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

# Use of Thematic Mapper Imagery to Assess Water Quality, Trophic State, and Macrophyte Distributions in Massachusetts Lakes

**By MARCUS C. WALDRON, PETER A. STEEVES, and JOHN T. FINN (Department of Forestry and Wildlife Management,**  **University of Massachusetts, Amherst)**

Water-Resources Investigations Report 01-4016

**Prepared in cooperation with the Massachusetts Department of Environmental Management** 

Northborough, Massachusetts 2001

### U.S. DEPARTMENT OF THE INTERIOR GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY Charles G. Groat, Director

The use of trade or product names in this report is for identification purposes only and does not constitute endorsement by the U.S. Government.



### For additional information write to: Copies of this report can be purchased from:

Chief, Massachusetts-Rhode Island District U.S. Geological Survey U.S. Geological Survey Branch of Information Services Water Resources Division Box 25286 10 Bearfoot Road Denver, CO 80225-0286 Northborough, MA 01532
or visit our web site at **http://ma.water.usgs.gov Contents III**  

# CONTENTS

Abstract ....................................................................................................................... .......................................................... 1 Introduction ................................................................................................................... ........................................................ 2 Study Methods.................................................................................................................. ..................................................... 3 Sampling and Analysis for Water-Quality Characteristics ........................................................................ .................. 5 Field Observations............................................................................................................. ................................ 5 Phytoplankton-Chlorophyll Concentration ........................................................................................ ............... 5 Lake Color..................................................................................................................... .................................... 5 Dissolved Organic Carbon Concentration......................................................................................... ................ 8 Analytical Quality Assurance................................................................................................... ......................... 8 Quality Assurance of Volunteer Data ............................................................................................ .............................. 9 Thematic Mapper-Based Assessment of Water Quality and Trophic State............................................................ ............... 13 Secchi Disk Transparency and Phytoplankton-Chlorophyll Concentration........................................................... ..... 13 Lake Color and Dissolved Organic Carbon Concentration.......................................................................... ............... 15 Thematic Mapper-Based Assessment of Macrophyte Distributions ................................................................... .................. 16 Field-Mapping of Macrophyte Distributions ...................................................................................... ........................ 16 Digitization and Processing of Field Maps ...................................................................................... ........................... 17 Image Interpretation ........................................................................................................... ......................................... 18 Observed Versus Predicted Macrophyte Distributions............................................................................. ................... 19 1996 Predictions Based on 1996 Interpretations................................................................................. .............. 19 1997 Predictions Based on 1997 Interpretations................................................................................. .............. 19 1996 Predictions Based On 1997 Interpretations................................................................................. ............. 19 Summary and Conclusions........................................................................................................ ............................................ 26 References Cited ............................................................................................................... .................................................... 27

FIGURES 1. Map showing locations of study lakes and Landsat-5 Worldwide Reference System paths and rows for Massachusetts .................................................................................................................. ...................................... 6 2. Example of field form used in volunteer field-data collection program.......................................................... ...... 10 3. Graphs showing relations between volunteer and U.S. Geological Survey staff measurements of ( A ) Secchi disk transparency; ( B ) phytoplankton-chlorophyll concentration; ( C ) color; and ( D ) surfacewater temperature .............................................................................................................. .................................... 12 4, 5. Graphs showing: 4. Relations between Secchi disk transparency and phytoplankton-chlorophyll concentration in Massachusetts lakes in ( A ) 1996; ( B ) 1997; and ( C ) 1998............................................................................ 14 5. Relations between color and dissolved organic carbon concentration in Massachusetts lakes .................... 16 6. Graphs comparing observed (field-mapped in summer 1996) and predicted (interpreted from July 1996 Thematic Mapper data) areal coverages of four aquatic macrophyte cover classes coverages in 12 Massachusetts lakes ............................................................................................................ ................................... 20 7. Maps showing observed (field-mapped in summer 1996) and predicted (interpreted from July 1996 Thematic Mapper data) areal coverages of four aquatic macrophyte cover classes coverages in Whitehall Reservoir, Hopkinton, Massachusetts............................................................................................ ........................ 21 8. Graphs comparing observed (field-mapped in summer 1997) and predicted (interpreted from August 1997 Thematic Mapper data) areal coverages of four aquatic macrophyte cover classes coverages in 12 Massachusetts lakes ............................................................................................................ ................................... 22 9. Maps showing observed (field-mapped in summer 1997) and predicted (interpreted from August 1997 Thematic Mapper data) areal coverages of four aquatic macrophyte cover classes coverages in Thompson Pond, Spencer, Massachusetts .......................................................................................... ................... 23**IV Contents** 10. Graphs comparing observed (field-mapped in summer 1996) and predicted (interpreted from August 1997 Thematic Mapper data) areal coverages of four aquatic macrophyte cover classes coverages in 12 Massachusetts lakes ............................................................................................................ ................................... 24 11. Maps showing observed (field-mapped in summer 1996) and predicted (interpreted from August 1997 Thematic Mapper data) areal coverages of four aquatic macrophyte cover classes coverages in East Brimfield Reservoir, Brimfield and Sturbridge, Massachusetts..................................................................... ........ 25

TABLES 1. Thematic Mapper spectral bands ............................................................................................... ............................. 3 2. Massachusetts lakes for which the distributions of floating, emergent, and submerged macrophytes were mapped in 1996, 1997, and 1998 for calibration of Landsat-5 Thematic Mapper imagery ................................... 8 3. Lakes sampled by Massachusetts Water Watch Partnership volunteers concurrently with U.S. Geological Survey staff for chlorophyll concentration, Secchi disk transparency, color, and water temperature in 1997 and 1998....................................................................................................................... ........................................... 11 4. Landsat-5 Thematic Mapper scenes used to assess water quality and trophic state of Massachusetts lakes ......... 13 5. Thematic Mapper spectral bands and combinations of bands used as models to test for correlations with water-quality and trophic-state data for Massachusetts lakes................................................................... .............. 15 6. Massachusetts lakes sampled in 1996, 1997, and 1998, and numbers of measurements of water-quality characteristics used to calibrate Landsat-5 Thematic Mapper imagery............................................................ ...... 31 7. Lake-water-quality data collected within 24 hours of Landsat-5 Thematic Mapper imaging of the lakes, and haze-corrected digital numbers corresponding to the station locations in the images..................................... 37

CONVERSION FACTORS, VERTICAL DATUM, AND ABBREVIATED WATER-QUALITY UNITS

CONVERSION FACTORS

Very small units of length are reported in millimeters (mm), micrometers ( μ m), or nanometers (nm). One centimeter equals 10 mm, 1 mm equals 1,000 μ m, and 1 μ m equals 1,000 nm.

VERTICAL DATUM

Sea level: In this report, “sea level” refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929)—a geodetic datum derived from a general adjustment of the first-order level nets of the United States and Canada, formerly called Sea Level Datum of 1929.

ABBREVIATED WATER-QUALITY UNITS:

Chemical concentration is reported in milligrams per liter (mg/L) or micrograms per liter ( μ g/L). Milligrams per liter is a unit expressing the concentration of chemical constituents in solution as mass (milligrams) of solute per unit volume (liter) of water. One thousand micrograms per liter is equivalent to one milligram per liter. For concentrations less than 7,000 mg/L, the numerical value is the same as for concentrations in parts per million. Specific electrical conductance of water is reported in microsiemens per centimeter at 25 degrees Celsius ( μ S/cm). Color is reported in platinum-cobalt units (PCU). **Multiply By To obtain**

centimeter (cm) 0.3937008 inch (in.) cubic meter (m 3 ) 264.17205 gallon (gal) cubic meter (m 3 ) 35.31467 cubic foot (ft 3 ) hectare (ha) 2.471 acre kilometer (km) 0.62137 mile (mi) meter (m) 3.280840 foot (ft) milliliter (mL) 0.00026417 gallon (gal) Water temperature is reported in degree Celsius ( ̊C), which can be converted to degree Fahrenheit ( ̊F) by the following equation:  ̊F = 1.8 ( ̊C) +32**Abstract 1** 

# Use of Thematic Mapper Imagery to Assess Water Quality, Trophic State, and Macrophyte Distributions in Massachusetts Lakes

By Marcus C. Waldron, Peter A. Steeves, and John T. Finn

**Abstract**

During the spring and summer of 1996,1997, and 1998, measurements of phytoplanktonchlorophyll concentration, Secchi disk transparency, and color were made at 97 Massachusetts lakes within 24 hours of Landsat Thematic Mapper imaging of the lakes in an effort to assesswater quality and trophic state. Spatial distributions of floating, emergent, and submerged macrophytes were mapped in 49 of the lakes at least once during the 3-year period. The maps were digitized and used to assign pixels in the thematic mapper images to one of four vegetation coverclasses—open water, 1–50 percent floating-andemergent-vegetation cover, 51–100 percentfloating-and-emergent-vegetation cover, and submerged vegetation at any density. The field data were collected by teams of U.S. GeologicalSurvey and Massachusetts Department of Environmental Management staff and by 76 volunteers. Side-by-side sampling by U.S. Geological Survey and volunteer field teams resulted in statistically similar chlorophyll determinations, Secchi diskreadings, and temperature measurements, but concurrent color determinations were not similar, possibly due to contamination of sample bottles issued to the volunteers. Attempts to develop predictive relations between phytoplankton-chlorophyll concentration, Secchi disk transparency, lake color, dissolved organic carbon, and various combinations of thematic mapper bands 1, 2, 3, and 4 digital numbers were unsuccessful, primarily because of the extremely low concentrations of chlorophyll in the lakes studied, and also because of the highly variable dissolved organic carbon concentrations. Predictive relations were developed betweenSecchi disk transparency and phytoplanktonchlorophyll concentration, and between color and dissolved organic carbon concentration. Phytoplankton-chlorophyll concentration was inversely correlated with Secchi disk transparency during all three sampling periods. The relations were very similar in 1996 and 1997 and indicated that 62 to 67 percent of the variability in Secchi disk transparency could be explained by the chlorophyll concentration. Analysis of color and dissolved organic carbon concentrations in water samples collected by U.S. Geological Survey field teams in 1996–98 indicated that 91 percent of the variance in color in Massachusetts lakes can be explained by variations in dissolved organic carbon. Areas of open-water, submerged vegetation, and two surface-vegetation-cover classes predicted from Thematic Mapper images acquired in the summer of 1996 closely matched the areas observed in a set of field observations. However, the same analysis applied to a set of data acquired in the summer of 1997 resulted in somewhat less reliable predictions, and an attempt to predict 1996 vegetation-cover areas using the relations developed in the 1997 analysis was unsuccessful.**2 Use of Thematic Mapper Imagery to Assess Water Quality, Trophic State, and Macrophyte Distributions in Massachusetts Lakes** 

### INTRODUCTION

Accelerated eutrophication due to changing drainage-basin activities is a significant problem affecting Massachusetts lakes (Massachusetts Water Resources Commission, 1994). This accelerated, or cultural, eutrophication is caused by nutrient-richeffluents from sewage treatment plants, runoff of fertilizers and animal wastes, stormwater runoff from impervious surfaces, leaching from septic systems, and increased soil erosion resulting from construction and other similar activities. Cultural eutrophication can lead to excessive growth of aquatic macrophytes, increased turbidity, depletion of dissolved oxygen, and subsequent loss of fish habitat. Massachusetts lakes are especially susceptible to the problem because most drainage basins are heavily developed and most lakes are subject to multiple uses. In addition, many lakes in Massachusetts were created or enlarged by impounding water behind dams, resulting in submerged soils within these impoundments that may provide an additional source of nutrients affecting the trophic state of thelakes. Trophic state, the extent of the effect of eutrophication due to nutrient enrichment, has been difficult to quantify in Massachusetts because many lakes develop dense beds of aquatic macrophytes in response to eutrophication, and most methods for assessing trophic state are based on the relative abundance of phytoplankton algae and do not take into account the biomass of macrophytes (Canfield and others, 1983). The recently adopted Massachusetts Policy onLake and Pond Management advocates a comprehensive approach to lake eutrophication that integrateseducation, watershed protection, and in-lake management in an attempt to reconcile desired uses of Massachusetts lakes with their ability to support those uses (Massachusetts Water Resources Commission, 1994). Central to the Massachusetts Policy on Lake and Pond Management is the need to assess lake-water quality at regular intervals and to identify trends (both negative and positive) in lake trophic state. With more than 3,000 named lakes, ponds, and reservoirs (for simplicity, the word “lake” will be used throughout this report to refer to any open body of water) inMassachusetts, the costs and logistical problems associated with a statewide lake-quality-monitoring program are substantial. The development of satellite resources such asthe Landsat Thematic Mapper (TM) and new techniques for processing and analyzing satellite data offer the potential for augmenting the data-collection and resource-evaluation efforts of State environmental agencies. Landsat images can provide high-resolutioninformation concerning a number of important limnologic features, including chlorophyll- a concentration,turbidity, color, algal production rates, nutrient concentrations, and surface-water temperatures (Scarpace and others, 1979; Verdin, 1985; Raitala, 1986; Shimoda and others, 1986). The availability of Landsat imagesdating back to the early 1970s allows for the development of long-term records of properties related to lake trophic state and can be used to identify trends (Witzig and Whitehurst, 1981; Lillesand and others, 1983).The U.S. Geological Survey (USGS), in cooperation with the Massachusetts Department of Environmental Management (MADEM), has investigated the use of Landsat TM data for Statewide assessment of lake quality and trophic state. Measurements of water temperature, Secchi disk transparency, color, and the concentration of phytoplankton chlorophyll were made in 97 lakes during the summers of 1996, 1997, and 1998, by USGS and MADEM staff and by a team of trained volunteers recruited by the MassachusettsWater Watch Partnership (MassWWP). The lake measurements were timed to coincide with Landsat-5 TMimaging of the State. During the same period, the midto-late-summer distributions of floating, emergent, and submerged macrophytes were mapped in 62 lakes, again by a combination of professional and volunteer field teams. The field data were correlated with data extracted from a set of four TM images, each image representing the eastern two-thirds of the State.**Study Methods 3** 

### The purpose of this report is to demonstrate how Landsat TM data may be used to assess the water quality and trophic state of Massachusetts lakes and to monitor the distributions of aquaticmacrophytes. The report describes methods of fielddata collection and procedures used for acquiring and processing the TM data. Field data collected byvolunteer water-quality monitoring teams are compared statistically with concurrent measurementsmade by USGS field teams. Results are presented separately for TM-based assessment of lake-water quality and trophic state and for TM-based mapping of lake-macrophyte distributions. Data collected during the study are available via the World Wide Web at http://ma.water.usgs.gov/lakesandponds/.
The authors wish to thank the volunteers and staff of the Massachusetts Water Watch Partnership for their generous contributions of time and other resources to this project. 

### STUDY METHODS

Landsat-5 orbits the earth at an altitude of 705 km in a near-polar, sun-synchronous orbit with a 16-day, 233-orbit repeat cycle. The primary imaging instrument on Landsat-5 is the TM, which senses reflected light energy in seven spectral bands, three in the visible range, three in the near- and mid-infrared,and one in the thermal infrared (table 1). The TM sensors have a spatial resolution of 120-by-120 m for the thermal-infrared band and 30-by-30 m for the other six spectral bands. The sensors can distinguish 256 levels of brightness (radiance) in each spectral band for each 30-by-30 m or 120-by-120 m picture element (pixel). The brightness levels are recorded as digital numbers (DNs) representing the average radiance measured over the ground area corresponding to each pixel.

**Table 1.** Thematic Mapper spectral bands

**Spectral**

**band Wavelength range**  **(micrometers) Nominal spectral**  **location Principal Application(s)** 

1 0.45–0.52 Blue-green Designed for maximum penetration of water. Used for bathymetric mapping of shallow water bodies. Also used for distinguishing soil from vegetation and deciduous from coniferous trees. 2 0.52–0.60 Green Designed to measure green reflectance peak of vegetation. Useful for assessing plant vigor. 3 0.63–0.69 Red Designed to measure light that is strongly absorbed by chlorophyll. Used for discriminating vegetation types. 4 0.76–0.90 Near infrared Useful for determining vegetation types, vigor, and biomass. Also used for distinguishing shorelines of water bodies. 5 1.55–1.75 Mid-infrared Measures moisture content of soil and vegetation. Penetrates thin clouds. Used to distinguish snow from clouds. 6 10.4–12.5 Thermal infrared Nighttime images are useful for thermal mapping and for estimating soil moisture. 7 2.08–2.35 Mid-infrared Measures absorption by hydroxyl ions in minerals. Used for mapping hydrothermally altered rocks associated with mineral deposits. Also sensitive to vegetation moisture content.**4 Use of Thematic Mapper Imagery to Assess Water Quality, Trophic State, and Macrophyte Distributions in Massachusetts Lakes** 

### Landsat imagery is subdivided into scenes based on a Worldwide Reference System (WRS) consisting of vertical paths and horizontal rows. Each combination of path and row describes a unique 185-by-170-kilometer rectangle of ground-surface area. The State of Massachusetts is represented by WRS paths 11, 12, and 13, and by rows 30 and 31 (fig. 1); however, because adjacent paths overlap by as much as 40 percent, most of the State appears in paths 12 and 13. If the images are shifted north along the two paths, then about 90 percent of the State can be imaged in only two scenes. Use of TM imagery to assess lake quality andtrophic state requires that predictive relations be developed between measured water-quality characteristics and the TM data. Ideally, these relations are based on measurements made at or close to the time of TM-data acquisition on a large number of lakes exhibiting the range of conditions likely to be encountered in theState. The 16-day Landsat-5 orbital repeat cycle provides about 10 opportunities for image acquisition between May 1 and September 30. However, thenumber of lakes that could be sampled during each flyover was limited by the small number of State and USGS personnel, boats, and equipment available for use in the study. The solution to this problem was to engage the Massachusetts Water Watch Partnership (MassWWP), which is affiliated with the University of Massachusetts and the Massachusetts Water Resources Research Center in Amherst, Mass., to recruit and train volunteers to sample lakes throughout the State.A total of 76 individuals participated as volunteers during the three spring–summer sampling periods. Twenty-one volunteers were involved in the first sampling period (1996), 61 during the second sampling period (1997), and 39 during the third sampling period (1998). All volunteers were trained in lake-sampling and sample-processing techniques in a series of hands-on training sessions conducted each spring by MassWWP, MADEM, and USGS staff. Equipment was provided to the volunteers for measuring Secchi disk transparency, for collecting and processingwater samples to be analyzed for color and phytoplankton-chlorophyll concentration, and for mapping distributions of macrophytes in the lakes. The volunteers’ efforts greatly increased the amount of water-quality data collected concurrently with TM image acquisition. MADEM and USGS field personnel collected data at 94 stations on 65 lakes and volunteers collected data at 68 stations on 48 lakes. Sixteen of the lakes were sampled jointly by USGS and volunteers for quality assurance purposes. Volunteers were able to collect data each time the satellite was overhead from May through September. Most of thelakes sampled by MADEM and USGS could be sampled only once due to resource limitations. A list of the study lakes, their locations, and the numbers and kinds of water-quality measurements made during the three study periods is presented in table 6 (at back of report). In addition, distributions of floating, emergent, and submerged macrophytes were mapped in 49 lakes at least once during the study either by volunteers or by professional field personnel (table 2). Selection of the study lakes was determinedpartly by the study requirement that the lakes be representative of lakes throughout the State and partly by other circumstances, including the affiliations andinterests of the volunteers and the program requirements of the MADEM. Most of the volunteers liveclose to the lakes they sampled. The MADEM collected data primarily from lakes in State parks, forests, and reservations. Additional lakes were added to thelist to ensure that the full range of trophic and waterquality conditions were represented in the data set. The lakes ranged in surface area from 4 to 696 ha with a median surface area of 36 ha. Seventy-five percent of the lakes had surface areas of 81 ha or less. Maximum depths of the lakes ranged from 2 to 30 m with a median of 7 m. Seventy-five percent of the lakes were less than 10 m deep.**Study Methods 5** 

### Sampling and Analysis for **Water-Quality Characteristics**

Sampling stations were established over the deepest part of each study lake. For lakes with surface areas greater than about 81 ha, or with multiple basins, as many as six stations were established and monitored separately. Stations either were marked with a buoy or were located by aligning two pairs of landmarks on the shore spaced at a 90 degree angle relative to the station. Exact locations (latitude and longitude) of stations sampled by USGS field teams were determined by a global positioning system (GPS). All other stations were marked on appropriate USGS 1:25,000-scale topographic sheets and their locations determined with a digitizer. Orbital schedules for Landsat-5 were obtained for each study period from the Earth Observation Satellite Company (EOSAT) in Lanham, Md. Sampling usually was scheduled for the morning of the flyover to coincide with the 9:45 a.m. equatorial crossing of the satellite, although data collected up to 24 hours before or after image acquisition were considered acceptable.

**Field Observations** 

### Upon arriving at a station, samplers completed a field form (fig. 2) in which they identified the lake and the station, and recorded maximum depth, percent cloud cover, barometric pressure, and air temperature. Surface-water temperature was measured either witha digital thermometer or with a standard alcohol thermometer. Secchi disk transparency was determined by lowering a standard 20-centimeter Secchi disk intothe water and noting the exact depth at which it disappeared, then raising the disk and noting the depth at which it reappeared. The Secchi disk transparency was recorded as the mean of the two readings to the nearest 0.1 m. Exact times of all field observations were recorded on the field sheet. **Phytoplankton-Chlorophyll Concentration** 



### Water samples for phytoplankton-chlorophyll determinations were collected by hand in brown plastic 1-liter bottles from a depth of about 0.25 m below the surface. The samples were returned on ice to shore where measured volumes were filtered onto 47 mmWatman GF/F glass-fiber filters using a maximum suction pressure of 0.5 atmospheres. The filters were folded in half and placed in a drying chamber where they were air dried at room temperature for 30 minutes. The dried filters were wrapped in aluminum foil and mailed overnight to the Environmental Analytical Laboratory at the University of Massachusetts, Amherst, for analysis. In the laboratory, the filterswere ground in alkalized 90-percent acetone and analyzed spectrophotometrically for chlorophyll- a and phaeophytin- a concentrations (American Public Health Association and others, 1995). For the purposes ofthis study, the phytoplankton-chlorophyll concentration was considered to be the sum of the measured chlorophyll- a and phaeophytin- a concentrations.

**Lake Color**



### Filtrate produced during field processing of the chlorophyll samples was transferred to clean, prelabeled glass or polyethylene bottles, which were shipped on ice overnight to the University of Massachusetts, Amherst, for analysis of color. Lake color was determined spectrophotometrically in a 5-centimeter cell at a wavelength of 425 nm. The measured absorbance was converted to platinum-cobalt units (PCU) with a standard curve (American Public Health Association and others, 1995).**6 Use of Thematic Mapper Imagery to Assess Water Quality, Trophic State, and Macrophyte Distributions in Massachusetts Lakes Figure 1.**  Locations of study lakes and Landsat-5 Worldwide 73 ° 00 ́

42 ° 30 ́ 72 ° 30 ́ 72 ° 00 ́

42 ° 00 ́ 

## 1

4

5 6 8

1 10

9 3

2 7

11

12

CONNECTICUT VERMONT NEW HAMPSHIRE

NEW YORK



## WRS PATH 13 ROW 31 **WRS PATH 13 ROW 30**

11009

33014
33019

12002 21083

21078 21005 33009

33017 33012

21011

21043 21044 32013

31004

31027 31044

31052 32055 36142 34051 34103 35035 35074
35017 35095

35090

81157 35041

36005

36173

36082

36155

36150

41016 41014 41008 41052 42005

42036

EXPLANATION

RIVER DRAINAGE BASINS 1. Hudson 11. Nashua 18. North Coastal 22. Cape Cod 2. Housatonic 12. Blackstone 19. Boston Harbor 23. Islands 3. Deerfield 13. Merrimack a.Mystic 24. Buzzards Bay 4. Westfield 14. Concord b.Neponset 25. Taunton 5. Farmington a.Assabet c.Weymouth 26. Narragansett Bay 6. Connecticut b.Concord and Wier and Mt. Hope 7. Millers and Sudbury 20. Charles Bay Shore 8. Chicopee 15. Shawsheen 21. South Coastal 27. Ten Mile 9. Quinebaug 16. Parker a.North and 10. French 17. Ipswich South River b.South Coastal Shore BASIN BOUNDARY

SUBBASIN BOUNDARY

NOMINAL LOCATION OF SATELLITE PATH OR ROW BOUNDARY. THE WORLDWIDE REFERENCE SYSTEM ( **WRS** ) NUMBERS ARE SHOWN IN **HELVETICA OBLIQUE** TYPE STUDY LAKE WITH POND AND LAKE IDENTIFICATION SYSTEM NUMBER 21043

0 40 80 MILES

0 40 80 KILOMETERS 46  ̊

72  ̊ 70  ̊ 68  ̊

ATLANTIC OCEAN INDEX MAP OF NEW ENGLAND STATES

44  ̊

42  ̊ MAINE
NEW YORK CANADA CANADA

VERMONT

NEW YORK CONNECTICUT RHODE ISLAND MASSACHUSETTS NEW HAMPSHIRE USA USA**Study Methods 7** 

## 11

14a
14b

20 13

21b

23 23 12

26 27 19b 18

21a 19a 16

9 17 15

25

24 22 19c

10

26

50 MILES

0

50 KILOMETERS 0 71 ° 30  ́ 71 ° 00  ́

70 ° 00  ́

70 ° 30  ́

41 ° 30  ́ 70 ° 30  ́ ATLANTIC OCEAN

Massachusetts Bay

Nantucket Sound RHODE ISLAND NEW HAMPSHIRE

81154

81153 81007

51027 51118 51024

51152

51179

51172 42064

96012 72008 72140 82061

82003

51112 82120

73062

62205 72125 82029 82058 82015 82042 HIGH ST. IMPOUNDMENT

82104 82119 82092 82011 82110 82118 82109 84001 91010

93014

71019 71047

71040

72017

72052

94007

95034
95119 95030 95054 95025

95151

96155 96302 96307 96218

96198 96333 62108

96039

96170

96091 

## WRS PATH 12 ROW 30

**WRS PATH 12 ROW 31**

**WRS PATH 11 ROW 31**

Reference System paths and rows for Massachusetts.**8 Use of Thematic Mapper Imagery to Assess Water Quality, Trophic State, and Macrophyte Distributions in Massachusetts Lakes Dissolved Organic Carbon**  **Concentration**


### Samples for DOC determinations were fi ltered through 0.45- μ m-pore-size silver fi lters into baked brown-glass bottles using a stainless steel fi ltration system. The samples were then stored on ice prior to analysis. DOC determinations were carried out by the Environmental Analytical Laboratory at the University of Massachusetts, Amherst. Analysis of DOC was by wet oxidation with carbon dioxide detection by infrared spectroscopy (Fishman and Friedman, 1989). **Analytical Quality Assurance** 

### Twelve sets of duplicate samples were collected at various sampling sites during the study and analyzedseparately for DOC by the USGS National Water Quality Laboratory and the University of Massachusetts Environmental Analytical Laboratory. Differences between DOC determinations by the two laboratoriesranged from 18 to 40 percent with a mean of 26 percent. Concentration differences among 12 duplicate determinations made by the Environmental Analytical Laboratory ranged from 0 to 18 percent with a mean of **Table 2.** Massachusetts lakes for which the distributions of floating, emergent, and submerged aquatic macrophytes were mapped in 1996, 1997, and 1998 for calibration of Landsat-5 Thematic Mapper imagery

[PALIS, Pond and Lake Identi fi cation System; X, mapped; blank space, not mapped; ---, no assigned code]

**Lake name PALIS**  **code 1996 1997 1998** 

**Floating Emer**  **gent Sub**  **merged Floating**  **Emer gent**  **Sub merged**  **Floating Emer**  **gent Sub**  **merged**

Althea Lake 84002 X X X Ashmere lake 21005 X X X Bare Hill Pond (USGS) 81007 X X X Bare Hill Pond (USGS) 81007 X X Bearse Pond 96012 X X
Big (Benton) Pond 31004 X X X Buckley-Dunton Lake 32013 X X X Charge Pond 95025 X X Chebacco Lake 93014 X X X Coes Reservoir 51024 X X X

Cook Pond 51027 X X Curlew Pond 95034 X X X Dudley Pond 82029 X X East Brim fi eld Reservoir (East) 41014 X X X East Brim fi eld Reservoir (West) 41014 X X X
Fearing Pond 95054 X X X Goose Pond 21043 X X X Greenwater Pond 21044 X X X Heard Pond 82058 X X X High Street Impoundment --- X X X

Horn Pond 71019 X X X X X X X X X Mauserts Pond 11009 X X X Merino Lake 42036 X X X Metacomet Lake 34051 X X Onota Lake 21078 X**Study Methods 9** 

### 7 percent. Color determinations made on the same sets of duplicates differed by 4 to 10 percent with a mean of 6 percent.Twelve sets of duplicate phytoplankton chlorophyll samples were analyzed during the study period by the University of Massachusetts Environmental Analytical Laboratory. The percent difference between duplicates ranged from 7 to 100 and the mean percent difference was 28. The highest percent differences were obtained from samples with extremely low chlorophyll concentrations (less than 1.0 μ g/L). 

### Quality Assurance of **Volunteer Data**

Measurements of phytoplankton-chlorophyll concentration, Secchi disk transparency, color, andwater temperature were made simultaneously at 26 stations on 16 lakes (table 3) by USGS and volunteer fi eld teams to determine the reproducibility and reliability of the data. Measurements usually were made from the same boat. Samples were processed separately by each team and were shipped together to the analytical laboratory. **Table 2.** Massachusetts lakes for which the distributions of floating, emergent, and submerged aquatic macrophytes were mapped in 1996, 1997, and 1998 for calibration of Landsat-5 Thematic Mapper imagery

— Continued

**Lake name PALIS**  **code 1996 1997 1998** 

**Floating Emer**  **gent Sub**  **merged Floating**  **Emer gent**  **Sub merged**  **Floating Emer**  **gent Sub**  **merged**

Patch Reservoir 51118 X X X Pequot Pond 32055 X X X Pontoosuc Lake 21083 Puffer Pond (USGS) 82092 X X X Puffer Pond 82092 X X X X
Rocky Pond 95119 X X X Spy Pond 71040 X X Sugden Reservoir 36150 X X X X X Thompson Pond 36155 X X X X X X X X Upper Spectacle Pond 31044 X X X

Waban Lake 72125 X X X X X X X X X Walden Pond 82109 X X X Wallum Lake (lower) 51172 X X Warners Pond 82110 X X X Webster Lake 42064 X X
Wequaquet Lake 96333 X X X White Pond (Concord) 82118 X X X X X X Whitehall Reservoir (NE) 82120 X X X Whitehall Reservoir (NW) 82120 X X X Whitehall Reservoir (SW) 82120 X X X
Winnekeag Lake 81157 X X Winter Pond 71047 X X X X X X X X X Winthrop Lake 72140 X X X X X X York Lake 31052 X X X**10 Use of Thematic Mapper Imagery to Assess Water Quality, Trophic State, and Macrophyte Distributions in Massachusetts Lakes** 

# USGS-MADEM-MassWWP Lake and Pond FIELD DATA

**Name of Lake: PALIS Code: Station No: Lat: Long:**  **Sampled By: Date:**

**Field Measurements ns =not sampled Time of Measurement**  **Maximum Depth: meters/feet Cloud Cover: % am/pm**  **Barometric Pressure: mmHg/inHg am/pm**
**Air Temperature: o**  

### C/ **o** 

### F am/pm
**Surface Water Temperature: o**  

### C/ **o** 

### F am/pm **Secchi Disk Depth: meters/feet am/pm**



## Water Samples Collected
**Date/Time of Sample: Collection Preparation Shipping Vol. Filtered (L)**  **Chlorophyll:**
**Color:**
**DOC:**



## Remarks

**Conversions Multipl**  **y b**  **y T**  **o obtain Feet 0.3048 Meters**  **Gallons 3.7853 Liters Atmospheres 760 mmHg**  **Pounds/sq in 51.715 mmHg**

**Temperature can be converted to degrees Celsius ( o**  **C) from degrees Fahrenheit ( o**  **F) by the following equation:**

**o C = (**  **o F-32) / 1.8** 

**Figure 2.** Example of field form used in volunteer field-data collection program.**Study Methods 11** 

### Comparisons of measurement results obtained by the two sampling teams are presented in fi gures 3 A through 3 B . There was good agreement betweenvolunteer and USGS Secchi disk transparency determinations ( fi g. 3 A ). The percent difference between the two sets of measurements ranged from 0 to 24 and the mean percent difference was 8. The two sets of phytoplankton-chlorophyll determinations were more variable ( fi g. 3 B ). Percent differences ranged from 7 to 54 and the mean was 24 percent. At concentrations greater than 7 μ g/L, the USGS samples consistently yielded 2

– 3 μ g/L more chlorophyll than did the volunteer samples. Agreement between color measurements made on USGS and volunteer water samples was not good ( fi g. 3 C ). Differences ranged from 2 to 200 percent. The mean percent difference was 72. The large differences may have resulted from inadequate cleaning of the volunteer sample containers. All USGS samples were submitted to the laboratory in baked glass bottles while volunteer samples were submitted in polyethylene bottles that had been used in a previous investigation.Comparisons of water temperature measurements were reasonably good ( fi g. 3 D ), given the fact that different types of measuring devices were used. Percent differences between USGS and volunteer measurements ranges from 0 to 17 with a mean of 3 percent. **Table 3.** Lakes sampled by Massachusetts Water Watch Partnership volunteers concurrently with U.S. Geological Survey staff for chlorophyll concentration, Secchi disk transparency, color, and water temperature in 1997 and 1998

[Raw data available on the Internet at http://water.usgs.gov. PALIS, Pond and Lake Identi fi cation System; USGS, U.S. Geological Survey; X, water samples collected or measurements made concurrently; --, not measured]

**Lake name Sampling**  **station PALIS**  **code Chlorophyll Secchi Color**  **Water Temperature** 
**Sampling**

**date USGS WWP USGS WWP USGS WWP USGS WWP** 

Long Pond 1 62108 8-27-97 X X -- -- X X X X Long Pond 2 62108 8-27-97 X X -- -- X X X X Long Pond 3 62108 8-27-97 X X -- -- X X X X Long Pond 4 62108 8-27-97 X X -- -- X X X X Long Pond 5 62108 8-27-97 X X -- -- X X X X
Long Pond Deep hole 62108 8-27-97 -- -- X X -- -- -- --

Lower Naukeag Lake 1 35041 8-04-98 X X X X -- -- X X Onota Lake 1 21078 6-01-98 X X X X X X X X Onota Lake 3 21078 6-01-98 X X X X X X X X Pontoosuc Lake 1 21083 6-01-98 X X X X X X X X

Stearns Mill Pond 1 82104 7-12-98 X X -- -- X X X X Upper Naukeag lake 1 35090 8-04-98 X X X X X X X X Wallum Lake 1 51172 6-10-98 X X X X X X X X Watatic Lake 1 35095 8-04-98 X X X X X X X X Webster Lake 1 42064 6-10-98 X X X X X X X X

Webster Lake 2 42064 6-10-98 X X X X X X X X White Pond (Concord) 1 82118 8-13-98 X X X X X X X X White Pond (Hudson/Stow) 1 82119 7-12-98 X X X X X X X X Whitins Reservoir 1 51179 6-10-98 X X X X X X X X Whitins Reservoir 2 51179 6-10-98 X X X X X X X X

Willet Pond 1 73062 7-28-98 X X X X X X X X Winnekeag Lake 1 81157 8-04-98 X X X X X X X X**12 Use of Thematic Mapper Imagery to Assess Water Quality, Trophic State, and Macrophyte Distributions in Massachusetts Lakes** 0 1 2 3 4 5 6 7 8

012345678
SECCHI DISK TRANSPARENCY MEASURED BY U.S. GEOLOGICAL SURVEY STAFF, IN METERSSECCCHI DISK TRANSPARENCY MEASUREDBY VOLUNTEERS, IN METERS

0 2 4 6 8 10 12 14 16 18

0 2 4 6 8 10 12 14 16 18 CHLOROPHYLL CONCENTRATIONS IN U.S. GEOLOGICAL

SURVEY SAMPLES, IN MICROGRAMS PER LITERCHLOROPHYLL CONCENTRATIONS IN VOLUNTEERSAMPLES, IN MICROGRAMS PER LITER 0 20 40 60 80 100

0 20 40 60 80 100
LAKE COLOR IN U.S. GEOLOGICAL SURVEY

SAMPLES, IN PLATINUM-COBALT UNITSLAKE COLOR IN VLOUNTEER SAMPLES,IN PLATINUM-COBALT UNITS **A.**

**B. C.** 

**D.**

18 19 20 21 22 23 24 25 26 27 28

18 19 20 21 22 23 24 25 26 27 28

WATER TEMPERATURE MEASURED BY U.S. GEOLOGICAL SURVEY STAFF, IN DEGREES CELSIUSWATER TEMPERATURE MEASURED BY VOLUNTEERS,IN DEGREES CELSIUS

**Figure 3.** Relations between volunteer and U.S. Geological Survey staff measurements of ( A ) Secchi disk transparency; ( B

) phytoplankton-chlorophyll concentration; ( C ) color; and ( D ) surface-water temperature. (Dotted line is line of one-to-one correspondence of paired measurements.)**Thematic Mapper-Based Assessment of Water Quality and Trophic State 13** 

### THEMATIC MAPPER-BASED **ASSESSMENT OF WATER QUALITY AND TROPHIC STATE** 

At the end of each spring

– summer study period, the available TM images were examined and ranked according to their degree of atmospheric interferencedue to haze and cloud cover, and the amount of lakewater-quality data available for correlation with pixelbrightness values. On this basis, four scenes were purchased from the USGS Earth Resources Observation Systems (EROS) Data Center (EDC) in Sioux Falls, South Dakota. Scene identi fi cation codes and other descriptive information are presented in table 4.Each scene comprises picture elements (pixels) representing either 30-by-30 m (for visible and re fl ectedinfrared (IR) wave bands) or 120-by-120 m (for the thermal-IR wave band) ground-resolution cells. This study used data from visible TM wave bands 1 (TM1, 0.45

– 0.52 μ m), 2 (TM2, 0.52

– 0.60 μ m), and 3 (TM3, 0.63

– 0.69 μ m), and re fl ected-IR wave band 4 (TM4, 0.76-0.90 μ m). Data for each pixel consist of digital numbers (DNs) ranging from 0 to 255 that represent the recorded intensity of re fl ected radiation in one of the wave bands. The scenes were radiometrically and geometrically corrected, rotated, and aligned to state plane coordinates by the EDC. Lake-water-quality data collected within 24 hours of acquisition of each TM scene were compiled and the brightness values for pixels corresponding to the station locations were extracted from the TM images. Brightness values for the three visible bands (TM1, TM2, and TM3) were then corrected for haze by regressing them against the corresponding values for the re fl ected-IR band (TM4). In the absence of scattering due to haze and other atmospheric irregularities, the intercepts of the regression lines should pass through the origin (Wilkie and Finn, 1996). In all four scenes, the regression lines intercepted the TM4 axes at some positive value, indicating the need for correction. The band was adjusted by the amount that the intercept shifted from the origin (Wilkie and Finn, 1996). Thecorrected TM values, plus the corresponding lakewater-quality data used in the analysis, are presented in table 7 (at back of report).



### Secchi Disk Transparency and **Phytoplankton-Chlorophyll Concentration** 

Phytoplankton-chlorophyll concentration was inversely correlated with Secchi disk transparency during all three sampling periods ( fi g. 4). The regression equations for the relations in 1996 and 1997 weresimilar, and indicated that 62 to 67 percent of the variability in Secchi disk transparency could be explained by the chlorophyll concentration. The unexplained variability is due to a combination of sampling andanalytical errors, variations in lake color, and the presence of suspensoids other than phytoplankton algae (Goldman and Horne, 1983). The relation was shifted signi fi cantly in the 1998 dataset. The slope of the regression line was similar tothat calculated for the previous two years, but the yintercept was nearly doubled, so that chlorophyll concentrations associated with a given Secchi disk transparency increased by an average of 135 percent over the previous two years. The apparent increase may be related to a change in the analytical instrumentation used in the Environmental Analysis Laboratory that
year. Secchi disk transparency values and phytoplankton-chlorophyll data corresponding to the four TM scenes were analyzed using simple linear regression to develop relations that could be used to predict the water-quality characteristics from the TM data. Twenty-eight combinations of haze-corrected DNs for TM bands 1, 2, 3, and 4 were used as models in the analysis (table 5). The analytical approach was to plot **Table 4** . Landsat-5 Thematic Mapper scenes used to assess water-quality and trophic state of Massachusetts lakes

[EDC, Earth Resources Observation Systems (EROS) Data Center; WRS, Worldwide Reference System]

**EDC scene identification**  **Image acquisition**  **date WRS**  **path WRS** 

**row**

LT5012031009620410 7-22-66 012 031.00000 LT5013030009720610 6-23-97 012 030.97174 LT5012030009723810 8-26-97 012 030.97000 LT5012031009816110 6-10-98 012 031.98000**14 Use of Thematic Mapper Imagery to Assess Water Quality, Trophic State, and Macrophyte Distributions in Massachusetts Lakes** -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0

-1.5 -0.5 0.5 1.5 2.5 3.5 log(Chlorophyll) = -1.229 log(Secchi) + 2.670

R 2 = 0.621

n = 65, p < 0.0001

NATURAL LOGARITHM OF SECCHI DISK TRANSPARENCYNATURAL LOGARITHM OFCHLOROPHYLL CONCENTRATION

**A** . 1996
-2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0

-1.5 -0.5 0.5 1.5 2.5 3.5 log(Chlorophyll) = -1.345 log(Secchi) + 2.470

R 2 = 0.676

n = 156, p < 0.0001 2

**B.**

1997NATURAL LOGARITHM OFCHLOROPHYLL CONCENTRATION

NATURAL LOGARITHM OF SECCHI DISK TRANSPARENCY



### the natural logarithms of the Secchi disk transparencies versus the phytoplankton-chlorophyll concentrations for a given scene to determine if the expected inverserelation existed between the two datasets. Obvious outliers were discarded and the remaining natural-logtransformed lake data were regressed against each of the TM models listed in table 5. No relations were observed that could be applied consistently to all the scenes and only a few of the models explained morethan 60 percent of the variability in either the chlorophyll or the Secchi disk data. The lack of any predictive relations between the TM data and phytoplankton-chlorophyll concentration or Secchi disk transparency was surprising given the long history of successful use of TM data to predict thewater quality and trophic state of inland waters. Beginning with the work of Lathrop and Lillesand (1986), who used some of the earliest available TM data toassess chlorophyll concentration, Secchi disk transparency, turbidity, and the concentration of suspended solids in Green Bay and central Lake Michigan, researchers have reported on the ability of the TM to resolve differences in these parameters. More recently, Khorram and others (1991) and Baban (1993, 1997)reported successful correlation of lake chlorophyll concentration and Secchi disk transparency with TM data using the same methods and TM models as this study. The most important difference between thesestudies and the current one is the extremely low concentrations of phytoplankton chlorophyll typicallyfound in Massachusetts lakes. Chlorophyll concentrations in the study lakes ranged from 0.5 to 84.5 μ g/L. However, the mean chlorophyll concentration was only 6.0 μ g/L and the median concentration was 3.1 μ g/L. Median chlorophyll concentrations in lakes studied by Lillesand and others (1983) generally were much higher, often ranging from 30 to more than 100 μ g/L. Values of that magnitude were observed in fewer than 5 of the 97 lakes included in this study. In addition, color of the study lakes ranged from less than 1 to 547 PCU, with a mean of 91 and a median of 49 PCU. The wide variation in color may have introduced **Figure 4.** Relations between Secchi disk transparency and phytoplankton-chlorophyll concentration in Massachusetts lakes in ( A ) 1996; ( B ) 1997; and ( C ) 1998.**Thematic Mapper-Based Assessment of Water Quality and Trophic State 15**NATURAL LOGARITHM OFCHLOROPHYLL CONCENTRATION

-2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0

-1.5 -0.5 0.5 1.5 2.5 3.5 log(Chlorophyll) = -1.140 log(Secchi) + 3.936

R 2 = 0.537

n = 192, p < 0.0001 2 

### C. 1998

NATURAL LOGARITHM OF SECCHI DISK TRANSPARENCY 

### additional variability into the relations betweenchlorophyll concentration, Secchi disk transparency, and the TM data. In any case, it appears that eutrophication of Massachusettslakes frequently is manifested more by proliferation of macrophytes than it is by growth of phytoplankton.



### Lake Color and Dissolved **Organic Carbon Concentration**

Analysis of color and dissolved organic carbon (DOC) concentrations in water samples collected by USGS fi eld teams in 1996

– 98 indicated that color in Massachusetts lakes largely is due to DOC. The relation, shown in fi gure 5, was highly signi fi cant with R 2 

### = 0.914. Samples collected by volunteers produced such variable results that no attempt was made to correlate them with TM data. **Figure 4.** Relations between Secchi disk transparency and phytoplankton-chlorophyll concentration in Massachusetts lakes in ( A ) 1996; ( B ) 1997; and ( C ) 1998

— Continued

.

**Table 5.** Thematic mapper spectral bands and combinations of bands used as models to test for correlations with water-quality and trophic-state data for Massachusetts lakes

[TM, Thematic Mapper; TM1, TM band 1; TM2, TM band 2; TM3, TM band 3; TM4, TM band 4]

TM1 TM4 ( ) 2 TM2 TM3 ------------ TM4 TM3

– TM4 TM3 + -------------------------------

TM2 TM1 ( ) ln TM1 TM2 ------------     ln TM2 TM1

– TM2 TM1 + -------------------------------

TM3 TM2 ( ) ln TM1 TM3 ------------     ln TM2 TM3

– TM2 TM3 + -------------------------------

TM4 TM3 ( ) ln TM2 TM3 ------------     ln TM4 TM3

– TM4 TM3 + -------------------------------     ln

TM1 ( ) 2 TM4 ( ) ln TM1 TM2 + 2 ------------------------------- TM2 TM1

– TM2 TM1 + -------------------------------     ln

TM2 ( ) 2 TM1 TM2 ------------ TM1 TM3 + 2 ------------------------------- TM2 TM3

– TM2 TM3 + -------------------------------     ln

TM3 ( ) 2 TM1 TM3 ------------ TM2 TM3 + 2 ------------------------------- TM2 TM3

–**16 Use of Thematic Mapper Imagery to Assess Water Quality, Trophic State, and Macrophyte Distributions in Massachusetts Lakes** 0 5 10 15 20 25 30

0 100 200 300 400 500 600
COLOR, IN PLATINUM-COBALT UNITS y

= 0.0437 x + 1.7106
R 2 = 0.914

n = 47, p < 0.0001

1996 1997 1998DISSOLVED ORGANIC CARBON CONCENTRATION,IN MILLIGRAMS PER LITER



### THEMATIC MAPPER-BASED **ASSESSMENT OF MACROPHYTE DISTRIBUTIONS** 

A method was developed for mapping distributions of macrophytes in lakes, ponds, and reservoirsusing TM images processed with a geographic information system (GIS). The TM-based mapping procedure consists of manually mapping the distributions of aquatic macrophyte beds in 10 to 15 representative lakes and relating the digitized fi eld-generated maps to a set of TM images of the lakes. These relations are then used to assign pixel-brightness values in the TM images to one of four vegetation-cover classes: open water (no macrophytes), moderately covered (up to 50 percent) with fl oating or emergent macrophytes, densely covered (51

– 100 percent) with fl oating or emergent macrophytes, and covered to any extent with submerged macrophytes. These vegetation-cover class assignments can then be extended to any lake that is visible in the same TM scene.



### Field-Mapping of Macrophyte **Distributions**

During 1996

– 98, distributions of fl oating, emergent, and submerged macrophytes were mapped in 44 Massachusetts lakes, ponds, and reservoirs by USGS and MADEM staff and by volunteers af fi liated with the MassWWP. Twenty-four sets of maps, 12 produced in 1996 and 12 produced in 1997 from 19 of the lakes,were used to develop the TM-based mapping procedure. Excessive cloud cover during mid-to-late summer 1998 precluded the use of maps produced in that year. The 19 lakes (table 2) are primarily in the eastern half of Massachusetts and represent the range of lake types in that part of the State. Surface areas of the lakes ranged from 7 to 233 ha with a median surface area of 29 ha. Maximum depths ranged from 2 to 16 m with a median depth of 6 m. Field-mapping was conducted in late summerafter the macrophytes had reached their maximum densities but before they began to senesce in early autumn. For each lake, a set of blank maps ( fi eld maps) was produced with a 1:24,000-scale (USGS Digital Line Graphs) outline of the lakeshore overlain by a lattice of cells representing the 30-by-30-meter spatial resolution of the TM images. These fi eld maps were used by observers to record the macrophyte distributions. Aquatic macrophyte beds were identi fi ed and mapped separately as fl oating, emergent, or submerged growth forms. Floating macrophytes, such as water lilies ( Nuphar sp., Nymphaea sp.) and water shield ( Brasenia schreberi ), commonly are found from the shoreline inward to depths of between 1 and 3 m. They may or may not be rooted in the sediments. Emergent macrophytes, such as cattails ( Typha sp.), **Figure 5.** Relations between color and dissolved organic carbon concentration in Massachusetts lakes.**Thematic Mapper-Based Assessment of Macrophyte Distributions 17** 

### grasses ( Phragmites sp.), rushes ( Juncus sp.), sedges ( Scirpus sp.), arrow arum ( Peltandra virginica ), and pickerelweed ( Pontederia cordata ), typically are rootedand have foliage that extends out of the water. Emergent macrophytes generally are found along the edges of lakes in shallow water rarely exceeding 1 m in depth. Submerged macrophytes, such as fanwort ( Cabomba sp.), various pondweeds ( Potamogeton sp., Najas sp.), coontail ( Ceratophyllum sp.), watermilfoil ( Myriophyllum sp.), and bladderwort ( Utricularia sp.), may occur from the shoreline across the entire lake bottom, but rarely extend beyond a depth of about 10 m because of hydrostatic pressure and the limited penetration of underwater light. Mapping of fl oating and emergent macrophytes consisted of moving slowly along the shoreline in a boat and recording the locations of the macrophyte beds on the fi eld maps. The lattice of 30-by-30 m cells superimposed on the lakeshore outline provided a scale by which observers could judge distances from the shore and accurately mark locations of the beds. The maps also indicated the positions of major landmarks such as roads, dams, and tributary streams, which provided additional reference points for mapping. Macrophyte density within the mapped beds was estimated by the observers as (1) open water, (2) sparse(greater than 0 but less than 25 percent cover), (3) moderate (greater than 25 percent but less than 50 percent cover), (4) dense (greater than 50 percent but less than75 percent cover), (5) very dense (greater than 75 percent cover but less than 100 percent cover), or (6) complete (100 percent cover). Visual comparison ofduplicate maps prepared at the same time by independent observers for three lakes in 1998 indicated that these density ranges were large enough to subsume minor differences or errors in the observers' density estimates. Mapping of submerged macrophytes consisted of establishing multiple transects extending from shore to shore across the lakes. Transects usually were spaced about 120 m apart, except in the largest lakes, wherethey were spaced about 200 m apart. Landmarks represented on the maps were used as control points in locating the transects. Sampling points were then located at intervals of 60 to 120 m along each transect, either by direct measurement with a range fi nder or by estimating the distance and marking the position relative to the30-by-30-meter cells printed on the map. At each sampling point, a weighted two-sided rake, 0.46 m in length, was lowered on a line and dragged along the lake bottom for a distance of about 2 m. The amount of plant material retrieved on the rake relative to that retrieved in an area with visible submerged vegetation was used to estimate the areal coverage of submerged macrophytes at that point. A submerged-vegetation distribution map was then produced for each lake based on the estimated areal coverages.



### Digitization and Processing of **Field Maps**

The hand-drawn fi eld maps of macrophyte distributions were digitized by scoring the centroid of each 30-by-30-meter cell as one of the six ranges of covervalues, based on the mapped locations of the macrophyte beds. The scores for each map were then used to populate the cells of a raster grid corresponding to the lattice originally plotted on the map. The resulting grids were vectorized, clipped into the lake shoreline boundaries, and merged into a single data layer for each vegetation-cover type. The three data layers were then merged into a single data layer, maintaining the cover values for each vegetation-cover type. Because the emergent vegetation was always close to the lake shorelines, and because it represented only a small part of the total covered area of most lakes, the cover values for fl oating and emergent vegetation types were combined into a single surfacevegetation type. Also, the six original vegetationcover classes were reduced to four summary classes:**18 Use of Thematic Mapper Imagery to Assess Water Quality, Trophic State, and Macrophyte Distributions in Massachusetts Lakes** 

### (1) open water, (2) 1

– 50 percent fl oating-andemergent-vegetation cover, (3) 51

– 100 percent fl oating-and-emergent-vegetation cover, and (4) submerged vegetation at all densities (when not hidden by surface vegetation), when preliminary analyses indicated a potential bias in favor of open water. The result of combining vegetation-cover classes with small areal distributions into larger summary cover classes was to reduce the in fl uence of the large areal extent of open water in many of the fi eld maps on the fi nal assignments of the TM pixel-brightness values.



### Image Interpretation

Data in the TM scenes were processed into ARC/INFO by creating raster grids for TM2, TM3, and TM4 DNs. Grids for individual lakes were generated from these three TM-scene raster grids and recti fi ed tothe lake grids. The individual lake grids were then vectorized, clipped into the lakeshore boundaries, and merged into a single data layer for each of the three TM bands. The three data layers were then merged into a single data layer maintaining the DNs for each TM band. The effects of atmospheric haze were removed from the data for TM2 and TM3 by subtracting thesmallest DNs for each wave band from all the brightness values for that wave band in the vector grid (Wilkie and Finn, 1996). For each 30-by-30-meter cell in the data layer, anormalized difference vegetation index (NDVI; Lillesand and Kiefer, 1994) was calculated using the hazecorrected DNs for TM3 and TM4 as follows:

This data layer was merged with the data layercontaining the four vegetation-cover classes. Inconsistencies in alignment of the 30-by-30-meter cells in thetwo data layers were corrected by bringing the combined data layer back into raster grid mode and using coordinates for each lake derived from the original TM images to rectify the cells in the vegetation-cover class data layer. The combined data layer was vectorized and 30-by-30-meter cells falling entirely within lakeshore boundaries were given a new attribute that differentiated them from the smaller cells that intersected the shorelines. Cells associated with islands in the lakes were similarly differentiated.

Cells that did not intersect with lake shorelines were grouped according to their NDVI values. For each NDVI value, the total areas were determined for the two surface vegetation-cover classes (1

– 50 percent and 51

– 100 percent fl oating and emergent) and for a hybrid vegetation-cover class consisting of open water and submerged vegetation. The vegetation-cover class comprising the largest total area of the three was then assigned to that NDVI value. In this way, each NDVI value in the dataset was associated with one of the three surface-vegetation cover classes or with open water. These associations were then used to assign vegetations cover classes to cells that intersected the lake shorelines. The vegetation-cover class assignments for each cell were then examined to determine if any should be changed based on the NDVI values of adjacent cells. If a given NDVI value predominated in the eight-cell neighborhood surrounding a cell, then that NDVI value was added to the cell as an alternative value. Next, allcells with that combination of NDVI value and alternative value were selected and assigned the vegetationcover class most frequently associated with the combination. In this way, some inconsistent assignments arising from the limited spatial resolution of the TM data were removed. To determine areas of submerged vegetation, all cells that were not assigned a surface-vegetation cover class in the NDVI analysis were isolated, and a ratio index was calculated by dividing the haze-corrected DNs for TM2 by those for TM3. The steps performedto assign NDVI values were then repeated on these isolated cells, the one difference being that the cells digitized as submerged vegetation were maintained and included as an option for assignment. NDVI TM 4 TM 3

– TM 4 TM 3 + ------------------------------ =**Thematic Mapper-Based Assessment of Macrophyte Distributions 19** 

### Observed Versus Predicted **Macrophyte Distributions**

Satellite images from July 22, 1996, and August26, 1997, were used, together with mapped distributions of 1996 and 1997 aquatic-vegetation cover in 19 study lakes, to develop predictive models relating the satellite data to the observed macrophyte distributions.Relations developed for the 1996 data were used to predict distributions in the original 1996 lakes, and relations developed for the 1997 data were used to predict distributions in the original 1997 lakes. Finally, the relations developed for the 1997 data were tested on the 1996 satellite scene and the predicted results compared with observed 1996 macrophyte distributions.

**1996 Predictions Based on 1996 Interpretations**  

### Figure 6 shows the relations between observed ( fi eld mapped in summer 1996) and predicted (interpreted from 1996 Thematic Mapper data) aquaticmacrophyte cover areas in twelve 1996 study lakes for each of the four vegetation-cover classes. For open water, the root-mean-squared-error (RMSE) of the prediction was 3.6 ha for observed cover areas ranging from 0 to 39.7 ha. Predicted open-watercover areas tended to be smaller than observed openwater cover areas. This result can been observed in fi gure 7, which shows maps of observed and predicted aquatic-vegetation cover for Whitehall Reservoir, in Hopkinton, Mass. Agreement between observed andpredicted cover areas for the other three vegetationcover classes was very good, with RMSE ranging from 1.3 ha for 51

– 100 percent fl oating-and-emergent-vegetation cover to 5.7 ha for submerged vegetation cover ( fi g. 6).

**1997 Predictions Based on 1997 Interpretations**  

### The TM-based maps developed from the 1997 data set did not match the observed 1997 maps as closely as did those developed from the 1996 data set. The TM-based mapping procedure predicted larger amounts of open-water cover area and smaller amounts of submerged vegetation cover area than were observed ( fi g. 8), although the RMSE values were similar tothose exhibited by the 1996 relations (6.3 ha for openwater cover and 5.3 ha for submerged vegetation cover). Lakes in the 1997 data set tended to have larger observed open-water cover areas than those in the 1996 data set ( fi g. 9). The median observed open-water cover area was 11.9 ha in the 1997 data set and 8.2 ha in the1996 data set. Similarly, observed cover areas for submerged vegetation were much smaller in the 1997 data set (median = 0.7 ha) than they were in the 1996 data set (median = 5.8 ha). Agreement between observed and predicted cover areas was better for the two fl oating-andemergent-vegetation cover classes (the RMSE was 2.5 ha for the 1

– 50 percent fl oating-and-emergent cover class and 1.1 ha for the 51

– 100 percent fl oatingand-emergent cover class) than it was for the open water and submerged-vegetation cover classes ( fi g. 8). Because most of the observed areas for these classes were very small (1.0 to 6.0 ha), however, the errors are signi fi cant.

**1996 Predictions Based on 1997 Interpretations** 


### An attempt to predict vegetation-cover class areas in the 1996 study lakes based on interpretations developed from the 1997 data set was unsuccessful. Large areas of submerged or fl oating and emergent vegetation were interpreted as open water for manylakes. Consequently, predicted cover areas for submerged vegetation and the 1

– 50 percent fl oating-andemergent-vegetation class were smaller than thecorresponding observed cover areas and had correspondingly large RMSE values [27.7 and 11.4 ha, respectively ( fi g. 10)]. The only exceptions were the areas predicted for the 51

– 100 percent fl oating-andemergent-vegetation cover class, which produced a RMSE of 1.1 ha over observed (1996) cover values ranging from 0 to 26.8 ha. The large discrepancy inpredicted versus observed areas of submerged vegetation can be seen in fi gure 11, which maps predicted and observed aquatic vegetation cover for East Brim fi eld Reservoir in Brim fi eld and Sturbridge, Mass.**20 Use of Thematic Mapper Imagery to Assess Water Quality, Trophic State, and Macrophyte Distributions in Massachusetts Lakes** 

### 0 10 20 30 40 50

0 10 20 30 40 50 RMSE = 3.6 ha 

## Open water

0 25 50 75 100 125 150

0 25 50 75 100 125 150 RMSE = 5.7 ha 

## Submerged vegetation

0 10 20 30 40 50 60

0 10 20 30 40 50 60 RMSE = 3.4 ha



## 1-50% Floating and emergent vegetation

0 10 20 30 40

0 10 20 30 40 RMSE = 1.3 ha 

## 51-100% Floating and

emergent vegetation

1996 OBSERVED COVER, IN HECTARES1996 PREDICTED COVER, IN HECTARES

**Figure 6.** Observed (field-mapped in summer 1996) and predicted (interpreted from July 1996 Thematic Mapper data) areal coverages of four aquatic macrophyte cover classes coverages in 12 Massachusetts lakes.**Thematic Mapper-Based Assessment of Macrophyte Distributions 21**EXPLANATION0 PERCENT VEGETATION (OPEN WATER)1 TO 50 PERCENT SURFACE VEGETATION51 TO 100 PERCENT SURFACE VEGETATIONSUBMERGED VEGETATIONOBSERVED VEGETATIONWHITEHALL RESERVOIR30 METER BY 30 METER CELLS30 METER BY 30 METER CELLSPREDICTED VEGETATIONWHITEHALL RESERVOIRLOCATION MAP

73  ̊ 00'

42  ̊ 30' 42  ̊ 00' 41  ̊ 30'

72  ̊ 00' 71  ̊ 00' 70  ̊ 00' ATLANTIC OCEAN Massachusetts Bay Nantucket Sound50 MILES050 KILOMETERS0**Figure 7.**Observed (field-mapped in summer 1996) and predicted (interpreted from July 1996 Thematic Mapper data) areal coverages of fouraquaticmacrophyte cover classes coverages in Whitehall Reservoir, Hopkinton, Massachusetts.**22 Use of Thematic Mapper Imagery to Assess Water Quality, Trophic State, and Macrophyte Distributions in Massachusetts Lakes** 

### 0 10 20 30 40 50

0 10 20 30 40 50

0 2 4 6 8 10 12 14 16

0 2 4 6 8 10 12 14 16 0 2 4 6 8 10 12 14

0 2 4 6 8 10 12 14

0 5 10 15 20

0 5 10 15 20 RMSE = 6.3 ha

RMSE = 2.5 ha RMSE = 5.3 ha

RMSE = 1.1 ha 

## Open water Submerged vegetation

1-50% Floating and emergent vegetation 51-100% Floating and emergent vegetation

OBSERVED COVER, IN HECTARESPREDICTED COVER, IN HECTARES

**Figure 8.** Observed (field-mapped in summer 1997) and predicted (interpreted from August 1997 Thematic Mapper data) areal coverages of four aquatic macrophyte cover classes coverages in 12 Massachusetts lakes.**Thematic Mapper-Based Assessment of Macrophyte Distributions 23**OBSERVED VEGETATIONTHOMPSON POND30 METER BY 30 METER CELLS30 METER BY 30 METER CELLSPREDICTED VEGETATIONTHOMPSON PONDEXPLANATION0 PERCENT VEGETATION (OPEN WATER)1 TO 50 PERCENT SURFACE VEGETATION51 TO 100 PERCENT SURFACE VEGETATIONSUBMERGED VEGETATIONLOCATION MAP

73  ̊ 00'

42  ̊ 30' 42  ̊ 00' 41  ̊ 30'

72  ̊ 00' 71  ̊ 00' 70  ̊ 00' ATLANTIC OCEAN Massachusetts Bay Nantucket Sound50 MILES050 KILOMETERS0**Figure 9.**Observed (field-mapped in summer 1997) and predicted (interpreted from August 1997 Thematic Mapper data) areal coverages of four aquaticmacrophyte cover classes coverages in Thompson Pond, Spencer, Massachusetts.**24 Use of Thematic Mapper Imagery to Assess Water Quality, Trophic State, and Macrophyte Distributions in Massachusetts Lakes** 

### 0 25 50 75 100 125 150

0 25 50 75 100 125 150 RMSE = 39.7 ha 

## Open water

0 25 50 75 100 125 150

0 25 50 75 100 125 150 RMSE = 27.7 ha 

## Submerged vegetation

0 10 20 30 40 50 60

0 10 20 30 40 50 60 RMSE = 11.4 ha 

## 1-50% Floating and emergent vegetation

0 5 10 15 20 25 30

0 5 10 15 20 25 30 RMSE = 1.1 ha 

## 51-100% Floating and

emergent vegetation

OBSERVED COVER, IN HECTARESPREDICTED COVER, IN HECTARES

**Figure 10.** Observed (field-mapped in summer 1996) and predicted (interpreted from August 1997 Thematic Mapper data) areal coverages of four aquatic macrophyte cover classes coverages in 12 Massachusetts lakes.**Thematic Mapper-Based Assessment of Macrophyte Distributions 25**OBSERVED VEGETATIONEAST BRIMFIELD RESERVOIR30 METER BY 30 METER CELLS30 METER BY 30 METER CELLSPREDICTED VEGETATIONEAST BRIMFIELD RESERVOIREXPLANATION0 PERCENT VEGETATION (OPEN WATER)1 TO 50 PERCENT SURFACE VEGETATION51 TO 100 PERCENT SURFACE VEGETATIONSUBMERGED VEGETATIONLOCATION MAP

73  ̊ 00'

42  ̊ 30' 42  ̊ 00' 41  ̊ 30'

72  ̊ 00' 71  ̊ 00' 70  ̊ 00' ATLANTIC OCEAN Massachusetts Bay Nantucket Sound50 MILES050 KILOMETERS0**Figure 11.**Observed (field-mapped in summer 1996) and predicted (interpreted from August 1997 Thematic Mapper data) areal coverages of four aquaticmacrophyte cover classes coverages in East Brimfield Reservoir, Brimfield and Sturbridge, Massachusetts.**26 Use of Thematic Mapper Imagery to Assess Water Quality, Trophic State, and Macrophyte Distributions in Massachusetts Lakes** 

### SUMMARY AND **CONCLUSIONS**

During the spring and summer of 1996, 1997, and 1998, measurements of phytoplankton- chlorophyll concentration, Secchi disk transparency, and color were made at 97 Massachusetts lakes within 24 hours of Landsat Thematic Mapper (TM) imaging of the lakes in an effort to use the TM imagery to assess lake-water quality. Spatial distribution of fl oating, emergent, and submerged macrophytes were mapped in 49 of the lakes at least once during the three-year period. The maps were digitized and used to assign pixels in the TM images to one of four vegetation cover classes

— open water, 1

– 50 percent fl oating-andemergent-vegetation cover, 51

– 100 percent fl oatingand-emergent-vegetation cover, and submerged vegetation at any density. Concurrent data collection and sampling by USGS and trained volunteer fi eld teams resulted in similar chlorophyll determinations, Secchi disk readings, and temperature measurements, but color determinations were highly variable, possibly due to contamination of sample bottles issued to the volunteers. Attempts to develop predictive relations between phytoplankton-chlorophyll concentration, Secchi disktransparency, lake color, dissolved oxygen concentration (DOC), and various combinations of TM band 1, 2, 3, and 4 digital numbers (DNs) were unsuccessful. The poor relations were primarily the result of the extremely low chlorophyll concentrations (median = 3.1 μ g/L) in the lakes studied, and also because of the highly variable DOC concentrations as indicated by color values ranging from less than 1 to 547 platinum-cobalt units (PCU). Predictive relations were developed betweenSecchi disk transparency and phytoplanktonchlorophyll concentration and between color andDOC concentration. Phytoplankton-chlorophyll concentration was inversely correlated with Secchi disk transparency during all three sampling periods. The regression equations for the relations in 1996 and 1997 were similar and showed that 62 to 67 percent of the variability in chlorophyll concentration could be explained by the Secchi disk transparency. Analysis of color and DOC concentrations in water samples collected by USGS fi eld teams in 1996

– 98 indicated that most of the color in Massachusetts lakes is due to DOC. Areas of open-water, submerged vegetation, and two surface-vegetation-cover classes predicted from TM images acquired in the summer of 1996 closely matched the areas observed in a set of fi eld observations. Agreement between observed and predicted 1996 submerged-macrophyte cover areas was at least as good as the 56- to 70-percent accuracy reported for mapping studies using visual interpretations of aerial photographs (Schloesser and others, 1987); however, the same analysis applied to a set of data acquired in the summer of 1997 resulted in somewhat less reliable predictions, and an attempt to predict 1996 vegetation cover areas using the relations developed in the 1997 analysis was unsuccessful. Differences in the predictive power of the two data sets appear to stem from differences in the relative sizes of the vegetation-cover areas used in the initial calibration of the NDVI values. The ranges of observed areas of the four vegetation-cover classes were similarin the 1996 data set. By contrast, open water predominated in lakes forming the 1997 data set, and the other vegetation-cover classes had much smaller and more variable ranges. Both the fi eld-mapping and the TMimaging processes are subject to error. Locations of the macrophyte beds indicated on the fi eld maps cannot be exact, and the TM images are limited by the 30-by-30- meter ground resolution of the instrument. Under these conditions, a preponderance of one type of vegetation cover class in the calibration data set is likely to result in more assignments of NDVI values to that cover class, simply because locational errors involving that cover class will tend to occur more frequently. It is also possible that the failure of the method to accurately predict the 1996 macrophyte distributions based on interpretations of 1997 data was due in part to this problem. Ideally, the method should be applied to a set of mapped lakes and then tested on a second set not used in the initial calibration. This was not possible given the limited number of fi eld maps available in the two data sets and the need for equal areal representation of**References Cited 27** 

### vegetation-cover classes. By careful selection of the initial set of lakes to ensure adequate representation of vegetation cover, it may be possible to use fewer lakes in the calibration process without sacri fi cing predictive power. The calibration data set also could be improved by using a global-positioning system to accurately locate and map the aquatic macrophyte beds.



### REFERENCES CITED

American Public Health Association, American Water Works Association, and Water Pollution Control Commission, 1995, Standard methods for the examination of water and wastewater (19th ed.): Washington, D.C., APHA, [variously paginated]. Baban, S.M.J., 1993, Detecting water quality parameters in the Norfolk Broads, U.K., using Landsat imagery: International Journal of Remote Sensing, vol. 14, no. 7, p. 1247

– 1267. _____1997, Environmental monitoring of estuaries; estimating and mapping various environmental indicators in Breydon Water Estuary, U.K., using Landsat TM imagery: Estuarine, Coastal, and Shelf Science, vol. 44, p. 589

– 598.
Can fi eld, D.E., Jr., Langland, K.A., Maceina, M.J., Haller, W.T., and Shireman, J.V., 1983, Trophic state classi fi cation of lakes with aquatic macrophytes: Canadian Journal of Fisheries and Aquatic Sciences, v. 40, p. 1713

– 1718. Fishman, M.J., and Friedman, L.C., eds., 1989, Methods for determination of inorganic substances in water and fl uvial sediments: U.S. Geological Survey Techniques of Water-Resources Investigations, book 5, chap. A1, 545 p. Goldman, C.R., and Horne, A.J., 1983, Limnology: New York, McGraw-Hill Book Co., 464 p. Khorram, Siamak, Cheshire, Heather, Geraci, Alberto L., and LaRosa, Guido, 1991, Water quality mapping of Agusta Bay, Italy, from Landsat-TM data: International Journal of Remote Sensing, vol. 12, no. 4, p. 803

– 808. Lathrop, R.G., Jr., and Lillesand, T.M., 1986, Use of Thematic Mapper data to assess water quality in Green Bay and central Lake Michigan: Photogrammetric Engineering and Remote Sensing, vol. 52, no. 5, p. 671

– 680. Lillesand, T.M., Johnson, W.L., Deuell, R.L., Lindstrom, O.M., and Meisner, D.E., 1983, Use of Landsat data to predict trophic state of Minnesota lakes: Photogrammetric Engineering and Remote Sensing, v. 49, no. 2, p. 219

– 229. Lillesand, T.M., and Kiefer, R.W., 1994, Remote sensing and image interpretation (3rd ed.): New York, John Wiley and Sons, Inc., 750 p. Massachusetts Water Resources Commission, 1994, Policy on lake and pond management: Boston, Massachusetts Water Resources Commission, Division of Water Resources, 5 p. Raitala, J.T., 1986, Satellite data in aquatic research

— Some ideas for future studies: Symposium on Remote Sensing for Resources Development and Environmental Management, Enschede, August, 1986, p. 755

– 758. Scarpace, F.L., Holmquist, K.W., and Fisher, L.T., 1979, Landsat analysis of lake quality: Photogrammetric Engineering and Remote Sensing, v. 45, no. 5, p. 623

– 633. Schloesser, D.W., Manny, B.A., Brown, C.L., and Jaworski, E., 1987, Use of low-altitude aerial photography to identify submersed macrophytes, in Color Aerial Photography in the Plant Sciences and Related Fields: Ann Arbor, University of Michigan, Proceedings of the 10th Biennial Workshop, 1984, p. 19

– 28. Shimoda, H., Etaya, M., Sakata, T., Goda, L., and Stelczer, K., 1986, Water quality monitoring of Lake Balaton using LANDSAT MSS data: Symposium on Remote Sensing for Resources Development and Environmental Management, Enschede, August, 1986, p. 765

– 770. U.S. Environmental Protection Agency, 1995, The state of the New England environment, 1970

– 1995: Boston, Mass., U.S. Environmental Protection Agency

– New England, Of fi ce of External Programs, 20 p. Verdin, J.P., 1985, Monitoring water quality conditions in a large western reservoir with Landsat imagery: Photogrammetric Engineering and Remote Sensing, v. 51, p. 343

– 353. Wilkie, D.S., and Finn, J.T., 1996, Remote sensing imagery for natural resources monitoring

— A guide for fi rst-time users: New York, Columbia University Press, 295 p. Witzig, A.S., and Whitehurst, C.A., 1981, Current use and technology of LANDSAT MSS data for lake trophic classi fi cation: Water Resources Bulletin, vol. 17, no. 6, p. 962

– 970.

# Tables 6 and 7**Table 6 31 Table 6.** Massachusetts lakes sampled in 1996, 1997, and 1998, and numbers of measurements of water-quality characteristics made for calibration of Landsat-5Thematic Mapper imagery—Continued**Lake name Sampling** **station PALIS** **code Town/city Drainage basin** **Sampled in: Total number of measurements 1996 1997 1998** **Chloro- phyll** **DOC Color Secchi Temper-** **ature**Lakes Sampled by Massachusetts Water Watch Partnership VolunteersBearse Pond 16 96012 Barnstable Cape Cod X X 8 -- 3 3 7Billington Sea 1 94007 Plymouth South Shore Coastal X 1 -- 2 3 3Billington Sea 3 94007 Plymouth South Shore Coastal X 1 -- 2 3 3Billington Sea 6 94007 Plymouth South Shore Coastal X 1 -- 2 3 3Boon Lake LBA1 82011 Stow/Hudson Assabet (Concord) X X X 6 -- 3 3 5Boon Lake LBA2 82011 Stow/Hudson Assabet (Concord) X X X 6 -- 1 3 3Boon Lake LBA3 82011 Stow/Hudson Assabet (Concord) X 2 -- -- -- --Buffumville Reservoir 1 42005 Oxford/Charlton French X 3 -- 3 3 3Carding Mill Pond 1 82015 Sudbury Sudbury (Concord) X X 2 -- 2 3 3Chabacco Lake 1 93014 Hamilton/Essex North Shore Coastal X -- -- -- 1 3Chandler Pond 1 72017 Boston Charles X X 5 -- 5 6 6Dudley Pond 1 82029 Wayland Sudbury (Concord) X 2 -- 4 4 4Fort Meadow Reservoir 1 82042 Marlborough/Hudson Assabet (Concord) X X 5 -- -- 1 2George Lake (Wales Pond) 1 41016 Wales Quinebaug X -- -- -- 1 1Goose Pond 1 21043 Lee/Tyringham Housatonic X X 10 -- 4 8 7Heard Pond 1 82058 Wayland Sudbury (Concord) X X X 10 -- 12 12 11High St. Impoundment 1 -- Maynard/Acton Assabet (Concord) X X 5 -- 4 5 5Horn Pond 1 71019 Woburn Mystic X X X 9 -- 8 10 10Jenkins Pond 1 96155 Falmouth Cape Cod X 4 -- 4 4 4Jenkins Pond 2 96155 Falmouth Cape Cod X 1 -- 1 1 1Long Pond 1 62108 Freetown/Lakeville Taunton X 5 -- 5 -- 6Long Pond 2 62108 Freetown/Lakeville Taunton X 5 -- 4 -- 6Long Pond 3 62108 Freetown/Lakeville Taunton X 5 -- 3 -- 6Long Pond 4 62108 Freetown/Lakeville Taunton X 5 -- 5 -- 6Long Pond 5 62108 Freetown/Lakeville Taunton X 5 -- 3 -- 6**Table 6.**Massachusetts lakes sampled in 1996, 1997, and 1998, and numbers of measurements of water-quality characteristics made for calibration of Landsat-5Thematic Mapper imagery[PALIS Code:PALIS, Pond and Lake Identification System.Total number of measurements:Chlorophyll, sum of chlorophyll-aand phaeophytin-aconcentrations; DOC, dissolved organic carbonconcentration; Secchi, Secchi disk transparency; Temperature, surface-water temperature. MADEM, Massachusetts Department of Environmental Management; S.F., State Forest; S.P., State Park;S.R., State Reservation; USGS, U.S. Geological Survey; --, not measured or unknown]**32 Use of Thematic Mapper Imagery to Assess Water Quality, Trophic State, and Macrophyte Distributions in Massachusetts Lakes**Lakes Sampled by Massachusetts Water Watch Partnership Volunteers—ContinuedLong Pond Deep hole 62108 Freetown/Lakeville Taunton X -- -- -- 1 1Lower Naukeag Lake 1 35041 Ashburnham Millers X X 10 -- 8 10 10Maspenock Lake Deep end 51112 Hopkinton/Milford Blackstone X X 11 -- 10 9 9Maspenock Lake Basin 51112 Hopkinton/Milford Blackstone X X 11 -- 9 8 8Merino Lake 1 42036 Dudley French X 13 -- 9 7 7Metacomet Lake Deep hole 34051 Belchertown Connecticut X X X 11 -- 11 11 11Middle Pond 1 96198 Barnstable Cape Cod X X 6 -- 4 8 8Mystic Lake 1 96218 Barnstable Barnstable X 2 -- 3 3 4Onota Lake 1 21078 Pittsfield Housatonic X X X 12 -- 11 18 15Onota Lake 2 21078 Pittsfield Housatonic X X X 5 -- 4 11 8Onota Lake 3 21078 Pittsfield Housatonic X 8 -- 6 7 7Pontoosuc Lake 1 21083 Pittsfield/Lanesboro Housatonic X X X 11 -- 9 18 14Puffer Pond 1 82092 Sudbury/Maynard Sudbury (Concord) X X X 14 -- 14 12 12Singletary Lake 1 51152 Sutton/Milbury Blackstone X X 2 -- 2 2 3Singletary Lake 2 51152 Sutton/Milbury Blackstone X 2 -- 2 2 2Snake Pond 1 96302 Sandwich Cape Cod X X 7 -- 4 7 7Spectacle Pond (Wilbraham) Beach 36142 Wilbraham Chicopee X 1 -- -- -- --Spectacle Pond (Wilbraham) Middle 36142 Wilbraham Chicopee X 2 -- -- 1 1Spectacle Pond (Sandwich) 1 96307 Sandwich Cape Cod X X 6 -- 2 2 6Spy Pond South 71040 Arlington Mystic X X 3 -- 3 5 1Spy Pond North 71040 Arlington Mystic X X 4 -- 4 4 8Stearns Mill Pond 1 82104 Sudbury Sudbury (Concord) X X X 14 -- 15 8 12Sugden Reservoir 1 36150 Spencer Chicopee X X 12 -- 11 13 13Thompson Pond 1 36155 Spencer Chicopee X X X 16 -- 10 19 21Thompson Pond 6 36155 Spencer Chicopee X -- -- 1 1 1Upper Naukeag Lake 1 35090 Ashburnham Millers X X 10 -- 9 11 11Waban Lake 2 72125 Wellesly Charles X X X 13 -- 11 13 13Wallum Lake 1 51172 Douglas Blackstone X X X 19 -- 14 15 10Warners Pond 1 82110 Concord Assabet (Concord) X X 5 -- 5 5 5Watatic Lake 1 35095 Ashburnham/Ashby Millers X X 10 -- 8 11 11**Table 6.**Massachusetts lakes sampled in 1996, 1997, and 1998, and numbers of measurements of water-quality characteristics made for calibration of Landsat-5Thematic Mapper imagery—Continued**Lake name Sampling** **station PALIS** **code Town/city Drainage basin** **Sampled in: Total number of measurements 1996 1997 1998** **Chloro- phyll** **DOC Color Secchi Temper-** **ature Table 6 33** Lakes Sampled by Massachusetts Water Watch Partnership Volunteers—ContinuedWebster Lake 1 42064 Webster French X X X 19 -- 19 16 10Webster Lake 2 42064 Webster French X X X 18 -- 18 14 15Wequaquet Lake 14 96333 Barnstable Cape Cod X X 9 -- 2 19 9Wequaquet Lake 15 96333 Barnstable Cape Cod X X 7 -- 2 7 7White Pond (Concord) 1 82118 Concord Sudbury (Concord) X X X 11 -- 12 12 12White Pond (Hudson/Stow) 1 82119 Hudson/Stow Assabet (Concord) X X X 10 -- 11 7 10Whitins Reservoir 1 51179 Douglas Blackstone X X X 15 -- 13 12 9Whitins Reservoir 2 51179 Douglas Blackstone X X 12 -- 11 10 11Willet Pond 1 73062 Walpole/Norwood/Westwood Neponset X X 3 -- 3 3 3Winnekeag lake 1 81157 Ashburnham Nashua X X 10 -- 10 11 11Winter Pond 1 71047 Winchester Mystic X X X 10 -- 10 10 9Winthrop Lake Deep hole 72140 Holliston Charles X X 4 -- 5 5 6Wyola Lake Center 34103 Shutesbury Connecticut X X X 12 -- 10 12 10Lakes Sampled by USGS and MADEM StaffAlthea Lake 1 84001 Lowel, Dracut, TyngsboroS.F.Merrimack X 2 -- 1 1 1Ashland Reservoir 1 82003 Ashland S.P. Sudbury (Concord) X 1 2 1 1 1Ashmere Lake 1 21005 Pittsfield S.F. Housatonic X 1 -- 1 1 1Ashmere Lake 2 21005 Pittsfield S.F. Housatonic X 1 -- 1 1 1Asnacomet Pond 1 36005 Hubbardston Chicopee X 1 1 1 1 1Babson Farm Quarry 1 -- Halibut Point S.P. North Shore Coastal X -- -- 1 1 1Benedict Pond Deep hole 21011 Beartown S.F. Housatonic X 2 -- 1 1 --Berry Pond Deep hole 12002 Pittsfield S.F. Kinderhook X 1 -- 1 1 1Big (Benton) Pond 1 31004 Otis S.F. Farmington X 1 -- 1 1 1Billington Sea 1 94007 Plymouth South Shore Coastal X 1 1 1 1 1Billington Sea 3 94007 Plymouth South Shore Coastal X 1 1 1 1 1Billington Sea 6 94007 Plymouth South Shore Coastal X 1 1 1 1 1Box Pond 1 72008 Bellingham/Mendon Charles X 1 -- 1 1 1Buckley-Dunton lake 1 32013 October Mt. S.F. Westfield X 1 -- 1 1 1Buckley-Dunton Lake Deep hole 32013 October Mountian S.F. Westfield X 1 -- 1 1 1**Table 6.**Massachusetts lakes sampled in 1996, 1997, and 1998, and numbers of measurements of water-quality characteristics made for calibration of Landsat-5Thematic Mapper imagery—Continued**Lake name Sampling** **station PALIS** **code Town/city Drainage basin** **Sampled in: Total number of measurements 1996 1997 1998** **Chloro- phyll** **DOC Color Secchi Temper-** **ature 34 Use of Thematic Mapper Imagery to Assess Water Quality, Trophic State, and Macrophyte Distributions in Massachusetts Lakes** Lakes Sampled by USGS and MADEM Staff—ContinuedBuckley-Dunton Lake Inlet 32013 October Mountian S.F. Westfield X 1 -- 1 1 1Cedar Pond 1 41008 Sturbridge Quinebaug X 1 1 1 1 1Charge Pond 1 95025 Myles Standish S.F. Buzzards Bay X 1 -- 1 1 1Cliff Pond 1 96039 Nickerson S.P. Cape Cod X 1 -- 1 1 1College Pond 1 95030 Myles Standish S.F. Buzzards Bay X 1 1 1 1 1Curlew Pond 1 95034 Myles Standish S.F. Buzzards Bay X 1 -- 1 1 1Denison Lake 1 35017 Otter River S.F. Millers X 1 4 1 1 1East Brimfield Reservoir 1 41014 Streeter Point Rec. Area Quinebaug X 1 1 1 1 1East Brimfield Reservoir 2 41014 Streeter Point Rec. Area Quinebaug X 1 1 1 1 1East Brimfield Reservoir 3 41014 Streeter Point Rec. Area Quinebaug X 1 1 1 1 1East Lake Waushacum 1 81153 Sterling Nashua X 1 -- 1 1 --Fearing Pond 1 95054 Myles Standish S.F. South Shore Coastal X 1 -- -- -- 1Flax Pond 1 96091 Nickerson S.P. Cape Cod X 1 -- -- -- 1Greenwater Pond 1 21044 October Mt. S.F. Housatonic X 1 -- 1 1 1Hallockville Pond 1 33009 Mohawk Trail S.F. Deerfield X 1 -- 1 1 1Hallockville Pond 2 33009 Mohawk Trail S.F. Deerfield X 1 -- 1 1 --Hopkinton Reservoir 1 82061 Hopkinton S.P. Sudbury (Concord) X 1 -- 1 1 1Jamaica Pond 1 72052 Boston Charles X 1 -- 1Laurel Lake 1 35035 Erving S.F. Millers X X 1 2 1 1 1Little Cliff Pond 1 96170 Nickerson S.P. Cape Cod X 1 -- 2 2 1Long Pond (Rutland) 1 36082 Rutland S.P. Chicopee X 1 2 1 1 1Long Pond 1 62108 Freetown/Lakeville Taunton X 1 1 1 -- 1Long Pond 2 62108 Freetown/Lakeville Taunton X 1 1 1 -- 1Long Pond 3 62108 Freetown/Lakeville Taunton X 1 1 1 -- 1Long Pond 4 62108 Freetown/Lakeville Taunton X 1 1 1 -- 1Long Pond 5 62108 Freetown/Lakeville Taunton X 1 1 1 -- 1Long Pond Deep hole 62108 Freetown/Lakeville Taunton X -- -- -- 1 1Lower Naukeag Lake 1 35041 Ashburnham Millers X X 1 1 1 1 1Mausert's Pond 1 11009 Clarksburg S.P. Hoosic X 1 -- 1 1 1Mcleod Pond Outlet 33012 Catamount S.F. Deerfield X 1 -- -- -- 1**Table 6.**Massachusetts lakes sampled in 1996, 1997, and 1998, and numbers of measurements of water-quality characteristics made for calibration of Landsat-5Thematic Mapper imagery—Continued**Lake name Sampling** **station PALIS** **code Town/city Drainage basin** **Sampled in: Total number of measurements 1996 1997 1998** **Chloro- phyll** **DOC Color Secchi Temper-** **ature Table 6 35** Lakes Sampled by USGS and MADEM Staff—ContinuedNorth Pond 1 33014 Savoy Mountain S.F. Deerfield X 1 -- -- -- --October Mountain Reservoir Deep hole -- October Mountian S.F. Housatonic X 1 -- 1 1 1Onota Lake 1 21078 Pittsfield Housatonic X X X 1 1 1 1 1Onota Lake 3 21078 Pittsfield Housatonic X 1 1 1 1 1Otis Reservoir 1 31027 Otis S.F. Farmington X -- -- 1 1 1Otis Reservoir 2 31027 Otis S.F. Farmington X -- -- 1 1 1Otis Reservoir 3 31027 Otis S.F. Farmington X -- -- 1 1 1Otis Reservoir 4 (outlet) 31027 Otis S.F. Farmington X -- -- 1 1 1Otis Reservoir 5 (northinlet)31027 Otis S.F. Farmington X -- -- -- -- 1Otis Reservoir 6 (southinlet)31027 Otis S.F. Farmington X -- -- -- -- 1Pentucket Pond Deep hole 91010 Georgetown Parker X 1 -- 1 1 --Pentucket Pond Inlet 91010 Georgetown Parker X 1 -- 1 1 --Pequot Pond 1 32055 Hampton Ponds S.P. Westfield X 1 -- 1 1 1Pequot Pond 2 32055 Hampton Ponds S.P. Westfield X 1 -- 1 1 1Plainfield Pond 1 33017 Plainfield Deerfield X 1 -- 1 1 1Pontoosuc Lake 1 21083 Pittsfield/Lanesboro Housatonic X X X 1 -- 1 1 1Rico Lake 1 -- Massasoit S.P. Taunton X 1 -- -- -- 1Rico Lake 2 -- Massasoit S.P. Taunton X 1 -- -- -- 1Rocky Pond 1 95119 Myles Standish S.F. South Shore Coastal X 1 -- 1 1 1Sheomet Lake 1 35074 Warwick S.F. Millers X X 2 -- 2 2 2South Pond 1 33019 Savoy Mountain S.F. Deerfield X 1 -- -- -- --Stearns Mill Pond 1 82104 Sudbury Sudbury (Concord) X X X 1 1 1 1 1Thompson Pond 1 36155 Rutland S.P. Chicopee X 1 -- 1 1 1Thompson Pond 2 36155 Rutland S.P. Chicopee X 1 -- 1 1 1Turner's Pond 1 95151 Acushnet Cedar Swamp S.R. South Shore Coastal X 1 1 1 1 1**Table 6.**Massachusetts lakes sampled in 1996, 1997, and 1998, and numbers of measurements of water-quality characteristics made for calibration of Landsat-5Thematic Mapper imagery—Continued**Lake name Sampling** **station PALIS** **code Town/city Drainage basin** **Sampled in: Total number of measurements 1996 1997 1998** **Chloro- phyll** **DOC Color Secchi Temper-** **ature 36 Use of Thematic Mapper Imagery to Assess Water Quality, Trophic State, and Macrophyte Distributions in Massachusetts Lakes** Lakes Sampled by USGS and MADEM Staff—ContinuedTurner's Pond 2 95151 Acushnet Cedar Swamp S.R. South Shore Coastal X 1 -- 1 1 1Turner's Pond 3 95151 Acushnet Cedar Swamp S.R. South Shore Coastal X 1 2 1 1 1Upper Naukeag Lake 1 35090 Ashburnham Millers X X 1 1 1 1 1Upper Spectacle Pond 1 31044 Otis S.F. Farmington X 1 -- 1 1 1Walden Pond Deep hole 82109 Walden Pond S.R. Concord X 1 -- -- -- 1Walker Pond 1 41052 Wells S.P. Quinebaug X 1 -- 1 1 1Walker Pond 3 41052 Sturbridge Quinebaug X 1 -- 1 1 1Wallum Lake 1 51172 Douglas S.F. Blackstone X 1 -- 1 1 1Watatic Lake 1 35095 Ashburnham/Ashby Millers X X 1 -- 1 1 1Watson Pond 6 62205 Taunton Taunton X 1 -- 1 1 1Webster Lake 1 42064 Webster French X X X 1 1 1 1 1Webster Lake 2 42064 Webster French X X X 1 1 1 1 1White Pond (Concord) 1 82118 Concord Sudbury (Concord) X X X 1 1 1 1 1White Pond (Hudson/Stow) 1 82119 Hudson/Stow Assabet (Concord) X X X 1 1 1 1 1Whitins Reservoir 1 51179 Douglas Blackstone X X X 1 1 1 1 1Whitins Reservoir 2 51179 Douglas Blackstone X X 1 1 1 1 1Whalom Pond 1 81154 Lunenburg/Leominster Nashua X 1 -- 1 1 1Whitehall Pond 1 36173 Rutland S.P. Chicopee X 1 1 1 1 1Whitehall Reservoir 1 82120 Hopkinton S.P. Sudbury (Concord) X 1 -- 1 1 1Whitehall Reservoir 2 82120 Hopkinton S.P. Sudbury (Concord) X 1 -- 1 1 1Whitehall Reservoir 3 82120 Hopkinton S.P. Sudbury (Concord) X 1 -- 1 1 1Willet Pond 1 73062 Walpole/Norwood/Westwood Neponset X X 1 1 1 1 1Winnekeag lake 1 81157 Ashburnham Nashua X X 1 -- 1 1 1York Lake 1 31052 Stansfield S.F. Farmington X 1 -- 1 1 1**Table 6.**Massachusetts lakes sampled in 1996, 1997, and 1998, and numbers of measurements of water-quality characteristics made for calibration of Landsat-5Thematic Mapper imagery—Continued**Lake name Sampling** **station PALIS** **code Town/city Drainage basin** **Sampled in: Total number of measurements 1996 1997 1998** **Chloro- phyll** **DOC Color Secchi Temper-** **ature Table 7 37** **Table 7.**Lake-water-quality data collected within 24 hours of Landsat-5 Thematic Mapper imaging of the lakes, and haze-corrected digital numbers correspondingto the station locations in the images—Continued**Station name PALIS code Station** **identifier Latitude** °′′′**Longitude**°′′′**Chloro phyll** **concentra tion** **Secchi disk trans** **parency Lake color** **Haze-corrected TM digital numbers TM Band 1 TM Band 2 TM Band 3 TM Band 4** July 22, 1996Ashland Reservoir 82003 1 42 14 42 71 27 41 4.9 2.2 85 5.1 3.6 5.2 9College Pond 95030 1 41 52 03 70 39 46 3.4 3.2 24 7.1 6.6 5.2 10Dudley Pond 82029 1 42 19 44 71 22 23 -- 1.5 135 18.1 13.6 14.2 22George Lake (Wales Pond) 41016 1 42 03 31 72 13 22 -- 3.0 -- 7.1 5.6 6.2 9Heard Pond 82058 1 42 21 13 71 23 01 -- .9 176 11.1 8.6 11.2 18Hopkinton Reservoir 82061 1 42 15 20 71 30 50 1.8 3.0 68 5.1 5.6 4.2 8Horn Pond 71019 1 42 28 13 71 09 30 5.6 2.2 -- 11.1 10.6 11.2 11Jamaica Pond 72052 1 42 19 04 71 07 12 1.3 5.6 9 10.1 7.6 7.2 11Singletary Lake 51152 1 42 09 40 71 46 50 -- 3.9 -- 8.1 5.6 5.2 9Thompson Pond 36155 2 42 18 30 71 58 10 7.4 1.3 234 14.1 6.6 8.2 13Turner's Pond 95151 1 41 40 46 70 58 40 4.6 .4 445 8.1 5.6 5.2 12Turner's Pond 95151 2 41 40 53 70 58 32 5.7 .5 383 12.1 10.6 10.2 20Turner's Pond 95151 3 41 41 05 70 58 26 7.6 .4 547 7.1 5.6 5.2 12Walden Pond 82109 1 42 26 20 71 20 31 1.3 6.2 62 22.1 13.6 13.2 22Wallum Lake 51172 1A 42 00 57 71 46 12 2.4 4.2 7 10.1 6.6 6.2 9Wallum Lake 51172 1B 42 00 57 71 46 12 2.2 4.9 15 10.1 6.6 6.2 9Whitehall Reservoir 82120 1 42 12 60 71 34 46 4.5 2.9 74 4.1 2.6 4.2 8Whitehall Reservoir 82120 2 42 13 53 71 34 06 3.1 2.1 103 6.1 3.6 4.2 8Whitehall Reservoir 82120 3 42 14 03 71 34 44 4.4 2.4 121 9.1 4.6 4.2 8Winthrop Lake 72140 1 42 11 23 71 25 26 -- 2.7 -- 4.1 3.6 5.2 9June 23, 1997Horn Pond 71019 1 42 28 13 71 09 30 5.4 1.9 34 28.2 18.0 24.1 16Lower Naukeag Lake 35041 1 42 39 52 71 57 38 2.9 1.9 30 23.2 11.0 17.1 12Maspenock Lake 51112 Deep end 42 12 10 71 33 29 1.9 -- 25 17.2 10.0 13.1 11Maspenock Lake 51112 Basin 42 11 29 71 33 20 2.9 -- 33 19.2 10.0 15.1 11Merino Lake 42036 1A 42 03 01 71 54 02 7.9 2.8 185 17.2 11.0 14.1 11**Table 7.**Lake-water-quality data collected within 24 hours of Landsat-5 Thematic Mapper imaging of the lakes, and haze-corrected digital numbers correspondingto the station locations in the images[PALIS code:PALIS; Pond and Lake Identification System.Latitude and longitude:In degrees, minutes, and seconds. PCU, platinum-cobalt units; TM, Thematic Mapper; m, meters; mg/L, microgramsper liter]**38 Use of Thematic Mapper Imagery to Assess Water Quality, Trophic State, and Macrophyte Distributions in Massachusetts Lakes**June 23, 1997—ContinuedMerino Lake 42036 1B 42 03 01 71 54 02 5.6 2.8 29 17.2 11.0 14.1 11Middle Pond 96198 1 41 40 18 70 24 59 .5 5.7 -- 35.2 20.0 27.1 20Pentucket Pond 91010 Deep hole 42 43 54 70 59 36 7.9 1.6 72 25.2 14.0 20.1 17Spy Pond 71040 1A 42 24 32 71 09 09 14.2 1.7 216 24.2 16.0 20.1 13Spy Pond 71040 1B 42 24 32 71 09 09 5.1 1.7 216 24.2 16.0 20.1 13Thompson Pond 36155 1 42 17 47 71 58 38 3.0 2.1 279 15.2 10.0 14.1 13Waban Lake 72125 2 42 17 14 71 18 35 2.2 3.8 137 18.2 11.0 14.1 11Walden Pond 82109 Deep hole 42 26 20 71 20 31 1.2 -- -- 18.2 11.0 12.1 10Wallum Lake 51172 1 42 00 57 71 46 12 1.2 5.2 22 18.2 11.0 13.1 10Warners Pond 82110 1A 42 47 52 71 24 08 10.5 1.7 308 22.2 11.0 18.1 14Warners Pond 82110 1B 42 47 52 71 24 08 7.1 1.7 80 22.2 11.0 18.1 14Webster Lake 42064 1A 42 03 14 71 50 56 2.4 4.0 10 20.2 12.0 16.1 11Webster Lake 42064 1B 42 03 14 71 50 56 1.6 4.0 15 20.2 12.0 16.1 11Webster Lake 42064 2 42 02 15 71 50 50 1.9 3.4 6 20.2 12.0 17.1 11White Pond (Concord) 82118 1 42 25 40 71 23 28 3.0 4.2 10 16.2 9.0 13.1 10Whitins Reservoir 51179 1 42 04 20 71 46 42 .9 4.4 21 20.2 11.0 15.1 12Winnekeag Lake 81157 1 42 39 48 71 53 55 2.8 2.3 45 15.2 10.0 13.1 10Winter Pond 71047 1 42 27 22 71 09 15 4.0 2.2 54 16.2 9.0 11.1 8August 26, 1997Bearse Pond 96012 16 41 40 35 70 20 00 6.4 3.1 -- 8.3 9.2 10.0 9Boon Lake 82011 LBA1 42 24 13 71 30 08 5.1 4.5 -- 14.3 10.2 10.0 11Boon Lake 82011 LBA2 42 23 47 71 29 39 10.6 2.1 -- 12.3 10.2 10.0 10Buffumville Reservoir 42005 1 42 56 47 71 18 17 3.3 3.3 51 16.3 10.2 11.0 12Chandler Pond 72017 1 42 20 41 71 09 58 -- .6 38 17.3 13.2 17.0 12Heard Pond 82058 1 42 21 13 71 23 01 71.1 .4 40 17.3 18.2 20.0 17Long Pond 62108 1A 41 48 43 70 56 39 3.1 -- 51 7.3 7.2 8.0 9Long Pond 62108 2A 41 48 06 70 56 29 2.6 -- 52 7.3 7.2 9.0 8Long Pond 62108 3A 41 46 43 70 56 56 5.8 -- 71 7.3 8.2 9.0 8Long Pond 62108 5A 41 48 47 70 57 09 1.9 -- 53 9.5 7.3 9.8 8**Table 7.**Lake-water-quality data collected within 24 hours of Landsat-5 Thematic Mapper imaging of the lakes, and haze-corrected digital numbers correspondingto the station locations in the images—Continued**Station name PALIS code Station** **identifier Latitude** °′′′**Longitude**°′′′**Chloro phyll** **concentra tion** **Secchi disk trans** **parency Lake color** **Haze-corrected TM digital numbers TM Band 1 TM Band 2 TM Band 3 TM Band 4** **Table 7 39**August 26, 1997—ContinuedLong Pond 62108 1B 41 48 43 70 56 39 2.4 -- 48 7.3 7.2 8.0 9Long Pond 62108 1C 41 48 43 70 56 39 -- -- 46 7.3 7.2 8.0 9Long Pond 62108 2B 41 48 06 70 56 29 1.5 -- 50 7.3 7.2 9.0 8Long Pond 62108 3B 41 46 43 70 56 56 3.7 -- -- 7.3 8.2 9.0 8Long Pond 62108 5B 41 48 47 70 57 09 2.1 -- -- 8.3 6.2 9.0 8Long Pond 62108 Deep hole 41 48 42 70 56 41 -- 2.1 -- 6.3 6.2 10.0 8Lower Naukeag Lake 35041 1 42 39 52 71 57 38 6.0 1.8 159 8.3 9.2 10.0 11Maspenock Lake 51112 Deep end 42 12 10 71 33 29 2.1 3.4 33 14.3 10.2 13.0 14Maspenock Lake 51112 Basin 42 11 29 71 33 20 2.0 2.1 26 13.3 11.2 13.0 11Merino Lake 42036 1 42 03 01 71 54 02 -- 2.1 -- 10.3 9.2 9.0 11Middle Pond 96198 1 41 40 18 70 24 59 1.9 4.4 -- 6.3 7.2 8.0 9Puffer Pond 82092 1 42 24 20 71 27 36 84.5 .4 132 16.3 18.2 21.0 15Thompson Pond 36155 1 42 17 48 71 58 38 1.7 3.2 78 12.3 8.2 11.0 13Upper Naukeag Lake 35090 1 42 39 39 71 55 50 -- 5.3 -- 12.3 10.2 8.0 10Waban Lake 72125 2 42 17 14 71 18 35 -- 2.7 -- 14.3 11.2 12.0 9Walden Pond 82109 Deep hole A 42 26 20 71 20 31 .9 3.5 -- 15.3 11.2 10.0 12Walden Pond 82109 Deep hole B 42 26 20 71 20 31 1.6 3.5 -- 15.3 11.2 10.0 12Watatic Lake 35095 1 42 40 49 71 56 22 -- 1.1 -- 10.3 9.2 10.0 12Wequaquet Lake 96333 15 41 40 08 70 20 28 6.1 2.6 -- 8.3 10.2 10.0 8White Pond (Concord) 82118 1 42 25 40 71 23 28 -- 8.8 -- 13.3 10.2 10.0 13Winnekeag Lake 81157 1 42 39 48 71 53 55 -- 3.1 -- 9.3 9.2 10.0 11June 10, 1998Maspenock Lake 51112 Deep end 42 12 10 71 33 29 4.5 3.0 42 8.5 5.5 8.7 11Maspenock Lake 51112 Basin 42 11 29 71 33 20 4.1 2.0 33 8.5 6.5 10.7 12Middle Pond 96198 1 41 40 18 70 24 59 1.8 5.6 3 15.5 10.5 16.7 16Mystic Lake 96218 1 41 40 32 70 25 02 5.4 4.3 1 13.5 10.5 14.7 16Puffer Pond 82092 1 42 24 20 71 27 36 16.1 .8 300 8.5 5.5 12.7 14**Table 7.**Lake-water-quality data collected within 24 hours of Landsat-5 Thematic Mapper imaging of the lakes, and haze-corrected digital numbers correspondingto the station locations in the images—Continued**Station name PALIS code Station** **identifier Latitude** °′′′**Longitude**°′′′**Chloro phyll** **concentra tion** **Secchi disk trans** **parency Lake color** **Haze-corrected TM digital numbers TM Band 1 TM Band 2 TM Band 3 TM Band 4** **40 Use of Thematic Mapper Imagery to Assess Water Quality, Trophic State, and Macrophyte Distributions in Massachusetts Lakes**June 10, 1998—ContinuedSpy Pond 71040 South 42 24 22 71 09 30 6.4 3.0 30 12.5 10.5 12.7 12Spy Pond 71040 North 42 24 32 71 09 09 9.1 2.2 49 14.5 10.5 14.7 11Stearns Mill Pond 82104 1 42 32 10 71 27 01 11.6 -- 98 10.5 7.5 12.7 9Waban Lake 72125 2 42 17 14 71 18 35 5.7 2.3 291 8.5 6.5 12.7 11Webster Lake 42064 1A 42 03 14 71 50 56 2.2 5.2 0 19.5 10.5 15.7 19Webster Lake 42064 1B 42 03 14 71 50 56 1.9 4.3 6 19.5 10.5 15.7 19White Pond (Concord) 82118 1 42 25 40 71 23 28 3.5 3.3 7 13.5 7.5 10.7 11White Pond (Hudson/Stow) 82119 1 42 23 30 71 28 49 1.4 6.2 12 9.5 6.5 9.7 12Whitins Reservoir 51179 1A 42 04 15 71 45 42 1.5 4.4 57 12.5 8.5 12.7 14Whitins Reservoir 51179 2A 42 04 21 71 46 43 1.1 4.0 27 12.5 8.5 13.7 16Whitins Reservoir 51179 1B 42 04 15 71 45 42 1.4 4.6 21 12.5 8.5 12.7 14Whitins Reservoir 51179 2B 42 04 21 71 46 43 1.3 3.7 27 12.5 8.5 13.7 16Winthrop Lake 72140 Deep hole 42 11 23 71 25 26 6.6 2.6 98 9.5 6.5 9.7 13**Table 7.**Lake-water-quality data collected within 24 hours of Landsat-5 Thematic Mapper imaging of the lakes, and haze-corrected digital numbers correspondingto the station locations in the images—Continued**Station name PALIS code Station** **identifier Latitude** °′′′**Longitude**°′′′**Chloro phyll** **concentra tion** **Secchi disk trans** **parency Lake color** **Haze-corrected TM digital numbers TM Band 1 TM Band 2 TM Band 3 TM Band 4**