

Digital data, 1:100,000, 1985,

Universal Transverse

Mercator projection,

Zone 15

CANADA

Pigeon Point

MINNESOTA MICHIGAN

Hat Point

Grand

Portage

Mineral

Center

EXPLANATION

Watersheds in the Grand Portage Reservation, Minnesota.

Grand Portage Indian Reservation

Swamp

Lake

Wauswaugoning Bay

Grand Portage Bay

1717

17

Pigeon

Red

Rock

Reservation River Creek

River

Reservation Boundary

Hollow

Rock Creek

Loon

Lake

Speckled

Trout

Lake

Center

Lake

Dutchman

Lake

Cuffs

Lake

Teal

Lake

L a k e S u p e r i o r

Suzie Island

Lucille Island

0

0

1 2

1 2 3 Kilometers

3 Miles

Grand Portage Creek Eagle Marsh

North

Lake

Taylor

Lake

Chevans

Lake

Mt. Maude

Lake

Poplar

Creek

Little

Lake

Grand

Portage

Island

Raspberry Point

Grand Portage National

Monument

Major watershed divides

Minor watershed divides

Turtle

Lake

Figure 3.
8

0

50

100

150

200

250

0

1

2

3

Daily discharge from Grand Portage Creek at Grand Portage, Minnesota, 04010510

Daily discharge from Reservation River near Hovland, Minnesota, 04010530

Discharge and runoff from Reservation River and Grand Portage Creek, Grand Portage Reservation, and rainfall at Grand

Portage Ranger Station, Minnesota, 1991 and 1992.

1991 1992

0

0.1

0.2

0.3

0.4

0.5

0

0.1

0.2

0.3

0.4

0.5

Daily runoff from Reservation River near Hovland, Minnesota, 04010530

Daily runoff from Grand Portage Creek at Grand Portage, Minnesota, 04010510

50

0

100

150

200

250

Daily rainfall at Grand Portage Ranger Station, 213296

RAINFALL, IN INCHES DISCHARGE, IN CUBIC FEET PER SECOND RUNOFF, IN INCHES

JAN.

JAN.

FEB.

FEB.

MAR.

APR.

MAY

MAR.

APR.

MAY

JUNE

JUNE

JULY

AUG.

SEPT.

JULY

AUG.

SEPT.

OCT.

NOV.

DEC.

OCT.

NOV.

DEC.

Figure 4.
9

10

11

12

13

14

15

16

17

18

1998 1999 2000

Daily precipitation at Grand Portage Ranger Station, cumulative departure from the mean of daily precipitation, and lake

stages of Loon and Cuffs Lakes, Grand Portage Reservation, Minnesota, March 1998 through December 2000.

0

0.5

1.0

1.5

2.0

2.5

3.0

-4

-2

0

2

4

6

8

10

Cumulative departure from mean of daily

precipitation at Grand Portage Ranger

Station from March 1998-

December 2000

CUMULATIVE DEPARTURE FROM

MEAN PRECIPITATION, IN INCHES

PRECIPITATION, IN INCHES LAKE STAGE, IN FEET ABOVE DATUM

Stage at Cuffs Lake near Grand Portage, Minnesota, 475647089443301

Stage at Loon Lake near Grand Portage, Minnesota, 475807089483501

Daily precipitation at Grand Portage Ranger Station, 213296

MAR.

APR.

MAY

JUNE

JULY

AUG.

SEPT.

OCT.

NOV.

DEC.

JAN.

JAN.

FEB.

FEB.

MAR.

APR.

MAY

MAR.

APR.

MAY

JUNE

JUNE

JULY

AUG.

SEPT.

JULY

AUG.

SEPT.

OCT.

NOV.

DEC.

OCT.

NOV.

DEC.

Figure 5.

were sampled more than once. The

ranges of the concentrations are

shown in table 2. The relative percentages of the major cations and anions

in the samples are shown in figure 9.

 Water from 11 of the 20 wells

sampled is a calcium-sodium-chloride

type (fig. 6). Water from GW-2, GW7, and GW-11 had much greater specific conductance concentrations of

major ions compared to the other

wells (fig. 6). The greater concentrations of calcium, sodium, and chloride

in these wells may be from the dissolution of the rock matrix (Shepard

Miller, Inc., 1995, p. 5–9), or the

upward discharge of brines from the

underlying Precambrian rocks (Kelly

and others, 1986, Shepard Miller,

Inc., 1995, p. 5–8, F. Paillet, U.S.

Geological Survey, written comm.,

January 5, 1998). Water that is compositionally similar to the water in

these wells has been found in the

Canadian Shield and in the upper peninsula of Michigan (Kelly and others,
10

Table 1. Wells, springs, streams, and lakes sampled in the Grand Portage Reservation, Minnesota, 1992–2001

[Latitudes and longitudes are referenced to the North American Datum of 1983 (NAD 1983)]

Map 

number 

(fig. 1)

Site type Station number Name Latitude Longitude [west] Date ampled Water quality sampling Tritium sampling Sulfur hexafluo- ride sam- pling

GW-1 Well 475229089520601 Olson, Grand Portage Reservation 47° 52′ 29′′ 89° 52′ 06′′ 10/18/2000 x

GW-2 Well 475229089520701 T62NR5E06CCC 47° 52′ 29′′ 89° 52′ 07′′ 09/15/1992 x

GW-3 Well 475237089515501 Evans, Grand Portage Reservation 47° 52′ 37′′ 89° 51′ 55′′ 08/16/1999 x xGW-4 Well 475325089491001 T63NR5E33CCD 47° 53′ 25′′ 89° 49′ 10′′ 09/19/1992 x

08/16/1999 x

GW-5 Well 475341089472301 Long, Grand Portage Reservation 47° 53′ 41′′ 89° 47′ 23′′ 08/16/1999 x xGW-6 Well 475431089461601 Sawmill, Grand Portage Reservation 47° 54′ 31′′ 89° 46′ 16′′ 08/16/1999 x xGW-7 Well 475500089510001 Mineral exploration well, Grand Portage Reservation 47° 55′ 00′′ 89° 51′ 00′′ 08/19/1999 xGW-8 Well 475505089444501 T63NR5E25ABA 47° 55′ 05′′ 89° 44′ 45′′ 09/15/1992 xGW-9 Well 475508089444101 Johnson, Grand Portage Reservation 47° 55′ 08′′ 89° 44′ 41′′ 08/17/1999 x x

08/31/2000 x

GW-10 Well 475549089430201 Paro, Grand Portage Reservation 47° 55′ 49′′ 89° 43′ 02′′ 08/17/1999 x x

GW-11 Well 475618089423801 T63NR6E17CAB 47° 56′ 18′′ 89° 42′ 38′′ 09/14/1992 x

08/17/1993 x

GW-12 Well 475650089425501 T63NR6E07DDD 47° 56′ 50′′ 89° 42 ′ 55′′ 09/16/1992 xGW-13 Well 475650089433401 Blackwell, Grand Portage Reservation 47° 56′ 50′′ 89° 43′ 34′′ 08/18/1999 xGW-14 Well 475710089390001 T63NR6E10AAA 47° 57′ 41′′ 89° 39′ 07′′ 09/14/1992 xGW-15 Well 475719089465201 T63NR5E03CCC 47° 57′ 19′′ 89° 46′ 52′′ 09/16/1992 x

10/18/2000 x

GW-16 Well 475755089410501 T63NR6E04CDA 47° 57′ 55′′ 89° 41′ 05′′ 09/15/1992 x

GW-17 Well 475801089410901 Pump house, Grand Portage Reservation 47° 58′ 01′′ 89° 41′ 09′′ 08/24/1999 xGW-18 Well 475821089415301 Landfill, Grand Portage Reservation 47° 58′ 21′′ 89° 41′ 53′′ 08/31/2000 x

GW-19 Well 475827089413501 T63NR6E04BBC 47° 58′ 27′′ 89° 41′ 35′′ 09/16/1992 x

GW-20 Well 480001089353401 Pigeon River State Park 48° 00′ 01′′ 89° 35′ 34′′ 08/18/1999 x xGW-21 Well 480002089360501 T64NR7E30BCB 48° 00′ 02′′ 89° 36′ 05′′ 09/15/1992 xGW-22 Well 480035089424201 Hart, Grand Portage Reservation 48° 00′ 35′′ 89° 42′ 42′′ 08/17/1999 x xSP-1 Spring 475400089470001 Spring 10, Grand Portage Reservation 47° 54′ 00′′ 89° 47′ 00′′ 08/24/1999 xSP-2 Spring 475700089460001 Spring 3, Grand Portage Reservation 47° 5′ 7 00′′ 89° 46′ 00′′ 08/24/1999 x x

08/31/2000 x10/18/2000 x

SP-3 Spring 475700089500001 Spring 1, Grand Portage Reservation 47° 57′ 00′′ 89° 50′ 00′′ 08/19/1999 x x

SP-4 Spring 475700089500002 Spring 4, Grand Portage Reservation 47° 57′ 00′′ 89° 50′ 00′′ 08/19/1999 x

08/31/2000 x

SP-5 Spring 475800089400002 Spring 9, Grand Portage Reservation 47° 58′ 00′′ 89° 40′ 00′′ 08/24/1999 x

10/18/2000 x

SP-6 Spring 475800089400002 Spring 2, Grand Portage Reservation 47° 58′ 00′′ 89° 40′ 00′′ 08/24/1999 x x

10/18/2000 x

SP-7 Spring 475800089410002 Spring 14, Grand Portage Reservation 47° 58′ 00′′ 89° 41′ 00′′ 08/25/1999 xSP-8 Spring 475800089470001 Spring 7, Grand Portage Reservation 47° 58′ 00′′ 89° 47′ 00′′ 08/17/1999 x xSW-1 Stream 475417089461701 Red Rock Stream below sawmill near Grand Portage 47° 54′ 17′′ 89° 46′ 17′′ 06/26/1997 x

10/08/1997 x05/04/1998 x

SW-2 Stream 475422089463801 Red Rock Stream above sawmill near Grand Portage 47° 54′ 22′′ 89° 46′ 38′′ 06/26/1997 x

05/05/1998 x
11

SW-3 Stream 475456089462801 Red Rock Stream tributary near Grand Portage 47° 54′ 56′′ 89° 46′ 28′′ 06/24/1997 x

05/05/1998 x

SW-4 Stream 475637089451401 Center Lake Creek wetland near Grand Portage 47° 56′ 37′′ 89° 45′ 14′′ 06/24/1997 x

10/07/1997 x05/05/1998 x

SW-5 Lake 475647089443701 Cuffs Lake, middle, near Grand Portage 47° 56′ 47′′ 89° 44′ 37′′ 06/24/1997 x

10/07/1997 x05/07/1998 x09/09/1998 1x

SW-6 Lake 475704089504401 Speckled Trout Lake near Grand Portage 47° 5′ 7 04′′ 89° 50′ 44′′ 06/25/1997 x

10/07/1997 x05/06/1998 x09/08/1998 x

SW-7 Lake 475710089412001 Grand Portage Bay (Site 7) near Grand Portage 47° 57′ 10′′ 89° 41′ 20′′ 08/16/1993 2xSW-8 Lake 475725089381301 Wauswaugoning Bay (Site 1) near Grand Portage 47° 57′ 25′′ 89° 38′ 13′′ 09/22/19943

08/22/19954 5x

SW-9 Lake 475728089391501 T63NR06E10ADB (Lake Superior) 47° 57′ 28′′ 89° 39′ 15′′ 08/16/1993 xSW-10 Stream 475729089505401 Swamp Lake wetland near Grand Portage 47° 57′ 29′′ 89° 50′ 54′′ 06/25/1997 x

10/07/1997 x05/06/1998 x09/10/1998 x

SW-11 Lake 475730089400001 Grand Portage Bay (Site 3) near Grand Portage, 47° 57′ 30′′ 89° 40′ 00′′ 08/16/19936 x

09/22/19947 x

SW-12 Lake 475740089410001 Grand Portage Bay (Site 6) near Grand Portage, 1 foot below 

surface

47° 57′ 40′′ 89° 41′ 00′′ 06/25/1996 8x

SW-13 Lake 475745089391501 Grand Portage Bay (Site 4) near Grand Portage, 1 foot below 

surface

47° 57′ 17′′ 89° 39′ 20′′ 08/16/1993 8x

SW-14 Lake 475757089394001 Grand Portage Bay (Site 5) near Grand Portage, 1 foot below 

surface

47° 57′ 57′′ 89° 39′ 40′′ 06/25/1996 8x

SW-15 Lake 475759089484701 Loon Lake, middle, near Grand Portage 47° 57′ 59′′ 89° 48′ 47′′ 06/26/1997 x

10/08/1997 x05/07/1998 1x09/09/1998 1x

SW-16 Lake 475813089393001 Little Lake near Grand Portage 47° 58′ 13′′ 89° 39′ 30′′ 06/24/1997 x

10/08/1997 x05/05/1998 x09/10/1998 x

1In addition to water quality analysis in samples taken from the lake, trace metals and organic compounds were analyzed in a sample taken from lake sediment.2Trace metals were analyzed in a sample taken from lake sediment.3Two samples were taken. One from 5 ft below the surface and one from 50 ft below the surface.4Sample from 50 ft below the surface.5In addition to water quality analysis in samples taken from the lake, organic compounds were analyzed in a sample taken from lake sediment.6Sample from 1 ft below surface.7Sample from 5 ft below surface.8In addition to water quality analysis in samples taken from the lake, trace metals were analyzed in a sample taken from lake sediment.

Table 1. Wells, springs, streams, and lakes sampled in the Grand Portage Reservation, Minnesota, 1992–2001 --Continued

[Latitudes and longitudes are referenced to the North American Datum of 1983 (NAD 1983)]

Map 

number 

(fig. 1)

Site type Station number Name Latitude Longitude [west] Date ampled Water quality sampling Tritium sampling Sulfur hexafluo- ride sam- pling
12

1986; Shepard Miller, Inc., 1995, F.

Paillet, U.S. Geological Survey, written comm., January 5, 1998). Lake

Superior has been interpreted as a

regional discharge area for deep

brines (Shepard Miller, 1995, p. 5–8).

Paillet and Olson (1994) reported that

saline water (fluid conductivity of

about 2 ohm-meters at 8 °C, corresponding to a total dissolved solids of

about 4,000 mg/L) in a borehole

drilled near Hollow Rock Creek

(HRC) (fig. 1) came from depths

greater than 200 ft. The salty water in

GW-2, GW-7, and GW-11 could be

the result of mixing of fresh rain

water with the deeper brine (Shepard

Miller, 1995, p. 5–8; F. Paillet, U.S.

Geological Survey, written comm.,

January 5, 1998). Two of the wells are

domestic supply wells, GW-2 and

GW-11. The third well, GW-7, is

believed to be a mineral exploration

well (M. Watkins, Grand Portage Reservation, oral comm., 2000). 

 Although wells GW-2 and GW-3

are close to each other (about 1,100 ft

apart), are completed the same type of

bedrock, and the elevations of the bottom of the wells are about the same

(table 1), the ionic composition of

samples from these wells are very different (fig. 6). Water in well GW-2 is

a calcium-sodium-chloride type,

whereas water in well GW-3 is a

sodium-bicarbonate type. The total

ionic concentration in well GW-2 is

91.06 meq/L; the total ionic concentration in well GW-3 is 6.56 meq/L.

Two reasons could explain these differences in water quality. First, well

GW-2 is about 100 ft from Lake

Superior and well GW-3 is about

1,000 ft from the lake. It is likely that

the source of water to well GW-2 is

from a regional and deeper groundwater system that intersects some of

the brine that discharges to Lake

Superior. Well GW-3 is farther from

the lake and may not intersect the

flow of the brine. Second, well GW-3

is about 300 ft from Reservation

River and may intersect fractures that

receive discharge that flows downward from the Reservation River to

the ground water.

The ionic composition of the

water sampled from well GW-11 during September 1992 is very different

than that of the water sampled from

the well during August 1993 (fig. 6).

The sampled water may come from

two different sources. Water in a well

completed in fractured rock may be a

mixture of shallow and deep ground

water. This mixture may change seasonally or following rain storms. The

water sampled in 1992 probably came

from deep ground water considering

that its ionic composition is similar to

water from wells GW-2 and GW-7,

which are also deep wells (table 1, fig.

6). The water sampled in 1993 probably came from shallow ground water

considering that its ionic concentrations are similar to water from springs

(figs. 6 and 7).

The ionic composition of water

from wells GW-15 and GW-22 is

similar to the ionic composition of

surface waters (fig. 9). The concentraTable 2. Ranges of pH, alkalinity, specific conductance, and ionic concentrations of water sampled in the Grand Portage Reservation, Minnesota, 

1992–99

 [Data from Ruhl, 1995, 1997; Winterstein, 2000; data collected 1999–2000 by the U.S. Geological Survey; additional specific conductance and pH data from Margaret 

Watkins, Grand Portage Reservation, written comm., 2000]

Property Values

Ground water 

sampled between 

1992–99

Spring water 

sampled in 1999

Surface water 

sampled between 

1993–98

Specific conductance, μS/cm Minimum 94 50 17

Maximum 5,250 252 164

Average 1,332 132 60

Number of values 22 8 76

pH, standard units Minimum 6.81 5.7 5.6

Maximum 10.2 8.6 9

Average 8.3 6.8 7.4

Number of values 22 8 75

Alkalinity, mg/L as CaCO3 Minimum 17 17 6

Maximum 205 61 78

Average 73 46 29

Number of values 22 8 35

Total concentration of ions in a sample, 

meq/L

Minimum 2.0 1.0 0.4

Maximum 80.4 4.7 3.6

Average 22.1 2.7 1.4

Number of values 19 8 35
13

Concentrations of cations and anions in water sampled from wells in the Grand Portage Reservation, Minnesota, 1992-99.

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fl oride u

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fl oride u

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fl oride u

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fl oride u

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fl oride u

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fl oride u

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fl oride u

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

50 40 30 20 10 0 10 20 30 40 50 50 40 30 20 10 0 10 20 30 40 50

MILLIEQUIVALENTS PER LITER MILLIEQUIVALENTS PER LITER

GW-13 475650089433401

8/18/1999

GW-15 475719089465201

9/16/1992

GW-16 475755089410501

9/15/1992

GW-11 475618089423801

8/17/1993

GW -17 475801089410901

8/24/1999

GW-19 475827089413501

9/16/1992

GW-20 480001089353401

8/18/1999

GW-22 480035089424201

8/17/1999

GW-3 475237089515501

8/16/1998

GW-4 475325089491001

9/19/1992

GW-4 475325089491001

8/19/1999

GW-5 475341089472301

8/16/1999

GW- 6 475431089461601

8/16/1999

GW-7 475500089510001

8/19/1999

GW-8 475505089444501

9/15/1992

GW-9 475508089444101

8/17/1999

GW-10 475549089430201

8/17/1999

GW-11 475618089423801

9/14/1992

GW-2 475229089520701

9/15/1992

GW-12 475650089425501

9/16/1992

GW-14 475710089390001

9/14/1992

GW-21 480002089360501

9/15/1992

Figure 6.
14

Concentrations of cations and anions in water sampled from springs in the

Grand Portage Reservation, Minnesota, 1992-99.

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

MILLIEQUIVALENTS PER LITER

3.0 2.5 2.0 1.0 1.5 0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0

SP-1 475400089470001

8/24/1999

SP-2 475700089460001

8/24/1999

SP-3 475700089500001

8/19/1999

SP-4 475700089500002

8/19/1999

SP-5 475800089400002

8/24/1999

SP-6 47580008940000

8/24/1999

SP-7 475800089410002

8/25/1999

SP-8 475800089470001

8/17/1999

Figure 7.

tions of ions in the water from these

wells are less than 3 meq/L (fig. 6),

the same as spring and surface waters

(figs. 7 and 8). Well GW-15 is 275 ft

deep and well GW-22 is 47 ft deep.

The recharge age of the water in well

GW-15 is about 1.5 years based upon

recharge-age dating by sulfur hexafluoride methods. It is likely that the

water in the well GW-15 is from bedrock fractures that contain recently

recharged ground water. 

Percentages of major ion concentrations in ground water, springs,

lakes, and streams in the Reservation

are shown in figure 9. Spring water

generally plots between surface

waters and ground waters indicating

that spring water is a mixture of surface and ground waters (fig. 9). This

mixing can also be seen in figure 7.

Some spring water (SP-1, SP-3, SP-4,

SP-6, and SP-8) is calcium-bicarbonate type water like surface water, while

other spring water (SP-5 and SP-7) is

similar to the calcium-sodium-chloride

type water in samples from about onehalf of the wells. 

 The major chemical constituents

in surface water are bicarbonate, calcium, and magnesium. The ionic concentrations for the three sampling sites

in Lake Superior, SW-8, SW-9, and

SW-11, are almost identical (fig. 8).

Water samples from lakes show almost

no seasonal variation in ionic concentrations, whereas water samples from

streams show seasonal variation (SW1 and SW-10; fig. 8). The concentrations of the calcium cation and bicarbonate and carbonate anions increase

in streams during periods of low flow

(samples taken in September and October, sites SW-1 and SW-10; fig. 8).

The water in the streams during periods of low flow is composed primarily

of shallow ground water. The diagrams

in figure 8 during low flow are very

similar to the diagrams for springs SP3, SP-4, and SP-8 (fig. 7). Stream sites

SW-2 and SW-3 were not sampled

during fall 1997 because both were

dry. Stream sites SW-1, SW-2, and

SW-3 were dry during fall 1998.

The concentrations of ions in Loon

Lake (SW-15) (fig. 8) are substantially

less than in Cuffs Lake (SW-5), Speckled Trout Lake (SW-6), and Little

Lake (SW-16). Loon Lake is located in

the highest area of the Grand Portage

Reservation, and the low ionic concentrations may occur because little

ground water flows into the lake. The

concentrations of ions in Little Lake

are substantially greater than in the

other lakes. Little Lake is spring fed

(Margaret Watkins, Grand Portage

Reservation, oral comm., 2001), and
15

the ionic concentrations are similar to

those for springs (fig. 7 and 8).

Physical data collected from

seven lakes within the Grand Portage

Reservation are listed in table 4. The

data were collected during 1997–2000

by the USGS and the Grand Portage

Reservation Environmental Department (Margaret Watkins, Grand Portage Reservation, written comm.,

2000). The USGS collected data

from four lakes and the Grand Portage

Reservation collected data from five

lakes (table 4). Physical and chemical

parameters that were measured

include specific conductance, pH,

oxygen reduction potential, temperature, turbidity, and dissolved oxygen.

The parameters were measured with a

portable, multiparameter meter. The

measurements listed in table 4 were

made in the center of each lake about

1 ft below the surface. 

Temperature and dissolved oxygen measurements in Center Lake

indicate that the lake is fed by ground

water. Center Lake is in a valley on

top of a dike (fig. 2). Although, Center Lake is a very shallow lake, about

12 ft deep, temperature and dissolved

oxygen measurements show that the

lake stratifies during the summer (fig.

10). The temperature in the hypolimnion remains constant at about 7°C all

summer. Typically, the hypolimnion

warms during the summer, as it does

for Taylor Lake (fig. 10). In addition,

the dissolved oxygen near the bottom

of Center Lake remains less than 1

mg/L all summer. 

Quality requirements for drinking water are the most stringent of

water-quality standards, and thus are

conservative standards against which

to evaluate water-quality data. The

U.S. Environmental Protection

Agency (USEPA) has established

drinking-water standards and health

advisories for some of the constituents

in the water in the Reservation (U.S.

Environmental Protection Agency,

2000). USEPA promulgates two levels of drinking-water standards. Maximum contaminant levels (MCLs) are

the highest level of a contaminant that

is allowed in drinking water. MCLs

are enforceable standards. Secondary

drinking-water regulations (SDWRs)

are non-enforceable Federal guidelines regarding cosmetic effects (such

as tooth or skin discoloration) or aesthetic effects (such as taste, odor, or

color) of drinking water. Several categories of non-enforceable health advisories (HAs) also exist. The most

stringent of the HAs is the lifetime

HA, which is defined by the USEPA

as “the concentration of a chemical in

drinking water that is not expected to

cause any adverse noncarcinogenic

effects for a lifetime of exposure.”

Table 5 lists the sampled constituents

for which standards and advisories

exist. 

DETERMINING THE 

RECHARGE AGE OF WATER 

FROM THE GRAND PORTAGE 

RESERVATION

Water from selected wells and

springs was analyzed for recharge-age

dates to determine when the water fell

as precipitation. Two environmental

tracers were used to date the water—

tritium and sulfur hexafluoride (SF6).

TRITIUM CONCENTRATIONS 

AND SOURCES

Tritium, a radioactive isotope of

hydrogen, has two possible sources in

water in the study area. First, it is naturally and continually produced in the

upper atmosphere by cosmic ray bombardment. Tritium concentrations

measured in precipitation near

Ottawa, Canada, before nuclear

device testing were about 48 pCi/L

(picocuries per liter). Second, tritium

was produced by atmospheric

nuclear-device testing from the early

1950’s through the mid 1960’s. This

testing greatly increased tritium concentrations in the atmosphere and in

precipitation from 1953 through the

mid 1980’s. Tritium concentrations in

precipitation from nuclear-device testing peaked in 1963 (Clark and Fritz,

1997). Maximum tritium concentrations measured in precipitation at

Ottawa, Canada, were 18,612 pCi/L

in June 1963 (International Atomic

Energy Agency/World Meteorological Organization, 1998).

Tritium concentrations in precipitation vary throughout the year. The

greatest transfer of tritium from the

stratosphere to the troposphere occurs

during the spring in mid-latitude

zones (Clark and Fritz, 1997). This is

due to seasonal disturbances in this

boundary by displacement of the jet

stream as upper level air circulation

reorganizes in the spring. This "spring

leak" annually recharges the hydrosphere with tritium. Tritium concentrations have been declining in

precipitation since the peak in 1963.

The decline of tritium in precipitation

is due not only to radioactive decay,

which decreases tritium levels by 5.5

percent per year, but also because tritium is being stored in ground water

and oceans and is not being returned

to the atmosphere (Clark and Fritz,

1997).

Two sources of tritium concentrations in precipitation were used in the

analysis. Tritium concentrations in

precipitation from 1953–86 are from

the computer program DEP.BAS

(Brian Cross, U.S. Geological Survey,

written commun., 2001). These concentrations are estimates of the concentration in precipitation near the

Grand Portage Reservation at the
16

Concentrations of cations and anions in water sampled from

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

MILLIEQUIVALENTS PER LITER

3.0 2.5 2.0 1.5 1.0 0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0

MILLIEQUIVALENTS PER LITER

SW-1 475417089461701

5/04/1998

SW-2 475422089463801

5/5/1998

SW-3 475456089462801

6/24/1997

SW-3 475456089462801

5/5/1998

SW-4 475637089451401

6/24/1997

SW-4 475637089451401

10/07/1997

SW-4 475637089451401

5/5/1998

SW-6 475704089504401

6/25/1997

SW-6 475704089504401

10/07/1997

SW-6 475704089504401

5/6/1998

SW-6 475704089504401

9/08/1998

SW-5 475647089443701

9/9/1998

SW-5 475647089443701

5/07/1998

SW-2 475422089463801

6/26/1997

SW-1 475417089461701

6/27/1997

SW-5 475647089443701

10/07/1997

SW-5 475647089443701

6/24/1997

SW-1 475417089461701

10/08/1997

Figure 8.

beginning of each month. The estimates were developed using procedures described in Michel (1989a and

1989b). The Minnesota Department

of Health measured the tritium in precipitation at the beginning of each

month from April 1996 through June

1999 at Ely, Minnesota, 62 miles west

of the Grand Portage Reservation (fig.

1) (James F. Walsh, Minnesota

Department of Health, written commun., 2001). 

Tritium decays with a half-life of

12.43 years. For the purposes of comparison in this report, all tritium concentrations measured in precipitation

have been adjusted for radioactive

decay to August 15, 1999. Ground

water that was precipitation before

atmospheric nuclear-device testing

began now has a tritium concentration
17

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Calcium

Magnesium

Sodium and

Potassium

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

Carbonate and

Bicarbonate

Sulfate

Chloride and

Fluoride

MILLIEQUIVALENTS PER LITER

3.0 2.5 2.0 1.5 1.0 0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0

MILLIEQUIVALENTS PER LITER

SW-11 475730089400001

8/16/1993

SW-11 475730089400001

9/22/1994

SW-16 475813089393001

5/5/1998

SW-16 475813089393001

9/10/1998

SW-10 475729089505401

5/6/1998

SW-10 475729089505401

9/10/1998

SW-16 475813089393001

6/24/1997

SW-16 475813089393001

10/8/1997

SW-10 475729089505401

6/25/1997

SW-10 475729089505401

10/07/1997

SW-15 475759089484701

5/07/1998

SW-15 475759089484701

9/9/1998

SW-8 475725089381301

8/22/1995

SW-9 475728089391501

8/16/1993

SW-15 475759089484701

6/26/1997

SW-15 475759089484701

10/8/1997

SW-8 475725089381301

9/22/1994

SW-8 475725089381301

9/22/1994

lakes and streams in the Grand Portage Reservation, Minnesota, 1992-99.

(5 feet below surface)

(50 feet below surface

of <3 pCi/L. The maximum estimated

concentration of tritium in precipitation near the Grand Portage Reservation was about 17,500 pCi/L in June

1963. Adjusted for decay to August

15, 1999, the tritium in ground water

recharged by this precipitation would

be about 2,500 pCi/L. The adjusted

tritium curve is shown in figure 11.

The tritium concentrations measured

in water from eight wells and four

springs of the Grand Portage Reservation during August 1999 are shown in

table 6 and figure 11.

SULFUR HEXAFLUORIDE 

SOURCES AND 

CONCENTRATIONS

Sulfur hexafluoride (SF6) concentrations were determined in water
18

Table 3. Hydrogeologic characteristics and well data for selected wells in the Grand P ortage Reservation, Minnesota, 1992–2000.

 [ft, foot;, min, minute; gal/min, gallon per minute; ft2/d, foot squared per day]

Map 

number 

(fig. 1)

USGS well number Aquifer unit Depth of well (ft) Depth below land surface to bottom of casing (ft) Depth below land surface to bedrock (ft) Depth below land sur- face to water (ft) Depth into bedrock pene- trated by well (ft) Borehole interval open to aquifer below static water level (ft) Pump test period (min) Reported well yield (gal/min) Drawdown (ft) Specific capacity (gal/min/ft) Estimated transmissiv- ity (ft2/d) Source of data

GW-1 475229089520601 -- -- -- -- -- -- -- -- -- -- -- -- --GW-2 475229089520701 MPD 230 46 40 5 190 184 120 3 195 1.5x10-2 3 Ruhl

GW-3 475237089515501 -- 303 27 4 -- -- -- -- -- -- -- --GW-4 475325089491001 MPD 404 25 5 46 399 358 60 4 49 8.2x10-2 20 Ruhl

GW-5 475341089472301 -- 225 26 3 -- -- -- -- -- -- -- --GW-6 475431089461601 -- 312 70 70 -- -- -- -- -- -- -- --GW-7 475500089510001 -- -- -- -- -- -- -- -- -- -- -- --GW-8 475505089444501 NSV 104 35 5 8 99 69 60 16 8 2.0x100 500 Ruhl

GW-9 475508089444101 -- 60 -- -- -- -- -- -- -- -- -- --GW-10 475549089430201 -- 370 22 20 10.5GW-11 475618089423801 NSV 350 35 34 0 316 315 10 16 100 1.6x10-1 30 Ruhl

GW-12 475650089425501 NSV 285 20 6 -- 279 265 -- -- -- -- -- RuhlGW-13 475650089433401 -- -- -- -- -- -- -- -- -- -- -- --GW-14 475710089390001 RAG 115 105 104 28 11 10 120 7 47 1.5x10-1 30 RuhlGW-15 475719089465201 NSV 275 28 23 22 253 247 -- 100 -- -- -- RuhlGW-16 475755089410501 RAG 155 150 92 -- 63 5 1,800 50 100 5.0x10-1 100 Ruhl

GW-17 475801089410901 -- -- -- -- -- -- -- -- -- -- -- --GW-18 475821089415301 -- -- -- -- -- -- -- -- -- -- -- -- --GW-19 475827089413501 UNC 84 79 -- 1+4

1Plus sign indicates water level is above land surface.

0 5 -- 10 -- -- -- Ruhl

GW-20 480001089353401 -- 185 -- -- -- -- -- -- -- -- -- --GW-21 480002089360501 RAG -- -- -- -- -- -- -- -- -- -- -- RuhlGW-22 480035089424201 -- 47 -- -- -- -- -- -- -- -- -- --
19

PERCENT OF TOTAL MILLIEQUIVALENTS PER LITER

0

20

40

60

80

100

CHLORIDE PLUS FLUORIDE

100

80

60

40

20

0

Percentage distribution of major ion concentrations in water samples from ground water, springs, lakes, and streams

in the Grand Portage Reservation, Minnesota, 1992-99.

Ground water

Surface water

Spring

Explanation

100

100

100

100

100

100

100

100

80

80

80

80

80

80

80

60

60

60

60

60

60

60

60

40

40

40

40

40

40

20

20

20

20

20

20

20

20

0

0

0

0

0

0

0

0

40

40

80

MAGNESIUM

SULFATE PLUS CHLORIDE

CARBONATE PLUS BICARBONATE

CALCIUM PLUS MAGNESIUM

SULFATE

SODIUM PLUS POTASSIUM

CALCIUM

Figure 9.

sampled from four wells and four

springs during August and October

2000 (tables 1 and 7). Sulfur hexafluoride is a trace atmospheric gas that is

primarily of anthropogenic origin but

also occurs naturally in fluid inclusions in some minerals and igneous

rocks, and in some volcanic and igneous fluids (Busenberg and Plummer,

1997; 2000). Atmospheric concentrations of SF6 are expected to continue

increasing. SF6 is also apparently

stable in reducing ground-water environments, and because there are relatively few uses of the compound, few

environments are contaminated by

anthropogenic sources. Ground water

can be dated with SF6 if it is in equilibrium with atmospheric SF6 at the

time of recharge, and does not contain

significant SF6 from other sources.

The dating range of SF6 is after 1970

(Busenberg and Plummer, 2000).

The estimated recharge ages of

the samples from four wells and four

springs are in table 7. The remarks

code of four of the samples indicated

that there was about a 1-mL air space

beneath the caps of the sampling bottle. This can contaminate the samples

with SF6 that was in the air at the time
20

Table 4. Field measurements at seven lakes in the Grand Portage Reservation, 1997-2000 (Data from Margaret Watkins, Grand Portage Reservation, written comm., 2000)

 [Values listed are for measurements made 1 foot below lake surface in the center of the lake unless otherwise noted. GPR, Grand Portage Reservation Environmental Department, USGS, U.S. Geological Survey; 

mg, milligrams; L, liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mV, millivolts; NTU, nephlometric turbidity units; >, greater than; <, less than; --, no data]

Agency 

making 

measurement

Date of 

measurement

Deepest 

measurement 

at site (feet 

below surface)

Air 

temperature

(degrees 

Celsius)

Barometric 

pressure

(inches of Hg)

Water 

temperature 

(degrees 

Celsius)

Dissolved 

oxygen 

(mg/L)

Specific 

conductance

(μS/cm)

pH

Oxygen 

reduction 

potential

(mV)

Turbidity

(NTU)

Secchi disk 

depth

(feet)

Center Lake

GPR 06/02/1999 9 7.2 28.59 12.4 5.93 35 5.6 380 -- 2.5GPR 06/28/1999 10 18.3 28.49 20.4 5.82 35 7.2 361 22.2 --GPR 07/13/1999 11 15.5 25.55 19.4 6.51 37 6.6 404 17.2 --GPR 08/10/1999 10 18.3 28.35 17.9 2.93 40 6.4 343 -- 2GPR 09/13/1999 9 11.7 28.33 14.2 5.67 46 7.8 405 -- 1GPR 10/11/1999 12 10 28.92 8.2 7.27 40 5.9 402 -- 2.5

Cuffs Lake (SW-5)

USGS 06/24/1997 4 20.0 -- 10.8 8.11 19.2 7.3 -- -- 4.1GPR 09/03/1997 1 12.8 29.30 14.8 5.76 42 6.2 353 -- --USGS 10/07/19971 1 -- 28.54 12.6 8.18 45.4 7.1 -- -- --

GPR 10/80/1997 1 15.6 -- 13.0 7.58 31 6.7 -- -- --GPR 10/10/1997 1 7.2 -- 9.9 8.55 39 6.4 -- 7 --GPR 06/23/1998 3 23.9 28.85 22.4 7.41 43 7.3 -- -- --GPR 07/13/1998 3 26.7 28.55 25.6 6.76 42 7.3 290 -- --GPR 07/15/1998 3 -- -- 23.1 6.84 31.7 6.5 394 4.3 --GPR 09/08/1998 2 15.5 28.96 16.9 7.4 45 6.9 267 0 --USGS 09/09/1998 21.3 16 15.8 29.06 7.7 50 7.4 -- -- >2.6

GPR 10/20/1998 4 4.4 28.94 7.0 8.7 42 6.7 343 1.4 --GPR 05/22/2000 4 17.2 29.80 13.8 10.33 37.9 7.2 413 -- --GPR 06/05/2000 4 24.3 29.88 18.1 9.34 35.1 6.8 326 -- --

GPR 07/03/2000 4 25.6 29.77 22.3 6.25 41 6.9 346 .6 --

Little Lake (SW-16)

USGS 06/24/1997 22.3 13 29.37 17.1 7.76 108 7.4 -- -- --

USGS 10/08/1997 20.5 -- 28.78 14.4 8.98 110 8.2 -- -- --

USGS 05/05/1998 22.2 -- 28.86 17.8 9.21 114 7.8 -- -- --USGS 09/10/1998 2<1.0 17 29.37 17.2 5.8 131 7.4 -- -- --

Loon Lake (SW-15)

USGS 06/26/1997 4 20 -- 19.8 8.11 19.2 7.3 -- -- 3.8USGS 10/08/19973 3.5 -- 28.03 12.8 9.7 21.9 7.4 -- -- 3.3

USGS 05/07/1998 3 -- 28.62 15.8 8.07 43 7.5 -- -- >4.0GPR 07/08/1998 4 23.9 28.34 25.0 9.02 19 9.0 342 -- --GPR 08/28/1998 4 18.3 28.20 21.2 8.25 20 7.1 321 -- --USGS 09/09/1998 3 17 28.54 17.9 8.99 23.9 7.3 -- -- 3.2GPR 09/09/1998 3 10 28.41 17.9 8.72 21 7.0 -- -- --GPR 10/19/1998 5 7.8 28.18 7.7 11.5 17 7.1 298 2.1 --GPR 50/23/2000 5 18.9 28.56 15.0 10.41 19 7.4 390 -- --GPR 06/07/2000 4 20 29.23 16.9 9.22 18.8 7.3 381 -- 3.3
21

North Lake

GPR 06/25/1998 5 15.6 28.25 19.6 6.61 96 7.4 -- 2 --GPR 07/13/1998 5 27.8 28.19 26.4 6.84 102 7.5 307 -- --GPR 08/28/1998 5 21.1 28.31 22.5 8.81 104 7.7 347 0 --GPR 10/14/1998 5 12.8 28.54 8.3 -- 79 7.5 327 0 --GPR 10/28/1998 6 7.2 28.57 7.3 10.22 72 7.3 258 -- --GPR 05/01/200 5 13.3 29.26 11.9 10.27 94 7.4 401 1.4 4.9GPR 06/05/2000 5 15.6 29.56 17.0 9.04 88.2 7.4 366 -- > 5

Speckled Trout Lake (SW-6)

USGS 06/25/1997 7.8 18 -- 20.1 8.39 38.5 8.0 -- -- 6.9USGS 10/07/1997 8.5 -- 28.38 12.9 9.25 41.5 7.7 -- -- 5.3USGS 05/06/19984 11.5 -- -- 14.7 9.11 37 7.8 -- -- 6.4USGS 09/08/19985 9.5 15 28.66 18.4 8.5 46.8 7.8 -- -- 5.5

Taylor Lake 

GPR 06/25/1998 19 18.3 28.16 19.9 8.44 44 7.8 -- -- --GPR 07/14/1998 18 29.4 29.29 24.5 7.84 48 8.5 360 -- --GPR 09/25/1998 19 21.1 28.07 15.6 8.56 46 7.6 321 0 --GPR 10/20/1998 18 4.4 28.51 8.1 10.84 42 7.4 289 0 --GPR 05/15/2000 21 20.0 29.32 12.3 10.97 46.3 7.8 347 -- 13.1GPR 06/06/2000 21 23.3 29.44 19.0 10.233 43.1 8.0 337 -- 16.4

1Measurement made 0.5 ft below surface of lake.2One measurement at this location.3Measurement made 0.5 below surface of lake. 4Measurement made 1.6 ft below surface of lake. 5Measurement made 1.5 ft below surface of lake. 

Table 4. Field measurements at seven lakes in the Grand Portage Reservation, 1997-2000 (Data from Margaret Watkins, Grand Portage Reservation, written comm., 2000) --Continued

 [Values listed are for measurements made 1 foot below lake surface in the center of the lake unless otherwise noted. GPR, Grand Portage Reservation Environmental Department, USGS, U.S. Geological Survey; 

mg, milligrams; L, liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mV, millivolts; NTU, nephlometric turbidity units; >, greater than; <, less than; --, no data]

Agency 

making 

measurement

Date of 

measurement

Deepest 

measurement 

at site (feet 

below surface)

Air 

temperature

(degrees 

Celsius)

Barometric 

pressure

(inches of Hg)

Water 

temperature 

(degrees 

Celsius)

Dissolved 

oxygen 

(mg/L)

Specific 

conductance

(μS/cm)

pH

Oxygen 

reduction 

potential

(mV)

Turbidity

(NTU)

Secchi disk 

depth

(feet)
22

5 10 15 20 25 30

WATER TEMPERATURE, DEGREES CELSIUS

25

20

15

10

5

0

06/02/1999

06/28/1999

07/13/1999

08/10/1999

09/13/1999

10/11/1999

Temperature and dissolved oxygen profiles for Taylor and Center Lakes, Grand Portage Reservation, Minnesota, 1999-2000.

0 2 4 6 8 10 12 14

DISSOLVED OXYGEN, MILLIGRAMS PER LITER

25

20

15

10

5

0

Taylor Lake

Center Lake

10/20/1998

05/15/2000

09/25/1998

06/25/1998

07/14/1998

09/25/1998 10/20/1998 05/15/2000 06/06/2000

06/02/1999

06/28/1999

07/13/1999

08/10/1999

09/13/1999

10/11/1999

06/06/2000

06/25/1998

07/14/1998

DEPTH BELOW LAKE SURFACE, IN FEET

Figure 10.

of sampling. Samples for two of the

sites were determined to be contaminated and were not used. Recharge

ages were determined for water from

the other two sites (GW-9 and GW18); however, the ages may be incorrect because of possible contamination. 
23

Table 5. U.S. Environmental Protection Agency drinking-water standards and health advisories

 [Standards and health advisories from U.S. Environmental Protection Agency (2000). data from Rhul 1995, Ruhl, 1997, and Winterstein, 2000; mg/L, milligrams per 

liter; μg/L, micrograms per liter; <, less than; --, level or advisory not set]

Constituent Unit Maximum 

contaminant level

Secondary 

drinking water 

regulations

Lifetime health 

advisory

Range of constituent 

in sampled waters, 

1991–2000

Number of wells or sites 

that exceeded levels or 

advisory, 1991–2000

pH -- 6.5–8.5 -- 5.6–10.2 9 wells

Total dissolved solids mg/L -- 500 -- 58–3,110 4 wells

Aluminum mg/L -- 0.05–0.2 -- <0.01–0.398 1 stream site

Ammonia mg/L -- -- 30 <0.015–0.074 0

Antimony μg/L 6 -- 6 <1–<1 0

Arsenic μg/L 50 -- -- <1–39 0

Barium mg/L 2 -- 2 <0.001–0.5 0

Beryllium μg/L 4 -- -- <2–<10 0

Boron mg/L -- -- 0.6 <0.01–0.736 2 wells

Chloride mg/L -- 250 -- <.1–1,600 6 wells

Chromium (total) mg/L 0.1 -- -- <0.001–0.002 0

Copper mg/L 1

1.3

1If this level is exceeded in over 10 percent of homes tested, treatment to reduce this level is initiated.

1.0 -- 0.001–0.01 0

Fluoride mg/L 4 2.0 4 <0.1–1.7 0

Iron mg/L -- 0.3 -- <0.01–2.86 5 wells

Manganese mg/L -- 0.05 -- <0.004–0.21 0

Mercury (inorganic) μg/L 0.2 -- 0.2 <0.1–<0.1 0

Molybdenum μg/L -- -- 40 <1–<10 0

Nickel mg/L -- -- 0.1 <<0.001–0.002 0

Nitrate mg/L as N 10 -- -- <0.01–0.2 0

Nitrite mg/L as N 1 -- -- <0.01–0.042 0

Nitrite plus nitrate mg/Las N 10 -- -- <0.01–0.32 0

Selenium μg/L 50 -- 50 <1–<1 0

Silver mg/L -- 0.1 -- <0.011–<0.001 0

Strontium mg/L -- -- 4 0.23–0.23 0

Sulfate mg/L -- 250 -- <0.1–194 0

Zinc mg/L -- 5 -- <0.003–0.260 0

RECHARGE AGES OF SAMPLED 

WATER

Tritium and SF6 dating techniques

indicate the mean residence time

(recharge age) of water in an aquifer,

but more information is needed to

determine the recharge age of the

water. The assumption in dating

ground water by these methods is that

precipitation percolates into the aquifer and th4en travels as a plug in a

well-defined path to the well or

spring. In actuality, water sampled

from an aquifer often contains water

from several years precipitation

(Clark and Fritz, 1997). Ground water

from several sources can mix as it

moves through the ground or bedrock.

Finally, the wells sampled in the

Grand Portage Reservation are not

cased in the bedrock and are open to

the entire bedrock (table 3). As a

result, the water in the wells may be a

mixture of young and old water from

different bedrock aquifers. 

Tritium concentrations of two of

the samples, GW-6 and GW-20, were

less than the detection limit. The

water in these samples was from precipitation that fell before 1953. The

water in the other 10 tritium samples

could have come from precipitation

that fell between 1953 and 1962, or

after 1970, or be a mixture of old and

young water (fig. 11). The recharge

age of water in SP-8 and GW-22 is

probably 1997 or later. SP-8 is a seep

on the side of a hill, and the water in

the spring probably comes from shallow ground water. Well GW-22 is

shallow, about 47 ft deep, and the

ionic concentrations in the sampled

water resemble those from surface

water or springs (figs. 7-9). In addition to being analyzed for tritium, one

well and two springs were sampled

for SF6 during fall 2000. The SF6 dating places the age of these samples

after 1983 (table 7, fig. 11). Therefore,

it is probable that the remaining five

tritium samples were composed of
24

Age of water in well GW-9by sulfur hexafluoride dating

Age of water in SP-2 bysulfur hexafluoride dating

Age of water in spring SP-6by sulfur hexafluoride dating

Tritium concentrations measured August 1999

Monthly tritium concentrations measured inprecipitation aged to August 15, 1999

Concentrations higher than 75 picocuries per liternot shownMonthly precipitation tritium conc ntrations aredecayed to August 15, 1999. From Michel, 1989aand b and from Minnesota Department of Health,written commun., 2001

e

Missing data

GW-22

GW-5

GW-22

GW-10

SP-3

SP-6

SP-8

SP-2, GW-3GW-9GW-6, GW-20

Tritium concentrations in wells and springs and estimated recharge age of water in one well and two springs by sulfur hexafluoride dating in the

Grand Portage Reservation, Minnesota, August 1999,

5

0

7570656055504540353025201510

TION, PICOCURIES PER LITER PRECIPITATION TRITIUM CONCENTRA

1950

1951

1952

1953

1954

1955

1956

1957

1958

1959

1960

1961

1962

1963

1964

1965

1966

1967

1968

1969

1970

1971

1972

1973

1974

1975

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

Figure 11.
25

Table 6. Tritium data collected from wells and springs in the Grand Portage Reservation, Minnesota, August 16–24, 1999

 [pCi/L, picocuries per liter; <, less than}

Map 

number Station number Station Name Tritium

(pCi/L)

Accuracy of analysis 

(plus or minus pCi/L)

GW-3 475237089515501 Evans, Grand Portage Reservation 24.6 2.6

GW-5 475341089472301 Long, Grand Portage Reservation 46.1 3.5

GW-6 475431089461601 Sawmill, Grand Portage Reservation <2.6 1.6

GW-9 475508089444101 Johnson, Grand Portage Reservation 22.7 2.2

GW-10 475549089430201 Paro, Grand Portage Reservation 40.3 3.2

GW-20 480001089353401 Pigeon River State Park <2.6 1.6

GW-22 480035089424201 Hart, Grand Portage Reservation 41.6 3.2

GW-22 480035089424201 Hart, Grand Portage Reservation 51.8 4.2

SP-2 475700089460001 Spring 3, Grand Portage Reservation 24.6 2.2

SP-3 475700089500001 Spring 1, Grand Portage Reservation 37.1 2.9

SP-6 475000089400002 Spring 2, Grand Portage Reservation 36.5 2.9

SP-8 475800089470001 Spring 7, Grand Portage Reservation 34.6 2.9

Table 7. Estimated recharge age of water by sulfur hexafluoride analysis in wells and springs in the Grand Portage Reservation, Minnesota, 

sampled August and October 2000

 [Two samples were taken at each site and analyzed]

Site No. Station Number Station Name Year water was 

precipitation

GW-1 475229089520601 Olson, Grand Portage Reservation 1973.5

GW-1 475229089520601 Olson, Grand Portage Reservation 1973

GW-9 475508089444101 Johnson, Grand Portage Reservation 1983.5

GW-9 475508089444101 Johnson, Grand Portage Reservation 1983

GW-15 475719089465201 T63NR5E03CCC 1989.5

GW-15 475719089465201 T63NR5E03CCC 1989.5

GW-18 475821089415301 Land fill, Grand Portage Reservation 1997.5

GW-18 475821089415301 Land fill, Grand Portage Reservation 1998

SP-2 475700089460001 Spring 3, Grand Portage Reservation Contaminated

SP-2 475700089460001 Spring 3, Grand Portage Reservation Contaminated

SP-2 475700089460001 Spring 3, Grand Portage Reservation 1987

SP-2 475700089460001 Spring 3, Grand Portage Reservation 1987

SP-4 475700089500002 Spring 4, Grand Portage Reservation Contaminated

SP-4 475700089500002 Spring 4, Grand Portage Reservation Contaminated

SP-5 475800089400002 Spring 9, Grand Portage Reservation 1997

SP-5 475800089400002 Spring 9, Grand Portage Reservation 1997

SP-6 475800089400002 Spring 3, Grand Portage Reservation 1998

SP-6 475800089400002 Spring 3, Grand Portage Reservation 1998

precipitation that fell after 1970.

SF6 dating placed the recharge

dates of water from four wells (GW1, GW-9, GW-15, and GW-18)

between 1973 and 1998 and the

recharge dates of water from three

springs (SP-2, SP-5, and SP-6)

between 1987 and 1998.

The age dating done for this study

can be used, along with other factors,

to determine the source of water in

two wells. The water in wells GW-6

and GW-20 (fig. 1) is from the

regional ground-water system, considering that the water is older than

1953, based on tritium dating. The

water in GW-1 may also be from the

same regional system based upon its

age, 1973, from SF6 dating. As noted

earlier, the water in GW-22 was precipitation 1998 or later; the water in

this well is probably from shallow

ground water. Springs SP-5, SP-6,

and SP-8 have water younger than

1997. Therefore, they are probably

discharge points for shallow ground

water. 
26

REFERENCES 

Baker, D.G., and Kuehnast, E.L., 

1978, Climate of Minnesota, Part 

X. Precipitation normals for Minnesota—1941–1970: University of 

Minnesota Agricultural Experiment Station Technical Bulletin 

314, 15 p.

Baker, D.G., Kuenhast, E.L., and 

Zandlo, J.A., 1985, Climate of 

Minnesota: Part XV. Normal temperatures (1951–1980) and their 

application: University of Minnesota Agricultural Experiment Station Technical Bulletin AD–SB 

2777, 66 p.

Busenberg, E., and Plummer, N.L., 

1997, Use of sulfur hexafluoride 

as a dating tool and as a tracer of 

igneous and volcanic fluids in 

ground water: Geological Society 

of America, Salt lake City, 1997, 

Abstracts and Programs, v. 29, no. 

6, p. A–78.

Busenberg, E., and Plummer, N.L., 

2000, Dating young groundwater 

with sulfur hexafluoride—Natural 

and anthropogenic sources of sulfur hexafluoride: Water Resources 

Research, v. 36, no. 10, p. 3011–

3030.

Clark, I.D., and Fritz, P., 1997, Environmental isotopes in hydrogeology: Boca Raton, Florida, Lewis 

Publishers, Inc., 352 p. 

Green, J.C., 1982, Geologic map of 

Minnesota, Two Harbors sheet, 

bedrock geology: Minnesota Geological Survey, scale 1:250,000.

Hem, J.D., 1992, Study and interpreSUMMARY

The Grand Portage Reservation is located in northeastern Cook County, Minnesota at the boundary between Minnesota, USA, and Ontario, Canada. Between 1991 and

2000 the U.S. Geological Survey (USGS) conducted a

series of studies, in cooperation with the Grand Portage

Band of Chippewa, to describe the water resources of the

Grand Portage Reservation. 

Ground water moves primarily through fractures in the

bedrock. The local ground-water system probably follows

the surface topography, flows through the thin unconsolidated material and shallow bedrock fractures and discharges to wetlands, seeps, springs, and nearby lakes and

streams. The regional ground-water flow system probably

discharges into regional lows such as the Lake Superior,

Pigeon River, and other streams and lakes. The deep

ground-water flow system probably flows from the interior

of Minnesota and Canada and discharges into Lake Superior. Lake Superior maybe the discharge point for brines in

the deep ground-water flow system. 

The watersheds of the streams in the Grand Portage

Reservation are small and stream slopes are steep; the

streams in the Grand Portage Reservation tend to be flashy.

The percent of rainfall at the Grand Portage Ranger Station

that become runoff in these watersheds is about 45 percent.

The lake stages of Loon and Cuffs Lakes were continuously measured during the ice free part of the year from

June 1998 through November 2000. The lake stages rise

and fall with rainfall. 

The pH of water in the Reservation is generally alkaline (pH greater than 7.0). The alkalinity of water in the

Reservation is low, less than 100 mg/L as CaCO3. The

concentrations of major ions are much greater in ground

water than in spring water and surface water.

Water from 11 of the 20 wells sampled are a calciumsodium-chloride type. Water from GW-2, GW-7, and GW11 had much greater specific conductance concentrations

of major ions compared to the other wells. The greater concentrations of calcium, sodium, and chloride in these wells

may be from the dissolution of the rock matrix, or the

upward discharge of brines from the underlying Precambrian rocks. 

Some spring water (SP-1, SP-3, SP-4, SP-6, and SP-8)

is calcium-bicarbonate type like surface water, whereas

other spring water (SP-5 and SP-7) is similar to the calcium-sodium-chloride type occurring in samples from

about one-half the wells. 

 The major chemical constituents in surface water are

bicarbonate, calcium, and magnesium. Water samples from

lakes show almost no seasonal variation in ionic concentrations, whereas water samples taken from streams show seasonal variation (SW-1 and SW-10). The concentrations of

the calcium cation and bicarbonate and carbonate anions

increase in streams during periods of low.

The water in selected wells and springs were analyzed

to determine the recharge age. The tritium concentrations

were measured in eight wells and four springs of the Grand

Portage Reservation during August 1999. Sulfur hexafluoride (SF6) concentrations were determined in water sampled from four wells and four springs during August and

October 2000. The tritium and SF6 concentrations were

used to determine the recharge age of the sampled water.

The recharge ages of two of the wells sampled for tritium,

GW-6 and GW-20, are before 1953. The recharge ages of

the remaining 10 samples for tritium are probably after

1970. The recharge ages of seven SF6 samples were

between 1973 and 1998.
27

tation of the chemical characteristics of natural water, 3rd edition: 

U.S. Geological Survey WaterSupply Paper 2254, 263 p., 2 pl.

International Atomic Energy 

Agency/World Meteorological 

Organization, 1998, Global network for isotopes in precipitation. 

The GNIP data base. Release 3, 

October 1999: URL: 

http://www.iaea.org/programs/ri/gnip/gnipmain.htm 

(accessed January 2002).

Kelly, W.C., Rye, R.O., and Livnat, 

A., 1986, Saline mine waters of 

the Keweenaw Peninsula, northern 

Michigan—Their nature, origin, 

and relation to similar deep waters 

in Precambrian crystalline rocks of 

the Canadian shield: American 

Journal of Science, v. 286, p. 281–

308.

Michel, R.L., 1989a, Tritium deposition over the continental United 

States, 1953–1983, in Atmospheric deposition: International 

Association of Hydrological Sciences, Oxfordshire, United Kingdom, p. 109–115.

______1989b, Tritium deposition in 

the continental United States, 

1953–1983: U.S. Geological Survey Water-Resources Investigations Report 89–4072, 46 p.

Omernik, J.M., 1987, Ecoregions of 

the conterminous United States: 

Annals of the Association of 

American Geographers, v. 77, p. 

118–125.

Paillet, F.L., and Olson, J.D., 1994, 

Analysis of the results of hydraulic-fracture stimulation of two 

crystalline bedrock boreholes, 

Grand Portage, Minnesota: U.S. 

Geological Survey WaterResources Investigations Report 

94–4044, 45 p.

Ruhl, J.F., 1995, Water resources of 

the Grand Portage Indian Reservation, northeastern Minnesota: U.S. 

Geological Survey WaterResources Investigations Report 

94–4199, 28 p.

_____ 1997, Physical and chemical 

properties of water and sediments, 

Grand Portage and Wauswaugoning Bays, Lake Superior, Grand 

Portage Indian Reservation, northeastern Minnesota, 1993–96: U.S. 

Geological Survey WaterResources Investigations Report 

97–1999, 13 p.

Shepard Miller, Inc., 1995, Environmental aspects of the proposed 

solution mining operation at the 

White Pine Mine, White Pine, 

Michigan – vol. 1. Text: Prepared 

for the Copper Range Co., White 

Pine, Michigan, unpaged. 

U.S. Army Corps of Engineers, 1999, 

Tracer dye tests work plan—

Former Finland Air Force Station 

(FFAS), Lake County, Minnesota: 

U.S. Army Corps of Engineers, 

Omaha District, USACE Contract 

No. DACW45–94–0044, unpaged.

U.S. Environmental Protection 

Agency, 2000, Drinking standards 

and health advisories: United 

States Environmental Protection 

Agency, Office of Water, EPA 

822–8–00–001, 12 p.

Wilde, F.D., and Radtke, D.B., eds., 

1998, Field measurements: U.S. 

Geological Survey Handbooks for 

Water-Resources Investigations, 

book 9, chap. A6, unpaged. 

Wilde, F.D., Radtke, D.B., Gibs, J., 

and Iwatsubo, R.T., eds., 1999a, 

Collection of water samples: U.S. 

Geological Survey Handbooks for 

Water-Resources Investigations, 

book 9, chap. A4, unpaged.

_____ 1999b, Processing of water 

samples: U.S. Geological Survey 

Handbooks for Water-Resources 

Investigations, book 9, chap. A5, 

unpaged.

Winterstein, T.A., 2000, Water-quality data from lakes and streams in 

the Grand Portage Reservation, 

Minnesota, 1997–98: U.S. Geological Survey Open-File Report 00–

364, 16 p.

Wyrick, G.G., and Borchers, J.W., 

1981, Hydrologic effects of stressrelief fracturing in an Appalachian 

valley: U.S. Geological Survey 

Water-Supply Paper 2177, 51 p. 
28

SUPPLEMENTAL INFORMATION
29

WATER-QUALITY DATA 

COLLECTED DURING 1999 

AND 2000

Water samples were collected

from 11 wells in the Grand Portage

Reservation during August 1999 (fig.

1; table S-1). Water was pumped from

the wells until specific conductance,

pH, and dissolved oxygen readings

became constant. The samples were

then collected and preserved in accordance with procedures in Wilde and

others (1999a; 1999b). The samples

were analyzed at the USGS National

Water Quality Laboratory (NWQL) in

Arvada, Colorado, for major ions,

nutrients, and trace metals.

Water samples were collected

from eight springs in the Grand Portage Reservation in August 1999 (fig.

1; table S-2). The locations of the

springs are reported only to the nearest minute (table 1); the springs are

located within the circles shown in

figure 1. The samples were collected

by pushing a small sand-point well

screen (2 in. in diameter) into the

ground at the source of the spring.

Water was pumped from inside the

sand-point with a peristaltic pump

until specific conductance, pH, and

dissolved oxygen readings became

constant. The samples were then collected and preserved in accordance

with procedures in Wilde and others

(1999a; 1999b). The samples were

analyzed at the NWQL in Arvada,

Colorado, for major ions, nutrients,

and trace metals.

Field measurements (specific

conductance, pH, temperature, and

dissolved oxygen) were made in

accordance with procedures described

in Wilde and Radtke (1998). The

measurements were made with a portable, multiparameter meter calibrated

at the start of each sampling day.

Alkalinity was determined in the field

by incremental titration of filtered

samples.

Two quality-assurance samples

were collected (table S-3). One replicate sample was collected from well

GW-4. One field blank was collected

before sampling at the Pigeon River

State Park well, GW-20. 

Replicate samples are collected to

assess the quality, reliability, and precision (reproducibility) of the data

generated by the analysis of the samples for chemical constituents. The

difference between the values for the

sample and the replicate sample are

shown in table S-4. The percent difference was calculated as:

where X1 is the value for the sample, and 

X2 is the value for the replicate

sample. 

The percent difference was less than

10 except for total ammonia plus

organic nitrogen and for dissolved

zinc.

The field blank was collected by

passing inorganic-free, de-ionized

water through all sample equipment

contacted by the actual sample. Field

blanks are collected to ensure that

equipment cleaning between sampling

sites remove all contamination from

the previous site, that sampling and

sample-processing procedures do not

contaminate the equipment, and that

transporting and handling the sampling equipment between sites does

not contaminate the equipment. The

concentrations of analyzed constituents in the field blank were below the

detection limit or near the detection

limit. 

Water samples were collected

from four springs and seven wells in

1999 (table 1) and analyzed for tritium. The samples were collected in

accordance with procedures specified

by the analyzing laboratory, the Environmental Isotope Laboratory, University of Waterloo, Ontario, Canada

(EIL) (Environmental Isotope Laboratory, written commun., Aug. 13,

1999). The samples were analyzed at

EIL for enriched tritium. The results

of the analysis for the tritium concentrations are in table 6. 

Water samples were collected

from four wells and four springs

August-October 2000 (table 1) and

analyzed for sulfur hexafluoride

(SF6). The samples were collected in

accordance with procedures specified

by the analyzing laboratories, the

Reston Dissolved Gas Laboratory and

the Reston SF6 Laboratory, U.S. Geological Survey, Reston, Virginia. The

samples were analyzed for concentrations of dissolved gases and SF6 and

the results were used to date the

recharge age of the sampled water

(table 7) .

100

1 2

1 2 ×

+

−

X X

X X
30

Table S-1.Water-quality data collected from wells in the Grand Portage Reservation, Minnesota, August 1999

 [mm, millimeter; mg/L, milligrams per liter; μg/L, micrograms per liter; °C, degrees Celsius; <, less than; E, estimated; --, no data]

Map 

number Station number Date

Flow rate

(gallon per 

minute)

Barometric 

pressure 

(mm of Hg)

Dissolved oxygen

(percent 

saturation)

Dissolved 

oxygen

(mg/L)

pH, field pH, labora- tory

Specific 

conductance, 

laboratory

(μS/cm at 25 °C)

Specific 

conductance, 

field

(μS/cm at 25 °C)

GW-3 475237089515501 08/16/1999 0.06 743 6 0.6 9.2 9.3 340 313GW-4 475325089491001 08/16/1999 -- 739 4 0.4 8.8 8.5 1700 1620GW-5 475341089472301 08/16/1999 0.8 742 1 0.2 10.2 9.8 759 688GW-6 475431089461601 08/16/1999 0.16 742 1 0.1 8.2 7.8 1930 E1960GW-7 475500089510001 08/19/1999 -- -- 6 0.6 7.2 7.4 4450 4300GW-9 475508089444101 08/17/1999 -- 750 15 1.8 8.4 8.3 546 617GW-10 475549089430201 08/17/1999 -- 750 3 0.3 7.8 7.8 2210 2150GW-13 475650089433401 08/18/1999 -- -- 2 0.2 9.1 8.9 630 608GW-17 475801089410901 08/24/1999 -- -- 0 0.4 7.4 7.5 839 878GW-20 480001089353401 08/18/1999 -- -- 1 0.1 9.2 8.6 772 729GW-22 480035089424201 08/17/1999 -- -- 58 6.5 6.8 6.8 120 109

Map 

number Station number Date

Air 

temperature

(°C)

Water temperature

(°C)

Dissolved 

calcium

(mg/L as Ca)

Dissolved 

magnesium

(mg/L as Mg)

Dissolved 

potassium

(mg/L as K)

Dissolved 

sodium 

(mg/L as Na)

Acid 

neutralizing 

capability, 

laboratory

(mg/L as 

CaCO3)

Alkalinity, field

(mg/L as 

CaCO3)

GW-3 475237089515501 08/16/1999 23.5 8.2 4.36 E.11 0.5 72.5 124 116GW-4 475325089491001 08/16/1999 23.5 14.1 65.9 0.58 2 257 44 31GW-5 475341089472301 08/16/1999 19 5.4 9.7 <.12 0.9 149 100 95GW-6 475431089461601 08/16/1999 23.5 15.4 92.1 16.4 2 219 27 28GW-7 475500089510001 08/19/1999 -- 10.9 504 3.74 1.1 321 32 27GW-9 475508089444101 08/17/1999 24 6.6 33.1 0.37 0.3 91.5 79 79GW-10 475549089430201 08/17/1999 26 9.6 246 19.8 1.8 135 103 98GW-13 475650089433401 08/18/1999 20 11.3 21.5 2.16 0.6 97.6 33 34GW-17 475801089410901 08/24/1999 -- 7.5 74.8 36.6 3.7 45.8 195 170GW-20 480001089353401 08/18/1999 20.5 6.5 14.8 10.3 6.4 113 46 44GW-22 480035089424201 08/17/1999 -- 10.1 13.8 5.18 0.4 2 56 60

Map 

number Station number Date Bicarbonate, field (mg/L as HCO3) Carbonate, field (mg/L as CO3) Dissolved chloride (mg/L as Cl) Dissolved fluoride (mg/L as F) Dissolved silica (mg/L as SiO2) Dissolved sulfate (mg/L as SO4) Total ammonia plus organic nitrogen (mg/L as N)

GW-3 475237089515501 08/16/1999 105 18 23.4 1 12.7 6.7 E.10GW-4 475325089491001 08/16/1999 38 0 453 1.2 22.3 58.2 0.21GW-5 475341089472301 08/16/1999 30 42 169 <.1 44.1 6.8 0.15GW-6 475431089461601 08/16/1999 3 0 467 1.6 10.1 50 <.10GW-7 475500089510001 08/19/1999 33 0 1410 1.7 16.4 24.8 E.10GW-9 475508089444101 08/17/1999 91 3 127 0.3 17.8 27.6 <.10GW-10 475549089430201 08/17/1999 120 0 619 0.2 19 11 0.1GW-13 475650089433401 08/18/1999 27 7 31.5 0.6 14.8 194 E.10GW-17 475801089410901 08/24/1999 207 0 89.4 0.9 23 117 0.1GW-20 480001089353401 08/18/1999 43 5 201 0.7 0.9 6.6 0.11GW-22 480035089424201 08/17/1999 73 0 0.2 <.1 17.1 4.3 0.38
31

Map 

number Station number Date

Dissolved 

ammonia

(mg/L as N)

Dissolved nitrite 

plus nitrate

(mg/L as N)

Dissolved nitrite

(mg/L as N)

Dissolved 

phosphorus

(mg/L as P)

Dissolved orthophosphorus

(mg/L as P)

Total 

phosphorus

(mg/L as P)

Total depth of 

well

(feet)

GW-3 475237089515501 08/16/1999 <.020 <.050 <.010 <.050 <.010 <.050 --GW-4 475325089491001 08/16/1999 <.020 <.050 <.010 <.050 <.010 <.050 404GW-5 475341089472301 08/16/1999 <.020 <.050 <.010 <.050 <.010 <.050 --GW-6 475431089461601 08/16/1999 0.072 <.050 <.010 <.050 <.010 <.050 --GW-7 475500089510001 08/19/1999 <.020 <.050 <.010 <.050 <.010 <.050 --GW-9 475508089444101 08/17/1999 <.020 <.050 <.010 <.050 <.010 <.050 --GW-10 475549089430201 08/17/1999 0.029 <.050 <.010 <.050 <.010 <.050 --GW-13 475650089433401 08/18/1999 <.020 <.050 <.010 <.050 <.010 <.050 --GW-17 475801089410901 08/24/1999 0.03 <.050 <.010 <.050 <.010 0.055 --GW-20 480001089353401 08/18/1999 <.020 <.050 <.010 <.050 <.010 <.050 --GW-22 480035089424201 08/17/1999 <.020 <.050 <.010 <.050 <.010 0.06 --

Map 

number Station number Date

Dissolved 

arsenic

(μg/L as As)

Dissolved 

barium

(μg/L as Ba)

Dissolved 

beryllium

(μg/L as Be)

Dissolved 

boron

(μg/L as B)

Dissolved iron

(μg/L as Fe)

Dissolved 

manganese

(μg/L as Mn)

Dissolved 

mercury

(μg/L as Hg)

Dissolved zinc

(μg/L as Zn)

GW-3 475237089515501 08/16/1999 <1.0 <1 <2 736 290 11 <.1 <20GW-4 475325089491001 08/16/1999 <1.0 61 <2 305 <10 3 <.1 <20GW-5 475341089472301 08/16/1999 <1.0 <1 <2 163 30 <2 <.1 <20GW-6 475431089461601 08/16/1999 1.5 33 <2 693 10 48 <.1 <20GW-7 475500089510001 08/19/1999 <1.0 150 <5 184 80 210 <.1 <60GW-9 475508089444101 08/17/1999 <1.0 8 <2 282 E10 3 <.1 <20GW-10 475549089430201 08/17/1999 3.9 110 <5 156 70 142 <.1 <60GW-13 475650089433401 08/18/1999 <1.0 9 <2 268 E10 13 <.1 <20GW-17 475801089410901 08/24/1999 3.3 30 <2 212 2860 103 <.1 248GW-20 480001089353401 08/18/1999 <1.0 59 <2 178 380 78 <.1 <20GW-22 480035089424201 08/17/1999 <1.0 8 <2 E9 2550 64 <.1 <20

Table S-1. Water-quality data collected form wells in the Grand Portage Reservation, Minnesota, August 1999--Continued
32

Table S-2. Water-quality data collected from springs in the Grand Portage Reservation, Minnesota, 1999

 [mg/L, milligrams per liter; μg/L, micrograms per liter; μS/cm, microSiemens per centimeter; °C, degrees Celsius; <, less than; E, estimated; --, no data; numbers in 

square brackets, [ ], are parameter codes, which are used to identify water-quality constituents and properties in the USGS National Water Information System and the 

U.S. Environmental Protection Agency Data Storage and Retrieval System]

Map 

number Station number Station name Date Barometric pressure

(mm of Hg) [25]

Dissolved oxygen

(percent saturation) [301}

SP-1 475400089470001 Spring 10, Grand Portage Reservation 08-24-99 -- 13

SP-2 475700089460001 Spring 3, Grand Portage Reservation 08-24-99 -- 35

SP-3 475700089500001 Spring 1, Grand Portage Reservation 08-19-99 -- 73

SP-4 475700089500002 Spring 4, Grand Portage Reservation 08-19-99 731 30

SP-5 475800089400002 Spring 9, Grand Portage Reservation 08-24-99 -- 46

SP-6 475800089400002 Spring 2, Grand Portage Reservation 08-24-99 -- 45

SP-7 475800089410002 Spring 14, Grand Portage Reservation 08-25-99 -- 77

SP-8 475800089470001 Spring 7, Grand Portage Reservation 08-17-99 731 60

Map 

number Station number Date

Dissolved 

oxygen

(mg/L) [300}

pH, whole water, 

field

(standard units) 

[400]

pH, whole water, 

laboratory

(standard units) 

[403]

Specific conductance, 

laboratory

(μS/cm at 25 °C) 

[90095]

Specific conductance, 

field

(μS/cm at 25 °C) [95]

SP-1 475400089470001 08-24-99 1.3 5.7 6.0 58 50

SP-2 475700089460001 08-24-99 4.2 8.6 8.6 138 123

SP-3 475700089500001 08-19-99 7.9 7.1 7.5 136 124

SP-4 475700089500002 08-19-99 2.9 6.3 7.0 145 132

SP-5 475800089400002 08-24-99 4.9 6.2 6.5 262 252

SP-6 475800089400002 08-24-99 4.9 6.4 6.8 125 112

SP-7 475800089410002 08-25-99 7.4 7.4 7.4 188 181

SP-8 475800089470001 08-17-99 7.0 7.1 6.7 102 84

Map 

number Station number Date

Air 

temperature

(°C) [20]

Water temperature

(°C) [10]

Dissolved calcium

(mg/L as Ca) 

[915]

Dissolved 

magnesium

(mg/L as Mg) 

[925]

Dissolved 

potassium

(mg/L as K) [935]

SP-1 400089470001 08-24-99 -- 15.1 5.95 2.58 .3

SP-2 700089460001 08-24-99 -- 6.6 14.5 1.94 .3

SP-3 700089500001 08-19-99 29.0 9.6 20.7 3.64 .1

SP-4 700089500002 08-19-99 29.0 15.6 17.8 5.95 .3

SP-5 800089400002 08-24-99 -- 11.5 17.7 6.51 .9

SP-6 800089400004 08-24-99 -- 10.3 12.1 3.87 .6

SP-7 800089410002 08-25-99 -- 16.1 14.5 5.12 .6

SP-8 800089470001 08-17-99 24.5 8.2 12.6 3.94 .3

Map 

number Station number Date

Dissolved sodium 

(mg/L as Na) 

[930]

Acid neutralizing 

capability, 

laboratory

(mg/L as CaCO3) 

[90410]

Alkalinity, filtered 

water, field

(mg/L as CaCO3) 

[39086}

Bicarbonate, 

filtered water, field

(mg/L as HCO3) 

[453]

Carbonate, filtered 

water, field

(mg/L as CO3) 

[452]

SP-1 400089470001 08-24-99 1.7 18 17 21 0

SP-2 700089460001 08-24-99 12.8 65 52 63 0

SP-3 700089500001 08-19-99 1.5 64 61 74 0

SP-4 700089500002 08-19-99 1.6 67 61 74 0

SP-5 800089400002 08-24-99 23.1 53 46 56 0

SP-6 800089400004 08-24-99 7.4 45 39 48 0

SP-7 800089410002 08-25-99 15.9 56 49 60 0

SP-8 800089470001 08-17-99 1.7 45 40 48 0
33

Map 

number Station number Date

Dissolved 

chloride

(mg/L as Cl) 

[940]

Dissolved fluoride

(mg/L as F) [950]

Dissolved silica

(mg/L as SiO2) 

[955]

Dissolved sulfate

(mg/L as SO4) 

[945]

Total ammonia plus 

organic nitrogen

(mg/L as N) [625]

SP-1 400089470001 08-24-99 .2 <.1 19.4 4.4 1.0

SP-2 700089460001 08-24-99 .4 .2 21.4 4.9 E.10

SP-3 700089500001 08-19-99 .4 <.1 14.6 3.8 1.3

SP-4 700089500002 08-19-99 .2 <.1 12.9 3.4 .25

SP-5 800089400002 08-24-99 41.2 <.1 14.7 6.4 .30

SP-6 800089400004 08-24-99 5.5 <.1 15.5 5.9 .25

SP-7 800089410002 08-25-99 20.1 <.1 15.1 2.7 .39

SP-8 800089470001 08-17-99 <.1 <.1 <.1 <.1 E.10

Map 

number Station number Date

Dissolved 

ammonia nitrogen

(mg/L as N) [608}

Dissolved nitrite 

plus nitrate 

nitrogen

(mg/L as N) [631]

Dissolved nitrite 

nitrogen

(mg/L as N) [613]

Dissolved 

phosphorus

(mg/L as P) [666]

Dissolved ortho

-phosphorus

(mg/L as P) [671]

SP-1 475400089470001 08-24-99 .039 <.050 <.010 <.050 <.010 

SP-2 475700089460001 08-24-99 <.020 <.050 <.010 <.050 <.010 

SP-3 475700089500001 08-19-99 <.020 .255 <.010 <.050 <.010 

SP-4 475700089500002 08-19-99 <.020 <.050 <.010 <.050 <.010 

SP-5 475800089400002 08-24-99 <.020 .070 <.010 <.050 <.010 

SP-6 475800089400002 08-24-99 <.020 <.050 <.010 <.050 <.010 

SP-7 475800089410002 08-25-99 <.020 <.050 <.010 <.050 <.010 

SP-8 475800089470001 08-17-99 <.020 .108 <.010 <.050 <.010 

Map 

number Station number Date

Total phosphorus

(mg/L as P)

[665]

Dissolved arsenic

(μg/L as As)

[1000]

Dissolved barium

(μg/L as Ba)

[1005]

Dissolved 

beryllium

(μg/L as Be)

[1010]

Dissolved boron

(μg/L as B)

[1020]

SP-1 475400089470001 08-24-99 E.034 <1.0 9 <2 E9

SP-2 475700089460001 08-24-99 <.050 <1.0 6 <2 73

SP-3 475700089500001 08-19-99 <.050 <1.0 1 <2 <16

SP-4 475700089500002 08-19-99 <.050 <1.0 5 <2 E11

SP-5 475800089400002 08-24-99 <.050 <1.0 15 <2 E14

SP-6 475800089400002 08-24-99 <.050 <1.0 12 <2 <16

SP-7 475800089410002 08-25-99 <.050 <1.0 16 <2 E12

SP-8 475800089470001 08-17-99 <.050 <1.0 E1 <2 17

Map 

number Station number Date

Dissolved iron

(μg/L as Fe)

[1046]

Dissolved manganese

(μg/L as Mn)

[1056]

Dissolved mercury

(μg/L as Hg)

[71890]

Dissolved zinc

(μg/L as Zn)

[1090]

SP-1 475400089470001 08-24-99 2200 262 <.1 <20

SP-2 475700089460001 08-24-99 <10 E1 <.1 <20

SP-3 475700089500001 08-19-99 <10 <2 <.1 <20

SP-4 475700089500002 08-19-99 380 138 <.1 <20

SP-5 475800089400002 08-24-99 20 <2 <.1 <20

SP-6 475800089400002 08-24-99 20 <2 <.1 <20

SP-7 475800089410002 08-25-99 60 24 <.1 <20

SP-8 475800089470001 08-17-99 20 3 <.1 <20

Table S-2. Water-quality data collected from springs in the Grand Portage Reservation, Minnesota, 1999--Continued
34

Table S-3. Quality-assurance samples from the Grand Portage Reservation, Minnesota, August 1999

 [mg/L, milligrams per liter; μg/L, micrograms per liter; °C, degrees Celsius; <, less than; E, estimated; --, no data]

Constituent

Replicate Sample

Well GW-4,

475325089491001

Field Blank

Well GW-20, 

480001089353401

Dissolved calcium (mg/L as Ca) 68.4 <.02

Dissolved magnesium (mg/L as Mg) 0.6 <.12

Dissolved potassium (mg/L as K) 2.0 <.1

Dissolved sodium (mg/L as Na) 258 <.1

Acid neutralizing capability, laboratory (mg/L as CaCO3) 37 2

Alkalinity, filtered water, field (mg/L as CaCO3) 31 --

Bicarbonate, filtered water, field (mg/L as HCO3) 28 --

Carbonate, filtered water, field (mg/L as CO3) 5 --

Dissolved chloride (mg/L as Cl) 452 <.1

Dissolved fluoride (mg/L as F) 1.3 <.1

Dissolved silica (mg/L as SiO2) 22.2 <.1

Dissolved sulfate (mg/L as SO4) 58.6 <.1

Total ammonia plus organic nitrogen (mg/L as N) 0.1 E.10

Dissolved ammonia nitrogen (mg/L as N) <.020 <.020

Dissolved nitrite plus nitrate nitrogen (mg/L as N) <.050 <.050

Dissolved nitrite nitrogen (mg/L as N) <.010 <.010

Dissolved phosphorus (mg/L as P <.050 <.050

Dissolved ortho-phosphorus (mg/L as P) <.010 <.010

Total phosphorus (mg/L as P) <.050 <.050

Dissolved arsenic (μg/L as As) 1.1 <1.0

Dissolved barium (μg/L as Ba) 62 <1

Dissolved beryllium (μg/L as Be) <2 <2

Dissolved boron (μg/L as B) 314 <16

Dissolved iron (μg/L as Fe) <10 <10

Dissolved manganese (μg/L as Mn) 3 <2

Dissolved mercury (μg/L as Hg) <.1 <.1

Dissolved zinc (μg/L as Zn) E11 <20
35

Table S-4. Percent difference between concentrations in field samples and replicate samples from well GW-4, Grand Portage Reservation, 

Minnesota, August 16, 1999 

 [mg/L, milligrams per liter; μg/L, micrograms per liter; °C, degrees Celsius; <, less than; E, estimated; --, no data]

Constituent Field sample Replicate Percent 

difference

pH, whole water, laboratory (standard units) 8.5 8.6 -0.6

Specific conductance, laboratory (μS/cm at 25 °C) 1700 1710 -0.3

Dissolved calcium (mg/L as Ca) 65.9 68.4 -1.8

Dissolved magnesium (mg/L as Mg) 0.58 0.6 -1.7

Dissolved potassium (mg/L as K) 2.0 2.0 0

Dissolved sodium (mg/L as Na) 257 258 -.2

Acid neutralizing capability, laboratory (mg/L as CaCO3) 44 37 8.6

Dissolved chloride (mg/L as Cl) 453 452 .1

Dissolved fluoride (mg/L as F) 1.2 1.3 -4

Dissolved silica (mg/L as SiO2) 22.3 22.2 .2

Dissolved sulfate (mg/L as SO4) 58.2 58.6 -.3

Total ammonia plus organic nitrogen (mg/L as N) 0.21 0.1 35.5

Dissolved ammonia nitrogen (mg/L as N) <.020 <.020 --

Dissolved nitrite plus nitrate nitrogen (mg/L as N) <.050 <.050 --

Dissolved nitrite nitrogen (mg/L as N) <.010 <.010 --

Dissolved phosphorus (mg/L as P) <.050 <.050 --

Dissolved ortho-phosphorus (mg/L as P) <.010 <.010 --

Total phosphorus (mg/L as P) <.050 <.050 --

Dissolved aluminum (μg/L as Al) -- -- --

Dissolved arsenic (μg/L as As) <1.0 1.1 --

Dissolved barium (μg/L as Ba) 61 62 -.8

Dissolved beryllium (μg/L as Be) <2 <2 --

Dissolved boron (μg/L as B) 305 314 -1.5

Dissolved iron (μg/L as Fe) <10 <10 --

Dissolved manganese (μg/L as Mn) 3 3 0

Dissolved mercury (μg/L as Hg) <.1 <.1 --

Dissolved selenium (μg/L as Se) <1.0 -- --

Dissolved silver (μg/L as Ag) <1 -- --

Dissolved zinc (μg/L as Zn) 14 E11 12