U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2006–5034

Prepared in cooperation with the

Grand Portage Band of Chippewa Indians

Ground-Water/Surface-Water Interaction 

in Nearshore Areas of Three Lakes on the 

Grand Portage Reservation, Northeastern 

Minnesota, 2003-04
Ground-Water/Surface-Water Interaction 

in Nearshore Areas of Three Lakes on the 

Grand Portage Reservation, Northeastern 

Minnesota, 2003–04

By Perry M. Jones

Prepared in cooperation with the Grand Portage Band of Chippewa Indians

Scientific Investigations Report 2006–5034

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

P. Lynn Scarlett, Acting Secretary

U.S. Geological Survey

P. Patrick Leahy, Acting Director

U.S. Geological Survey, Reston, Virginia: 2006

For product and ordering information:

World Wide Web: http://www.usgs.gov/pubprod

Telephone: 1-888-ASK-USGS

For more information on the USGS--the Federal source for science about the Earth, its natural and living resources, 

natural hazards, and the environment:

World Wide Web: http://www.usgs.gov

Telephone: 1-888-ASK-USGS

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the 

U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Jones, P.M., 2006, Ground-water/surface-water interaction in nearshore areas of three lakes on the Grand Portage 

Reservation, northeastern Minnesota, 2003–04: U.S. Geological Survey Scientific Investigations Report 2006–5034, 

49 p.

Prepared by the U.S. Geological Survey in Mounds View, Minnesota (http://mn.water.usgs.gov/)
iii

Contents

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

Introduction.....................................................................................................................................................2

Background............................................................................................................................................2

Purpose and Scope ..............................................................................................................................4

Acknowledgments................................................................................................................................4

Physical Setting and Hydrology ..................................................................................................................4

Grand Portage Reservation.................................................................................................................4

North Lake..............................................................................................................................................7

Teal Lake.................................................................................................................................................7

Taylor Lake .............................................................................................................................................7

Previous Hydrologic Studies......................................................................................................................11

Methods of Study.........................................................................................................................................11

Analyses of Existing Aerial Photography........................................................................................11

Water Quality.......................................................................................................................................11

Precipitation................................................................................................................................12

Lake-Sediment Temperatures..................................................................................................12

Surface- and Pore-Water Quality ...........................................................................................12

Quality Assurance......................................................................................................................13

Results of Analyses .....................................................................................................................................14

Existing Aerial Photography..............................................................................................................14

Water Quality.......................................................................................................................................14

Precipitation................................................................................................................................14

Lake-Sediment Temperatures..................................................................................................15

North Lake..........................................................................................................................15

Teal Lake.............................................................................................................................18

Taylor Lake .........................................................................................................................19

Surface-Water and Pore-Water Quality ................................................................................21

North Lake..........................................................................................................................30

Teal Lake.............................................................................................................................31

Taylor Lake .........................................................................................................................36

Quality Assurance......................................................................................................................37

Ground-Water/Surface-Water Interaction..............................................................................................38

North Lake............................................................................................................................................39

Teal Lake...............................................................................................................................................42

Taylor Lake ...........................................................................................................................................42

Implications of Ground-Water/Surface-Water Interactions ................................................................45

Summary........................................................................................................................................................45

References....................................................................................................................................................47
iv

Figures

1–5. Maps showing:

1. Location of study area and study sites, Grand Portage Reservation, northeastern 

Minnesota ......................................................................................................................................3

2. Upper bedrock geology of the Grand Portage Reservation, northeastern Minnesota.....6

3. North Lake area, Grand Portage Reservation, northeastern Minnesota, land-surface 

elevations, bogs, swamps, high tree line, drainage channels, watershed boundary, 

lake-sediment temperatures, and water-quality-sampling sites sampled in August 2003 

and May 2004.................................................................................................................................8

4. Teal Lake area, Grand Portage Reservation, northeastern Minnesota, land-surface 

elevations, bogs, swamps, meadows, marshes, high tree line, drainage channels, 

watershed boundary, lake-sediment temperatures, and water-quality-sampling sites 

sampled in September 2003 ........................................................................................................9

5. Taylor Lake area, Grand Portage Reservation, northeastern Minnesota, land-surface 

elevations, bogs, swamps, lowlands, watershed boundary, lake-sediment temperatures, and water-quality-sampling sites sampled in August–September 2004................10

6–8. Graphs showing:

6. Comparison of oxygen-18/oxygen-16 ratios and deuterium/protium ratios with northern 

Wisconsin meteoric waterline for bulk precipitation sampled at North Lake and Grand 

Portage precipitation stations, and for surface water and pore water sampled from 

North Lake, August 2003 and May 2004, Teal Lake, September 2003, and Taylor Lake, 

August–September 2004, Grand Portage Reservation, northeastern Minnesota ...........16

7. Percentage distribution of major ion concentrations determined for surface water and 

pore water sampled from North Lake, August 2003 and May 2004, Teal Lake, September 2003, and Taylor Lake, August and September 2004, Grand Portage Reservation, 

northeastern Minnesota............................................................................................................32

8. Concentrations of cations and anions in surface water and pore water sampled from 

North Lake, August 2003, North Lake, May 2004, Teal Lake, September 2003, and Taylor 

Lake, August and September 2004, Grand Portage Reservation, northeastern Minnesota................................................................................................................................................34

9–12. Maps showing:

9. Nearshore locations of ground-water inflow and surface-water outseepage for North 

Lake, Teal Lake, and Taylor Lake, Grand Portage Reservation, northeastern Minnesota, 

determined on basis of lake-sediment temperatures and water-quality data.................40

10. Nearshore locations of ground-water inflow and surface-water outseepage for North 

Lake, Grand Portage Reservation, northeastern Minnesota, determined on basis of 

lake-sediment temperatures, onsite water-quality measurements, major constituent 

and nutrient concentrations, and oxygen-18/oxygen-16 and deuterium/protium 

ratios .............................................................................................................................................41

11. Nearshore locations of ground-water inflow and surface-water outseepage for Teal 

Lake, Grand Portage Reservation, northeastern Minnesota, determined on basis of 

lake-sediment temperatures, onsite water-quality measurements, major constituent 

and nutrient concentrations, and oxygen-18/oxygen-16 and deuterium/protium

ratios .............................................................................................................................................43

12. Nearshore locations of ground-water inflow and surface-water outseepage for Taylor 

Lake, Grand Portage Reservation, northeastern Minnesota, determined on basis of 

lake-sediment temperatures, onsite water-quality measurements, major constituent 

and nutrient concentrations, and oxygen-18/oxygen-16 and deuterium/protium 

ratios .............................................................................................................................................44
Tables

1. Geologic units on the Grand Portage Reservation, northeastern Minnesota, and their 

water-bearing characteristics....................................................................................................5

2. Water-quality data for bulk precipitation samples collected at North Lake and Grand 

Portage precipitation stations, Grand Portage Reservation, northeastern Minnesota, 

2004 ...............................................................................................................................................15

3. Temperature measurements made in surface water and lake sediment of North Lake, 

Grand Portage Reservation, northeastern Minnesota, August 2003 and May 2004........17

4. Temperature measurements made in surface water and lake sediment of Teal Lake, 

Grand Portage Reservation, northeastern Minnesota, September 2003 ..........................19

5. Temperature measurements made in surface water and lake sediment of Taylor Lake, 

Grand Portage Reservation, northeastern Minnesota, August and September 2004.....20

6. Water-quality data for surface water and pore water collected from North Lake area, 

August 2003 and May 2004, Teal Lake area, September 2003, and Taylor Lake area, 

August and September 2004, Grand Portage Reservation, northeastern Minnesota.....22

7. Sequential replicate samples from North Lake, August 2003, Teal Lake, September 

2003, and Taylor Lake, September 2004, Grand Portage Reservation, northeastern Minnesota ...........................................................................................................................................38
Conversion Factors, Abbreviations, and Datums

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

micrometer (μm) 0.00003937 inch (in.)

mile (mi) 1.609 kilometer (km)

Area

acre 4,047 square meter (mi2)

square mile (mi2) 259.0 hectare (ha)

square mile (mi2) 2.590 square kilometer (km2)

Volume

gallon (gal) 3.785 liter (L)

milliliter (mL) 0.0338 ounce, fluid (oz)

Flow rate

gallon per minute (gal/min) 0.06309 liter per second (L/s)

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F=(1.8×°C)+32.

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

°C=(°F-32)/1.8.

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (μS/cm at 

25 °C).

Concentrations of chemical constituents in water are given either in milligrams per liter (mg/L) 

or micrograms per liter (μg/L).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

vi 
Abstract

The U.S. Geological Survey (USGS), in cooperation with 

the Grand Portage Band of Chippewa Indians, applied three 

techniques to assess ground-water/surface-water interaction 

in nearshore areas of three lakes (North, Teal, and Taylor) on 

the Grand Portage Reservation in northeastern Minnesota. 

At each lake, analyses of existing aerial photographs, in-situ 

temperature measurements of shoreline lake sediment, and 

chemical analyses of surface water and pore water were conducted. Surface-water and pore-water samples were analyzed 

for major constituents, nutrients, and stable isotopes of oxygen 

and hydrogen. Bulk precipitation samples were collected and 

analyzed (1) for nutrient concentrations to determine nutrient 

input to the lakes through atmospheric deposition and (2) for 

stable isotope ratios of oxygen and hydrogen to determine 

a meteoric waterline that was needed for the stable isotope 

analyses of surface-water and pore-water samples.

Total nitrogen concentrations in the precipitation samples 

ranged from 0.51 to 8.4 mg/L (milligrams per liter) as nitrogen at the North Lake precipitation station and from 0.42 to 

2.3 mg/L as nitrogen at the Grand Portage precipitation station. Oxygen-18/oxygen-16 and deuterium/protium isotope 

ratios for the bulk precipitation samples lie relatively close to 

a meteoric waterline for northern Wisconsin, except for the 

ratios for samples collected on May 20, 2004.

Analyses of existing aerial photographs, nearshore lakesediment temperatures, and seasonal isotope ratios of surfacewater and pore-water samples were the most valuable data 

for identifying locations of ground-water inflow and surfacewater outseepage. Analyses of existing aerial photographs 

of the three lakes indicated the location of potential inflow 

channels and lineaments identifying potential ground-water 

inflow locations for pore-water sampling. Lake-sediment 

temperatures at potential ground-water inflow locations ranged 

from 4 to 16 oC, varying between lakes, seasons, and climatic 

conditions. Major constituent chemistry was valuable at 

Taylor Lake, and to a limited extent at North and Teal Lakes, 

in confirming results from the isotope and lake-sediment 

temperature data.

Ground-Water/Surface-Water Interaction in Nearshore 

Areas of Three Lakes on the Grand Portage Reservation, 

Northeastern Minnesota, 2003–04

By Perry M. Jones

Ground-water inflow to North Lake likely occurs along 

the southwest and south shores, and along portions of the 

west, southeast, north, and northeast shores. Relatively cool 

lake-sediment temperatures along the southwest, south, west, 

and southeast shores, and in isolated beaver channels along 

the north and northeast shores of North Lake indicate potential ground-water inflow at these locations. Both localized 

ground-water inflow and surface-water outseepage occurs 

along portions of the north, northeast, southeast, and south 

shores, varying seasonally. Conflicting evidence for groundwater flow conditions exist for the northwest and north-northwest pore-water samples. Only minor differences in the major 

constituent concentrations were seen between the surfacewater and pore-water samples from the North Lake area with 

the exception of iron and manganese concentrations.

Ground-water inflow likely takes place along the southsouthwest and north shores of Teal Lake, with a mixture of 

ground-water inflow and surface-water outseepage occurring 

in other areas of the lake. Cooler lake-sediment temperatures 

occurred along the south-southwest, west, and northwest 

shores, portions of the north shore, and in channels identified 

in aerial photographs throughout the lake, indicating potential 

ground-water inflow at those locations. Warmer lake-sediment 

temperatures along the northeast and portions of the southwest 

and northwest shores of Teal Lake indicate potential locations 

where surface-water outseepage or little ground- and surfacewater interaction occurs. The major constituent concentrations were higher in the pore-water samples collected from the 

south-southwest and northeast shores of Teal Lake, indicating 

ground-water inflow. Cation adsorption, cation exchanges 

with hydrogen ions, and chelation with organic materials 

occurring in the fen surrounding the lake likely resulted in the 

low dissolved calcium, magnesium, and sodium concentrations in north, northwest, and west pore-water samples from 

the Teal Lake area. Pore-water samples from the south-southwest, north, and southwest shores of Teal Lake had isotopic 

compositions that plotted closest to the meteoric waterline, 

indicating that little evaporation or transpiration occurred in 

these samples and that ground-water inflow may be occurring 

at these locations. Surface-water outseepage from Teal Lake 

likely occurs along the northeast shore even though major 

 
constituent concentrations were high. Major constituent concentrations may be high because of a nearby beaver dam.

Ground-water inflow to Taylor Lake likely occurs at the 

north and south pore-water sampling sites. Higher major constituent concentrations and the least evaporative isotope ratios 

were found in pore-water samples along the south, north, and 

west shores of Taylor Lake, indicating potential locations of 

ground-water inflow. However, a combination of warmer and 

cooler lake-sediment temperatures along the west lowland 

indicated that ground-water inflow and surface-water outseepage may occur at that location. Surface-water outseepage 

likely occurs from Taylor Lake along the south shore through 

a surface-water drainage channel to a downgradient bog. 

Warmer lake-sediment temperatures along portions of the 

south and southeast shores indicate that surface-water outseepage may occur at those locations. Both ground-water inflow 

and surface-water outseepage may occur along the west, 

southeast, and east shores of Taylor Lake, varying seasonally 

and with local precipitation.

Knowledge of general water-flow directions in lake 

watersheds and how they may change seasonally can help 

water-quality specialists and lake managers address a variety 

of water-quality and aquatic habitat protection issues for lakes. 

Results from this study indicate that ground-water and surfacewater interactions at the study lakes are complex, and the 

ability of the applied techniques to identify ground-water 

inflow and surface-water outseepage locations varied among 

the lakes. Measurement of lake-sediment temperatures proved 

to be a reliable and relatively inexpensive reconnaissance 

technique that lake managers may apply in complex settings 

to identify general areas of ground-water inflow and surfacewater outseepage. 

Introduction

Background

The availability of good quality water from lakes and 

wetlands on the Grand Portage Reservation in northeastern 

Minnesota is an important concern of the Grand Portage Band 

of Chippewa Indians. Development and changing landuse practices may affect the quality and quantity of water 

resources on the reservation. To effectively protect the water 

quality and quantity of the lakes and wetlands, an understanding of exchanges between ground water and surface water on 

local and regional scales is needed. Numerous hydrologic 

studies have been done on the reservation, but none of these 

studies has focused on determining ground-water/surfacewater interactions of lakes and wetlands.

The Grand Portage Reservation is located along the 

northwest shore of Lake Superior in northeastern Cook 

County, Minnesota, at the boundary between Minnesota, USA, 

and Ontario, Canada (fig. 1). The resident population on the 

Grand Portage Reservation is approximately 573 (U.S. Census 

Bureau, 2004), with a total reservation enrollment of approximately 1,089 (Bureau of Indian Affairs, 2001).

An important task in the protection of lakes is identifying and quantifying the components of a lake’s water balance. 

Commonly, one of the most difficult components to assess 

in this balance is the amount and location of ground-water 

inflow to lakes. On the Grand Portage Reservation, most of 

the ground-water inflow to lakes occurs through fractures 

and bedding planes in igneous and sedimentary bedrock. In 

fractured-flow terrains, ground-water inflow to open-basin 

lakes often is not a substantial component to the overall water 

balance of the lake (Rosenberry and Winter, 1993). However, 

for most closed-basin lakes, ground-water inflow is a substantial component to the lake’s water balance. 

Mapping for source areas of ground-water discharge to 

lakes in terrains dominated by bedrock fractures and bedding planes is difficult because of the complex nature of 

ground-water flow. Detailed assessments of bedding plane 

and fracture orientations in bedrock around the lakes can help 

in identifying potential locations of ground-water inflow. 

Hydraulic-head data also are needed to determine flow directions in the fractures. Because of large changes in topography 

and associated hydraulic-head gradients on the reservation, 

ground-water inflow can be relatively rapid, with lake-water 

levels rising relatively quickly in response to ground-water 

discharge and overland flow following precipitation (Winterstein, 2002). 

Physical, chemical, and biological techniques exist for 

determining the location of ground-water flow to lakes. Physical techniques include monitoring of hydraulic-head conditions in wells and piezometers around lakes, conducting lineament analyses, and mapping areas of iron, calcium, and other 

types of precipitates commonly present at seeps. Attempts 

were made in the early 1990s on the Grand Portage Reservation to install piezometers to measure head differences along 

the shore of lakes on the reservation (Tim Cowdery, U.S. Geological Survey, oral commun., January 25, 2003). Thin, 

unconsolidated, lakeshore sediments and the bedrock shores 

with complex fracture patterns found along many of the lakes 

on the reservation made installation of piezometers impractical. Lineament analyses tend to be successful in delineating 

ground-water flow patterns in areas where bedrock is at or 

close to the land surface (Dengnan and Clark, 2002), which is 

common throughout the reservation. Chemical techniques for 

determining ground-water inflow to lakes include monitoring 

pore-water quality in lakeshore sediment, assessing major ion 

chemistry (Robbins and others, 1997; Alexander and others, 

2001), and isotopic compositions of water (Krabbenhoft and 

others, 1994; Kendall and others, 1997; Schuster and others, 

2002). Schuster and others (2002) pointed to the importance 

of aquatic plants in the littoral zone affecting calcium concentrations in pore water, therefore limiting the use of major constituent chemistry for determining locations of ground-water 

inflow, and stressed the importance of stable isotope values for 

evaluation of ground-water/surface-water interactions. In-situ 

   Ground-Water/Surface-Water Interaction of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota
measurements of surface-water and lake-sediment temperatures have been used successfully to delineate ground-water 

and surface-water interactions in lakes (Schneider, 1962; Lee, 

1985; Rosenberry and others, 2000; Alexander and others, 

2001) and streams (Stonestrom and Constantz, 2003; Conant, 

2004). Biological techniques include assessment of shoreline 

distribution and species assemblage of aquatic plants (Lodge 

and others, 1989; Rosenberry and others, 2000). 

The U.S. Geological Survey (USGS), in cooperation 

with the Grand Portage Band of Chippewa Indians, conducted 

a study to assess ground-water/surface-water interactions in 

nearshore areas of three lakes, North, Teal, and Taylor Lakes 

(fig. 1), on the Grand Portage Reservation in 2003 and 2004. 

These three lakes were selected on the basis of the relatively high specific conductance values of water from these 

lakes compared to other lakes on the reservation. The high 

specific conductance values of the lake water may indicate 

that ground-water inflow is an important component of the 

water balance of the lakes. The objective of the study was to 

identify areas of ground-water inflow to the three lakes and 

surface-water outseepage to local aquifers through the assessment of existing aerial photographs and water-quality data. 

No attempt was made to identify areas of ground-water inflow 

or surface-water outseepage in deeper water beyond the littoral 

zone of the lakes. 

Grand Portage 

Indian Reservation

Ely

Hovland

Cook County 

MINNESOTA 

Wauswaugon 

g

Bay

Grand Portage

Bay

Deronda Bay 

in 

Lake Superior 

Swamp

 Lake

Loon

Lake 

Speckled 

Trout 

Lake 

Center

Lake 

Dutchman 

Lake Cuffs 

Lake 

Teal 

Lake 

North

Lake 

Taylor 

Lake 

Chevans 

Lake 

Mt. Maude 

Lake 

Little

Lake 

Turtle 

Lake 

Swede

Lake 

Reservation boundary

Pigeon 

Red Rock

Reservation R iver

Creek

River

Hollow Rock 

Creek 

Poplar 

Creek

Grand 

Portage Ck.

1 2 3 4 MILES 5

0 1 2 3 4 5 KILOMETERS 

0 1 6

36 31

1

6

31

36

1 6

31

36

36 31

R. 5 E. R. 6 E. R. 7 E. 

T. 

62

N.

T. 

63

N.

T. 

64

N.

R. 4 E. 

17

17

61

61

Grand

Portage

National Monument

MINNESOTA 

MICHIGAN

ONTARIO, 

CANADA 

47o52'30"

48o

89o52'30" 45' 37'30" 89o30'

Grand

Portage

Mineral

Center

Hat Point Grand

Portage

Island

Raspberry Point 

Lucille Island 

uzie Is land S

Base from Minnesota Departomet of Transportation

Base map 97, 1:24,000, 1997, U.S. Albers Equal Area projection

Standard parallels 29o30' and 45o30', central meridian -96o

Mount Sophie 

Pigeon Pt. 

Grand Portage Indian Reservation

Lake watershed of study sites

Precipitation station

EXPLANATION 

Figure 1. Location of study area and study sites, Grand Portage Reservation, northeastern Minnesota.

Introduction   
Purpose and Scope

This report presents the results from three techniques 

used to assess ground-water/surface-water interaction in nearshore areas of three lakes on the Grand Portage Reservation. 

Analyses of existing aerial photographs, in-situ temperature 

measurements of shoreline lake sediment, and water-quality 

data from surface- and pore-water samples collected in 2003 

and 2004 were used. Rain-water-quality data also were collected. Available geologic and hydrologic data collected in 

previous USGS investigations were used in the analyses of the 

collected data. Information from scientific literature and other 

sources were used in data interpretation. 

The terms ground-water inflow and surface-water outseepage are used throughout the report. In this report, groundwater inflow refers to ground-water flow into a lake, and 

surface-water outseepage refers to the flow of surface water 

from lakes through lake sediment into local aquifers. Surfacewater discharge is used to describe surface-water flow from 

the lake through a surface channel or stream. Lineament is 

used to describe any linear feature where preferential groundwater flow may occur, such as along fractures in bedrock or 

glacial eskers and drumlins.

Acknowledgments

The author thanks the Grand Portage Reservation 

Environmental Department, in particular Margaret Watkins, 

Shannon Judd, and Kathryn King, for providing assistance in 

the collection of water samples, temperature data, and other 

activities needed to complete this study. The author also 

thanks Laurel Woodruff, Michael Menheer, Landon Gryczkowski, and Thomas Reppe, USGS, for their assistance in the 

collection and processing of water samples. The author thanks 

Robert Borgstede, USGS, for his work on the figures for this 

report.

Physical Setting and Hydrology 

Grand Portage Reservation

The Grand Portage Reservation is about 88 mi2 in area 

and con­tains numerous hills, small valleys, streams, lakes, and 

wetlands within boreal and mixed hardwood forest communities. The majority of the forest is second growth and undisturbed as the reservation was almost entirely logged during 

the late 1800s and early 1900s (Winterstein, 2002). Most of 

the residential areas and tourist and historical attractions are 

located in the commu­nity of Grand Portage, along State Highway 61, and along State Highway 17 east of Mineral Center 

(fig. 1). A thorough description of the physical setting and 

hydrology for the Grand Portage Reservation is provided in 

Winterstein (2002).

Climate on the reservation is continental and locally 

affected by Lake Superior, with cold winters and warm summers. The annual normal temperature (1951–80) for the 

reservation is about 38 °F (Baker and others, 1985), with mean 

monthly normal temperatures ranging from about 8 °F in January to 62 °F in July and August. Mean annual precipitation is 

about 28 in. (Baker and Kuehnast, 1978), with about twothirds of the precipitation occurring as rain between April and 

November. 

The topography and hydrology of the Grand Portage 

Reservation is affected by bedrock geology. Table 1 lists 

the geologic units on the reservation and their water-bearing 

characteristics. The Rove Formation of the Animikie Group 

is the oldest bedrock on the reservation and covers much of 

the northern part of the reservation (fig. 2) (Green, 1982; 

Miller and others, 2002). This formation is Paleoproterozoic 

in age and consists of nearly flat-lying argillaceous siltstone, 

carbonaceous shale, mudstone, and greywacke (Miller and 

others, 2001). Sandstone and conglomerate of the Puckwunge 

Formation of early Mesoproterozoic age overlay the Rove 

Formation as a narrow east-west strip through the center of the 

reservation and on parts of the chain of islands in Lake Superior between Hat Point and Pigeon Point (figs. 1 and 2) (Miller 

and others, 2001). Northeast- and northwest-trending Pigeon 

River diabase dikes of Mesoproterozoic age cut and cover the 

Rove Formation in parts of the northern half of the reservation (fig. 2) (Miller and others, 2001). The Rove Formation is 

partially metamorphosed near the dikes. Pigeon Point gabbro 

(sill) emplaces the Rove Formation between Wauswaugoning 

Bay and Pigeon Point (figs. 1 and 2).

In the southwestern half of the reservation and on Lucille 

and nearby islands, diabase dikes and the lower northeastern 

sequence of the North Shore Volcanics Group lava of Mesoproterozoic age, mostly consisting of the Grand Portage basalt 

and Hovland lavas, cover the Puckwunge Formation to the 

southwest (fig. 2) (Miller and others, 2001). The Pigeon River 

diabase dikes trend to the northeast and southeast, cutting 

through the North Shore Volcanics Group (fig. 2). Swarms 

of east-trending Grand Portage diabase dikes cut through 

the Grand Portage basalt along Lake Superior shore between 

Deronda Bay and Raspberry Point and cut through the Rove 

Formation northeast of Wauswaugoning Bay (fig. 2). Undifferentiated granophyric and quartzfelsic-monzodioritic rocks 

of unknown age cover a portion of the Pigeon River diabase 

dike at and near Red Rock Creek (figs. 1 and 2). Brule 

Lake-Hovland-Reservation River diabase was emplaced as 

a sheet-like intrusion on the Hovland lavas along the Lake 

Superior shore in the southwestern corner of the reservation 

(fig. 2) (Miller and others, 2001). At the location where Red 

Rock Creek discharges into Lake Superior and Deronda Bay, 

Red Rock porphyritic rhyolite and Deronda Bay andesite of 

the North Shore Volcanics Group are present (figs. 1 and 2), 

being emplaced at about the same time as the Hovland lavas 

(1,107 million years ago) (Davis and Green, 1997).

   Ground-Water/Surface-Water Interaction of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota
Physical Setting and Hydrology 

Table 1. Geologic units on the Grand Portage Reservation, northeastern Minnesota, and their water-bearing characteristics.

[Geologic nomeclature is that of the U.S. Geological Survey and differs somewhat from that of the Minnesota Geological Survey. gal/min, gallons per minute; 

K, potassium]

System Series Geologic unit Lithology 

(Miller and others, 2002) Water-bearing characteristics

Quaternary Pleistocene Glacial lake clay Clay, silt, sand, and boulders. Deposits too thin and impermeable to yield adequate 

domestic water supplies.

Quaternary Pleistocene Glacial till Clay, sand, silt, pebbles, cobbles, and 

boulders.

Most deposits too thin and impermeable to yield adequate 

domestic water supplies. Ruhl (1995) reported a well 

yield of 2 gal/min. Only used for domestic or irrigation 

supplies.

Precambrian Proterozoic Era/

Mesoproterozoic–lower 

northeast sequence of North 

Shore Volcanics Group

Hovland lavas Mixed suite of intergranular basalt, 

basaltic andesite, icelandite, and 

rhyolite.

No available information, but likely similar to Grand 

Portage basalt.

Precambrian Proterozoic Era/

Mesoproterozoic–lower 

northeast sequence of North 

Shore Volcanics Group

Red Rock porphyritic 

rhyolite

Reddish to tan, aphanitic rhyolite; 

contains quartz, 

K-feldspar, and oxidized mafic 

phenocrysts.

No available information.

Precambrian Proterozoic Era/

Mesoproterozoic–lower 

northeast sequence of North 

Shore Volcanics Group

Deronda Bay andesite Brown, aphanitic to fine-grained 

andesite, sparsely plagioclasephyric flow.

No available information.

Precambrian Proterozoic Era/

Mesoproterozoic–lower 

northeast sequence of North 

Shore Volcanics Group

Grand Portage basalt Intergranular transitional basalt and 

basaltic andesite flows.

Highly variable yields, but generally low yields ranging 

from less than 1 to 100 gal/min (Ruhl, 1995), adequate 

for domestic water supplies.

Precambrian Proterozoic Era/

Mesoproterozoic–

Keweenawan volcanic rocks

Pigeon Point gabbro 

(sill)

Olivine gabbro, intermediate rocks, 

and granophyre.

No available information, but likely similar to Brule LakeHovland-Reservation River diabase/gabbro.

Precambrian Proterozoic Era/

Mesoproterozoic–

Keweenawan volcanic rocks

Pigeon River diabase 

(dikes)

Olivine diabase. No available information, but likely similar to Brule LakeHovland-Reservation River diabase/gabbro.

Precambrian Proterozoic Era/

Mesoproterozoic–

Keweenawan volcanic rocks

Brule Lake-HovlandReservation River 

diabase/gabbro

Ophitic olivine gabbro, locally 

monzodioritic, fine- to coarsegrained.

Generally low yields ranging from less than 1 to 4 gal/min 

(Ruhl, 1995), sometimes adequate for domestic water 

supplies.

Precambrian Proterozoic Era/

Mesoproterozoic–

Keweenawan volcanic rocks

Grand Portage diabase 

(dikes)

Basalt to trachybasalt, unit forms 

east-trending swarm cutting 

Grand Portage basalt and the 

Rove Formation.

No available information.

Precambrian Proterozoic Era/Mesoproterozoic Logan diabase 

(intrusion)

Diabase to gabbro, locally 

granophyic, upper part commonly 

plagioclase-phyric, forms thick 

sill and northeast-trending dikes 

in Rove Formation.

No available information.

Precambrian Proterozoic Era/Mesoproterozoic Miscellaneous diabase 

(intrusion)

Isolated hypabyssal intrusions 

within Keweenawan volcanic or 

Paleoproterozoic rocks, poorly 

exposed.

No available information, but likely similar to Brule LakeHovland-Reservation River diabase/gabbro.

Precambrian Proterozoic Era/Mesoproterozoic Undifferentiated 

granophyric rocks

Isolated hypabyssal intrusions 

of granophyre rocks within 

Keweenawan volcanic or 

Paleoproterozoic rocks, age 

uncertain, poorly exposed.

No available information.

Precambrian Proterozoic Era/Mesoproterozoic Undifferentiated 

quartzfelsicmonzodioritic rocks

Isolated hypabyssal intrusions 

of intermediate rocks within 

Keweenawan volcanic or 

Paleoproterozoic rocks, age 

uncertain, poorly exposed.

No available information.

Precambrian Proterozoic Era/Mesoproterozoic Puckwunge Formation Quartz arenite; gray, crossbedded; some quartz-pebble 

conglomerate.

No available information.

Precambrian Proterozoic Era/Paleoproterozoic Rove Formation Argillaceous siltstone, carbonaceous 

shale, mudstone, and greywacke.

Highly variable yields, but generally low yields ranging 

from less than 1 to 50 gal/min (Ruhl, 1995); adequate 

for domestic water supplies.
Glacial till and lake clay of Pleistocene age cover much 

of the Paleoproterozoic and Proterozoic bedrock of the 

reservation. These glacial deposits are thin, generally less than 

50 ft thick, and consist mainly of poorly sorted glacial till 

and lake clay of low permeability (Winterstein, 2002). The 

glacial till was part of ground and end moraines deposited 

during advances and subsequent wasting of several ice sheets 

that moved southwesterly and westerly out of Lake Superior 

(Wright, 1972). Post-glacial alluvium, beach deposits, and 

peat also are present above the bedrock of the reservation.

 The land surface of the reservation rises from Lake 

Superior in the southeast to highlands in the center of the 

reservation and then declines to the Pigeon River in the north 

(fig. 1). Land-surface elevations range from about 602 ft at 

the shores of Lake Superior to about 1,814 ft at Mount Sophie. 

Large changes in elevations occur along the diabase dikes and 

gabbro intrusions crossing the reservation.

In general, rivers and streams in the southeastern part of 

the reservation flow towards Lake Superior, whereas surfacewater flow in the northeastern part is towards the Pigeon River 

(fig. 1). The courses of rivers and streams are affected by the 

diabase dikes, crossing the dikes along fault and fracture zones 

(Winterstein, 2002). Numerous lakes and wetlands are present, with the lakes lying mainly between the diabase dikes. 

Wauswaugon 

g

Bay

Grand Portage

Bay

Deronda Bay 

in 

Lake Superior 

bhrd

bhrd

diab

diab

diab

diab

diab

fgpu

fgpu

fgpu

kps

kps

kps

kps

lidb

lidb

ndba

ngpb

ngpb

ngpb

ngpb

ngpb

ngpb

fimu

nhvl

nhvl

nhvl bhdg

nrrr

nrrr

ppgb

prdb

prdb

prdb

prdb

prdb

prdb

prdb

prv

prv

prv

prv

prv

prv

prv

prv

Teal 

Lake 

North

Lake 

Taylor 

Lake 

Reservation boundary

1 2 3 4 MILES 5

0 1 2 3 4 5 KILOMETERS 

0

MINNESOTA 

MICHIGAN

ONTARIO, 

CANADA 

47o52'30"

48o

89o52'30" 45' 37'30" 89o30'

Hat Point Grand

Portage

Island

Raspberry Point 

Lucille Island 

uzie Is land S

Base from Minnesota Departomet of Transportation

Base map 97, 1:24,000, 1997, U.S. Albers Equal Area projection

Standard parallels 29o30' and 45o30', central meridian -96o

Source: Miller, J.D., Jr., Green, J.C., Severson, M.J., Chandler, V.W., Hauck, 

S.A., Peterson, D.M., and Wahl, T.E., 2002, Geology and mineral potential 

of the Duluth Complex and related rocks of northeastern Minnesota: 

Minnesota Geological Survey Report of Investigations 58, 207 p.

Pigeon Pt. 

Pigeon Point gabbro (sill)

Pigeon River diabase

Rove Formation

Puckwunge Formation

Grand Portage basalt

Miscellaneous diabase

 intrusion

EXPLANATION 

Deronda Bay andesite 

Undifferentiated granophyric rocks

Red Rock porphyritic rhyolite 

Undifferentiated quartzfelsic- 

 monzodioritic rock 

Brule Lake-Hovland-Reservation 

 River diabase 

Hovland lavas

Brule Lake-Hovland diabase/gabbro

Logan intrusion-diabase

No geologic information

Grand Portage diabase dike

Lake watershed of study sites

Boundary of Grand Portage Indian 

 Reservation

ppgb

prdb

prv

kps

ngpb

diab

ndba

fgpu

nrrr

fimu

bhrd

nhvl

bhdg

lidb

Figure 2. Upper bedrock geology on the Grand Portage Reservation, northeastern Minnesota.

 Ground-Water/Surface-Water Interaction of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota
Surface-water discharge often is affected by beaver 

activity. Inactive and active dams and lodges were present 

on all three lakes assessed in this study; however, the activity 

seemed to be greater in North and Teal Lakes. A conservative estimate of beaver populations on the reservation in 2005 

was 180 beavers with 45 active lodges (Margaret Watkins, 

Grand Portage Reservation Environmental Department, oral 

commun., March 15, 2005). Lodges often were located in 

areas where ground-water inflow was thought to occur.

Ground water in the reservation primarily moves through 

fractures in the Mesoproterozoic bedrock and in the Rove 

Formation. Little is known about the orientation and extent 

of fracturing on the reservation because little fracture mapping and hydrologic assessment of the fractures have been 

done. Paillet and Olson (1994) mapped fracture orientations 

and hydraulic properties in two boreholes drilled in the North 

Shore Volcanics Group within 2 mi of Lake Superior.

Surface water is used for most public water supplies, 

whereas ground water is used for domestic water supplies. 

The city of Grand Portage extracts water from Lake Superior. 

Most of the domestic wells are located within 2 mi of Lake 

Superior (Winterstein, 2002). Ground water on the reservation 

often is too saline to be used for water supplies, consisting of 

calcium-, sodium-, and chloride-rich water (Olcott and others, 

1978; Winterstein, 2002). Throughout the reservation, springs 

also are used by individuals whose wells are completed in 

deep fractured bedrock aquifers supplying unusable saline and 

(or) iron-rich water.

North Lake

North Lake is a small, shallow lake, with a maximum 

depth of approximately 7 ft and an approximate surface area 

of 4.9 acres (fig. 3). The lake is relatively high at an elevation of 1,486 ft. In the spring, surface water flows into North 

Lake from the south through a small drainage originating from 

Swede and Turtle Lakes (figs. 1 and 3). In the summer and 

fall, surface-water flow in the drainage only occurs during 

major precipitation. Surface-water discharge from the lake 

occurs through an outflow channel to the northwest. Watershed area for North Lake, which includes Turtle and Swede 

Lakes, is about 0.4 mi2. 

The bedrock geology of the North Lake area consists 

of Grand Portage basalt of the North Shore Volcanic Group 

(fig. 2) (Green, 1982; Miller and others, 2002). In general, the 

basalt is overlain by less than 6 ft of glacial till, consisting of 

unstratified clay, silt, sand, gravel, and boulders, and isolated 

deposits of peat (Olcott and others, 1978). 

Land cover in the North Lake watershed consists of 

northern white cedar, white spruce, balsam fir mix, black 

spruce, aspen, and white birch (U.S. Geological Survey, 

2005d). A northern rich fen (shrub swamp) surrounds most of 

the lake with the exception of a 54-acre northern rich tamarack swamp (bog) that is attached to the northeast part of the 

lake (fig. 3) (U.S. Fish & Wildlife Service, 1994; Minnesota 

Department of Natural Resources, 2003). No large game fish 

are present, but Phoxinus eos (northern redbelly dace) and 

Culaea inconstans (brook stickleback) minnows are found in 

the lake (Margaret Watkins, Grand Portage Reservation Environmental Department, oral commun., March 15, 2005).

Teal Lake

Teal Lake is shallow, with a maximum depth of approximately 5 ft and an approximate surface area of 72 acres 

(fig. 4). The lake is relatively low at an elevation of 948 ft. 

The perimeter of the lake is completely encompassed by a 

northern rich fen and northern cedar swamp (fig. 4) (U.S. Fish 

& Wildlife Service, 1994). Surface-water inflow occurs 

through several drainage channels around the lake cutting the 

fen and swamp. Surface-water discharge occurs through an 

outflow channel located to the northeast of the lake. The location and shape of the channels vary over time with changes 

in beaver activity. The watershed area for Teal Lake is about 

0.8 mi2.

The bedrock geology of the Teal Lake area consists of 

the Rove Formation of the Animikie Group (fig. 2) (Green, 

1982; Miller and others, 2002). Keweenawan Pigeon River 

diabase dikes bound upstream parts of the watershed, cutting 

through the Rove Formation (fig. 2). Stratified glacial lake 

clay with some silt and sands overlie the bedrock (Olcott and 

others, 1978).

Land cover in the lowlands surrounding Teal Lake 

consists of a mixture of black spruce, northern white cedar, 

deciduous shrub, and tamarack (U.S. Geological Survey, 

2005d). The uplands of the Teal Lake watershed consist of 

aspen, white birch, balsam fir mix, black spruce, white spruce, 

and northern white cedar. No large game fish are present, 

but Culaea inconstans (brook stickleback) and Pimephales 

promelas (fathead) minnows are found in the lake (Margaret 

Watkins, Grand Portage Reservation Environmental Department, oral commun., March 15, 2005).

Taylor Lake

Taylor Lake is much deeper than Teal and North Lakes, 

having a maximum depth of about 26 ft (fig. 5). The lake 

is approximately 32 acres in area and sits at an elevation of 

about 1,543 ft. No apparent surface-water inflow occurs to the 

lake, but surface-water inflow may occur in the spring from 

a bog north of the lake through a lowland (fig. 5). Surface 

water flows out of the lake to the south over a beaver dam to 

a downgradient bog (fig. 5). The watershed area for Taylor 

Lake is relatively small compared to the size of the lake, being 

about 0.2 mi2.

The bedrock geology of the Taylor Lake area consists of 

Grand Portage basalt. Younger Pigeon River diabase dikes cut 

Physical Setting and Hydrology 
(A) Sampled August 2003

(B) Sampled May 2004

0.05 0.1MILE

0 0.05 0.1 KILOMETER

0

Base from Minnesota Department of Transportation

Base map 99, 1:24,000, 1999

U.S. Albers projection

R. 5 E.

R. 5 E.

8 9

17 16

T.

63

N.

D

D

D

D

D

NW N

S

SW

B

B

B B B

B

B

B

BB

B B BB

B B B B

B B B

B

B

B

B

B

B

B

B

B

B

B B B

B

89o49'35" 30" 89o49'25"

North Lake

(elev. 1,486 feet)

1500

1500

1500

1500

1520

1520

1480

8 9

17 16

T.

63

N.

S

SW

NNW

NE

SE

North Lake

(elev. 1,486 feet)

1500

1500

1500

1500

1520

1520

1480

(surface

water)

(surface

water)

Sources for native plant communities from: U.S. Fish and Wildlife 

Service, 1994, National wetlands inventory digital data, October 1991 

to 1994: Information available on web, accessed March 11, 2005, at 

http://www.nwi.fws.gov., and Minnesota Department of Natural 

Resources, 2003, Field guide to the native plant communities of 

Minnesota, Laurentian Mixed Forest Province: St. Paul, Minnesota, 

Minnesota Department of Natural Resources,p. 198-200, 203-204, 

283-287.

47o57'

89o49'35" 30" 89o49'25"

B

B

B B

B

B

B

B

B

B

B

B

B

B

B

46

45

47o56'55"

D

B

B

B

B

B

B

B

B

B

B

EXPLANATION

Northern rich tamarack swamp–bogs

Northern rich fen–shrub swamp

Topographic contour–shows elevation

 of land surface above NAVD 88.

 Contour interval 20 feet

Boundary of North Lake watershed

Features identified in analysis

 of existing aerial photographs

 High tree line (lineament)

 Drainage channel

Lake-sediment temperature site and 

 map number–Degrees Celsius, 

 measurements listed in table 3

 6 to 7.9

 8 to 9.9

 10 to 11.9 (not shown on map)

 12 to 13.9

 14 to 15.9

 16 to 17.9

 18 to 19.9

 20 to 21.9

 22 to 23.9

 24 to 25.9

Water-quality sampling site–Letters are 

 site identifier SW

1500

42

39

44

31

29

27

33

18

15

44

43

42

38

37

39

40

41

36

50

49

48

47

47o57'

47o56'55"

D

D

D

D

D

D

1

2

3 4 5

6 7

8 10 9

11 13 12 14

15 16

17 18

20 19

21

22

23 24

25

26

27

28

29

30

31

32 33 34

35

Outflow

channel

Outflow

channel

Figure 3. North Lake area, Grand Portage Reservation, northeastern Minnesota, land-surface elevations, bogs, swamps, high tree line, 

drainage channels, watershed boundary, lake-sediment temperatures, and water-quality-sampling sites sampled in (A) August 2003 and 

(B) May 2004.

 Ground-Water/Surface-Water Interaction of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota
27 26

34 35

T.

64

N.

R. 6 E.

Multiple  channels

B

B

B B

B

B

B

B

B

B B

B

BB

B

B

B

B

B

1

2

3

4 5

6

7

8

10 9 11 12

13

14

15

16

17

18

19

D

D

D

D

D

D

D

N

NE

SSW

SW

W

NW

89o40' 30" 89o39'

30"

47o59'15"

47o59'45"

0.25 0.5

0.25 0.5 KILOMETER

 MILE

0

0

900

940

960

980

980

1000

1020

1040

1040

1060

1080

1080

1100

1120

1100

1140

1180

960

980

980

1000

1000

1020

1020

10401060

1080 1080

980

1100

960

980

1000

1000

1020

1040

1040 1060

1060

1080

1080

1100

1100

1100

1120

1120

1120

1140

1140

1140

1160

1200

960

980

1000

1100

1200

1260

1180

1020

1020

61

Teal Lake

(elev. 948 feet)

Base from Minnesota Department of Transportation

Base map 99, 1:24,000, 1999

U.S. Albers projection

Sources for native plant communities from: U.S. Fish and Wildlife 

Service, 1994, National wetlands inventory digital data, October 1991 

to 1994: Information available on web, accessed March 11, 2005, at 

http://www.nwi.fws.gov., and Minnesota Department of Natural 

Resources, 2003, Field guide to the native plant communities of 

Minnesota, Laurentian Mixed Forest Province: St. Paul, Minnesota, 

Minnesota Department of Natural Resources,p. 198-200, 203-204, 

283-287.

Outflow

channel

(surface

water)

Lake-sediment temperature site and

map number–Degrees Celsius,

 measurements listed in table 4

 4 to 5.9

 6 to 7.9 (not shown on map)

 8 to 9.9 (not shown on map)

 10 to 11.9

 12 to 13.9

 14 to 15.9

 16 to 17.9

 18 to 19.9

Water-quality sampling site–Letters

 are site identifiers

B

B

B

B

B

B

B

B

EXPLANATION

Northern cedar swamp–bogs

Northern rich fen–shrub swamp

Wet meadow

Wooded swamp

Deep marsh

Topographic contour–shows

 elevation of land surface above

 NAVD 88. Contour interval 20 feet

Boundary of Teal Lake watershed

Features identified in analysis

 of existing aerial photographs

 High tree line (lineament)

 Drainage channel

DSW

1120

19

12

10

13

2

8

Figure 4. Teal Lake area, Grand Portage Reservation, northeastern Minnesota, lake-surface elevations, bogs, swamps, meadows, 

marshes, high tree line, drainage channels, watershed boundary, lake-sediment temperatures, and water-quality-sampling sites 

sampled in September 2003.

Physical Setting and Hydrology 
17 16

20 21

T.

63

N.

R. 5 E.

BB

B

B

BB

BBB

B

B

B B

B

B

B B B

BBBB

BB

B B

BBBB B B B

B

B B

B

1 2

3

4

5 6

7

8

9

10

11

12

13

14

15

16

17 18 19

20

21

22

23

24 25

26

27 28

29

30 31 32

33

34

35

36

37

1520

1540

1560

1580

1600

1620

1640

1660

1500

1480

1520

1540

1560

1580

1600

1620

1640

1660

1520

1520

1540

1560

1580

1600

1620

1640

1660

1680

1540

1560

1580

1600

1620

1640

1540

1560

1580

1600

1640

1540

1560

1580

1600

1540

1560

1580

1600

1580

D

D

D D

D

D

D

D

D

W

W (surface water) E (surface

water)

N

NE

E

SE

S

NENE

89o50' 89o49'30"

47o56'15"

47o56'

0.25 0.5 MILE

0 0.25 0.5 KILOMETER

0

Taylor Lake

(elev. 1543 feet)

Base from Minnesota Department of Transportation

Base map 99, 1:24,000, 1999

U.S. Albers projection

Sources for native plant communities from: U.S. Fish and Wildlife 

Service, 1994, National wetlands inventory digital data, October 1991 

to 1994: Information available from web accessed March 11, 2005, at 

http://www.nwi.fws.gov. and Minnesota Department of Natural 

Resources, 2003, Field guide to the native plant communities of 

Minnesota, Laurentian Mixed Forest Province: St. Paul, Minnesota, 

Minnesota Department of Natural Resources,p. 198-200, 203-204, 

283-287.

B

B

B

D

EXPLANATION

Bogs

Wooded swamp

Feature identified in analyses

 of existing aerial photographs

Lowlands

Topographic contours–shows

 elevation of land surface above

 NAVD 88. Contour interval 20 feet

SE

Boundary of Taylor Lake watershed

Lake-sediment temperature site and

map number–Degrees Celsius,

 measurements listed in table 4

 12 to 13.9

 14 to 15.9

 16 to 17.9

Water-quality sampling site–Letters

 are site identifier

1600

27

24

19

Figure 5. Taylor Lake area, Grand Portage Reservation, northeastern Minnesota, land-surface elevations, bogs, swamps, lowlands, watershed boundary, lake-sediment tempertures, and water-quality-sampling sites sampled in August–September 2004.

10 Ground-Water/Surface-Water Interaction of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota
the Grand Portage basalt from the northeast to the southwest 

(Green, 1982; Miller and others, 2002). In general, the basalt 

and dikes are overlain by less than 6 ft of glacial till, consisting of unstratified clay, silt, sand, gravel, and boulders, and 

isolated deposits of peat (Olcott and others, 1978). 

Land cover in the Taylor Lake watershed consists 

mainly of aspen and white birch in the uplands, with black 

spruce and balsam fir mix in lowland areas around the lake 

(U.S. Geological Survey, 2005d). Upgradient bogs and 

wooded swamps are present east and northeast of Taylor Lake 

(fig. 5). The lake is stocked with Oncorhynchus mykiss (rainbow trout), Salvelinus fontinalis (brook (speckled) trout), and 

Lepomis gibbosus (pumpkinseed sunfish) (Margaret Watkins, 

Grand Portage Reservation Environmental Department, oral 

commun., March 15, 2005).

Previous Hydrologic Studies

From 1991 to the present, the USGS has cooperated 

with the Grand Portage Band of Chippewa Indians on five 

previous studies characterizing surface-water and groundwater resources on the reservation. However, none of these 

hydrologic studies focused on ground-water/surface-water 

interactions or on determining locations of ground-water 

inflow to lakes. 

Ruhl (1995) estimated transmissivity values and storage 

coefficients for the three principal fractured bedrock aquifers on the reservation—North Shore Volcanic Group basalt, 

Keweenawan volcanic rocks, and intrusive diabase and gabbro 

dikes, and Rove argillite, slate, and greywacke. As part of this 

3-year study, the effects of hydrofracturing were tested on two 

low-producing boreholes on the reservation. The hydrofracturing slightly improved flow rates from 0.05 and 0.25 gal/min 

to 1.5 and 1.2 gal/min, respectively (Paillet and Olson, 1994). 

Ruhl (1997) determined the physical and chemical properties of water, suspended sediment, and bottom sediment of 

the Grand Portage and Wauswaugoning Bays of Lake Superior. Winterstein (2000) reported surface-water-quality data 

collected by the USGS during 1997 and 1998 from four lakes, 

two wetlands, and two streams on the reservation. A guidance 

document and monitoring program were developed by Goldstein (2000) to identify factors affecting the quality of aquatic 

resources on the reservation. Hydrologic and water-quality 

data collected by the USGS and the Grand Portage Reservation Environmental Department, between 1991 and 2000 on 

the reservation were assessed by Winterstein (2002). 

Methods of Study

Analyses of existing aerial photographs, in-situ temperature measurements in lakeshore sediment, and water-quality 

analyses of collected surface-water and pore-water samples 

were done for the three study lakes on the reservation. Analyses of existing aerial photographs were done to identify drainages and potential fracture zones in the watershed for each 

lake in hopes of delineating preferential ground-water inflow 

to the lakes. These analyses were done prior to onsite surveys 

and sampling to identify locations in the lake where in-situ 

temperature measurements and pore-water sampling would be 

done. Bulk precipitation samples were collected to determine 

a meteoric waterline for stable isotope analyses of surfacewater and pore-water samples and to assess total nitrogen 

concentrations in precipitation falling on the reservation. Insitu pore-water temperatures in lakeshore sediment, hereafter 

referred to as lake-sediment temperatures, were measured at 

locations of potential ground-water inflow and surface-water 

outseepage to local ground-water systems to confirm these 

hydrologic conditions. Once lake-sediment temperatures 

indicated potential ground-water inflow, onsite water-quality 

measurements of the pore water were made, and pore-water 

samples were collected for major constituent, nutrient, and 

oxygen and hydrogen isotope analyses. The assessments 

were done at North Lake in August 2003 and May 2004, at 

Teal Lake in September 2003, and Taylor Lake in August–

September 2004. 

Analyses of Existing Aerial Photography 

Analyses of aerial photographs were done on the watersheds for the three study lakes using National Aerial Photography Program (NAPP) photographs from 1991, 1992, 1999, and 

2000 (U.S. Geological Survey, 2005e), and Digital Orthophoto 

Quadrangles (DOQ) from 1991 (Minnesota Department of 

Natural Resources, 2005). The photographs were viewed with 

a four-power stereoscope to identify surface-water drainages and any linear features where preferential ground-water 

flow may occur. Drainages and lineaments obtained from 

these analyses were used only to provide insight into possible 

ground-water inflow locations to focus in-situ lake-sediment 

temperature surveys and pore-water sampling along the shores 

of the lakes. Onsite confirmations of the identified drainage and lineament features were limited to views from the 

lakes and short onsite excursions along the lakeshore. More 

detailed analyses and onsite confirmation surveys would need 

to be done to determine the fracture patterns for source-water 

delineation throughout the lake watersheds. Morey (1981) 

conducted a much larger scale lineament assessment for northeastern Minnesota, which was used in this study as an initial 

guide in the analyses of aerial photographs.

Water Quality

Bulk precipitation samples were collected for total 

nitrogen and stable isotope analyses. Surface-water and lakesediment temperatures were measured along the lakeshores 

to determine where small and large differences between the 

two temperature measurements occurred, indicating potential 

locations for surface-water outseepage to local ground-water 

Methods of Study  11
systems and ground-water inflow to lakes. Surface-water and 

pore-water samples were collected at both potential surfacewater outseepage and ground-water inflow locations.

Precipitation

Bulk precipitation samples were collected in 2004 from 

two stations located on the reservation—Grand Portage and 

North Lake precipitation stations (fig. 1). Samples were collected in openings of the forest canopies for total nitrogen, 

oxygen-18/oxygen-16 ratio, and deuterium/protium ratio 

analyses. Bulk precipitation was collected from five rain 

storms in 4-L baked amber glass bottles with plastic collection 

funnels. Samples were collected by the water-quality specialist of the Grand Portage Reservation from the Grand Portage 

and the North Lake precipitation stations following rainfall on 

May 20, May 31, July 5, and July 29, 2004, and a sample was 

collected at the Grand Portage precipitation station following rainfall on August 24–25, 2004. Total precipitation at the 

Grand Portage precipitation station for the May 20, May 31, 

July 5, July 29, and August 24–25 rainfall was 0.09, 2.18, 

0.85, 0.06, and 0.09 in., respectively (Larry Dahl, Grand Portage Reservation Environmental Department–Forestry, written 

commun., March 18, 2005) (Minnesota Climatology Working Group, 2005). The amber glass bottles used to collect the 

precipitation samples were deployed by the water-quality specialist of the Grand Portage Reservation within 24 hours of the 

start of anticipated precipitation and collected within 24 hours 

following the end of rainfall. Between rainfall, the bottles and 

funnels were rinsed with deionized water and dried. 

Once collected, the sample water was poured into separate bottles for chemical analyses. The sampled water for 

total nitrogen analyses was poured into a 125-mL translucent 

polyethylene bottle with a plastic cap, acidified with 1 mL 

of 4.5-normal sulfuric acid, placed in a chilled cooler, and 

shipped within 24 hours after rainfall to the USGS National 

Water-Quality Laboratory, Lakewood, Colorado. Sample 

water for oxygen-18/oxygen-16 ratio and deuterium/protium 

ratio analyses was poured into a 60-mL clear glass bottle with 

a polyseal cap, placed in a chilled cooler, and shipped within 

24 hours after rainfall to the USGS Reston Stable Isotope Laboratory, Reston, Virginia. Total nutrient analyses were done 

between 6 and 18 days after sampling by alkaline persulfate 

digestion (Patton and Kryskalla, 2003), whereas the oxygen18/oxygen-16 ratio and deuterium/protium ratio analyses were 

done between 30 to 108 days after sampling using a carbondioxide-water equilibrium technique (Epstein and Mayeda, 

1953) and a gaseous hydrogen equilibrium procedure (Coplen 

and others, 1991), respectively.

Lake-Sediment Temperatures

In-situ temperature measurements were made in lake 

sediment along the shores of North, Teal, and Taylor Lakes. 

These lake-sediment measurements were made along the 

lakeshores from a canoe, in beaver-made channels flowing 

to the lakes, and on the fens and swamps surrounding the 

lakes. In-situ temperature measurements of lake sediment are 

indicative of pore-water and sediment temperatures. These 

measurements were made along the shorelines because it was 

impractical to collect temperature data for the entire lakes, 

and ground-water inflow to shallow lakes of Minnesota is 

less likely to occur with depth and distance from the shore as 

thicker accumulations of low-permeable organic sediment are 

present (Rosenberry and others, 2000). These temperature 

measurements provided a basis to identify the major groundwater inflow locations where water-quality samples could be 

collected to further confirm the inflow of ground water. For 

the most part, the lake sediment along the shorelines of the 

three lakes consisted of loose, organic materials, silt, and sand. 

Logs, boulders, and other low-permeable materials also were 

present on the lake bottoms. 

A thermocouple probe was used to make the temperature 

measurements. The probe consisted of a thermocouple placed 

at the end of a 6-ft stainless steel hollow tube with a stainless 

steel screen secured at the end of the tube to prevent sediment 

from entering the tube. The thermocouple was connected to a 

handheld display, which showed the temperature reading. The 

thermocouple probe was calibrated using a thermally regulated 

water bath and a registered thermometer before and after the 

collection of temperature data. The use of a towed temperature probe, such as used by Lee (1985), was not attempted at 

the lakes because of the dense aquatic vegetation and the presence of abundant rotting logs in the littoral zones of the lakes.

Temperature measurements were made during the early 

spring and late summer months when the difference between 

lake-water and ground-water temperatures was thought to 

be the largest. At each measurement location, surface-water 

temperature was taken with the thermocouple probe, and then 

the probe was imbedded by hand into the sediment as deep as 

possible. The water column depth to the sediment interface 

and depth of probe insertion into the sediment were recorded 

at each location. Water depths ranged from 0.1 to 4.9 ft at 

each measurement location, and insertion depths into the sediment ranged from 0.2 to 5.0 ft, with most depths greater than 

0.5 ft. Rosenberry and others (2000) found at Shingobee Lake 

in northern Minnesota that areas of ground-water discharge 

could be mapped effectively by measuring temperature only 

a few centimeters beneath the lakebed along a lake shoreline. 

Temperature stabilization in the surface water and lake sediment took approximately 3 to 10 minutes at each location, 

depending upon the temperature difference between the air, 

surface water, and pore water.

Surface- and Pore-Water Quality

Surface-water and pore-water samples were collected at 

locations where in-situ temperature measurements and onsite 

water-quality measurements of pore water in the lake sedi-

12 Ground-Water/Surface-Water Interaction of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota
ment indicated potential ground-water inflow to the lakes 

or surface-water outseepage to local ground-water systems. 

Surface-water samples were collected following USGS protocols outlined in the USGS National Field Manual for the 

Collection of Water-Quality Data (U.S. Geological Survey, 

variously dated). Surface-water and pore-water samples were 

collected at the three lakes for major constituents, nutrients, 

and oxygen and hydrogen isotope analyses. Major constituent 

and nutrient analyses were done by the USGS National WaterQuality Laboratory, Lakewood, Colorado, whereas the oxygen 

and hydrogen isotope analyses were done by the USGS 

Reston Stable Isotope Laboratory, Reston, Virginia. Alkalinity and bicarbonate concentrations were determined by USGS 

hydrologic technicians through inflection point titrations of the 

alkalinity samples performed within 24 hours after sampling. 

Replicate samples also were collected at each of the three 

lakes (see section on “Quality Assurance”).

Onsite water-quality measurements were made using a 

water-quality multiprobe meter prior to the collection of surface-water and pore-water samples. These measurements were 

specific conductance, pH, air temperature, water temperature, 

dissolved oxygen concentration, and barometric pressure. The 

specific conductance, pH, and dissolved oxygen probes on 

the multiprobe meter were calibrated on each of the sampling 

dates prior to sampling. Onsite water-quality measurements 

of surface water were made by lowering the multiprobe meter 

into the lake 2 to 3 ft below the water surface. Onsite waterquality measurements of pore water were made by pumping 

pore water into the multiprobe cup through a 0.25-in. outsidediameter, stainless-steel tube inserted into the lake sediment 

and connected to 0.19-in. inside-diameter, C-Flex tubing. 

The stainless-steel tube was slotted at one end with four 1-in. 

slots to allow pore water to enter the tube. The stainless-steel 

tubing was inserted between 0.5 and 3.0 ft into the lake sediment. The C-Flex tubing was run through a peristaltic pump 

to extract pore water from the sediment. 

Surface-water samples were collected at approximately 

the centers of North and Teal Lakes (figs. 3 and 4). Two 

surface-water sites on Taylor Lake (fig. 5) were sampled to 

assess any variability in major constituent, nutrient, and stable 

isotope chemistry at shallow depths across the lake. Historically, onsite water-quality measurements at the two sites have 

varied with depth and spatially (Margaret Watkins, Grand 

Portage Reservation Environmental Department, oral commun., August 31, 2004), which could be the result of offshore 

ground-water discharge. The surface-water samples were 

collected 2 to 3 ft below the water surface using a peristaltic 

pump and 0.19-in. inside-diameter, C-Flex tubing. 

Pore-water samples were collected at lakeshore locations 

of potential ground-water inflow and surface-water outseepage in the three lakes. The pore-water samples were collected 

using the same stainless-steel tube/C-Flex tubing/peristaltic 

pump sampling set-up used to collect the onsite water-quality 

measurement data. The samples were collected immediately 

following the collection of onsite water-quality measurement 

data. Like the onsite water-quality measurement data, porewater samples were collected at lake-sediment depths between 

0.5 and 3.0 ft. 

For each of the analyzed constituents, the sample filtration, preservation, and shipping methods were the same for the 

surface-water and pore-water samples, except for the nutrient 

samples. The water samples collected for anion, dissolved 

solids, and alkalinity analyses were filtered during sampling 

using a 0.45-μm pore-sized filter and stored in 250-mL 

polyethylene bottles. Water collected for cation analyses was 

filtered during sampling using a 0.45-μm pore-sized filter, 

preserved with sufficient nitric acid to maintain the water’s 

pH at less than 2.0 standard units, and stored in a 250-mL 

acid-rinsed, polyethylene bottle. Unfiltered, unpreserved 

water samples were collected in 250-mL polyethylene bottles 

for determining specific conductance and pH values made 

at the USGS National Water-Quality Laboratory (NWQL). 

Unfiltered surface-water samples for nutrient analysis were 

collected in 125-mL translucent polyethylene bottles and 

preserved with 1 mL of 4.5-normal sulfuric acid to determine 

total ammonia plus organic nitrogen concentrations and total 

phosphorus concentrations. Surface-water samples for the 

other nitrogen and phosphorus constituent analyses were 

filtered using a 0.45-μm pore-sized filter and collected in 

125-mL brown polyethylene bottles. Methods used for sample 

analysis are available at the USGS National Water-Quality 

Laboratory Web site (U.S. Geological Survey, 2005f).

Pore-water samples for all of the nitrogen and phosphorus constituent analyses were filtered using a 0.45-μm 

pore-sized filter and collected in 125-mL brown polyethylene 

bottles. The total ammonia plus organic nitrogen analyses 

and total phosphorus concentrations were determined for the 

pore-water samples using alkaline persulfate digestion and 

semiautomated colorimetric analyses (U.S. Geological Survey, 

2005f). All of the major constituent and nutrient samples 

were shipped within 24 hours in chilled coolers to the USGS 

National Water-Quality Laboratory for analyses. Like bulk 

precipitation samples, unfiltered, unpreserved surface-water 

and pore-water samples were collected for oxygen-18/oxygen16 ratio and deuterium/protium ratio analyses in 60-mL clear 

glass bottles with polyseal caps and shipped in chilled coolers 

within 24 hours after sampling to the USGS Reston Stable 

Isotope Laboratory.

Quality Assurance

Quality assurance and quality control are high priorities 

for USGS laboratories. The USGS National WaterQuality Laboratory, Lakewood, Colorado, has a rigorous set of 

procedures for assuring and controlling the quality of received 

water samples and analytical results determined by the 

laboratory (Ludtke and others, 2000; U.S. Geological Survey, 

2005c). The USGS Reston Stable Isotope Laboratory, Reston, 

Virginia, has an internal quality-assurance policy and works 

directly with the USGS National Water-Quality Laboratory to 

assure the quality of their analytical results (U.S. Geological 

Survey, 2005b). All of the water-quality data and pore-water 

Methods of Study  13
sampling site information, including quality-assurance and 

control-sample information, are stored in the USGS National 

Water Information System (NWIS) database (U.S. Geological 

Survey, 2005g). Field log books and sample field forms were 

used to record onsite water-quality measurements, lakesediment temperature data, and water-quality instrument 

calibration data.

One sequential replicate water sample was collected at 

each of the three lakes. A sequential replicate sample is a 

water sample collected consecutively following the collection of the regular sample to assess variability among samples 

resulting from sample collection, processing, shipping, and 

laboratory procedures performed at different sampling times 

(U.S. Geological Survey, 2005a). The replicate samples were 

collected following protocols outlined in the USGS National 

Field Manual for the Collection of Water-Quality Data 

(U.S. Geological Survey, 2005a). 

Results of Analyses

The oxygen and hydrogen isotope chemistry coupled 

with the lake-sediment temperatures proved to be the best 

tools for determining ground-water inflow to the three lakes. 

Drainages and lineaments identified in the analyses of existing 

aerial photographs were valuable in selecting the location of 

temperature measurements and pore-water sampling. In some 

cases, large differences in the major constituent chemistry 

between the surface water and pore water provided evidence 

of ground-water inflow. However, cation exchange in hydrogen ions, cation adsorption, and chelation occurring in the 

surrounding fens and swamps affected the major constituent 

concentrations of inflowing ground water, especially in porewater samples collected at Teal Lake.

Existing Aerial Photography 

Three potential drainage channels and two lineaments 

were identified in the analyses of existing aerial photographs 

of North Lake. The drainage channels are located to the south, 

northwest, and north of North Lake (fig. 3), and all trend 

generally to the north. There are two north-northwest-trending lineaments located south of North Lake near the southern 

drainage channels (fig. 3). Lineaments identified on the aerial 

photographs are likely lines of taller trees, which may represent a fracture zone where ground water is prevalent.

Multiple drainage channels and a lineament were identified in the analyses of existing aerial photographs of Teal 

Lake. These drainages are located north, northwest, west, 

and southwest of the lake (fig. 4). These drainage channels 

often correlate with locally lower land-surface elevations and 

are likely all flowing to the lake because they are all higher in 

elevation than Teal Lake. A north-northwest-trending lineament was identified on the aerial photographs northwest of 

the lake (fig. 4) and is likely a line of taller trees, which may 

represent a fracture zone where ground water is prevalent. 

No distinct lineaments or drainage channels were identified in the vicinity of Taylor Lake through the analyses of 

existing aerial photographs. Only apparent lowlands in the 

north, northeast, east, south, and west where ground-water 

inflow and surface-water outseepage may occur were identified (fig. 5). The lowland identified in the west (fig. 5) may 

provide only a relatively small amount of ground-water inflow 

to or surface-water outseepage from the lake because the 

watershed boundary of the lake is relatively close to the lake 

shore in that lowland.

Water Quality

Nine bulk-precipitation samples were collected between 

May and August 2004 at the two precipitation stations on 

the reservation. A total of 106 surface-water and 106 lakesediment temperature measurements were made along the 

shores of the three lakes. Six surface-water and 24 pore-water 

samples, including replicate samples, were collected at the 

three lakes for water-quality analyses between August 2003 

and August 2004.

Precipitation

Total nitrogen concentrations ranged from 0.51 to 

8.4 mg/L as nitrogen in precipitation samples from the North 

Lake precipitation station and from 0.42 to 2.3 mg/L as 

nitrogen in the precipitation samples from the Grand Portage precipitation station (table 2). These concentrations 

are similar to the total nitrogen concentrations measured for 

bulk precipitation at the National Atmospheric Deposition 

Program/National Trends Network precipitation monitoring 

site at Hovland, Minnesota (National Atmospheric Deposition Program/National Trends Network, 2005) (fig. 1). The 

three largest concentrations were found in rain-water samples 

collected from the North Lake precipitation station (table 2). 

The North Lake precipitation station was located in a denser 

forested area than the Grand Portage precipitation station, and 

therefore, the forest canopy may catch and retain more of the 

atmospheric nitrogen from dry deposition that could wash off 

into the collected rain samples. 

Oxygen-18/oxygen-16 ratios ranged from -5.0 to -8.1 per 

mil (table 2), whereas deuterium/protium ratios ranged from 

-28.8 to -56.4 per mil for bulk precipitation samples collected 

from the North Lake and Grand Portage precipitation stations. 

All of these ratios except for the ratios for samples collected 

on May 20, 2004, lie relatively close to a meteoric waterline 

determined by Krabbenhoft and others (1994) for precipitation 

in northern Wisconsin (fig. 6A). Oxygen-18 and deuterium 

values for river water in northern Wisconsin are similar to 

values in northeastern Minnesota (Kendall and Coplen, 2001), 

and therefore, the meteoric waterline for northern Wisconsin 

14 Ground-Water/Surface-Water Interaction of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota
was used to evaluate the bulk precipitation isotopic ratios for 

the North Lake and Grand Portage precipitation stations. 

Bulk precipitation samples collected on May 20, 2004, 

at both the North Lake and Grand Portage precipitation stations lie far to the right of the northern Wisconsin meteoric 

waterline (fig. 6A), indicating that the oxygen-18/oxygen-16 

ratios for these samples are larger than the meteoric waterline. 

Potential explanations for these larger oxygen-18/oxygen-16 

ratios for the May 20 samples are evaporation of the samples, 

which occurs when sample bottle caps are loose or made with 

foam inner liners (Tyler Coplen, U.S. Geological Survey, written commun., September 16, 2004), or a different source of 

water for the May 20 precipitation than for the other precipitation samples. Because most of the ratios are relatively close 

to the northern Wisconsin meteoric waterline, this meteoric 

waterline was used to assess the oxygen and hydrogen isotopes 

for the collected surface-water and pore-water samples.

Lake-Sediment Temperatures

Lake-sediment temperatures at the three lakes ranged 

from 4 to 25 oC. Lake-sediment temperatures at identified ground-water inflow locations were generally between 

4 and 16 oC, varying greatly between the lakes, seasons, and 

the climatic conditions prior to and during the temperature 

measurements. Differences between the surface-water and 

lake-sediment temperatures at the temperature measurement 

locations ranged from -1 to 10 oC.

North Lake

Surface-water temperatures ranged from 16 to 25 oC 

in August 2003, with all but one value between 20 to 25 oC 

(table 3). In May 2004, surface-water temperatures ranged 

from 9 to 17 oC. A total of 50 lake-sediment temperature measurements were made in the North Lake area, with 35 measurements in August 2003 and 15 measurements in May 2004 

(table 3). Lake-sediment temperatures along the shore of 

North Lake varied from 15 to 25 oC in August 2003, and from 

6 to 12 oC in May 2004. Multiple regression analysis of the 

lake-sediment temperature, probe depth into lake sediment, 

and water-depth data indicated that no relations (all p-values 

>0.43) existed between the variables, implying that the depth 

into lake sediment and water depth of the lake were unlikely 

factors affecting the lake-sediment temperature measurements 

at North Lake.

In August 2003, lake-sediment temperatures between 

14 and 18 oC occurred along the southwest, south, west, and 

southeast shores (fig. 3A), and in isolated beaver channels in 

the north and northeast. The cooler temperatures in the south 

were measured near a north-south trending drainage and a 

lineament found between North and Swede Lakes (figs. 1 and 

3A). Beaver dens commonly were present in the cool-temperature beaver channels in the north and northeast. The lower 

temperatures to the west and southwest are associated with a 

western extension of the northern rich fen surrounding the lake 

(fig. 3A). Beaver activity is common throughout this western 

extension of the fen. Lake-sediment temperatures above 18 oC 

were found throughout North Lake but were focused along the 

northwestern, northern, and southern lakeshores.

In May 2004, lake-sediment temperatures between 6 and 

8 oC occurred along the southeast, west, southwest, north, 

northeast, and east shores of North Lake (fig. 3B). In an onsite 

survey of the south shore, surface-water discharge from Swede 

Lake to North Lake was noted near site 47 where lake-sediment temperature was 7 oC. Warmer lake-sediment 

Table 2. Water-quality data for bulk precipitation samples collected at North Lake and Grand Portage precipitation stations, Grand Portage Reservation, northeastern Minnesota, 2004.

[mg/L, milligrams per liter; per mil, parts per thousand]

Station name

(fig. 1) Station number Date of collection (month/day/year)

Total nitrogen 

(mg/L as N)

Oxygen-18/

oxygen-16 ratio, 

unfiltered water, 

per mil

Deuterium/

protium ratio, 

unfiltered water, 

per mil

North Lake 

precipitation station

475702089493601 5/20/2004 3.15 -6.07 -56.40

5/31/2004 .51 -7.93 -48.50

7/5/2004 2.77 -7.80 -53.50

7/29/2004 8.36 -5.62 -31.50

Grand Portage 

precipitation station

475814089412801 5/20/2004 .67 -5.39 -54.60

5/31/2004 .59 -6.91 -44.80

7/5/2004 .42 -8.10 -56.10

7/29/2004 2.29 -5.02 -28.80

8/24/2004 1.53 -7.39 -44.40

Results of Analyses  15
Figure 6. Comparison of oxygen-18/oxygen-16 ratios and deuterium/protium ratios with northern Wisconsin meteoric waterline for 

(A) bulk precipitation sampled at North Lake and Grand Portage precipitation stations, and for surface water and pore water sampled 

from (B) North Lake, August 2003 and May 2004, (C) Teal Lake, September 2003, and (D) Taylor Lake, August-September 2004, Grand 

Portage Reservation, northeastern Minnesota.

16  Ground-Water/Surface-Water Interaction of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota DEUTERIUM/PROTIUM RATIO, PER MIL DEUTERIUM/PROTIUM RATIO, PER MIL DEUTERIUM/PROTIUM RATIO, PER MIL DEUTERIUM/PROTIUM RATIO, PER MIL

-20

-25

-30

-35

-40

-45

-50

-55

-60

-40

-45

-50

-55

-60

-65

-70

-75

-80

-85

-90

-40

-45

-50

-55

-60

-65

-70

-75

-80

-85

-90

-40

-45

-50

-55

-60

-65

-70

-75

-80

-85

-90

OXYGEN-18/OXYGEN-16 RATIO, PER MIL OXYGEN-18/OXYGEN-16 RATIO, PER MIL

OXYGEN-18/OXYGEN-16 RATIO, PER MIL OXYGEN-18/OXYGEN-16 RATIO, PER MIL

-9 -8 -7 -6 -5 -4 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4

-13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4

Equation for evaporation 

line deuterium/protium = 4.6 

(oxygen-18/oxygen-16) - 29.4

R2 = 0.98

Equation for evaporation 

line deuterium/protium = 4.1 

(oxygen-18/oxygen-16) - 33.7

R2 = 0.98

Equation for evaporation 

line deuterium/protium = 3.9 

(oxygen-18/oxygen-16) - 31.8

R2 = 0.94

(A) Bulk precipitation sampled at North Lake and Grand Portage 

precipitation stations, May - August 2004

(B) Surface water and pore water sampled at North Lake, 

August 2003 and May 2004

(C) Surface water and pore water sampled at Teal Lake, 

September 2003

(D) Surface water and pore water sampled at Taylor Lake, 

August-September 2004

Northern Wisconsin meteoric waterline 

 (Krabbenhoft and others, 1994)

North Lake precipitation station

Grand Portage precipitation station

EXPLANATION EXPLANATION

Northern Wisconsin meteoric waterline

 (Krabbenhoft and others, 1994)

Evaporation line

Surface water (lake) August 2003

Surface water (lake) May 2004

Pore water, August 2003–Letters are site identifier

Pore water, May 2004–Letters are site identifier

EXPLANATION

Northern Wisconsin meteoric waterline

 (Krabbenhoft and others, 1994)

Evaporation line

Surface water (lake)

Pore water–Letters are site identifier

SSW

N

SW

NW

NE

W

S

N

W

E

SE

NNE

NE

SE

NE

SW

SW

S

S

NNW

NW

N

EXPLANATION

Northern Wisconsin meteoric waterline

 (Krabbenhoft and others, 1994)

Evaporation line

Surface water (lake)

Pore water–Letters are site identifer
Table 3. Temperature measurements made in surface water and lake sediment of North Lake, Grand Portage Reservation, northeastern Minnesota, August 2003 and May 2004.

[ft, feet; o C, degrees Celsius; --, no data]

Map 

number 

(fig. 3)

Latitude 

(degrees, 

minutes, 

seconds)

Longitude 

(degrees, minutes, 

seconds)

Date (month/

day/year)

Time 

(24-hour)

Surface-water temperature in North 

Lake (oC)

Lakesediment 

temperature

(oC)

Probe depth 

into lake 

sediment

(ft)

Water 

depth

(ft)

1 N 47o 56’ 55” W 89o 49’ 28” 8/27/2003 9:50 16 15 1.0 --

2 N 47o 56’ 56” W 89o 49’ 27.5” 8/27/2003 10:06 23 22 1.0 1.7

3 N 47o 56’ 56.5” W 89o 49’ 27.5” 8/27/2003 10:15 21 18 2.0 4.5

4 N 47o 56’ 56” W 89o 49’ 26” 8/27/2003 10:25 21 19 4.0 2.5

5 N 47o 56’ 56” W 89o 49’ 23.5” 8/27/2003 10:36 20 17 2.2 1.4

6 N 47o 56’ 57” W 89o 49’ 23.5” 8/27/2003 10:47 21 19 2.0 4.2

7 N 47o 56’ 57.5” W 89o 49’ 22.5” 8/27/2003 10:54 23 21 2.0 4.3

8 N 47o 56’ 58” W 89o 49’ 22.5” 8/27/2003 11:08 23 19 3.0 3.2

9 N 47o 56’ 58.5” W 89o 49’ 23” 8/27/2003 11:18 23 21 2.5 3.5

10 N 47o 56’ 58.5” W 89o 49’ 23.5” 8/27/2003 11:27 23 15 2.0 4.6

11 N 47o 56’ 59” W 89o 49’ 24” 8/27/2003 11:43 24 21 2.0 4.8

12 N 47o 56’ 59” W 89o 49’ 25” 8/27/2003 11:55 25 21 2.0 4.9

13 N47o 56’ 59” W 89o 49’ 25.5” 8/27/2003 12:06 23 15 3.5 3.5

14 N 47o 56’ 59” W 89o 49’ 27” 8/27/2003 12:22 23 20 2.3 4.0

15 N 47o 56’ 59.5” W 89o 49’ 28” 8/27/2003 12:29 24 25 3.0 1.6

16 N 47o 56’ 59.5” W 89o 49’ 28.5” 8/27/2003 12:36 25 21 3.4 2.8

17 N 47o 56’ 59.5” W 89o 49’ 29.5” 8/27/2003 12:47 24 16 2.3 4.3

18 N 47o 57’ 0” W 89o 49’ 30” 8/27/2003 13:20 24 22 2.3 4.1

19 N 47o 57’ 00.5” W 89o 49’ 31” 8/27/2003 13:31 24 22 4.0 1.4

20 N 47o 57’ 00.5” W 89o 49’ 31.5” 8/27/2003 13:43 24 18 5.0 1.0

21 N 47o 57’ 00.0” W 89o 49’ 33.0” 8/27/2003 13:54 23 20 3.0 2.6

22 N 47o 57’ 00.5” W 89o 49’ 34” 8/27/2003 14:02 23 19 1.2 3.8

23 N 47o 57’ 01.5” W 89o 49’ 36.5” 8/27/2003 14:13 23 22 2.0 1.0

24 N 47o 57’ 01.5” W 89o 49’ 35.5” 8/27/2003 14:20 22 21 2.0 2.0

25 N 47o 57’ 01.5” W 89o 49’ 36.5” 8/27/2003 14:26 23 22 .2 2.2

26 N 47o 57’ 0.0” W 89o 49’ 35.5” 8/27/2003 14:34 24 19 2.5 3.8

27 N 47o 56’ 59.0” W 89o 49’ 35.0” 8/27/2003 14:45 23 18 2.0 4.2

28 N 47o 56’ 58.5” W 89o 49’ 34.5” 8/27/2003 14:56 23 17 3.4 2.6

29 N 47o 56’ 58.0” W 89o 49’ 34.0” 8/27/2003 15:06 22 18 2.0 4.0

30 N 47o 56’ 57.0” W 89o 49’ 33.5” 8/27/2003 15:17 23 19 3.0 3.2

Results of Analyses  17
temperatures were present in the northwest and west. These 

warmer temperatures ranged from 9 to 12 oC, falling into the 

range of measured surface-water temperatures (table 3).

Teal Lake

Surface-water temperatures varied from 14 to 22 oC 

(table 4). Because of poor weather conditions and limited 

time, no temperature measurements were made along the 

southeastern shore of Teal Lake (fig. 4). A total of 18 lakesediment temperature measurements were made along the 

lakeshore during September 2003, whereas one temperature 

measurement was made near the center of the lake and close 

to the surface-water sampling site (fig. 4). Lake-sediment 

temperatures along the shore of Teal Lake ranged from 4 to 

19 oC with all but one of the temperatures between 11 and 

19 oC (table 4). 

Statistical analysis of the lake-sediment temperature, 

probe depth into lake sediment, and lake-water depth data for 

Teal Lake implied that probe depth into lake sediment and 

lake-water depth were unlikely factors affecting the lakesediment temperature measurements at Teal Lake. Results 

from multiple regression analysis of the data indicated that 

no relation (p-value = 0.76) existed between lake-sediment 

temperature and probe depth into lake sediment and a weak 

relation (p-value = 0.08) existed between lake-sediment 

temperature and water depth of the lake. However, this weak 

relation was affected mainly by the data point with the coolest 

lake-sediment temperature (4 oC) measured at Teal Lake and 

was not existent when the single data point was removed from 

the regression analysis (p-value = 0.72). 

Lake-sediment temperatures between 4 to 14 oC occurred 

along the south, west, and northwest shores, and portions 

of the north shore of Teal Lake (fig. 4). Similar to the north 

Table 3. Temperature measurements made in surface water and lake sediment of North Lake, Grand Portage Reservation, northeastern Minnesota, August 2003 and May 2004.—Continued

[ft, feet; o C, degrees Celsius; --, no data]

Map 

number 

(fig. 3)

Latitude 

(degrees, 

minutes, 

seconds)

Longitude 

(degrees, minutes, 

seconds)

Date (month/

day/year)

Time 

(24-hour)

Surface-water temperature in North 

Lake (oC)

Lakesediment 

temperature

(oC)

Probe depth 

into lake 

sediment

(ft)

Water 

depth

(ft)

31 N 47o 56’ 56.5” W 89o 49’ 33.5” 8/27/2003 15:27 23 15 2.7 3.3

32 N 47o 56’ 55.5” W 89o 49’ 31.0” 8/27/2003 15:39 22 21 1.5 4.6

33 N 47o 56’ 56.0” W 89o 49’ 29.5” 8/27/2003 15:45 23 22 4.0 1.8

34 N 47o 56’ 56.0” W 89o 49’ 28.5” 8/27/2003 15:53 24 21 5.0 1.4

35 N 47o 56’ 55.0” W 89o 49’ 27.5” 8/27/2003 16:01 23 17 1.7 2.3

36 N 47o 57’ 1.0” W 89o 49’ 24” 5/18/2004 12:17 9 6 4.5 1.5

37 N 47o 57’ 2.0” W 89o 49’ 36” 5/18/2004 13:29 13 12 2.5 1.5

38 N 47o 57’ 1.0” W 89o 49’ 35” 5/18/2004 14:07 17 12 .5 1.0

39 N 47o 57’ 1.0” W 89o 49’ 33” 5/18/2004 14:53 14 9 .5 1.5

40 N 47o 57’ 1.0” W 89o 49’ 31” 5/18/2004 15:15 15 9 1.0 1.5

41 N 47o 57’ 2.0” W 89o 49’ 28” 5/18/2004 15:33 11 6 1.0 1.5

42 N 47o 57’ 1.0” W 89o 49’ 37” 5/19/2004 9:55 13 6 1.5 2.0

43 N 47o 56’ 59.0” W 89o 49’ 37” 5/19/2004 10:23 12 8 2.0 1.5

44 N 47o 56’ 58.0” W 89o 49’ 37” 5/19/2004 10:50 14 12 1.0 .5

45 N 47o 56’ 57.0” W 89o 49’ 37” 5/19/2004 11:10 14 7 1.5 1.0

46 N 47o 56’ 56.0” W 89o 49’ 38” 5/19/2004 11:50 15 7 1.5 2.0

47 N 47o 56’ 55.0” W 89o 49’ 27” 5/19/2004 13:37 13 6 2.0 2.0

48 N 47o 56’ 56.0” W 89o 49’ 24” 5/19/2004 14:09 11 7 1.0 1.0

49 N 47o 56’ 57.0” W 89o 49’ 21” 5/19/2004 14:35 11 6 1.0 2.0

50 N 47o 56’ 58.0” W 89o 49’ 21” 5/19/2004 15:00 11 6 1.5 2.5

18  Ground-Water/Surface-Water Interaction of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota
shore of North Lake, cool lake-sediment temperatures in the 

northwest and north were found in or near channels that ran 

through the fens and swamps surrounding Teal Lake. Beaver 

dens and activity were prevalent in these channels. The extent 

of these drainage channels were identified in the analyses of 

existing aerial photographs. A cool-temperature measurement 

along the west shore at site 16 was near a drainage channel 

found at a topographic low point in a northwest-trending diabase dike west of Teal Lake (fig. 4). A very cold lakesediment temperature (4 oC) was measured at site 19 in a 

drainage channel located along the south shore where an 

upwelling spring was present. This temperature was 8 degrees 

cooler than the second coolest temperature measured in lake 

sediment at Teal Lake (table 4) and may represent the low end 

member of the temperature-mixing range between lake and 

ground-water temperatures. Iron-oxide precipitates originating from an upgradient spring were present at the bottom of 

drainage channel upgradient from the upwelling spring. 

Warmer lake-sediment temperatures between 15 and 

19 oC were present in the northeast, southwest, and portions 

of the northwest shore of Teal Lake (fig. 4). This temperature 

range falls within the range of measured surface-water temperatures. The warmer temperatures in lake sediment of the 

northeast shore were located at or near a surface-water outflow 

channel (fig. 4). A warm temperature (17 oC) also was found 

for lake sediment near the center of the lake close to where 

surface-water samples were collected (fig. 4).

Taylor Lake

Surface-water temperatures ranged from 13 to 17 oC, with 

temperature differences between the surface water and lake 

sediment ranging only from 0 to 3 oC (table 5). A total 

Table 4. Temperature measurements made in surface water and lake sediment of Teal Lake, Grand Portage Reservation, northeastern 

Minnesota, September 2003.

[ft, feet; o C, degrees Celsius; --, no data]

Map number 

(fig. 4)

Latitude

(degrees, minutes, 

seconds)

Longitude

(degrees, minutes, 

seconds)

Date 

(month/

day/

year)

Time

(24-hour)

Surfacewater

temperature, 

in Teal Lake

(oC)

Lakesediment 

temperature

(oC)

Probe depth 

into lake 

sediment

(ft)

Water 

depth

(ft)

1 N 47o 59’ 29” W 89o 39’ 23” 9/3/2003 10:24 18 17 2.0 4.0

2 N 47o 59’ 34.5” W 89o 39’ 14.5” 9/3/2003 10:41 19 17 2.0 4.2

3 N 47o 59’ 36” W 89o 39’ 15.5” 9/3/2003 10:55 22 15 2.5 3.5

4 N 47o 59’ 35.5” W 89o 39’ 16” 9/3/2003 11:08 21 18 2.5 2.3

5 N 47o 59’ 35.5” W 89o 39’ 16.5” 9/3/2003 11:19 22 17 2.0 2.8

6 N 47o 59’ 36” W 89o 39’ 17.5” 9/3/2003 11:35 21 16 2.5 3.5

7 N 47o 59’ 32.5” W 89o 39’ 13.5” 9/3/2003 13:33 20 16 1.5 2.8

8 N 47o 59’ 30.5” W 89o 39’ 13.5” 9/3/2003 13:53 21 19 1.0 3.0

9 N 47o 59’ 38.5” W 89o 39’ 32” 9/3/2003 14:55 20 13 2.5 2.5

10 N 47o 59’ 38” W 89o 39’ 33” 9/4/2003 10:05 17 12 3.0 3.0

11 N 47o 59’ 38” W 89o 39’ 34.5” 9/4/2003 10:19 17 14 4.0 2.0

12 N 47o 59’ 38.5” W 89o 39’ 26.5” 9/4/2003 11:00 19 11 -- --

13 N 47o 59’ 37” W 89o 39’ 36.5” 9/4/2003 10:45 18 15 3.5 2.5

14 N 47o 59’ 35.5” W 89o 39’ 40.5” 9/4/2003 11:00 19 11 3.0 2.5

15 N 47o 59’ 32.5” W 89o 39’ 42.5” 9/4/2003 11:14 20 16 2.5 3.5

16 N 47o 59’ 30.5” W 89o 39’ 44” 9/4/2003 11:31 22 13 3.0 3

17 N 47o 59’ 24” W 89o 39’ 41.5” 9/4/2003 13:51 19 14 3.5 2.5

18 N 47o 59’ 21.5” W 89o 39’ 35.5” 9/4/2003 14:02 19 15 3.8 2.2

19 N 47o 59’ 19” W 89o 39’ 33.5” 9/4/2003 14:35 14 4 2.5 .1

Results of Analyses  19
Table 5. Temperature measurements made in surface water and lake sediment of Taylor Lake, Grand Portage Reservation, northeastern Minnesota, August and September 2004.

[ft, feet; o C, degrees Celsius; --, no data]

Map number 

(fig. 5)

Latitude

(degrees, minutes, 

seconds)

Longitude 

(degrees, minutes, 

seconds)

Date 

(month/

day/

year)

Time 

(24-hour)

Surfacewater 

temperature 

(oC)

Lakesediment 

temperature 

in Taylor 

Lake (oC)

Probe 

depth into 

lake 

sediment 

(ft)

Water 

depth

(ft)

1 N 47o 56’ 9.5” W 89o 50’ 0” 8/31/2004 11:00 16 16 1.0 2.0

2 N 47o 56’ 9” W 89o 50’ 1” 8/31/2004 11:15 14 14 1.0 1.5

3 N 47o 56’ 9” W 89o 50’ 0.5” 8/31/2004 11:25 14 13 .5 2.0

4 N 47o 56’ 9” W 89o 49’ 59.5” 8/31/2004 11:35 14 14 1.0 2.0

5 N 47o 56’ 9” W 89o 50’ 0” 8/31/2004 11:45 16 13 1.5 3.0

6 N 47o 56’ 9” W 89o 50’ 0.5” 8/31/2004 12:00 16 13 2.0 3.5

7 N 47o 56’ 7.5” W 89o 49’ 59.5” 8/31/2004 12:10 16 14 1.0 3.5

8 N 47o 56’ 8” W 89o 49’ 58.5” 8/31/2004 12:15 16 13 2.0 3.0

9 N 47o 56’ 3.5” W 89o 49’ 24” 8/31/2004 13:55 15 15 .3 3.0

10 N 47o 56’ 5” W 89o 49’ 56.5” 8/31/2004 14:20 15 15 .5 1.5

11 N 47o 56’ 7” W 89o 49’ 57.5” 9/1/2004 9:50 15 15 .5 1.5

12 N 47o 56’ 7.5” W 89o 49’ 57” 9/1/2004 10:00 15 15 .5 2.0

13 N 47o 56’ 5” W 89o 49’ 56.5” 9/1/2004 10:05 16 16 1.0 1.8

14 N 47o 56’ 5” W 89o 49’ 56” 9/1/2004 10:10 15 14 1.0 1.0

15 N 47o 56’ 5” W 89o 49’ 55.5” 9/1/2004 10:17 15 15 .5 1.0

16 N 47o 56’ 4.5” W 89o 49’ 55” 9/1/2004 10:23 15 15 .8 1.0

17 N 47o 56’ 3.5” W 89o 49’ 54.5” 9/1/2004 10:28 15 14 1.3 1.0

18 N 47o 56’ 2.5” W 89o 49’ 53” 9/1/2004 10:45 16 15 1.3 1.0

19 N 47o 56’ 2” W 89o 49’ 51” 9/1/2004 11:00 16 16 .5 2.0

20 N 47o 56’ 1” W 89o 49’ 49” 9/1/2004 11:05 16 16 1.5 1.5

21 N 47o 56’ 1” W 89o 49’ 48” 9/1/2004 11:15 13 12 1.0 1.0

22 N 47o 56’ 0” W 89o 49’ 46” 9/1/2004 13:00 16 15 .5 1.5

23 N 47o 56’ 1” W 89o 49’ 44.5” 9/1/2004 13:25 15 13 .8 .5

24 N 47o 56’ 1.5” W 89o 49’ 43.5” 9/1/2004 13:45 16 15 .3 .5

25 N 47o 56’ 2” W 89o 49’ 41.5” 9/1/2004 13:55 16 15 .5 .5

26 N 47o 56’ 1.5” W 89o 49’ 39” 9/1/2004 14:00 16 14 1.0 1.0

27 N 47o 56’ 2” W 89o 49’ 38.5” 9/1/2004 14:05 16 13 1.0 1.5

28 N 47o 56’ 2” W 89o 49’ 37” 9/1/2004 14:15 15 13 1.0 1.0

29 N 47o 56’ 2” W 89o 49’ 36.5” 9/1/2004 14:20 16 14 .5 .8

30 N 47o 56’ 2” W 89o 49’ 35” 9/1/2004 14:30 16 14 .5 1.0

20 Ground-Water/Surface-Water Interaction of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota
of 37 lake-sediment temperature measurements were made at 

Taylor Lake. Cooler-than-normal August 2004 air temperatures resulted in small temperature differences between surface 

water and lake sediment (fig. 5, table 5). Lake-sediment 

temperatures along the shore of Taylor Lake varied from 12 to 

16 oC. Because of this small range in temperature differences, 

it was more difficult to use lake-sediment temperatures to 

identify the location of ground-water inflow.

Statistical analysis of the lake-sediment temperature, 

probe depth into lake sediment, and lake-water depth data for 

Taylor Lake implied that probe depth into lake sediment and 

lake-water depth were unlikely factors affecting the lakesediment temperature measurements at Taylor Lake. Results 

from multiple regression analysis of the data indicated that no 

relation existed between lake-sediment temperature and water 

depth of the lake and that a relation (p-value = 0.01) existed 

between lake-sediment temperature and probe depth into lake 

sediment. However, this relation was affected mainly by two 

data points occurring at the deepest probe depth into lake 

sediment (2.0 ft) at Taylor Lake and was not existent when the 

two data points were removed from the regression analysis 

(p-value = 0.17). 

Lake sediment along large portions of the north, northeast, east, and southeast shores of Taylor Lake were impossible to penetrate with the hand-driven, thermometer probe 

because of the presence of impermeable bedrock at or near 

the lakebed. Where the probe could be used, it only could 

be inserted to relatively shallow depths at Taylor Lake. The 

lakeshore in these areas consists of submerged logs, boulders, 

gravels, and hard bedrock. Thermometer-probe penetration 

depths were much less at Taylor Lake than at North and Teal 

Lakes (tables 3, 4, and 5). 

Cooler lake-sediment temperatures at several locations 

were found downgradient from valleys and other topographic 

lows. Lake-sediment temperatures ranging from 12 to 14 oC 

were located in the northeast, east, southeast, portions of 

the south, and the far western shores of Taylor Lake (fig. 5). 

Upgradient from the northeast shore location is a lowland that 

trends to the northeast to a bog and wooded swamp, which 

may be sources of ground-water inflow (fig. 5). A steep valley 

also is located upgradient from the far west shore of Taylor 

Lake where lake-sediment temperatures range from 12 to 

14 oC (fig. 5). 

Lake-sediment temperatures between 14 and 16 oC were 

found along the south and southwest shores and portions of 

the north and east shores of Taylor Lake (fig. 5). Warmer 

lake-sediment temperatures (15 oC) in the south (site 22) were 

found near a beaver dam and channel where surface water 

discharges to a bog to the south (table 5; fig. 5). 

Surface-Water and Pore-Water Quality

Surface-water and pore-water quality differences were 

observed at Taylor and Teal Lakes, and to a lesser extent at 

North Lake. Differences were observed in onsite water-quality measurements and constituent concentrations. Some of 

these differences resulted from the presence of ground-water 

inflow, whereas others resulted from chemical reactions occurring in the surrounding fens and swamps. Specific conductance values for surface water ranged from 47 to 129 μS/cm 

(table 6), whereas values for pore water where ground-water 

inflow occurred ranged from 123 to 504 μS/cm. The low dissolved oxygen and high total ammonia plus organic nitrogen 

concentrations in most of the pore-water samples indicated 

that reducing conditions are present along the shores of the 

three lakes. 

Poor ionic balances (large percentage differences in cation and anion concentrations) were found in several poreTable 5. Temperature measurements made in surface water and lake sediment of Taylor Lake, Grand Portage Reservation, northeastern Minnesota, August and September 2004.—Continued

[ft, feet; o C, degrees Celsius; --, no data]

Map number 

(fig. 5)

Latitude

(degrees, minutes, 

seconds)

Longitude 

(degrees, minutes, 

seconds)

Date 

(month/

day/

year)

Time 

(24-hour)

Surfacewater 

temperature 

(oC)

Lakesediment 

temperature 

in Taylor 

Lake (oC)

Probe 

depth into 

lake 

sediment 

(ft)

Water 

depth

(ft)

31 N 47o 56’ 2.5” W 89o 49’ 34.5” 9/1/2004 14:40 16 14 1.0 0.8

32 N 47o 56’ 3” W 89o 49’ 26” 9/1/2004 14:55 17 14 1.0 1.0

33 N 47o 56’ 3” W 89o 49’ 24” 9/1/2004 15:00 15 13 .5 1.0

34 N 47o 56’ 7.5” W 89o 49’ 30.5” 9/2/2004 9:50 14 13 .5 .5

35 N 47o 56’ 8.5” W 89o 49’ 33” 9/2/2004 10:00 14 13 .5 .5

36 N 47o 56’ 8.5” W 89o 49’ 34.5” 9/2/2004 10:10 13 13 .5 1.0

37 N 47o 56’ 8” W 89o 49’ 36.5” 9/2/2004 10:15 16 16 1.0 1.5

Results of Analyses 21
Table 6. Water-quality data for surface water and pore water collected from North Lake area, August 2003 and May 2004, Teal Lake 

area, September 2003, and Taylor Lake area, August and September 2004, Grand Portage Reservation, northeastern Minnesota. 

[mm, millimeter; Hg, mercury; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; μg/L, micrograms per liter; 

oC, degrees Celsius; per mil, parts per thousand; <, less than; E, estimated; --, no data; values in blue, surface water; values in red, pore water]

Water-quality sampling site

(figs. 3–5) Site number

Date

(month/day/

year)

Time

(24-hour) Sample type

Barometric pressure (mm 

of Hg)

Specific 

conductance, 

onsite

(μS/cm at 

25 oC)

North Lake, August 2003

North Lake near Mineral Center 475658089492701 8/26/2003 11:00 Surface water 722 101

Southwest channel (SW) 475656089493301 8/26/2003 14:30 Pore water 722 163

Northwest shore (NW) 475700089493401 8/26/2003 16:00 Pore water 722 126

North shore (N) 475660089493001 8/27/2003 15:00 Pore water 727 124

South shore (S) 475655089492801 8/27/2003 10:30 Pore water 727 157

North Lake, May 2004

North Lake near Mineral Center 475658089492701 5/18/2004 11:30 Surface water 730 86

Southwest channel (SW) 475656089493301 5/19/2004 13:00 Pore water 730 162

South shore (S) 475655089492801 5/19/2004 12:00 Pore water 730 147

North-northwest shore (NNW) 475702089493602 5/18/2004 16:00 Pore water 730 132

Northeast shore (NE) 475701089492401 5/18/2004 12:30 Pore water 730 136

Southeast shore (SE) 475657089492201 5/19/2004 14:30 Pore water 728 79

Teal Lake, September 2003

Teal Lake near Grand Portage 475930089392301 9/3/2003 10:30 Surface water 736 129

Northeast shore (NE) 475935089391601 9/3/2003 12:30 Pore water 735 335

North shore (N) 475938089392601 9/4/2003 11:00 Pore water 744 53

Northwest shore (NW) 475935089394101 9/4/2003 12:30 Pore water 743 71

West shore (W) 475931089394401 9/4/2003 13:30 Pore water 743 73

Southwest shore (SW) 475924089394101 9/4/2003 14:30 Pore water 743 72

South-southwest (SSW) 475919089393301 9/4/2003 15:30 Pore water 743 504

Taylor Lake, August and September 2004

Taylor Lake - east near Mineral Center 475604089492901 8/31/2004 11:30 Surface water 722 47

Taylor Lake - west near Mineral Center 475605089494701 8/31/2004 12:30 Surface water 722 47

North-northeast shore (NNE) 475609089493201 9/1/2004 11:30 Pore water 728 61

Northeast shore (NE) 475609089493001 9/1/2004 10:30 Pore water 727 46

South shore (S) 475601089494801 9/1/2004 13:30 Pore water 728 211

North shore (N) 475608089493701 9/1/2004 12:00 Pore water 728 285

West shore (W) 475609089500001 9/1/2004 15:00 Pore water 728 245

Southeast shore (SE) 475602089493801 9/2/2004 12:30 Pore water 721 74

East shore (E) 475604089492201 9/2/2004 10:30 Pore water 722 123

22 Ground-Water/Surface-Water Interaction of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota
Table 6. Water-quality data for surface water and pore water collected from North Lake area, August 2003 and May 2004, Teal 

Lake area, September 2003, and Taylor Lake area, August and September 2004, Grand Portage Reservation, northeastern 

Minnesota.—Continued

[mm, millimeter; Hg, mercury; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; μg/L, micrograms per 

liter; oC, degrees Celsius; per mil, parts per thousand; <, less than; E, estimated; --, no data; values in blue, surface water; values in red, pore water]

Water-quality sampling site

(figs. 3–5)

Date

(month/

day/

year)

Sample type

Specific 

conductance, 

laboratory

(μS/cm at 25

oC)

pH, onsite

(standard 

units)

pH, laboratory

(standard 

units)

Air temperature 

(oC)

Water 

temperature (oC)

North Lake, August 2003

North Lake near Mineral Center 8/26/2003 Surface water 100 7.0 6.8 -- 21.9

Southwest channel (SW) 8/26/2003 Pore water 162 6.0 6.4 -- 17.7

Northwest shore (NW) 8/26/2003 Pore water 124 6.1 6.5 -- 22.9

North shore (N) 8/27/2003 Pore water 116 5.9 6.4 22.0 18.6

South shore (S) 8/27/2003 Pore water 152 5.6 6.4 21.5 18.6

North Lake, May 2004

North Lake near Mineral Center 5/18/2004 Surface water 94 6.9 6.7 15.0 11.8

Southwest channel (SW) 5/19/2004 Pore water 150 5.8 6.7 24.0 9.9

South shore (S) 5/19/2004 Pore water 137 5.4 6.0 24.5 10.6

North-northwest shore (NNW) 5/18/2004 Pore water 114 5.7 6.5 16.5 13.1

Northeast shore (NE) 5/18/2004 Pore water 139 5.5 6.4 17.0 8.0

Southeast shore (SE) 5/19/2004 Pore water 80 5.8 6.7 20.5 9.6

Teal Lake, September 2003

Teal Lake near Grand Portage 9/3/2003 Surface water 130 7.1 7.4 18.0 18.8

Northeast shore (NE) 9/3/2003 Pore water 309 5.6 6.9 -- 20.2

North shore (N) 9/4/2003 Pore water E 57 3.6 3.9 17.0 10.8

Northwest shore (NW) 9/4/2003 Pore water 75 3.9 4.2 18.0 13.7

West shore (W) 9/4/2003 Pore water 77 4.5 5.2 20.0 13.2

Southwest shore (SW) 9/4/2003 Pore water 71 5.3 5.8 20.0 14.1

South-southwest (SSW) 9/4/2003 Pore water 490 5.4 6.3 20.0 10.6

Taylor Lake, August and September 2004

Taylor Lake - east near Mineral Center 8/31/2004 Surface water 48 7.0 7.8 17.5 17.2

Taylor Lake - west near Mineral Center 8/31/2004 Surface water 49 7.3 7.9 17.5 17.1

North-northeast shore (NNE) 9/1/2004 Pore water 62 6.0 6.4 13.5 14.7

Northeast shore (NE) 9/1/2004 Pore water 49 6.4 6.6 13.0 15.1

South shore (S) 9/1/2004 Pore water 152 5.9 6.5 14.0 13.6

North shore (N) 9/1/2004 Pore water 270 5.9 6.3 15.5 16.2

West shore (W) 9/1/2004 Pore water 146 5.7 6.0 14.0 14.2

Southeast shore (SE) 9/2/2004 Pore water 63 6.2 6.3 16.5 14.1

East shore (E) 9/2/2004 Pore water 80 5.6 5.9 15.0 15.1

Results of Analyses 23
Table 6. Water-quality data for surface water and pore water collected from North Lake area, August 2003 and May 2004, Teal Lake 

area, September 2003, and Taylor Lake area, August and September 2004, Grand Portage Reservation, northeastern Minnesota.—

Continued

[mm, millimeter; Hg, mercury; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; μg/L, micrograms per liter; o C, 

degrees Celsius; per mil, parts per thousand; <, less than; E, estimated; --, no data; values in blue, surface water; values in red, pore water

Water-quality sampling site

(figs. 3–5)

Date

(month/day/

year)

Sample 

type

Dissolved 

oxygen 

(mg/L)

Dissolved 

oxygen 

(percent 

saturation)

Dissolved 

calcium 

(mg/L as Ca)

Dissolved 

magnesium 

(mg/L as Mg)

North Lake, August 2003

North Lake near Mineral Center 8/26/2003 Surface water 6.3 74 13.6 2.76

Southwest channel (SW) 8/26/2003 Pore water .2 3 21.6 4.43

Northwest shore (NW) 8/26/2003 Pore water .6 7 18.1 3.19

North shore (N) 8/27/2003 Pore water .4 4 15.4 3.12

South shore (S) 8/27/2003 Pore water .3 3 23.0 2.66

North Lake, May 2004

North Lake near Mineral Center 5/18/2004 Surface water 7.0 66 14.8 2.42

Southwest channel (SW) 5/19/2004 Pore water .3 2 24.6 4.89

South shore (S) 5/19/2004 Pore water .2 2 24.9 2.49

North-northwest shore (NNW) 5/18/2004 Pore water 5.4 52 19.5 3.62

Northeast shore (NE) 5/18/2004 Pore water .2 2 17.2 5.19

Southeast shore (SE) 5/19/2004 Pore water .2 1 12.3 2.24

Teal Lake, September 2003

Teal Lake near Grand Portage 9/3/2003 Surface water 8.5 94 10.1 4.46

Northeast shore (NE) 9/3/2003 Pore water .6 7 26.6 10.7

North shore (N) 9/4/2003 Pore water .3 3 2.39 1.27

Northwest shore (NW) 9/4/2003 Pore water .2 2 2.51 1.62

West shore (W) 9/4/2003 Pore water .2 2 5.76 2.32

Southwest shore (SW) 9/4/2003 Pore water 1.8 18 11.4 3.64

South-southwest (SSW) 9/4/2003 Pore water 2.1 19 30.4 11.7

Taylor Lake, August and September 2004

Taylor Lake - east near Mineral Center 8/31/2004 Surface water 8.8 95 6.55 1.46

Taylor Lake - west near Mineral Center 8/31/2004 Surface water 8.6 91 6.58 1.47

North-northeast shore (NNE) 9/1/2004 Pore water .8 8 8.80 2.20

Northeast shore (NE) 9/1/2004 Pore water 2.9 29 7.07 1.65

South shore (S) 9/1/2004 Pore water 1.8 17 16.2 4.50

North shore (N) 9/1/2004 Pore water .9 9 30.1 13.4

West shore (W) 9/1/2004 Pore water .3 3 24.5 4.80

Southeast shore (SE) 9/2/2004 Pore water 1.3 13 11.0 1.83

East shore (E) 9/2/2004 Pore water .2 2 12.0 2.69

24 Ground-Water/Surface-Water Interaction of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota
Table 6. Water-quality data for surface water and pore water collected from North Lake area, August 2003 and May 2004, Teal Lake 

area, September 2003, and Taylor Lake area, August and September 2004, Grand Portage Reservation, northeastern Minnesota.—

Continued

[mm, millimeter; Hg, mercury; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; μg/L, micrograms per liter; oC, 

degrees Celsius; per mil, parts per thousand; <, less than; E, estimated; --, no data; values in blue, surface water; values in red, pore water]

Water-quality sampling site

(figs. 3–5)

Date

(month/day/

year)

Sample 

type

Dissolved 

sodium 

(mg/L as 

Na)

Dissolved 

potassium (mg/L 

as K)

Bicarbonate, 

filtered 

water, onsite (mg/L 

as HCO3)

Alkalinity, 

filtered water, onsite 

(mg/L as 

CaCO3)

Dissolved 

sulfate 

(mg/L as 

SO4)

North Lake, August 2003

North Lake near Mineral Center 8/26/2003 Surface water 0.96 E 0.09 62 51 0.6

Southwest channel (SW) 8/26/2003 Pore water 1.32 .39 92 75 E .1

Northwest shore (NW) 8/26/2003 Pore water 1.00 .18 71 58 .2

North shore (N) 8/27/2003 Pore water 1.06 .24 67 55 .5

South shore (S) 8/27/2003 Pore water 1.15 .40 95 78 .2

North Lake, May 2004

North Lake near Mineral Center 5/18/2004 Surface water 1.17 < .16 54 44 2.5

Southwest channel (SW) 5/19/2004 Pore water 1.42 .22 93 76 1.4

South shore (S) 5/19/2004 Pore water 1.34 < .16 90 73 < .2

North-northwest shore (NNW) 5/18/2004 Pore water 1.45 < .16 78 64 < .2

Northeast shore (NE) 5/18/2004 Pore water 1.75 .19 86 71 < .2

Southeast shore (SE) 5/19/2004 Pore water 1.04 E.10 49 40 1.2

Teal Lake, September 2003

Teal Lake near Grand Portage 9/3/2003 Surface water 7.58 .84 28 23 3.6

Northeast shore (NE) 9/3/2003 Pore water 7.75 .97 171 140 .6

North shore (N) 9/4/2003 Pore water 1.03 E .16 0 0 .4

Northwest shore (NW) 9/4/2003 Pore water 3.12 .45 0 0 .3

West shore (W) 9/4/2003 Pore water 4.91 < .16 11 9 E .2

Southwest shore (SW) 9/4/2003 Pore water 2.28 .49 24 20 .7

South-southwest (SSW) 9/4/2003 Pore water 38.7 .65 40 33 2.0

Taylor Lake, August and September 2004

Taylor Lake - east near Mineral Center 8/31/2004 Surface water .71 E .12 27 22 .7

Taylor Lake - west near Mineral Center 8/31/2004 Surface water .65 .17 27 22 .7

North-northeast shore (NNE) 9/1/2004 Pore water .80 .20 34 28 .2

Northeast shore (NE) 9/1/2004 Pore water .68 E .12 27 22 .5

South shore (S) 9/1/2004 Pore water 1.32 .77 114 93 .3

North shore (N) 9/1/2004 Pore water 1.75 1.73 188 154 .2

West shore (W) 9/1/2004 Pore water .25 < .16 136 111 < .9

Southeast shore (SE) 9/2/2004 Pore water .77 .33 37 31 .31

East shore (E) 9/2/2004 Pore water 1.14 <.16 54 44 E .1

Results of Analyses 25
Table 6. Water-quality data for surface water and pore water collected from North Lake area, August 2003 and May 2004, Teal Lake 

area, September 2003, and Taylor Lake area, August and September 2004, Grand Portage Reservation, northeastern Minnesota.—

Continued

[mm, millimeter; Hg, mercury; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; μg/L, micrograms per liter; o C, 

degrees Celsius; per mil, parts per thousand; <, less than; E, estimated; --, no data; values in blue, surface water; values in red, pore water]

Water-quality sampling site

(figs. 3–5)

Date

(month/day/

year)

Sample 

type

Dissolved 

chloride (mg/L 

as Cl)

Dissolved 

fluoride (mg/L 

as F)

Dissolved 

bromide (μg/L 

as Br)

Dissolved 

silica (mg/L as 

SiO2)

North Lake, August 2003

North Lake near Mineral Center 8/26/2003 Surface water E 0.12 < 0.2 -- 7.02

Southwest channel (SW) 8/26/2003 Pore water .43 < .2 -- 22.6

Northwest shore (NW) 8/26/2003 Pore water E .15 < .2 -- 23.3

North shore (N) 8/27/2003 Pore water E .19 < .2 -- 17.3

South shore (S) 8/27/2003 Pore water .35 < .2 -- 27.9

North Lake, May 2004

North Lake near Mineral Center 5/18/2004 Surface water .25 < .2 -- 6.16

Southwest channel (SW) 5/19/2004 Pore water .48 < .2 0.03 13.9

South shore (S) 5/19/2004 Pore water E .12 < .2 .05 19.4

North-northwest shore (NNW) 5/18/2004 Pore water .65 < .2 .37 16.3

Northeast shore (NE) 5/18/2004 Pore water .22 < .2 .02 31.3

Southeast shore (SE) 5/19/2004 Pore water E .12 < .2 < .02 10.4

Teal Lake, September 2003

Teal Lake near Grand Portage 9/3/2003 Surface water 19.6 < .2 -- .74 

Northeast shore (NE) 9/3/2003 Pore water 14.6 < .2 E .12 44.4

North shore (N) 9/4/2003 Pore water .89 < .2 E .38 16.8

Northwest shore (NW) 9/4/2003 Pore water 12.3 < .2 -- 3.89

West shore (W) 9/4/2003 Pore water 12.1 < .2 -- 4.74

Southwest shore (SW) 9/4/2003 Pore water 4.50 < .2 E .17 8.09

South-southwest (SSW) 9/4/2003 Pore water 125 < .2 -- 15.0

Taylor Lake, August and September 2004

Taylor Lake - east near Mineral Center 8/31/2004 Surface water < .20 < .2 -- .93

Taylor Lake - west near Mineral Center 8/31/2004 Surface water E .10 < .2 -- .92

North-northeast shore (NNE) 9/1/2004 Pore water < .20 < .2 .08 2.80

Northeast shore (NE) 9/1/2004 Pore water < .20 < .2 < .02 1.89

South shore (S) 9/1/2004 Pore water .67 < .2 .49 19.0

North shore (N) 9/1/2004 Pore water .36 < .2 < .80 29.2

West shore (W) 9/1/2004 Pore water < .20 < .2 .73 27.3

Southeast shore (SE) 9/2/2004 Pore water .26 < .2 .08 3.30

East shore (E) 9/2/2004 Pore water E .16 < .2 .35 5.82

26  Ground-Water/Surface-Water Interaction of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota
Table 6. Water-quality data for surface water and pore water collected from North Lake area, August 2003 and May 2004, Teal Lake 

area, September 2003, and Taylor Lake area, August and September 2004, Grand Portage Reservation, northeastern Minnesota.—

Continued

[mm, millimeter; Hg, mercury; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; μg/L, micrograms per liter; 

oC, degrees Celsius; per mil, parts per thousand; <, less than; E, estimated; --, no data; values in blue, surface water; values in red, pore water]

Water-quality sampling site

(figs. 3–5)

Date

(month/day/

year)

Sample 

type

Dissolved 

nitrite 

nitrogen 

(mg/L as N)

Dissolved 

nitrite and 

nitrate 

nitrogen 

(mg/L as N)

Dissolved 

ammonia 

nitrogen 

(mg/L as 

N)

Total ammonia plus 

organic 

nitrogen 

(mg/L as N)

Dissolved 

organic 

nitrogen 

(mg/L as 

N)1

North Lake, August 2003

North Lake near Mineral Center 8/26/2003 Surface water < 0.008 < 0.06 < 0.04 0.65 10.65

Southwest channel (SW) 8/26/2003 Pore water < .008 < .06 2.48 2.9 1.41

Northwest shore (NW) 8/26/2003 Pore water < .008 < .06 1.05 1.5 1.48

North shore (N) 8/27/2003 Pore water < .008 < .06 1.95 2.6 1.61

South shore (S) 8/27/2003 Pore water < .008 < .06 2.76 3.4 1.59

North Lake, May 2004

North Lake near Mineral Center 5/18/2004 Surface water < .008 < .06 E .02 1.31 1.29

Southwest channel (SW) 5/19/2004 Pore water < .008 < .06 .24 1.52 1.28

South shore (S) 5/19/2004 Pore water < .008 < .06 .76 11.2 14.39

North-northwest shore (NNW) 5/18/2004 Pore water < .008 < .06 .12 11.0 1.92

Northeast shore (NE) 5/18/2004 Pore water < .008 < .06 2.19 12.4 1.24

Southeast shore (SE) 5/19/2004 Pore water < .008 <.06 .12 1.32 1.20

Teal Lake, September 2003

Teal Lake near Grand Portage 9/3/2003 Surface water < .008 < .06 < .04 .76 1.76

Northeast shore (NE) 9/3/2003 Pore water < .008 < .06 8.85 11 12.2

North shore (N) 9/4/2003 Pore water .018 < .12 1.05 2.2 11.1

Northwest shore (NW) 9/4/2003 Pore water E .005 < .06 .84 1.5 1.66

West shore (W) 9/4/2003 Pore water E .005 < .06 .06 .66 1.60

Southwest shore (SW) 9/4/2003 Pore water E .015 < .12 .97 2.1 11.2

South-southwest (SSW) 9/4/2003 Pore water < .008 < .06 1.16 1.8 1.59

Taylor Lake, August and September 2004

Taylor Lake - east near Mineral Center 8/31/2004 Surface water < .008 < .06 < .04 .33 1.33

Taylor Lake - west near Mineral Center 8/31/2004 Surface water < .008 < .06 < .05 .33 1.33

North-northeast shore (NNE) 9/1/2004 Pore water < .008 < .06 < .06 1.50 1.44

Northeast shore (NE) 9/1/2004 Pore water < .008 < .06 < .07 1.43 1.41

South shore (S) 9/1/2004 Pore water .012 < .06 < .08 14.4 1.44

North shore (N) 9/1/2004 Pore water < .008 < .06 < .09 13.0 .62

West shore (W) 9/1/2004 Pore water E .004 < .06 < .10 1.82 1.82

Southeast shore (SE) 9/2/2004 Pore water < .008 < .06 < .11 1.70 1.48

East shore (E) 9/2/2004 Pore water .01 < .06 < .12 11.2 1.95

Results of Analyses 27
Table 6. Water-quality data for surface water and pore water collected from North Lake area, August 2003 and May 2004, Teal Lake 

area, September 2003, and Taylor Lake area, August and September 2004, Grand Portage Reservation, northeastern Minnesota.—

Continued

[mm, millimeter; Hg, mercury; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; μg/L, micrograms per liter; 

o C, degrees Celsius; per mil, parts per thousand; <, less than; E, estimated; --, no data; values in blue, surface water; values in red, pore water]

Water-quality sampling site

(figs. 3–5)

Date

(month/day/

year)

Sample 

type

Total nitrogen 

(mg/L as N)

Total phosphorus (mg/L as P)

Dissolved 

phosphate 

(mg/L as P)

Dissolved 

orthophosphorus 

(mg/L as P)

North Lake, August 2003

North Lake near Mineral Center 8/26/2003 Surface water 10.65 0.012 E 0.004 < 0.02

Southwest channel (SW) 8/26/2003 Pore water 12.89 -- .099 .07

Northwest shore (NW) 8/26/2003 Pore water 11.53 -- .018 E .01

North shore (N) 8/27/2003 Pore water 12.56 -- .211 .19

South shore (S) 8/27/2003 Pore water 13.35 -- .240 .21

North Lake, May 2004

North Lake near Mineral Center 5/18/2004 Surface water 1.31 .007 E .003 < .02

Southwest channel (SW) 5/19/2004 Pore water .52 -- .021 .02

South shore (S) 5/19/2004 Pore water 1.2 -- .027 .02

North-northwest shore (NNW) 5/18/2004 Pore water 1.0 -- .027 .01

Northeast shore (NE) 5/18/2004 Pore water 2.4 -- .123 .11

Southeast shore (SE) 5/19/2004 Pore water .32 -- .004 < .02

Teal Lake, September 2003

Teal Lake near Grand Portage 9/3/2003 Surface water 1.76 .010 E .003 < .02

Northeast shore (NE) 9/3/2003 Pore water 111.0 -- .802 .79

North shore (N) 9/4/2003 Pore water 12.18 -- .148 .12

Northwest shore (NW) 9/4/2003 Pore water 11.51 -- .099 .08

West shore (W) 9/4/2003 Pore water 1.67 -- .029 .02

Southwest shore (SW) 9/4/2003 Pore water 12.14 -- .145 .12

South-southwest (SSW) 9/4/2003 Pore water 11.75 -- .051 .04

Taylor Lake, August and September 2004

Taylor Lake - east near Mineral Center 8/31/2004 Surface water 1.33 .011 .005 <.02

Taylor Lake - west near Mineral Center 8/31/2004 Surface water 1.33 .010 E .003 <.02

North-northeast shore (NNE) 9/1/2004 Pore water .50 -- .015 .01

Northeast shore (NE) 9/1/2004 Pore water .43 -- .010 < .02

South shore (S) 9/1/2004 Pore water 4.42 -- .323 .40

North shore (N) 9/1/2004 Pore water 2.97 -- .521 .02

West shore (W) 9/1/2004 Pore water .82 -- .045 .04

Southeast shore (SE) 9/2/2004 Pore water .70 -- .053 .04

East shore (E) 9/2/2004 Pore water 1.20 -- .099 .08

28  Ground-Water/Surface-Water Interaction of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota
Table 6. Water-quality data for surface water and pore water collected from North Lake area, August 2003 and May 2004, Teal Lake 

area, September 2003, and Taylor Lake area, August and September 2004, Grand Portage Reservation, northeastern Minnesota.—

Continued

[mm, millimeter; Hg, mercury; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; μg/L, micrograms per liter; o C, 

degrees Celsius; per mil, parts per thousand; <, less than; E, estimated; --, no data; values in blue, surface water; values in red, pore water]

Water-quality sampling site

(figs. 3–5)

Date

(month/

day/year)

Sample type

Dissolved 

boron 

(μg/L as B)

Dissolved 

iron 

(μg/L as 

Fe)

Dissolved 

manganese 

(μg/L as 

Mn)

Ionic 

balance 

(percentage 

difference)2

Oxygen-18/ 

oxygen-

16 ratio, 

unfiltered 

water, 

per mil

Deuterium/

protium 

ratio, 

unfiltered 

water, 

per mil

North Lake, August 2003

North Lake near Mineral Center 8/26/2003 Surface water 9.6 100 1.50 -3.9 -7.22 -62.10

Southwest channel (SW) 8/26/2003 Pore water 16 1,030 27.5 1.7 -9.31 -72.20

Northwest shore (NW) 8/26/2003 Pore water 16 931 33.0 4.2 -7.88 -66.10

North shore (N) 8/27/2003 Pore water 15 951 20.9 .9 -7.56 -63.20

South shore (S) 8/27/2003 Pore water 24 1,580 49.8 -1.9 -8.95 -70.90

North Lake, May 2004

North Lake near Mineral Center 5/18/2004 Surface water E 6.3 32 E .7 2.7 -11.12 -80.80

Southwest channel (SW) 5/19/2004 Pore water E 5.2 581 30.6 5.2 -9.58 -73.10

South shore (S) 5/19/2004 Pore water 7.5 1,040 65.1 3.5 -8.79 -67.40

North-northwest shore (NNW) 5/18/2004 Pore water < 7.0 11,800 638 21.1 -8.16 -67.90

Northeast shore (NE) 5/18/2004 Pore water 14 636 20.9 -.8 -10.75 -77.60

Southeast shore (SE) 5/19/2004 Pore water E 5.7 329 5.4 2.2 -12.14 -84.80

Teal Lake, September 2003

Teal Lake near Grand Portage 9/3/2003 Surface water 11 43 < .4 5.9 -5.01 -50.3

Northeast shore (NE) 9/3/2003 Pore water 18 2,480 63.0 -8.6 -8.44 -68.5

North shore (N) 9/4/2003 Pore water E 5.6 563 5.9 80 -11.02 -72.2

Northwest shore (NW) 9/4/2003 Pore water 7.5 483 13.0 9.9 -8.48 -63.9

West shore (W) 9/4/2003 Pore water E 6.6 186 2.3 15 -7.25 -59.8

Southwest shore (SW) 9/4/2003 Pore water E 6.5 319 3.7 30 -9.97 -70

South-southwest (SSW) 9/4/2003 Pore water 15 1,400 34.5 .4 -11.31 -78.2

Taylor Lake, August and September 2004

Taylor Lake - east near Mineral Center 8/31/2004 Surface water E 5.6 46 < .8 2.5 -5.82 -57.80

Taylor Lake - west near Mineral Center 8/31/2004 Surface water E 5.8 38 < .8 2.6 -5.92 -57.40

North-northeast shore (NNE) 9/1/2004 Pore water E 4.0 1,930 94.2 16 -6.01 -58.00

Northeast shore (NE) 9/1/2004 Pore water E 4.8 303 41.4 8.7 -6.02 -58.40

South shore (S) 9/1/2004 Pore water < 21 17,600 287 8.1 -8.12 -67.00

North shore (N) 9/1/2004 Pore water < 35 31,200 541 18 -7.10 -61.70

West shore (W) 9/1/2004 Pore water < 7.0 35,400 345 23 -6.84 -62.30

Southeast shore (SE) 9/2/2004 Pore water E 5.7 1,240 95.3 13 -6.30 -59.10

East shore (E) 9/2/2004 Pore water E 4.5 9,430 130 22 -6.50 -60.10

1

Estimated from the concentrations of other nitrogen constituents.

2

Represents percentage difference between total cation and total anion concentrations.

Results of Analyses 29
water samples from the North, Teal, and Taylor Lake areas 

(table 6). These poor ionic balances were all positive, indicating that the total cation concentrations were greater than the 

total anion concentrations. These high percentage differences 

indicate that either the samples were not in equilibrium during 

sampling, biases occurred during analysis, or anions that are 

major contributors to the overall major constituent chemistry 

of the water were not measured. For some of the pore-water 

samples with poor ionic balances, dissolved oxygen concentrations were relatively high, indicating that some water from the 

lake may have been drawn into the sampling tube during sample collection. The mixing of drawn-in surface water and pore 

water in the sampled water could result in a state of chemical 

disequilibrium in the sample, potentially causing problems 

with the ionic balance. The smell of hydrogen sulfide gas was 

noted during the collection of some pore-water samples at the 

three lakes. The loss of sulfate ions in the water because of 

the production of hydrogen sulfide gas and other non-gaseous, 

sulfide complexes could be responsible for poor ionic balances 

in the water samples. Concentrations of hydrogen sulfide gas 

and non-gaseous, sulfide complexes were not measured onsite 

or in the collected water samples. 

North Lake

One surface-water sample and four pore-water samples 

were collected in August 2003, and one surface-water sample 

and five pore-water samples were collected in May 2004 at 

North Lake (table 6). The surface-water samples were collected in the east-central part of the lake, whereas pore-water 

samples were collected at various locations along the shore 

(fig. 3). Most of the pore-water samples were collected near 

locations where cooler lake-sediment temperatures were 

measured.

Specific conductance values for the surface- and porewater samples from the North Lake area were all less than 

200 μS/cm (table 6). Specific conductance values for the 

southwest channel and south shore pore-water samples collected in August 2003 and May 2004 were the highest of all 

of the samples collected. The higher pH values for surface 

water may be caused by chemical reactions and biological 

activity in the lake. pH values for the pore water were within 

the pH range for water in Picea mariana (black spruce) stands 

of northwestern Minnesota alkaline peatlands (Bares and 

Wali, 1979). Water temperatures of pore water sampled in 

August 2003 and May 2004 were all cooler than the surfacewater samples, except for pore-water temperatures from the 

northwest and north-northwest shores, which were similar 

to temperature data collected for North Lake surface water. 

Surface water in North Lake generally had lower specific 

conductance values, higher onsite pH values, and higher dissolved oxygen concentrations than pore water collected from 

the area (table 6). The dissolved oxygen concentrations for the 

pore-water samples were all less than 0.7 mg/L, except for the 

pore-water sample collected from the north-northwest shore in 

May 2004. The water temperature and dissolved oxygen concentration for the north-northwest pore-water sample collected 

in May 2004 were much higher than the other pore-water 

samples collected in May 2004 (table 6). 

Surface-water alkalinity and bicarbonate values were less 

than most pore-water values, with the exception of the porewater sample from the southeast shore collected in May 2004. 

Specific conductance, alkalinity, and bicarbonate values for 

the southeast shore pore-water sample were slightly less than 

the surface-water values. However, pH values and dissolved 

oxygen concentrations for the southeast shore pore-water 

sample were much less than surface-water values and concentrations (table 6). Alkalinity and bicarbonate values for the 

pore-water samples collected from the northwest and north 

shores in August 2004 were only slightly more than values for 

the surface-water sample, with low dissolved oxygen concentrations (table 6).

Total nitrogen and dissolved phosphorus concentrations 

in surface water were less than in pore-water samples, with 

notable variability in nitrogen concentrations among the porewater samples (table 6). Measurable concentrations of total 

nitrogen in surface water consisted only of dissolved organic 

nitrogen, whereas total nitrogen in pore water consisted of 

total ammonia plus organic nitrogen. Total ammonia plus 

organic nitrogen concentrations were greater than 1.0 mg/L 

for all of the pore-water samples collected in August 2003 

(table 6), indicating reduced conditions in the lake sediment. 

In May 2004, total ammonia plus organic nitrogen concentrations were greater in pore-water samples from the south and 

northeast shores than in the other pore-water samples (table 6). 

Total nitrogen and ammonia plus nitrogen concentrations were 

less than 0.60 mg/L as nitrogen for the southwest channel and 

southeast shore pore-water samples collected in May 2004, 

which is equal to or less than one-half of the total nitrogen 

concentrations in the other pore-water samples (table 6). In 

August 2003, the total nitrogen concentration in southwest 

channel pore water was higher, 2.9 mg/L as nitrogen. In 

general, total nitrogen and phosphorus concentrations in 

pore-water samples collected in May 2004 were less than in 

pore-water samples collected in August 2003. This decrease 

in concentrations is likely because of the flushing of spring 

snowmelt water through the lake sediment. 

The percentage differences between the total cation and 

anion concentrations for the surface-water and pore-water 

samples from the North Lake area were between -5 and 

+5 percent for the surface-water samples and for eight of 

the nine pore-water samples (table 6). The difference in the 

ionic balance for the May 2004 pore-water sample collected 

from the north-northwest shore was +21.1 percent, with the 

positive difference indicating higher total cation concentration than total anion concentration. A sulfate concentration 

below the detection level and a strong hydrogen-sulfide smell 

during sampling indicate an underestimate of the total sulfur 

concentration, resulting in the highly positive ionic balance 

difference. The total sulfur concentrations may include 

sulfate, hydrogen sulfide gas, and other non-gaseous, sulfide complexes. The small difference between onsite and 

30 Ground-Water/Surface-Water Interaction of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota
laboratory specific conductance values for the north-northwest 

pore-water sample (table 6) indicates that the sampled water 

may have been in chemical disequilibrium when sampled and 

that changes in the dissolved major constituent concentrations 

could have occurred between the time of onsite water-quality 

measurement and sample collection and (or) analysis. At surface-water outseepage locations, chemical disequilibrium may 

be a common occurrence as oxygenated surface water seeps 

into low-oxygenated pore water.

Differences in major constituent concentrations were 

small between the surface water and pore water in the North 

Lake area relative to differences observed in the Teal and Taylor Lake areas (figs. 7 and 8, table 6). Both the surface water 

and pore water in the North Lake area are a predominantly 

calcium bicarbonate type, with large calcium and bicarbonate 

concentrations in most of the pore-water samples (figs. 7 and 

8). The only exception was the pore-water sample collected 

along the southeast shore in May 2004. The calcium and 

bicarbonate concentrations in this sample were less than in the 

surface-water samples for both August 2003 and May 2004 

(table 6). Calcium concentrations in the pore water ranged 

from 12 to 25 mg/L as calcium, with concentrations of 14 and 

15 mg/L as calcium in the surface water. Pore water from the 

south shore and southwest channel sampled in August 2003 

and May 2004 had the highest calcium and bicarbonate concentrations and indicates potential locations for ground-water 

inflow (fig. 8). Pore water from the northwest shore sampled 

in August 2003 and from the north-northwest shore sampled 

in May 2004 was only slightly higher in calcium and bicarbonate concentrations than the surface water (fig. 8, table 6). 

The distribution of cation and anion concentrations in the 

surface-water sample for North Lake (fig. 8) was very similar 

to the distribution for surface-water samples from Swamp 

Lake (fig. 1) collected by Winterstein (2000) and presented in 

Winterstein (2002).

Dissolved chloride concentrations were less than 

0.7 mg/L for all of the surface-water and pore-water samples 

(table 6). The low specific conductance values and chloride 

concentrations of the pore water indicated that the residence 

time of the water likely is small or that the parent materials are 

highly resistant to dissolution, with the lake water obtained 

from local sources. 

Dissolved silica, iron, and manganese concentrations 

were higher in all of the pore-water samples than in the surface-water samples from the North Lake area, being notably 

higher in the south pore-water samples collected in August 

2003 and May 2004 and the north-northwest pore-water 

sample collected in May 2004 (table 6). Dissolved silica 

concentrations ranged from 6.2 to 7.0 mg/L in the two surfacewater samples and from 10 to 31 mg/L in pore water. In seven 

of the nine pore-water samples, both dissolved iron and manganese concentrations were an order of magnitude higher than 

concentrations in the surface-water samples (table 6). Similar 

to total nitrogen and phosphorus concentrations, dissolved 

boron concentrations in the pore-water samples were lower in 

May 2004 than in pore-water samples in August 2003, with 

concentrations in the August 2003 pore-water samples higher 

than in the surface-water sample. The flushing of spring 

snowmelt water through the lake sediment is the likely cause 

for these concentration reductions. 

Oxygen-18/oxygen-16 and deuterium/protium ratios 

for surface-water and pore-water samples collected in the 

North Lake area in August 2003 and May 2004 lie along an 

evaporation line with a slope of 4.6 and a y-intercept of -29.4 

(fig. 6B). For the August 2003 samples, the most evaporative 

signature was for the surface-water sample collected at North 

Lake because the oxygen-18/oxygen-16 and deuterium/protium ratios lie the farthest from the meteoric waterline relative 

to other samples (fig. 6B). This is to be expected because 

evaporation rates are high off the lake surface in the summer, 

increasing the stable isotope ratios over time. In May 2004, 

the surface water had an isotopic composition that plotted 

close to the meteoric waterline (fig. 6B), along a portion of 

the line where late winter and early spring precipitation from 

northern Wisconsin plotted (Krabbenhoft and others, 1994). 

Snowmelt water that entered the lake in late April and early 

May likely had lower oxygen-18/oxygen-16 and deuterium/

protium ratios and was a major contributor to the spring water 

budget of the small, shallow lake. The isotopic ratios for the 

August 2003 and May 2004 pore-water samples collected 

along the north and northeast shores, respectively, were similar 

to the ratios for the August 2003 and May 2004 surface-water 

samples, respectively (fig. 6B), potentially indicating surfacewater outseepage at those locations.

The least evaporative signature for the August 2003 samples is for the southwest channel sample, falling closer to the 

meteoric waterline than the other pore-water samples (fig. 6B). 

However, the oxygen-18/oxygen-16 and deuterium/protium 

ratios for this sample do not fall along the meteoric waterline, 

indicating that some evaporation, probably from an upgradient 

wetland or lake, affected the water contributed to the lake at 

that location. The stable isotope ratios for samples collected 

in August 2003 and May 2004 at the southwest channel are 

very similar, indicating a relatively constant isotopic composition over time (fig. 6B). This temporal conservative nature 

also can be seen in the south, northwest, and north-northwest 

pore-water samples, but these samples have a more evaporative signature than the southwest channel sample (fig. 6B). 

Teal Lake

One surface-water sample and six pore-water samples 

were collected in September 2003 from the Teal Lake area 

(table 6). The surface-water sample was collected just east 

of the center of the lake, and pore-water samples were collected at various locations along the shore (fig. 4). Pore-water 

samples collected along the northwest, west, southwest, and 

south-southwest shores were located at or near drainage channels identified in the analyses of existing aerial photographs 

(fig. 4). No pore-water samples were collected along the 

southeast shore of Teal Lake because no lake-sediment temperature data were collected along that part of the lakeshore.

Results of Analyses 31
PERCENT

CALCIUM

100

80

60

40

20

0

0

40

20

60

80

100

MAGNESIUM

0

20

40

60

80

100

SODIUM PLUS POTASSIUM

SODIUM PLUS POTASSIUM

CHLORIDE, FLUORIDE,

NITRITE PLUS NITRATE

CHLORIDE, FLUORIDE,

NITRITE PLUS NITRATE

0

0

20

10

40

60

80

100

100

100

80

90

60

40

20

0

CARBONATE PLUS BICARBONATE

CARBONATE PLUS

BICARBONATE

100

80

60

40

20

0

SULFATE

0

0

20

20

10

40

60

80

100

SULFATE PLUS CHLORIDE

SULFATE PLUS CHLORIDE

0

0

20

20

10

40

60

80

100

CALCIUM PLUS MAGNESIUM

100

80

60

40

20

0

100

80

60

40

20

P

0

ERCENT

PERCENT

NE

S

(A) North Lake, August 2003 and May 2004

Surface water (lake), August 2003

Pore water, August 2003

Surface water (lake), May 2004

Pore water, May 2004

(Letters are site identifers; table 6)

EXPLANATION

Figure 7. Percentage distribution of major ion concentrations determined for surface water and pore water sampled from (A) North 

Lake, August 2003 and May 2004, (B) Teal Lake, September 2003, and Taylor Lake, August and September 2004, Grand Portage 

Reservation, northeastern Minnesota.

32 Ground-Water/Surface-Water Interaction of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota
(B) Teal Lake, September 2003, and Taylor Lake, August and September 2004

PERCENT

CALCIUM

100

80

60

40

20

0

0

20

40

60

80

100

MAGNESIUM

0

20

40

60

80

100

SODIUM PLUS POTASSIUM

CHLORIDE, FLUORIDE,

NITRITE PLUS NITRATE

0

20

40

60

80

100

100

80

60

40

20

0

CARBONATE PLUS BICARBONATE

100

80

60

40

20

0

SULFATE

0

20

40

60

80

100

SULFATE PLUS CHLORIDE

0

20

40

60

80

100

CALCIUM PLUS MAGNESIUM

100

80

60

40

20

0

100

80

60

40

20

P

0

ERCENT

PERCEN

NE T

SW

W

NW

SSW

N

NE SW W

SSW

NW

N

SSW

NW

W

N

SW

NE

N

S

W

SE

Teal Lake surface water

Teal Lake pore water

Taylor Lake surface water

Taylor Lake pore water

(Letters are site identifiers; table 6)

EXPLANATION

CHLORIDE, FLUORIDE,

NITRITE PLUS NITRATE

CARBONATE PLUS

BICARBONATE

0

10

100

90

SODIUM PLUS POTASSIUM

0

20

10

SULFATE PLUS CHLORIDE

0

20

10

Figure 7. Percentage distribution of major ion concentrations determined for surface water and pore water sampled from (A) North 

Lake, August 2003 and May 2004, (B) Teal Lake, September 2003, and Taylor Lake, August and September 2004, Grand Portage 

Reservation, northeastern Minnesota.—Continued

Results of Analyses 33
Figure 8. Concentrations of cations and anions in surface water and pore water sampled from (A) North Lake, August 2003, 

(B) North Lake, May 2004, (C) Teal Lake, September 2003, and (D) Taylor Lake, August and September 2004, Grand Portage 

Reservation, northeastern Minnesota.

Milliequivalents per liter

2 1 0 1 2

Milliequivalents per liter

4 2 0 2 4

Milliequivalents per liter

2 1 0 1 2

Milliequivalents per liter

4 2 0 2 4

North Lake near Mineral Center

Southwest channel into North Lake

Northwest shore of North Lake

North shore of North Lake

South shore of North Lake

EXPLANATION EXPLANATION

EXPLANATION EXPLANATION

Sodium potassium

Magnesium

Calcium Carbonate plus bicarbonate

Chloride

Sulfate

North Lake near Mineral Center

Southeast shore of North Lake

Southwest channel into North Lake

North-northwest shore of North Lake

Northeast shore of North Lake

South shore of North Lake

Teal Lake near Grand Portage

Northeast shore of Teal Lake

North shore of Teal Lake

Northwest shore of Teal Lake

West shore of Teal Lake

Southwest shore of Teal Lake

South-southwest shore of Teal Lake

Taylor Lake - east near Mineral Center

Taylor Lake - west near Mineral Center

North-northeast shore of Taylor Lake

Northeast shore of Taylor Lake

South shore of Taylor Lake

North shore of Taylor Lake

West shore of Taylor Lake

Southeast shore of Taylor Lake

East shore of Taylor Lake

Sodium potassium

Magnesium

Calcium Carbonate plus bicarbonate Chloride

Sulfate

Sodium potassium

Magnesium

Calcium Carbonate plus bicarbonate

Chloride

Sulfate

Sodium potassium

Magnesium

Calcium Carbonate plus bicarbonate

Chloride

Sulfate

(A) North Lake, August 2003 (B) North Lake, May 2004

(C) Teal Lake, September 2003 (D) Taylor Lake, August and September 2004

Blue - Surface water

Red - Pore water

EXPLANATION

34 Ground-Water/Surface-Water Interaction of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota
The specific conductance value for the surface-water 

sample was 129 μS/cm. Specific conductance values for the 

pore-water samples ranged widely from 53 to 504 μS/cm 

(table 6). The lowest values occurred in pore-water samples 

from along the north, northwest, west, and southwest shores, 

with all of the values less than 75 μS/cm. Alkalinity values for 

these four samples were less than 21 mg/L as calcium carbonate. The highest specific conductance values occurred in the 

northeast and south-southwest pore-water samples, with values 

of 335 and 504 μS/cm, respectively. 

The pH values for the pore-water samples were lower 

than the surface-water value for Teal Lake. The pH for the 

surface-water sample from Teal Lake (7.1 standard units) 

was similar to the surface-water samples collected at North 

Lake (table 6), whereas pH values for the pore-water samples 

tended to be divided into two pH ranges. Pore-water samples 

collected along the northeast, southwest, and south-southwest 

shores had pH values ranging from 5.3 to 5.6 standard units, 

which were similar to values for pore-water samples from 

the North Lake area and values determined by Bares and 

Wali (1979) for water in Picea mariana (black spruce) stands 

of northwestern Minnesota alkaline peatlands. Pore-water 

samples collected along the north, northwest, and west shores 

had pH values ranging from 3.6 to 4.5 standard units (table 6).

The low specific conductance and low pH values for the 

north, northwest, and west pore-water samples likely are associated with the well-developed fen along these shores, which 

has high organic content (fig. 4). As organic content increases 

with fen development, the capacity of the soil to adsorb and 

exchange cations increases, resulting in sharp declines in 

cation concentrations and leading to a dominance of hydrogen 

ions in pore water (Mitsch and Gosselink, 1993). Any ground 

water flowing into the fen environment has ionic strengths too 

low to increase the low pH conditions in the pore water. These 

processes result in low specific conductance and pH values in 

the pore water. Wilde and Randall (1951) found similar low 

specific conductance and pH values for black spruce/tamarack 

bog water in Wisconsin. Pore water in poor (low-mineral 

input) fens in northern Minnesota tend to have similar low pH 

values and low calcium concentrations (Glaser, 1992).

Water temperatures for the pore-water samples were notably colder than for the surface-water sample from Teal Lake, 

except for the pore-water sample collected along the northeast 

shore (table 6). The water temperature for the northeast porewater sample was 20.2 oC, 1.4 oC higher than the water temperature of the surface-water sample. Temperatures for the 

other pore-water samples ranged from 10.6 to 14.1 oC. The 

warmer water temperature for the northeast pore-water sample 

is similar to other relatively warm lake-sediment temperatures 

measured along the northeast shore (fig. 4).

Dissolved oxygen concentrations for the pore-water 

samples were much lower than the concentration in the surface-water sample, with values ranging from 0.2 to 2.1 mg/L 

(table 6). Concentrations for the southwest and southsouthwest pore-water samples are notably higher than concentrations for the other pore-water samples, indicating that a 

small volume of surface water may have been drawn through 

the sediment and into the sampling tube during sampling.

Total nitrogen and phosphorus concentrations were 

higher in the pore-water samples than in the surface-water 

sample from the Teal Lake area, with the exception of the 

west pore-water sample (table 6). The total nitrogen and total 

ammonia plus organic nitrogen concentrations for the west 

pore-water sample were similar to concentrations present in 

the surface-water sample. As with the North Lake pore-water 

samples, dissolved nitrogen in the surface water consisted only 

of dissolved organic nitrogen, whereas dissolved nitrogen in 

the pore water consisted mainly of total ammonia plus organic 

nitrogen. Pore-water sampled from the northeast shore had 

much higher total nitrogen and total ammonia plus organic 

nitrogen concentrations than the other pore-water samples 

(table 6). These high concentrations may be associated with 

the presence of detritus and decomposition associated with a 

beaver dam at that location (Naiman and others, 1994).

The major constituent chemistry of the pore water at 

Teal Lake varied substantially because of chemical reactions 

occurring in the surrounding fens and swamps. Percentage 

differences for ionic balances were greater than 10 percent for 

the north, west, and southwest pore-water samples, whereas 

percentage differences for the other pore-water samples and 

the surface-water sample were between -10 and +10 percent 

(table 6). The ionic balances for the north, west, and southwest pore-water samples are positive, indicating that the total 

cation concentrations are greater than the total anion concentrations. Similar to the May 2004 north-northwest pore-water 

sample from the North Lake area, the low sulfate concentrations and strong hydrogen-sulfide smell during sampling indicate an underestimate of the total sulfur concentrations under 

unstable, changing chemical conditions.

Dissolved calcium, magnesium, sodium, sulfate, and 

chloride concentrations in pore-water samples collected along 

the north, northwest, west, and southwest shores were lower 

or similar to concentrations in the Teal Lake surface-water 

sample (fig. 8, table 6). The low calcium, magnesium, and 

sodium concentrations in the north, northwest, and west porewater samples, and to a lesser extent the southwest pore-water 

sample, are likely a result of cation exchanges with hydrogen 

ions, cation adsorption, and chelation occurring in the fen surrounding the lake as discussed earlier (Mitsch and Gosselink, 

1993). Dissolved silica, iron, and manganese concentrations 

were higher in pore-water samples than in the surface-water 

sample (table 6). These ions are less likely to be exchanged 

with other ions in the fen soils and, therefore, would be 

expected to be more concentrated in the pore water. The low 

sulfate concentrations are likely a result of the conversion of 

sulfate to hydrogen sulfide gas and other non-gaseous, sulfide 

complexes. The low chloride concentrations along the north 

and southwest shores indicate that dilution may be causing the 

lower cation and anion concentrations at these locations. 

Major chemical constituents are widely disseminated in 

the pore water of the Teal Lake area, with the major constituent chemistry of the surface-water sample being generally a 

Results of Analyses 35
mix of the chemistry of all of the pore-water samples (figs. 7 

and 8). The southwest and northeast pore-water samples 

are generally calcium magnesium bicarbonate water, with 

major constituent concentrations much higher in the northeast 

pore-water sample (table 6). Of all the Teal Lake pore-water 

samples, the major constituent chemistry of the northeast porewater sample was most similar to major constituent chemistry 

of the North Lake pore-water samples (figs. 7 and 8). Southsouthwest, west, north, and northwest pore-water samples consisted of a mixture of calcium, magnesium, and sodium, with 

chloride being the dominant anion (figs. 7 and 8). Of these 

four samples, iron, manganese, and boron concentrations are 

notably higher in the south-southwest pore-water sample. This 

sample was collected at an upwelling spring where iron-oxide 

precipitates were present in a channel bottom upgradient of 

the spring. The relatively high chloride and boron concentrations in the pore-water sample from the south-southwest shore 

were much lower than concentrations measured by Allen and 

others (1997) and Tipping and Allen (1997) in ground water 

of the North Shore Volcanics Group. The west pore-water 

sample was the most similar in major constituent chemistry to 

the surface-water sample collected at Teal Lake (fig. 7). The 

percentage distributions of cations for the southwest, northeast, and north pore-water samples were similar to the cation 

distribution for rock samples collected from the diabase dike 

at the Grand Portage National Monument (Laurel Woodruff, 

U.S. Geological Survey, oral commun., March 8, 2005).

Oxygen-18/oxygen-16 and deuterium/protium ratios for 

surface-water and pore-water samples collected from the Teal 

Lake area lie along an evaporation line with a slope of 3.9 and 

a y-intercept of -31.8 (fig. 6C). The most evaporative signature was for the surface-water sample (fig. 6C). The porewater samples collected along the south-southwest, north, and 

southwest shores had isotopic compositions that lie closest to 

the meteoric waterline (fig. 6C). These samples lie along portions of the meteoric waterline where spring precipitation isotope ratios for northern Wisconsin plotted, indicating that the 

ground water potentially discharging to these shores entered 

the ground-water system from spring recharge. Oxygen-18/

oxygen-16 and deuterium/protium ratios for the northeast, 

northwest, and west pore-water samples lie along the evaporation line between the surface-water sample ratio and the 

meteoric waterline (fig. 6C). 

Taylor Lake

Two surface-water samples and seven pore-water samples 

were collected in August 2004 from the Taylor Lake area 

(table 6). The surface-water samples were collected in the 

southeast and west-central parts of the lake (fig. 5). Only 

minor differences occurred in the water chemistry of the two 

surface-water samples (table 6). Pore-water samples were collected at various locations along the lakeshore (fig. 5). 

Obtaining representative samples for the pore water was 

difficult in many shore locations of Taylor Lake because lake 

sediment was thin. Similar to the thermocouple probe, the 

stainless-steel sampling tube could not be driven into lake 

sediment along the northeast, north, east, and southeast shores 

of Taylor Lake because the lake bottom consisted only of logs, 

boulders, gravels, and bedrock. Therefore, no pore-water 

samples were collected at those locations. Where present, lake 

sediment was generally less than 2.0 ft thick along the shores 

(table 5). As a result, the stainless-steel sampling tube could 

penetrate only to relatively shallow depths in the sediment 

at many of the sampling locations. During initial attempts 

to collect pore-water samples along the north-northeast and 

northeast shores, the specific conductance decreased and dissolved oxygen concentrations increased during pumping to 

values similar to the surface water. These results indicate that 

water from the lake may have penetrated through the thin lake 

sediment into the sampling tube during sampling. Therefore, 

as the samples were collected at each site, the percentages of 

infiltrating surface water and pore water varied in the samples. 

In those instances water samples probably do not represent the 

actual pore-water chemistry. 

Onsite specific conductance values for the two surfacewater samples collected from Taylor Lake were 47 μS/cm, 

whereas pore-water specific conductance values were grouped 

into two ranges, one between 46 and 74 μS/cm and the other 

between 211 and 285 μS/cm (table 6). The onsite specific 

conductance value for the east pore-water sample was 

123 μS/cm, lying between the two ranges. Pore-water samples 

in the lower specific conductance range (north-northeast, 

northeast, and southeast shores) had specific conductance 

values, alkalinity, and major constituent concentrations, except 

for iron and manganese concentrations, similar to the surfacewater samples. However, because of the highly conductive 

nature of the fractures located along the shoreline, pumping 

during sample collection may have temporarily drawn in lake 

water directly to the sampling location through the fractures. Seasonal sampling of the sites would need to be done 

to determine if these are surface-water-outseepage locations. 

Alkalinity concentrations for the north-northeast, northeast, 

and southeast pore-water samples ranged from 22 to 31 mg/L 

as calcium carbonate (table 6).

Similar to North and Teal Lakes, pH values for the 

surface-water samples from Taylor Lake were higher than the 

pH values for the pore-water samples (table 6). The surfacewater samples had in-situ pH values of 7.0 and 7.3 standard 

units, similar to North and Teal Lakes (table 6). The pH 

values for all Taylor Lake pore-water samples ranged from 5.6 

to 6.4 standard units, within the pH range for Picea mariana 

(black spruce) stands determined by Bares and Wali (1979) 

for a peatland in northwestern Minnesota. pH differences of 

more than 1.0 standard unit were found during initial attempts 

to collect pore-water samples along the east shore within relatively short horizontal distances, roughly 1 ft.

The range in pore-water temperatures was much smaller 

in the Taylor Lake area than in the North and Teal Lake areas 

due in part to the relatively cool air temperatures in August 

2004. Pore-water temperatures ranged from 13.6 to 16.2 oC, 

whereas surface-water temperatures were 17.1 and 17.2 oC 

36  Ground-Water/Surface-Water Interaction of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota
(table 6). The coolest temperatures were measured in porewater samples collected along the south, west, and southeast 

shores.

Dissolved oxygen concentrations were less than 

3.0 mg/L for all of the pore-water samples, with concentrations less than 1.0 mg/L for four of the seven pore-water 

samples (table 6). These low dissolved oxygen concentrations indicate that reducing conditions likely occur in the lake 

sediment. Dissolved oxygen concentrations for the northeast, 

south, and southeast pore-water samples were slightly higher 

than concentrations for the other pore-water samples, indicating that a volume of surface water may have been drawn 

through the sediment and into the sampling tube during sampling. The relatively high specific conductance values for the 

south pore-water sample indicate that the volume of surface 

water that may have been drawn into the sampling tube was 

very small.

Total nitrogen concentrations were greater in the porewater samples than in the surface-water samples of the Taylor 

Lake area, but the concentrations were generally lower than 

concentrations in pore-water samples from North and Teal 

Lakes (table 6). These lower total nitrogen concentrations 

may be because of the greater lake depth and a lower amount 

of beaver activity at Taylor Lake. Total ammonia plus organic 

nitrogen concentrations were greater in the south and north 

pore-water samples than in the other pore-water samples from 

the Taylor Lake area (table 6). The south and north pore-water 

samples were collected near beaver dams and dens, respectively, where nutrient concentrations tend to be relatively high 

(Naiman and others, 1994).

Percentage differences for ionic balances were greater 

than 10 percent for five of the seven pore-water samples collected in the Taylor Lake area (table 6). All of these balances 

were positive, indicating that the total cation concentrations 

were greater than the total anion concentrations. As indicated 

earlier, some water from the lake may have been drawn into 

the sampling tube while collecting several of the pore-water 

samples from the Taylor Lake area, potentially resulting in 

chemical disequilibrium in the samples and causing problems 

with the ionic balance. Also, the smell of hydrogen sulfide gas 

was present in all of the pore-water samples, indicating that 

the amount of total dissolved sulfur may have been underestimated in the ionic balances.

All of the surface-water and pore-water samples collected 

in the Taylor Lake area were a calcium magnesium bicarbonate type water (figs. 7 and 8). The percentage distributions of 

major ions for the surface water and pore water were similar 

to the water samples collected from the North Lake area, 

with only minor differences in the distributions between the 

samples for the Taylor Lake area (fig. 7). Sulfate, chloride, 

fluoride, nitrate, and nitrite concentrations were relatively low 

in all of the surface-water and pore-water samples compared 

to bicarbonate concentrations (figs. 7 and 8, table 6). The 

cation distributions for the north, west, and southeast porewater samples were slightly different from the distributions 

of the other surface-water and pore-water samples. The south 

and west samples had higher percentages of calcium, whereas 

the north sample had a lower percentage of calcium compared 

to the other samples (fig. 7). The west pore-water sample 

also had a lower percentage of sodium and potassium than the 

other samples. The distribution of cation and anion concentrations in the surface-water sample for Taylor Lake was very 

similar to the distribution for surface-water samples for nearby 

Speckled Trout and Loon Lakes presented in Winterstein 

(2002) (figs. 1 and 8). 

Iron and manganese concentrations were higher for the 

pore-water samples than concentrations in the surface-water 

samples (table 6). Concentrations were notably higher in the 

pore-water samples collected along the south, north, and west 

shores of Taylor Lake. Some iron-oxide precipitates, likely 

bacteria-oxidized iron (Wetzel, 1983), were observed at these 

locations. 

Oxygen-18/oxygen-16 and deuterium/protium ratios for 

surface-water and pore-water samples collected in the Taylor 

Lake area lie along an evaporation line with a slope of 4.1 and 

a y-intercept of -33.7 (fig. 6D). This slope value is between 

values obtained from North and Teal Lakes. A comparison 

between the three slope values indicates an apparent negative relation between the slope values and lake-surface area 

for the three lakes. However, this relation does not consider 

the effect of temporal variations in sample collection because 

the samples were collected during different years for Teal and 

Taylor Lakes.

The two surface-water samples for Taylor Lake were the 

most evaporative because they plotted farthest from the meteoric waterline, with stable isotope ratios for the two samples 

lying close to each other along the evaporation line (fig. 6D). 

Stable isotope ratios for north-northeast and northeast porewater samples lie near the surface-water samples (fig. 6D).

The least evaporative isotope ratios for the Taylor Lake 

samples were for the south, north, and west pore-water 

samples (fig. 6D). The pore-water samples collected along 

the east and southeast shores of Taylor Lake had similar stable 

isotope ratios, lying between the ratios for the surface-water 

and least-evaporative isotope ratio samples (fig. 6D). However, the major constituent concentrations differ between the 

two samples, with specific conductance values and the major 

constituent concentrations being higher in the east pore-water 

sample (table 6).

Quality Assurance

The percentage differences between original and replicate 

samples for major constituents, nutrient, and stable isotope 

concentrations were better than ± 5 percent for all of the constituents except for dissolved potassium and dissolved chloride 

in one original/replicate sample set and dissolved phosphorus 

and total phosphorus in another original/replicate set (table 7). 

Hem (1992) stated that for constituent concentrations greater 

than 100 mg/L, percentage differences should be better than 

± 5 percent, whereas for concentrations less than 1 mg/L, 

percentage differences generally are not better than ± 10 perResults of Analyses 37
cent and can be poorer. For the constituents of the replicate 

samples with high percentage differences between the original 

and replicate samples, concentrations were less than 1 mg/L, 

with two of the concentrations low enough to only be 

estimated values (table 7). At these low concentrations, only 

small changes in concentrations resulted in large percentage 

differences. No blank or spike samples were collected in 

the study.

Ground-Water/Surface-Water 

Interaction 

Water-quality data collected during this study indicate 

that most of the ground-water inflow to the three lakes likely 

occurs through fractures or zones of fractures located along 

the shorelines. This type of ground-water inflow is common 

in fractured-rock terrains. Beaver dens and activity were common in channels developed near fractures along the shorelines. 

It could be possible that beavers build their dens in these channels because ground-water inflow to these channels keep water 

temperatures relatively constant throughout the year.

Table 7. Sequential replicate samples from North Lake, August 2003, Teal Lake, September 2003, and Taylor Lake, September 2004, 

Grand Portage Reservation, northeastern Minnesota.

[Values in parentheses are percentage differences between concentrations in onsite samples and replicate samples; mg/L, milligrams per liter; μg/L, micrograms per liter; <, less than; E, estimated; --, no data]

Constituent

Southwest 

channel of North Lake, 

475656089493301, 

8/26/2003, 14:32 hours

Teal Lake near 

Grand Portage, 

475930089392301, 

9/3/2003, 10:32 hours

Southeast shore 

of Taylor Lake, 

475602089493801, 

9/2/2004, 12:35 hours

Dissolved calcium (mg/L as Ca) 20.8 (1.9) 9.40 (3.6) 10.6 (1.9)

Dissolved magnesium (mg/L as Mg) 4.55 (-1.3) 4.40 (0.7) 1.80 (0.8)

Dissolved potassium (mg/L as K) .42 (-3.7) .77 (4.3) .25 (13.8)

Dissolved sodium (mg/L as Na) 1.34 (-0.8) 7.55 (0.2) .75 (1.3)

Dissolved chloride (mg/L as Cl) .42 (1.2) 20.0 (-1.0) E .17 (20.9)

Dissolved fluoride (mg/L as F) < .2 (--) < .2 (--) < .2 (--)

Dissolved silica (mg/L as SiO2) 23.2 (-1.3) .76 (-1.3) 3.33 (-0.5)

Dissolved sulfate (mg/L as SO4) E .1 (0) 3.7 (-1.4) .3 (0)

Total nitrogen (mg/L as N) -- -- .69 (0.7)

Total ammonia plus organic nitrogen (mg/L as N) 2.9 (-0.3) .79 (-1.9) --

Dissolved ammonia nitrogen (mg/L as N) 2.46 (0.4) < .04 (--) .23 (-2.2)

Dissolved nitrite nitrogen (mg/L as N) < .008 (--) < .008 --) < .008 (--)

Dissolved phosphorus (mg/L as P) .100 (-0.5) E .004 (-14.3) .055 (-1.9)

Dissolved ortho-phosphorus (mg/L as P) .08 (-2.0) < .02 (--) .04 (-2.3)

Total phosphorus (mg/L as P) -- .009 (5.3) --

Dissolved boron (μg/L as B) 15 (3.0) 11 (-2.7) < 7.0 (--)

Dissolved iron (μg/L as Fe) 1,010 (1.0) 40 (3.6) 1,190 (2.1)

Dissolved manganese (μg/L as Mn) 28.7 (-2.1) < .4 (--) 94.8 (0.3)

Dissolved bromide (μg/L as Br) -- -- .08 (0)

Oxygen-18/oxygen-16 ratio, unfiltered water, per mil -9.24 (-0.4) -5.02 (-0.1) -6.3 (0)

Deuterium/protium ratio, unfiltered water, per mil -71.40 (-0.6) -51.40 (-1.1) -59.90 (0.7)

38  Ground-Water/Surface-Water Interaction of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota
Analyses of existing aerial photographs, nearshore lakesediment temperatures, and seasonal isotope ratios of surfacewater and pore-water samples were the most valuable data for 

identifying locations of ground-water inflow. Major constituent chemistry was valuable at Taylor Lake, and to a limited 

extent at North and Teal Lakes, in confirming results from 

the isotope and lake-sediment temperature data. However, 

lake-sediment temperatures were not as useful for identifying 

areas of ground-water inflow at Taylor Lake because of the 

cooler-than-normal air temperatures in August 2004. Major 

constituent chemistry worked well where large concentration 

differences between surface-water and pore-water chemistry 

existed, such as in pore-water samples from the south-southwestern shore of Teal Lake.

The lack of notable concentration differences and 

potential cation exchanges, cation adsorption, and chelation 

in fens and swamps surrounding lakes confounded the use of 

major constituent chemistry to identify locations of groundwater inflow to North and Teal Lakes, respectively. Highland 

lakes, such as North Lake and, to a lesser extent, Taylor Lake, 

tend to receive localized ground water that has relatively low 

dissolved-ion concentrations. This localized ground water 

has a short residence time, less contact time with the formations, and as a result, less time to react chemically with the 

rock matrix. Therefore, localized ground water tends to have 

lower ionic concentrations than more regional water. Chemical reactions in upgradient fens and swamps also reduce major 

constituent concentrations in ground water that discharges 

from these fens and swamps and eventually recharges the 

highland lakes. 

Variables that were not evaluated at these study sites but 

that may be valuable in locating areas of ground-water inflow 

are shoreline vegetation, forest cover, and beaver activity. 

Tamarack, manna grass, and white cedars commonly were 

present in areas where ground-water inflow apparently occurs. 

During pore-water sampling, the location of manna grass commonly was used to locate sampling sites where ground-water 

discharge was likely to occur. 

North Lake

Analyses of existing aerial photographs, lake-sediment 

temperature, and water-quality data indicate that ground-water 

inflow to North Lake likely occurs along the southwest and 

south shores (fig. 9A), and portions of the west, north, southeast, and northeast shores. The southern drainage channel 

identified in the analyses of existing aerial photographs of 

North Lake is likely a location for potential ground-water 

inflow rather than surface-water outseepage because the channel is higher in elevation than the lake, with surface water 

in the channel following snowmelt and precipitation flowing towards the lake (fig. 3). Relatively cool lake-sediment 

temperatures along the southeast, south, southwest, and west 

shores (fig. 3), and in isolated beaver channels in the north and 

northeast of North Lake indicate potential ground-water inflow 

at these locations (fig. 10A). The high specific conductance 

values and high dissolved calcium and bicarbonate concentrations for the pore-water samples from the southwest channel 

and south shore in August 2003 and May 2004 indicate that 

inflowing ground water with higher specific conductance 

values than the surface water is potentially more of a component of these pore-water samples than of the other pore-water 

samples (figs. 10B and 10C). The consistent oxygen-18/

oxygen-16 and deuterium/protium ratios for the south, 

southwest channel, and north-northwest pore-water samples 

indicate a predominance of ground-water inflow at those locations (figs. 6B and 10D). In general, pore water with a consistent isotopic composition over time is affected more by ground 

water (Krabbenhoft and others, 1994). The more evaporative 

isotopic compositions of the south and the north-northwest 

pore-water samples than for the southwest channel pore-water 

sample indicate that the south and the north-northwest samples 

either are less affected by ground-water inflow than pore water 

from the southwest channel location or likely receive ground 

water from upgradient wetlands where more evaporation 

occurs (fig. 6B).

Conflicting evidence for ground-water flow conditions 

exist for the northwest and north-northwest pore-water samples for the North Lake area. Warm lake-sediment temperatures, similar to water temperatures in the lake, relatively high 

dissolved oxygen concentrations, and low total ammonia plus 

organic nitrogen concentrations in pore-water samples from 

the northwest and north-northwest shores indicate that surfacewater outseepage or little ground-water and surface-water 

interaction occurs at the locations (figs. 10A and 10B). The 

high organic nitrogen concentration in the pore-water sample 

from the north-northwest shore (table 6) further indicates the 

potential for surface-water outseepage. However, consistent 

stable isotope ratios for pore-water samples from the northwest and north-northwest shores indicate a mixing of surfacewater and some potential ground-water inflow (figs. 6B and 

10D). Possible explanations for the temporal conservative 

nature in stable isotope ratios are local differences in flow 

conditions between the August 2003 and May 2004 sampling 

sites and a lag in the pore-water isotopic response to seasonal 

isotopic changes in the lake water because of low-permeability 

sediment. The northwestern drainage channel identified in the 

analyses of existing aerial photographs is lower in elevation 

than North Lake and, therefore, is likely a location for more 

surface-water outseepage rather than ground-water inflow. 

A combination of ground-water inflow and surface-water 

outseepage from North Lake likely occurs along portions of 

the north, northeast, southeast, and south shores (fig. 9A). 

Ground-water inflow or surface-water outseepage could be 

occurring in the northern drainage channel identified in the 

analyses of existing aerial photographs because the difference 

in elevation between the channel and lake is small (fig. 3). 

Similarities in the oxygen-18/oxygen-16 and deuterium/ 

protium ratios for the surface-water samples and the north 

and northeast pore-water samples of North Lake indicate that 

surface-water outseepage was occurring or these samples were 

Ground-Water/Surface-Water Interaction 39
8 9

17 16

T.

63

N.

North Lake

(elev. 1,486 feet)

1500

1500

1500

1500

1520

1520

1480

27 26

34 35

T.

64

N.

R. 6 E.

D

D

D

D

D

D

N

NE

SSW

SW

W

NW

89o40' 30" 89o39'

30"

47o59'15"

47o59'45"

900

960

1000

1000

1100

1000

1000

960

1000

1000

1100

1100

1140

960

1000

61

Teal Lake

(elev. 948 feet)

17 16

20 21

T.

63

N.

R. 5 E.

D D

D

D D

D

D

W

N

NNE

NE

E

S

SE

89o50' 89o49'30"

47o56'15"

47o56'

1520

1540

1560

1600

1640

1660

1500

1540

1580

1600

1620

1540

1560

1600

1640

1540

1560

1580

1600

1640

1540

1560

1580

1600

1560

1600

1560

1600

1580

Taylor Lake

(elev. 1543 feet)

1000

1200

1100

980

940

1180

1200 1200

1200 1280

1540 1540 1480

1520

1660 1680

R. 5 E.

0.05 0.1 MILE

0 0.05 0.1 KILOMETER

0

0.25 0.5 MILE

0 0.25 0.5 KILOMETER

0

0.25 0.5

0.25 0.5 KILOMETER

 MILE

0

0

(A) North Lake

(B) Teal Lake

(C) Taylor Lake

EXPLANATION

DSW

Bogs

Shrub swamp

Wet meadow

Wooded swamp

Deep marsh

Topographic contours–shows

 elevation of land surface above

 NAVD 88. Contour interval 20 feet

Watershed boundary

Ground-water inflow

Mix of ground-water inflow

 or surface-water outseepage

Water-quality sampling site–Letters 

 are site identifer

1000

Mapping credit for (A) North Lake area, (B) Teal Lake area,

and (C) Taylor Lake area.

Sources for native plant communities from: U.S. Fish and Wildlife 

Service, 1994, National wetlands inventory digital data, October 1991 

to 1994: Information available on web, accessed March 11, 2005, at 

http://www.nwi.fws.gov., and Minnesota Department of Natural 

Resources, 2003, Field guide to the native plant communities of 

Minnesota, Laurentian Mixed Forest Province: St. Paul, Minnesota, 

Minnesota Department of Natural Resources,p. 198-200, 203-204, 

283-287.

Base credit for (A) North Lake area, (B) Teal Lake area,

and (C) Taylor Lake area.

Base from Minnesota Department of Transportation

Base map 99, 1:24,000, 1999

U.S. Albers projection

S

SW

NNW

NE

SE

47o57'

47o56'55"

89o49'35" 30" 89o49'25"

D

D

D

D

D

Figure 9. Nearshore locations of ground-water inflow and surface-water outseepage for (A) North Lake, (B) Teal Lake, and (C) Taylor 

Lake, Grand Portage Reservation, northeastern Minnesota, determined on the basis of lake-sediment temperatures and water-quality

data.

40 Ground-Water/Surface-Water Interaction of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota
8 9

17 16

T.

63

N.

R. 5 E.

8 9

17 16

T.

63

N.

R. 5 E.

8 9

17 16

T.

63

N.

R. 5 E.

8 9

17 16

T.

63

N.

R. 5 E.

0.05 0.1 MILE

0 0.05 0.1 KILOMETER

0

North Lake

(elev. 1,486 feet)

North Lake

(elev. 1,486 feet)

North Lake

(elev. 1,486 feet)

North Lake

(elev. 1,486 feet)

(A) Lake-sediment temperatures (B) Onsite water-quality measurements

(C) Major constituent and nutrient concentrations (D) Oxygen-18/oxygen-16 and deuterium/protium ratios

Base from Minnesota Department of Transportation

Base map 99, 1:24,000, 1999

U.S. Albers projection

Sources for native plant communities from: U.S. Fish and Wildlife 

Service, 1994, National wetlands inventory digital data, October 1991 

to 1994: Information available on web, accessed March 11, 2005, at 

http://www.nwi.fws.gov., and Minnesota Department of Natural 

Resources, 2003, Field guide to the native plant communities of 

Minnesota, Laurentian Mixed Forest Province: St. Paul, Minnesota, 

Minnesota Department of Natural Resources,p. 198-200, 203-204, 

283-287.

EXPLANATION

D

Northern rich tamarack

 swamp (bogs)

Northern rich fen

 (shrub swamp)

Topographic contours–shows

 elevation of land surface above

 NAVD 88. Contour interval 20 feet

Boundary of North Lake watershed

Ground-water inflow

Surface-water outseepage

Either ground-water inflow

 or surface-water outseepage

Water-quality sampling site–Letters 

 are site identifer

SW 1500

1500

1500

1500

1500

1520

1520

1480

1500

1500

1500

1500

1520

1520

1480

1500

1500

1500

1500

1520

1520

1480

1500

1500

1500

1500

1520

1520

1480

S

SW

NNW

NE

SE

47o57'

47o56'55"

89o49'35" 30" 89o49'25"

D

D

D

D

D

S

SW

NNW

NE

SE

47o57'

47o56'55"

89o49'35" 30" 89o49'25"

D

D

D

D

D

S

SW

NNW

NE

SE

47o57'

47o56'55"

89o49'35" 30" 89o49'25"

D

D

D

D

D

S

SW

NNW

NE

SE

47o57'

47o56'55"

89o49'35" 30" 89o49'25"

D

D

D

D

D

Figure 10. Nearshore locations of ground-water inflow and surface-water outseepage for North Lake, Grand Portage Reservation, 

northeastern Minnesota, determined on basis of (A) lake-sediment temperatures, (B) onsite water-quality measurements, (C) major 

constituent and nutrient concentrations, and (D) oxygen-18/oxygen-16 and deuterium/protium ratios.

Ground-Water/Surface-Water Interaction 41
affected by upgradient surface water (figs. 6B and 10D). The 

large tamarack swamp located north of the north and northeast 

shores is likely contributing water to local surface water and 

pore water of North Lake (fig. 3). The low specific conductance and bicarbonate values for the southeast pore-water 

sample indicate that this pore water may be from surface-water 

outseepage or more likely affected by upgradient wetlands 

(fig. 10B). However, low pH values and dissolved oxygen 

concentrations for the southeast pore-water sample do not 

indicate surface-water outseepage. Upgradient wetlands may 

be affecting isotopic ratios along the southeast shore because 

the oxygen-18/oxygen-16 and deuterium/protium ratios for 

the May 2004 sample lie near the meteoric waterline similar to the May 2004 surface-water sample and the northeast 

pore-water sample (fig. 6B). However, no sample was collected at the southeast location in August 2003 for temporal 

comparison. Lake-sediment temperatures above 18 oC were 

found along portions of the south shore and throughout North 

Lake, indicating potential surface-water outseepage or little 

ground-water and surface-water interaction at those locations 

(fig. 10A).

Teal Lake

Ground-water inflow likely takes place along the southsouthwest and north shores of Teal Lake, with a mixture of 

ground-water inflow and surface-water outseepage occurring 

in other areas of the lake (fig. 9B). Lake-sediment temperatures indicate that ground-water inflow occurs along the southsouthwest, west, and northwest shores, portions of the north 

shore, and in channels identified in the analyses of existing 

aerial photographs where lake-sediment temperatures were 

less than 15 oC (figs. 4 and 11A). High major constituent concentrations in the south-southwest pore-water sample further 

indicate the presence of ground-water inflow at that location 

(fig. 11C). The pore-water samples from the south-southwest, 

north, and southwest shores had isotopic compositions that 

lie closest to the meteoric waterline (fig. 6C), indicating that 

ground-water inflow occurred at these locations (fig. 11D). 

The low specific conductance values for the north, northwest, 

west, and southwest pore-water samples were likely because 

of cation adsorption or relation between inflowing ground 

water and soils in the fens and swamps but probably was not 

the result of surface-water outseepage.

Ground-water inflow and surface-water outseepage from 

Teal Lake likely occurs along the northeast shore (fig. 9B). 

Warmer lake-sediment temperatures in the northeast and 

portions of the southwest and northwest shores of Teal Lake 

(fig. 4) indicate potential locations where surface-water 

outseepage or little ground-water and surface-water interaction occurs (fig. 11A). However, surface-water outseepage 

is unlikely or only localized along the southwest and northwest shores because low-permeability diabase dikes located 

to the west and south are higher in elevation than Teal Lake, 

preventing any regional surface-water outseepage (fig. 4). 

The low permeabilities of the diabase dikes likely restrict 

ground-water inflow to the lake from the west and south to 

within the drainage channels that cross the dikes and the lake’s 

watershed. Warmer water temperatures along the northeast 

shore indicate potential surface-water outseepage (fig. 11A); 

however, the high major constituent concentrations in the 

northeast pore-water sample indicate potential ground-water 

inflow (fig. 11C). Local beaver activity near the northeast 

shore may result in the high major constituent concentrations 

(Naiman and others, 1994). Oxygen-18/oxygen-16 and deuterium/protium ratios for pore-water samples from the northeast, 

northwest, and west shores indicate that some evaporation 

has occurred with this water but not as much as with surface 

water (fig. 6C). The likely source of this pore water is ground 

water flowing south from fens and swamps to the north (fig. 4) 

where some evaporation likely occurred but not as much as in 

the surface-water sample. The warm lake-sediment temperature (17 oC) found near the center of the lake indicates that 

little ground-water/surface-water interaction occurs at that 

location (fig. 4).

Taylor Lake

Ground-water inflow to Taylor Lake likely occurs along 

the north and south shores (fig. 9C). Two lowlands to the 

north and northeast of Taylor Lake (fig. 5) identified in the 

analyses of existing aerial photographs are topographically 

higher than the lake and, therefore, are more likely areas of 

ground-water inflow rather than surface-water outseepage. 

Cooler lake-sediment temperatures along the northeast shore 

of Taylor Lake indicate that ground-water inflow likely is 

occurring at that location (fig. 12A), with an upgradient lowland, bog, and wooded swamp likely sources of ground water. 

Warmer lake-sediment temperature along the north shore 

indicates that some minor surface-water outseepage may occur 

at that location (fig. 12A). Major constituent chemistry and 

isotope values for pore-water samples collected in the Taylor Lake area indicate that ground-water inflow is occurring 

along the south and likely the north and west shores (figs. 12C

and 12D). These samples had isotope evaporative signatures 

most similar to the meteoric waterline, the highest specific 

conductance values, and the highest calcium, magnesium, 

bicarbonate, silica, iron, and manganese concentrations for the 

Taylor Lake pore-water samples. However, the isotopic values 

for these samples do not fall close to the meteoric waterline 

(fig. 6D), indicating that some evaporative water, probably 

from an upgradient wetland or lake, is contributing water to 

the lake at those locations. The high iron and manganese 

concentrations in pore-water samples from along the south, 

north, and west shores of Taylor Lake indicate the presence of 

iron seeps at those locations (table 6). Iron seeps are common 

along the shores of lakes and wetlands in northern Minnesota 

(Harder, 1919; Robbins and others, 1997). A combination of 

warmer and cooler lake-sediment temperatures along the west 

lowland indicates that ground-water inflow and surface-water 

outseepage may occur at that location (fig. 12A).

42 Ground-Water/Surface-Water Interaction of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota
27 26

34 35

T.

64

N.

R. 6 E.

27 26

34 35

T.

64

N.

R. 6 E.

27 26

34 35

T.

64

N.

R. 6 E.

27 26

34 35

T.

64

N.

R. 6 E.

D

D

D

D

D

D

N

NE

SSW

SW

W

NW

D

D

D

D

D

D

N

NE

SSW

SW

W

NW

D

D

D

D

D

D

N

NE

SSW

SW

W

NW

D

D

D

D

D

D

N

NE

SSW

SW

W

NW

89o40' 30" 89o39'

30"

47o59'15"

47o59'45"

89o40' 30" 89o39'

30"

47o59'15"

47o59'45"

89o40' 30" 89o39'

30"

47o59'15"

47o59'45"

89o40' 30" 89o39'

30"

47o59'15"

47o59'45"

0.25 0.5

0.25 0.5 KILOMETER

 MILE

0

0

900

960

1000

1000

1100

1000

1000

960

1000

1000

1100

1100

1140

960

1000

900

960

1000

1000

1100

1000

1000

960

1000

1000

1100

1100

1140

960

1000

900

960

1000

1000

1100

1000

1000

960

1000

1000

1100

1100

1140

960

1000

900

960

1000

1000

1100

1000

1000

960

1000

1000

1100

1100

1140

960

1000

1200

1100

980 1180

1200 1200

1200 1280

1200

1100

980 1180

1200 1200

1200 1280 1200

1100

980 1180

1200 1200

1200 1280

1200

1100

980 1180

1200 1200

1200 1280

61

61

61

61

Teal Lake

(elev. 948 feet)

(A) Lake-sediment temperatures (B) Onsite water-quality measurements

(C) Major constituent and nutrient concentrations (D) Oxygen-18/oxygen-16 and deuterium/protium ratios

Teal Lake

(elev. 948 feet)

Teal Lake

(elev. 948 feet)

Teal Lake

(elev. 948 feet)

Base from Minnesota Department of Transportation

Base map 99, 1:24,000, 1999

U.S. Albers projection

Sources for native plant communities from: U.S. Fish and Wildlife 

Service, 1994, National wetlands inventory digital data, October 1991 

to 1994: Information available on web, accessed March 11, 2005, at 

http://www.nwi.fws.gov., and Minnesota Department of Natural 

Resources, 2003, Field guide to the native plant communities of 

Minnesota, Laurentian Mixed Forest Province: St. Paul, Minnesota, 

Minnesota Department of Natural Resources,p. 198-200, 203-204, 

283-287. EXPLANATION

Northern cedar swamp (bogs)

Northern rich fen (shrub swamp)

Wet meadow

Wooded swamp

Surface-water outseepage

Either ground-water inflow

 or surface-water outseepage

Water-quality sampling site–Letters 

 are site identifer

DSW

Deep marsh

Topographic contours–shows

 elevation of land surface above

 NAVD 88. Contour interval 20 feet

Boundary of Teal Lake watershed

Ground-water inflow

1000

Figure 11. Nearshore locations of ground-water inflow and surface-water outseepage for Teal Lake, Grand Portage Reservation, 

northeastern Minnesota, determined on basis of (A) lake-sediment temperatures, (B) onsite water-quality measurements, (C) major 

constituent and nutrient concentrations, and (D) oxygen-18/oxygen-16 and deuterium/protium ratios.

Ground-Water/Surface-Water Interaction 43
17 16

20 21

T.

63

N.

R. 5 E.

17 16

20 21

T.

63

N.

R. 5 E.

17 16

20 21

T.

63

N.

R. 5 E.

17 16

20 21

T.

63

N.

R. 5 E.

D D

D

D D

D

D

W

N

NNE

NE

E

S

SE

D D

D

D D

D

D

W

N

NNE NE

E

S

SE

D D

D

D D

D

D

W

N

NNE

NE

E

S

SE

D D

D

D D

D

D

W

N

NNE NE

E

S

SE

89o50' 89o49'30"

47o56'15"

47o56'

89o50' 89o49'30"

47o56'15"

47o56'

89o50' 89o49'30"

47o56'15"

47o56'

89o50' 89o49'30"

47o56'15"

47o56'

0.25 0.5 MILE

0 0.25 0.5 KILOMETER

0

1520

1540

1560

1600

1640

1660

1500

1540

1580

1600

1620

1540

1560

1600

1640

1540

1560

1580

1600

1640

1540

1560

1580

1600

1560

1600

1560

1600

1580

1520

1540

1560

1600

1640

1660

1500

1540

1580

1600

1620

1540

1560

1600

1640

1540

1560

1580

1600

1640

1540

1560

1580

1600

1560

1600

1560

1600

1580

1520

1540

1560

1600

1640

1660

1500

1540

1580

1600

1620

1540

1560

1600

1640

1540

1560

1580

1600

1640

1540

1560

1580

1600

1560

1600

1560

1600

1580

1520

1540

1560

1600

1640

1660

1500

1540

1580

1600

1620

1540

1560

1600

1640

1540

1560

1580

1600

1640

1540

1560

1580

1600

1560

1600

1560

1600

1580

1540 1540 1480

1520

1660 1680

1540 1540 1480

1520

1660 1680

1540 1540 1480

1520

1660 1680

1540 1540 1480

1520

1660 1680

Taylor Lake

(elev. 1543 feet)

(A) Lake-sediment temperatures 

Taylor Lake

(elev. 1543 feet)

Taylor Lake

(elev. 1543 feet)

Taylor Lake

(elev. 1543 feet)

(B) Onsite water-quality measurements

(C) Major constituent and nutrient concentrations (D) Oxygen-18/oxygen-16 and deuterium/protium ratios

Base from Minnesota Department of Transportation

Base map 99, 1:24,000, 1999

U.S. Albers projection

Sources for native plant communities from: U.S. Fish and Wildlife 

Service, 1994, National wetlands inventory digital data, October 1991 

to 1994: Information available on web, accessed March 11, 2005, at 

http://www.nwi.fws.gov., and Minnesota Department of Natural 

Resources, 2003, Field guide to the native plant communities of 

Minnesota, Laurentian Mixed Forest Province: St. Paul, Minnesota, 

Minnesota Department of Natural Resources,p. 198-200, 203-204, 

283-287.

EXPLANATION

Bogs

Wooded swamp

Topographic contours–shows

 elevation of land surface above

 NAVD 88. Countour interval 20 feet

Boundary of Taylor Lake watershed

D

Ground-water inflow

Surface-water outseepage

Either ground-water inflow

 or surface-water outseepage

Water-quality sampling site–Letters 

 are site identifer

SW

1600

Figure 12. Nearshore locations of ground-water inflow and surface-water outseepage for Taylor Lake, Grand Portage Reservation, 

northeastern Minnesota, determined on basis of (A) lake-sediment temperatures, (B) onsite water-quality measurements, (C) major 

constituent and nutrient concentrations, and (D) oxygen-18/oxygen-16 and deuterium/protium ratios.

44 Ground-Water/Surface-Water Interaction of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota
Surface-water outseepage likely occurs from Taylor Lake 

along portions of the south shore through a surface-water 

drainage channel to a downgradient bog (fig. 5). Warmer 

lake-sediment temperatures measured along portions of the 

south and southeast shores (fig. 12A) and the high dissolved 

oxygen concentrations found along the south and southeast 

shores indicate a potential for surface-water outseepage. 

Warmer lake-sediment temperatures also found along the west, 

southwest, northeast, and portions of the north and east shores 

of Taylor Lake (fig. 5) indicate that potential surface-water 

outseepage to local aquifers or little ground-water and surfacewater interaction occurs at those locations (fig. 12A).

Similarities between stable isotope ratios, specific 

conductance values, alkalinity, and major constituent concentrations for surface-water samples and north-northeast and 

northeast pore-water samples from the Taylor Lake area indicate that surface-water outseepage potentially occurs at these 

locations (fig. 9C). The high dissolved oxygen concentration 

for the northeast pore-water samples also indicates that some 

surface-water outseepage may occur at those locations. However, as discussed earlier, surface water may have been drawn 

into the sampling tubing from the lake through fractures during sampling along the north-northeast and northeast shores.

Ground-water inflow and surface-water outseepage may 

occur along the west, southeast, and east shores of Taylor Lake 

(fig. 9C), varying seasonally or in response to large amounts 

of precipitation. A lowland to the west of Taylor Lake (fig. 5) 

either could be a location of ground-water inflow to the lake or 

surface-water outseepage to the ground-water system because 

the difference in topography between the lake and the lowland 

is small and both cool and warm lake-sediment temperatures 

were measured at that location. Stable isotope ratios, specific 

conductance values, and bicarbonate and major constituent 

concentrations for the southeast pore-water sample indicate 

that a mixture of surface-water outseepage and ground-water 

inflow may occur along the southeast shore (fig. 9C). Aerial 

photography analyses identified a lowland to the east of Taylor 

Lake (fig. 5) that either could be a location of ground-water 

inflow or surface-water outseepage because the difference in 

topography between the lake and the lowland is small. The 

stable isotope ratios for the east pore-water sample (fig. 6D) 

indicate that the east shore may be a location where a mixture 

of surface and ground water occurs (fig. 12D). The large 

differences in onsite water-quality measurements (specific 

conductance, pH, temperature, and dissolved oxygen) found 

along the east shore within relatively short horizontal distances 

further indicate a mixing of surface and ground water or local 

evapotranspiration effects. The large pH differences could be 

caused by vegetation factors (Mitsch and Gosselink, 1993). 

However, no notable changes in vegetation were seen along 

the east shore. 

Implications of Ground-Water/SurfaceWater Interactions

Knowledge of general water-flow directions in lake 

watersheds and how they may change seasonally can help 

water-quality specialists and lake managers address a variety of water-quality and aquatic habitat protection issues for 

lakes. Current (2006) concerns over nutrient criteria, impaired 

waters, and invasive aquatic plants in lakes are all issues where 

understanding ground-water/surface-water interactions in a 

lake are needed to make wise management decisions. In fractured-rock settings, identifying ground-water inflow locations 

to lakes can indicate the location of upgradient springs, which 

may be valuable sources of water to small communities where 

finding adequate sources of water is difficult.

Results from this study indicate that ground-water and 

surface-water interactions at the study lakes are complex, and 

the ability of the applied techniques to identify ground-water 

inflow and surface-water outseepage locations varied among 

the lakes. These variations are in part a result of the complexity of local geology, chemical reactions in fens upgradient and 

surrounding the lakes, and the fracture-flow bedrock setting. 

Seasonal variabilities of ground-water inflow and surfacewater outflow locations and flow rates were not determined for 

this study, and should be assessed before determining water 

balances of a lake.

Measurement of lake-sediment temperatures proved 

to be a reliable and relatively inexpensive reconnaissance 

technique that lake managers may apply in complex settings 

to identify general areas of ground-water inflow and surfacewater outseepage. In the complex settings of the three study 

lakes, nearshore lake-sediment temperatures were shown to 

be valuable information in identifying ground-water inflow 

and surface-water outseepage locations, but interpretations 

of the temperature measurements were most powerful when 

combined with interpretation of seasonal pore-water-quality 

data and aerial photographs. Lake-sediment temperatures are 

relatively simple to measure and can be measured and interpreted within a short period of time. Statistical analyses of the 

lake-sediment temperatures demonstrated that lake sediment 

and water depths were unlikely factors in determining the 

lake-sediment temperature, further simplifying the interpretation of the temperature data. 

Summary

The U.S. Geological Survey (USGS), in cooperation with 

the Grand Portage Band of Chippewa Indians, applied three 

techniques to assess ground-water/surface-water interaction 

in nearshore areas of three lakes (North, Teal, and Taylor) on 

the Grand Portage Reservation in northeastern Minnesota. At 

each lake, the analyses of existing aerial photographs, in-situ 

temperature measurements of shoreline lake sediment, and 

Summary 45
chemical analysis of surface water and shoreline pore water 

were conducted. Surface-water and pore-water samples were 

analyzed for major constituents, nutrients, and stable isotopes 

of oxygen and hydrogen. No attempt was made to identify 

areas of ground-water inflow or surface-water outseepage to 

local aquifers in deeper water beyond the littoral zone of the 

lake. Bulk precipitation samples were collected and analyzed 

for nutrient concentrations to determine nutrient input to the 

lakes through atmospheric deposition and for stable isotope 

ratios of oxygen and hydrogen to determine a meteoric waterline that was needed for the stable isotope analyses of surfacewater and pore-water samples. 

Total nitrogen concentrations in the precipitation samples 

ranged from 0.51 to 8.4 mg/L as nitrogen at the North Lake 

precipitation station and from 0.42 to 2.3 mg/L as nitrogen at 

the Grand Portage precipitation station. These concentrations 

are similar to the total nitrogen concentrations measured for 

bulk precipitation at the National Atmospheric Deposition 

Program/National Trends Network precipitation monitoring site at Hovland, Minnesota. Oxygen-18/oxygen-16 and 

deuterium/protium isotope ratios for most of the bulk precipitation samples lie relatively close to a meteoric waterline for 

precipitation in northern Wisconsin.

Analyses of existing aerial photographs, nearshore 

lake-sediment temperatures, and seasonal isotope ratios of 

surface-water and pore-water samples were the most valuable data for identifying locations of ground-water inflow and 

surface-water outseepage. Identified drainages and lineaments 

in the analyses of existing aerial photographs were valuable 

in directing the location of temperature measurements and 

pore-water sampling. Lake-sediment temperatures at potential 

ground-water inflow locations ranged from 4 to 16 oC, varying 

between lakes, seasons, and climatic conditions. Cooler-thannormal August 2004 air temperatures resulted in only small 

temperature differences between surface water and lake sediment at Taylor Lake, making it difficult to use lake-sediment 

temperatures to identify the location of ground-water inflow. 

Major constituent chemistry was valuable at Taylor Lake, and 

to a limited extent at North and Teal Lakes, in confirming 

results from the isotope and lake-sediment temperature data. 

The major constituent chemistry of inflowing ground water 

often was affected by cation adsorption, cation exchanges with 

hydrogen ions, and chelation occurring in the surrounding fens 

and swamps, in particular for pore-water samples collected 

from the Teal Lake area.

Ground-water inflow to North Lake likely occurs along 

the southwest and south shores, and along portions of the 

west, southeast, north, and northeast shores. Cooler temperatures in August 2003 occurred along the southwest, south, 

west, and southeast shores, and in isolated channels along the 

north and northeast shores of North Lake, indicating potential 

ground-water inflow at these locations. Analyses of oxygen 

and hydrogen isotopes from pore-water samples collected in 

August 2003 and May 2004 from North Lake indicate that 

ground-water inflow was occurring along the south, southwest, 

and potentially along the southeast shores. A mix of groundwater inflow and surface-water outseepage from North Lake 

likely occurs along portions of the north, northeast, southeast, 

and south shores, varying seasonally. Conflicting evidence 

for ground-water flow conditions exist for the northwest and 

north-northwest pore-water samples. Warm lake-sediment 

temperatures, similar to water temperatures in the lake, high 

dissolved oxygen concentrations, and relatively low ammonia 

concentrations along the northwest and north-northwest shores 

indicate that surface-water outseepage or little ground-water 

and surface-water interaction occurs at the locations. The 

high organic nitrogen concentration along the north-northwest 

shore further indicates the potential for surface-water outseepage. However, consistent stable isotope ratios for pore-water 

samples from the northwest and north-northwest shores 

indicate a mixing of surface water and some potential groundwater inflow. Only minor differences in the major constituent concentrations were seen between the surface-water and 

pore-water samples from North Lake area with the exception 

of iron and manganese concentrations. Dissolved silica, iron, 

and manganese concentrations were higher in all of the porewater samples than in the surface-water samples from North 

Lake, being notably higher in the south pore-water samples for 

August 2003 and May 2004 and the north-northwest porewater sample for May 2004.

Ground-water inflow likely takes place along the southsouthwest and north shores of Teal Lake, with a mixture of 

ground-water inflow and surface-water outseepage occurring 

in other areas of the lake. Cooler lake-sediment temperatures 

occurred along the south-southwest, west, and northwest 

shores, portions of the north shore, and in channels identified 

in aerial photographs throughout the lake, indicating potential 

ground-water inflow at those locations. Warmer lake-sediment 

temperatures along the northeast and portions of the southwest 

and northwest shores of Teal Lake indicate potential locations 

where surface-water outseepage or little ground-water and 

surface-water interaction occurs. The percentage distribution 

of major constituents is widely dispersed for the pore water 

in the Teal Lake area, with the major constituent chemistry 

of the surface-water sample being generally a mix of the 

chemistry of all of the pore-water samples. Major constituent 

concentrations were higher in the pore-water samples collected from the south-southwest and northeast shores of Teal 

Lake. Cation adsorption, cation exchanges with hydrogen 

ions, and chelation occurring in the fen surrounding the lake 

likely resulted in the low dissolved calcium, magnesium, and 

sodium concentrations in north, northwest, and west porewater samples from the Teal Lake area. Low sulfate concentrations in these samples likely result from sulfate reduction 

occurring in the fen substrate, with the production of hydrogen 

sulfide gas. The low chloride concentrations along the north 

and the southwest shores indicate that dilution may be causing 

the lower cation and anion concentrations at these locations. 

Pore-water samples from the south-southwest, north, and 

southwest shores of Teal Lake had isotopic compositions that 

plotted closest to the meteoric waterline, indicating that these 

locations may be where ground-water inflow was occurring. 

46  Ground-Water/Surface-Water Interaction of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota
Surface-water outseepage from Teal Lake likely occurs along 

the northeast shore, even though major constituent concentrations were high. Major constituent concentrations may be 

high because of a nearby beaver dam.

Ground-water inflow to Taylor Lake likely occurs along 

the north and south shores. Higher major constituent 

concentrations and the least evaporative isotope ratios were 

found in south, north, and west pore-water samples from the 

Taylor Lake area, indicating potential locations of groundwater inflow. However, a combination of warmer and cooler 

lake-sediment temperatures along the west lowland indicate 

that ground-water inflow and surface-water outseepage may 

occur at that location. Surface-water outseepage from Taylor 

Lake likely occurs along the south shore through a surfacewater drainage channel to a downgradient bog. Warmer 

lake-sediment temperatures along portions of the south and 

southeast shores indicate that surface-water outseepage may 

occur at those locations. Both ground-water inflow and surface-water outseepage may occur along the west, southeast, 

and east shores of Taylor Lake, varying seasonally and with 

local precipitation. 

Knowledge of general water-flow directions in lake 

watersheds and how they may change seasonally can help 

water-quality specialists and lake managers address a variety of water-quality and aquatic habitat protection issues for 

lakes. Results from this study indicate that ground-water and 

surface-water interactions at the study lakes are complex, and 

the ability of the applied techniques to identify ground-water 

inflow and surface-water outseepage locations varied among 

the lakes. Measurement of lake-sediment temperatures proved 

to be a reliable and relatively inexpensive reconnaissance 

technique that lake managers may apply in complex settings 

to identify general areas of ground-water inflow and surfacewater outseepage.

References

Alexander, S., Setterholm, D., Tipping, R., and Meyer, G., 

2001, The influence of ground water on the quality of lakes 

in the Carnelian-Marine Watershed District: Minneapolis, 

University of Minnesota, Report to the Carnelian-Marine 

Watershed District, 33 p.

Allen, D.E., Seyfried, W.E., and Tipping, R.G., 1997, Boron, 

bromide, and chloride in groundwaters and rocks of the 

North Shore of Lake Superior, evidence for seawater incursion into the Mid-Continent Rift, in 43rd Annual Institute 

on Lake Superior Geology Proceedings Volume: Program 

and Abstracts, v. 43, part 1, p. 1–2.

Baker, D.G., and Kuehnast, E.L., 1978, Climate of Minnesota, 

part X. Precipitation normals for Minnesota—1941–1970: 

Minneapolis, 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: Minneapolis, University of Minnesota Agricultural Experiment Station Technical Bulletin 

AD–SB 2777, 66 p.

Bares, R.H., and Wali, M.K., 1979, Chemical relations and 

litter production of Picea mariana and Larix laricina stands 

on an alkaline peatland in northern Minnesota: Vegetation, 

v. 40, p. 79–94.

Bureau of Indian Affairs, 2001, BIA enrollment and total 

resident service, area population by tribe, data from BIA 

Labor Force Report, and accepted corrections: Information 

available on the Web, accessed March 15, 2005, at 

http://brc.arch.uiuc.edu/ihbg/negreg/July/

response34_bia.pdf

Conant, B.C., Jr., 2004, Delineating and quantifying ground 

water discharge zones using streambed temperatures: 

Ground Water, v. 42, no. 2, p. 243–257.

Coplen, T.B., Wildman, J.D., and Chen, J., 1991, Improvements in the gaseous hydrogen-water equilibration technique for hydrogen isotope ratio analysis: Analytical 

Chemistry, v. 63, p. 910–912.

Davis, D.W., and Green, J.C., 1997, Geochronology of the 

North American Midcontinent rift in western Lake Superior 

and implications for its geodynamic evolution: Canadian 

Journal of Earth Sciences, v. 34, no. 4, p. 476–488. 

Dengnan, J.R., and Clark, S.C., Jr., 2002, Fracture-correlated 

lineaments at Great Bay, southeastern New Hampshire: U.S. 

Geological Survey Open-File Report 02–13, 14 p.

Epstein, S., and Mayeda, T., 1953, Variation of O-18 content 

of water from natural sources: Geochimica Cosmochimica 

Acta, v. 4, p. 213­–224.

Glaser, P.H., 1992, Vegetation and water chemistry, in Wright, 

H.E., Jr., Coffin, B.A., and Aaseng, N.E., eds., 1992, The 

patterned peatlands of Minnesota: Minneapolis, Minnesota, 

The University of Minnesota Press, p. 22–23.

Goldstein, R.M., 2000, Grand Portage Reservation environmental monitoring program: U.S. Geological Survey OpenFile Report 00–69, 13 p.

Green, J.C., 1982, Geologic map of Minnesota, Two Harbors 

sheet, bedrock geology: Minnesota Geological Survey, 

scale 1:250,000.

Harder, E.C., 1919, Iron depositing bacteria and their geologic 

relations: U.S. Geological Survey Professional Paper 113, 

89 p.

Hem, J.D., 1992, Study and interpretation of the chemical 

characteristics of natural water (3rd ed.): U.S. Geological 

Survey Water-Supply Paper 2254, 263 p., 2 pl.

References 47
Kendall, C., and Coplen, T.B., 2001, Distribution of oxygen18 and deuterium in river waters across the United States: 

Hydrological Processes, v. 15, p. 1363–1393.

Kendall, C., Evans, W.C., Reddy, M.M., and Schuster, P.F., 

1997, Applications of stable isotopes in the Shingobee River 

headwaters area, in Winter, T.C., ed., 1997, Interdisciplinary research initiative—hydrological and biogeochemical 

research in the Shingobee River headwaters area, northcentral Minnesota: U.S. Geological Survey Water-Resources 

Investigations Report 96–4215, p. 63–70.

Krabbenhoft, D.P., Bowser, C.J., Kendall, C., and Gat, J.R., 

1994, Use of oxygen-18 and deuterium to assess the hydrology of ground-water/lake systems, in Baker, L.A. ed., Environmental chemistry of lakes and reservoirs: Washington, 

D.C., American Chemical Society, Monograph no. 237, 

p. 67–90.

Lee, D.R., 1985, Methods for locating sediment anomalies in 

lakebeds that can be caused by groundwater flow: Journal 

of Hydrology, v. 79, p. 187–193.

Lodge, D.M., Krabbenhoft, D.P., and Striegl, R.G., 1989, A 

positive relationship between groundwater velocity and submersed macrophyte biomass in Sparkling Lake, Wisconsin: 

Limnology and Oceanography, v. 34, no. 1, p. 235–239.

Ludtke, A.S., Woodworth, M.T., and Marsh, P.S., 2000, Quality-assurance results for routine water analyses in U.S. Geological Survey laboratories, water year 1998: U.S. Geological Survey Water-Resources Investigations Report 00–4176, 

198 p.

Miller, J.D., Jr., Green, J.C., Severson, M.J., Chandler, V.W., 

Hauck, S.A., Peterson, D.M., and Wahl, T.E., 2002, Geology and mineral potential of the Duluth Complex and 

related rocks of northeastern Minnesota: Minnesota Geological Survey Report of Investigations 58, 207 p.

Miller, J.D., Jr., Green, J.C., Severson, M.J., Chandler, V.W., 

and Peterson, D.M., 2001, Geologic map of the Duluth 

complex and related rocks, northeastern Minnesota: Minnesota Geological Survey Miscellaneous Map M–119, 2 pl.

Minnesota Climatology Working Group, 2005, Historical 

climate data retrieval: Information available on the Web, 

accessed March 15, 2005, at http://climate.umn.edu/

hidradius/radius.asp

Minnesota Department of Natural Resources, 2003, Field 

guide to the native plant communities of Minnesota, the 

Laurentian Mixed Forest Province: St. Paul, Minnesota, 

Minnesota Department of Natural Resources, p. 198–200, 

203–204, 283–287.

Minnesota Department of Natural Resources, 2005, Digital 

orthophoto quadrangles—the Minnesota Department of 

Natural Resources Data Deli: Information available on 

the Web, accessed April 21, 2005, at http://maps.dnr.state.

mn.us/deli/metadata.html?id=L370000071006

Mitsch, W.J., and Gosselink, J.G., 1993, Wetlands (2nd ed.): 

New York, Van Nostrand Reinhold, p. 383–386.

Morey, G.B., 1981, Lineament map, Two Harbors sheet, Minnesota: Minnesota Geological Survey Miscellaneous Map 

M–45, 1 pl.

Naiman, R.J., Gilles, P., Johnston, C.A., and Pastor, J., 1994, 

Beaver influences on the long-term biogeochemical characteristics of boreal forest drainage networks: Ecology, v. 75, 

no. 4, p. 905–921.

National Atmospheric Deposition Program/National Trends 

Network, 2005, National Atmospheric Deposition Program/

National Trends Network wet deposition data for monitoring location MN08: Information available on the Web, 

accessed March 4, 2005, at http://nadp.sws.uiuc.edu/sites/

siteinfo.asp?id=MN08&net=NTN

Olcott, P.G., Ericson, D.W., Felsheim, P.E., and Broussard, W.L., 1978, Water resources of the Lake Superior 

watershed, northeastern Minnesota: U.S. Geological 

Survey Hydrologic Investigations Atlas HA–582, 2 sheets, 

scales 1:500,000 and 1:1,000,000.

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 Water-Resources Investigations Report 94–4044, 45 p.

Patton, C.J., and Kryskalla, J.R., 2003, Methods of analysis by 

the U.S. Geological Survey National Water-Quality Laboratory—evaluation of alkaline persulfate digestion as an alternative of Kjeldahl digestion for determination of total and 

dissolved nitrogen and phosphorus in water: U.S. Geological Survey Water-Resources Investigations Report 03–4174, 

33 p.

Robbins, E.I., LaBaugh, J.W., Merk, D.A., Parkhurst, R.S., 

Puckett, L.J., Rosenberry, D.O., Schuster, P.F., Shelito, P.A., 

and Soteroplos, T.P., 1997, Bacterial clues to ground water 

discharge sites—iron seeps in the Shingobee and Crow 

Wing watersheds, northern Minnesota, in Winter, T.C., 

ed., 1997, Interdisciplinary research initiative—hydrological and biogeochemical research in the Shingobee River 

headwaters area, north-central Minnesota: U.S. Geological 

Survey Water-Resources Investigations Report 96–4215, 

p. 177–186.

Rosenberry, D.O., Striegl, R.G., and Hudson, D.C., 2000, 

Plants as indicators of focused ground water discharge to 

a northern Minnesota lake: Ground Water, v. 38, no. 2, 

p. 296–303.

48  Ground-Water/Surface-Water Interaction of Three Lakes on the Grand Portage Reservation, Northeastern Minnesota
Rosenberry, D.O., and Winter, T.C., 1993, The significance 

of fracture flow to the water balance of a lake in fractured 

crystalline rock terrain, in Proceedings of the XXIVth Congress International Association of Hydrogeologists – Hydrogeology of Hard Rocks: As, Norway, 1993, p. 967–977.

Ruhl, J.F., 1995, Water resources of the Grand Portage Indian 

Reservation, northeastern Minnesota: U.S. Geological Survey Water-Resources Investigations Report 94–4199, 28 p.

Ruhl, J.F., 1997, Physical and chemical properties of water and 

sediments, Grand Portage and Wauswaugoning Bays, Lake 

Superior, Grand Portage Indian Reservation, northeastern 

Minnesota: U.S. Geological Survey Water-Resources Investigations Report 97–1999, 13 p.

Schneider, R., 1962, An application of thermometry to the 

study of ground water: U.S. Geological Survey WaterSupply Paper 1544–B, 16 p.

Schuster, P.F., Reddy, M.M., LaBaugh, J.W., Parkhurst, R.S., 

Rosenberry, D.O., Winter, T.C., Antweiler, R.C., and Dean, 

W.E., 2002, Characterization of lake water and ground 

water movement in the littoral zone of Williams Lake, a 

closed-basin lake in north-central Minnesota: Hydrological 

Processes, v. 17, p. 823–838.

Stonestrom, D.A., and Constantz, J., 2003, Heat as a tool 

for studying the movement of ground water near streams: 

U.S. Geological Survey Circular 1260, 96 p.

Tipping, R.G., and Allen, D., 1997, Hydrogeology of salineand boron-bearing ground waters in the North Shore 

Volcanic Group, Minnesota, in 43rd Annual Institute on 

Lake Superior Geology Proceedings Volume: Program and 

Abstracts, v. 43, part 1, p. 61–62.

U.S. Census Bureau, 2004, American FactFinder, population finder: Information available on the Web, accessed 

November 2, 2005, at http://factfinder.census.gov/servlet/

SAFFPopulation?_event=Search&geo_id=01000US&_

geoContext=01000US&_street=&_county=grand+portage

&cityTown=grand+portage&_state=04000US27&_zip=&_

lang=en&_sse=on&ActiveGeoDiv=geoSelect&_

useEV=&pctxt=fph&pgsl=010

U.S. Fish & Wildlife Service, 1994, National wetlands 

inventory digital data, October 1991 to 1994: Information 

available on Web, accessed March 11, 2005, at 

http://www.nwi.fws.gov

U.S. Geological Survey, 2005a, National field manual for the 

collection of water-quality data: Information available on 

the Web, accessed February 14, 2005, at 

http://www.geo.utexas.edu/courses/376l/

usgs_field_manual.htm

U.S. Geological Survey, 2005b, Quality assurance plan of the 

Reston Stable Isotope Laboratory: Information available on 

the Web, accessed February 14, 2005, at 

http://isotopes.usgs.gov/Quality.htm

U.S. Geological Survey, 2005c, Quality control at the U.S. 

Geological Survey National Water-Quality Laboratory: 

Information available on the Web, accessed February 14, 

2005, at http://nwql.usgs.gov/Public/pubs/QC_Fact/

text.html

U.S. Geological Survey, 2005d, Upper Midwest Gap Analysis Program: Information available on the Web, accessed 

March 11, 2005, at http://www.umesc.usgs.gov/

umgaphome.html

U.S. Geological Survey, 2005e, National Aerial Photography Program (NAPP): Information available on the Web, 

accessed April 21, 2005, at http://edc.usgs.gov/guides/

napp.html

U.S. Geological Survey, 2005f, USGS National Water-Quality 

Laboratory, use and documentation of standard laboratory 

procedures in the U.S. Geological Survey Water Resources 

Division: Information available on the Web, accessed October 31, 2005, at http://wwwnwql.cr.usgs.gov/USGS/

meth/WRDMethodCategory.html

U.S. Geological Survey, 2005g, NWISWeb data for Minnesota: Information available on the Web, accessed November 1, 2005, at http://waterdata.usgs.gov/mn/nwis/

U.S. Geological Survey, variously dated, National field manual 

for the collection of water-quality data: U.S. Geological 

Survey Techniques of Water-Resources Investigations, 

book 9, chaps. A1–A9, available online at 

http://pubs.water.usgs.gov/twri9A

Wetzel, R.G., 1983, Limnology (2nd ed.): Philadelphia, Pennsylvania, W.B. Saunders Company, p. 309–312.

Wilde, S.A., and Randall, G.W., 1951, Chemical characteristics of groundwater in forest and marsh soils of Wisconsin: 

Transactions of the Wisconsin Academy of Sciences, Arts 

and Letters, v. 40, p. 251–259.

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.

Winterstein, T.A., 2002, Hydrology and water quality of 

the Grand Portage Reservation, northeastern Minnesota, 

1991–2000: U.S. Geological Survey Water-Resources 

Investigations Report 02–4156, 35 p.

Wright, H.E., Jr., 1972, Quaternary history of Minnesota, in

Sims, P.K., and Morey, G.B., eds., 1972, Geology of Minnesota, a centennial volume: St. Paul, Minnesota, Minnesota 

Geological Survey, p. 515–546.

References 49