Bathymetric Survey and Storage Capacity of Upper Lake 

Mary near Flagstaff, Arizona

Open-File Report 2008–1098

U.S. Department of the Interior

U.S. Geological Survey
Inside front cover
Bathymetric Survey and Storage Capacity of Upper Lake 

Mary near Flagstaff, Arizona

Open-File Report 2008–1098

By Nancy J. Hornewer and Marilyn E. Flynn

U.S. Department of the Interior

U.S. Geological Survey
ii

U.S. Department of the Interior

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2008

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Suggested citation:

Hornewer, N.J., and Flynn, M.E., 2008, Bathymetric survey and storage capacity of Upper Lake Mary near Flagstaff, 

Arizona: U.S. Geological Survey Open-File Report 2008-1098, 18 p.

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FRONT COVER

U.S. Geological Survey personnel setting up surveying equipment by Upper Lake Mary, Arizona.
 iii

Contents

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

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

Purpose and Scope...............................................................................................................................1

Acknowledgments................................................................................................................................1

Description of Study Area ............................................................................................................................2

Methods...........................................................................................................................................................3

Data Collection......................................................................................................................................3

Data Postprocessing............................................................................................................................4

Results. .............................................................................................................................................................5

References Cited..........................................................................................................................................18

Figures

1. Location of Upper Lake Mary study area near Flagstaff, Arizona.....................................................2

2. Map showing locations of three data-collection methods used at Upper Lake Mary: 

bathymetric data, lake-survey data, and land-survey data...........................................................3

3. Contour map showing lakebed elevations up to the spillway elevation 

for Upper Lake Mary.............................................................................................................................6

Tables

1. Elevation-area and elevation-storage capacity information for Upper Lake Mary........................8

2. Comparison of summary lake statistics between surveys for Upper Lake Mary .........................18
iv

Conversion Factors

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 4,047 square meter (m2)

acre 0.004047 square kilometer (km2)

square mile (mi2) 2.590 square kilometer (km2) 

Volume

million gallons (Mgal) 3,785 cubic meter (m3)

acre-foot (acre-ft) 1,233 cubic meter (m3)

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

°C=(°F-32)/1.8

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 (NGVD 29).

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

Elevation, as used in this report, refers to distance above the vertical datum.

Abbreviations Used In This Report

DGPS Differentially corrected global positioning system

GPS Global positioning system

LMWTP Lake Mary Water Treatment Plant

NAD 83 North American Datum of 1983

NAVD 88 North American Vertical Datum of 1988

NGS National Geodetic Survey

NGVD 29 National Geodetic Vertical Datum of 1929

NSSDA National Standard for Spatial Data Accuracy

OPUS On-line Positioning User Service

RTK GPS Real-time kinematic differentially corrected global positioning system

TGO Trimble Geomatics Office software

TIN Triangulated irregular network

USGS U.S. Geological Survey

Inch/Pound to SI
Bathymetric Survey and Storage Capacity of Upper Lake 

Mary near Flagstaff, Arizona

By Nancy J. Hornewer and Marilyn E. Flynn

Abstract

Upper Lake Mary is a preferred drinking-water source 

for the City of Flagstaff, Arizona. Therefore, storage capacity 

and sedimentation issues in Upper Lake Mary are of interest 

to the City. The U.S. Geological Survey, in cooperation with 

the City of Flagstaff, collected bathymetric and land-survey 

data in Upper Lake Mary during late August through October 

2006. Water-depth data were collected using a single-beam, 

high-definition fathometer. Position data were collected using 

real-time differential global position system receivers. Data 

were processed using commercial software and imported into 

geographic information system software to produce contour 

maps of lakebed elevations and for the computation of area 

and storage-capacity information.

At full pool (spillway elevation of 6,828.5 feet above 

mean sea level), Upper Lake Mary has a storage capacity of 

16,300 acre-feet, a surface area of 939 acres, a mean depth 

of 17.4 feet, and a depth near the dam of 39 feet. It is 5.6 

miles long and varies in width from 308 feet near the central, 

narrow portion of the lake to 2,630 feet in the upper portion. 

Comparisons between this survey and a previous survey conducted in the 1950s indicate no apparent decrease in reservoir 

area or storage capacity between the two surveys.

Introduction

A combination of ground water from well fields throughout the Flagstaff area and surface water from Upper Lake 

Mary are used to supply drinking water to the City of Flagstaff, Arizona. Upper Lake Mary is a preferred source because 

it is one of the most economical water supplies for the City 

(City of Flagstaff Utilities Department, 2004). Over time, the 

storage capacity of a lake can decrease because of sediment 

accumulation. It is therefore important to periodically resurvey a lake to update area and storage-capacity information so 

managers are better able to oversee the resource.

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

with the City of Flagstaff, collected bathymetric and landsurvey data in Upper Lake Mary during late August through 

October 2006. Water-depth data were collected using a singlebeam, high-definition fathometer. Position data were collected 

using real-time differentially corrected global position system 

(DGPS) receivers. Data were processed using commercial 

software and imported into geographic information system 

software to produce contour maps of lakebed elevations and 

for the computation of area and storage-capacity information.

Purpose and Scope

This report describes the methods used to collect 

bathymetric and land-survey data and discusses dataprocessing techniques that were used to produce the 

bathymetric-surface model, contour map of lakebed 

elevations, and an elevation-area and elevation-storage 

capacity (hereinafter referred to as area and storage capacity) 

table for Upper Lake Mary. The units used in this report are 

those used by the City of Flagstaff.

Acknowledgments

Jack Rathjen and Troy Truman from the Lake Mary 

Water Treatment Plant (LMWTP) provided information 

regarding the history of Lake Mary, as well as area and 

storage-capacity information from an earlier survey. Ron 

Doba and Randy Pellatz from the City of Flagstaff provided 

information regarding the dam structure and settlementmonument survey data. Jim Duncker from the USGS Illinois 

Water Science Center provided assistance and guidance 

with the collection of the bathymetric data. Gary Wilson and 

Joseph Richards from the USGS Missouri Water Science 

Center provided much assistance with data postprocessing 

and interpretation. Emmet McGuire and many other personnel 

from the USGS Arizona Water Science Center helped with 

this data-collection effort.
2 Bathymetric Survey and Storage Capacity of Upper Lake Mary

To Flagstaff

Tucson

Phoenix

Flagstaff

ARIZONA

Upper Lake Mary

111°30'

35°04'

0 0.5 1 MILES

0 0.5 1 KILOMETERS

111°31'

111°29' 111°28'

35°03'

111°32'

Dam Spillway

Boat Ramps

Boat Ramp

Upper

Lake

Mary

Lake Mary Road

Bathymetric contours shown

in Figure 3A

Bathymetric contours shown

in Figure 3B

Base from digital orthophoto quadrangle, with photo image taken on October 16, 1997 (lake 

was approximately 28 percent full in October 1997; blue line represents approximate 

edge-of-water during bathymetric survey in late August and early September 2006; mean 

water-surface elevation during survey was 6,813.8 feet).

Universal Transverse Mercator projection,

Zone 12

Description of Study Area 

Upper Lake Mary is located approximately 10 miles 

(mi) southeast of Flagstaff in the Plateau Uplands hydrologic 

province region of north-central Arizona (fig. 1). It lies in 

a graben formed by two high-angle faults that run parallel 

along the north and south shores for the entire length of the 

lake (Blee, 1987). To the north, the Anderson Mesa Fault has 

an average displacement of about 250 feet (ft). To the south, 

the Lake Mary Fault has an average displacement of about 

100 ft. Because of the faulting, the bedrock that underlies 

the lake is highly fractured to a depth of several hundred feet 

(Blee, 1987).

Flagstaff is located in a semiarid area and receives an 

average of 22.91 inches (in.) of precipitation per year, which 

includes 109.8 in. of snowfall per year. The Flagstaff area has 

an average annual temperature of 45.9°F with large diurnal 

changes (National Oceanic and Atmospheric Administration, 2006).

Upper Lake Mary is an artificial lake formed by an 

earthen dam constructed in 1941 by the City of Flagstaff. In 

1951 the City raised the crest of the dam approximately 10 ft 

to the current elevation of 6,835.5 ft above mean sea level 

and improved the spillway, (Pellatz, 2006). The spillway is a 

concrete channel with sidewalls (Blee, 1987). 

The drainage area for Upper Lake Mary is approximately 

51 square miles ( mi2; City of Flagstaff Utilities Department, 

2004). Inflow to the lake largely comes from spring snowmelt; however, there are small contributions from rainfall and 

from ephemeral streams, such as Babbit Spring and Newman 

Canyon. Water losses from the lake include evaporation, leakage, water-supply withdrawals, and spillage (Blee, 1987).

Figure 1. Location of Upper Lake Mary study area near Flagstaff, Arizona. 
Methods 3

Methods 

Data Collection

During the time of data collection, late August through 

October 2006, Upper Lake Mary decreased from approximately 30 percent capacity to 25 percent capacity or from 

14.8 ft to 16.3 ft below the spillway elevation (Lake Mary 

Water Treatment Plant, written commun., 2007). A combination of bathymetric data and land-survey data up to the 

spillway elevation (or slightly above spillway elevation) were 

required to produce accurate area and storage-capacity information because the lake was below the spillway elevation.

Elevation data collected during this investigation are 

referenced to the City of Flagstaff monument 27, located on the 

spillway. This investigation used an elevation of 6,828.548 ft 

referenced to the National Geodetic Vertical Datum of 1929 

(NGVD 29), measured by the City of Flagstaff, as the base 

elevation for monument 27 (Pellatz, 2006). Note that during 

this investigation, three data files collected over periods of 

3.5 hours, 5.7 hours, and 5.6 hours were downloaded from

the base station positioned on monument 27. The files were 

processed using the Geoid-2003 model option of the On-line 

Positioning User Service (OPUS; National Geodetic Survey, 

2006) at the National Geodetic Survey (NGS) to obtain an 

elevation referenced to the North American Vertical Datum 

of 1988 (NAVD 88). The average OPUS solution for monument 27 was 6,831.508 ft. This information allows an elevation referenced to NGVD 29 to be converted to an elevation 

referenced to NAVD 88.

Bathymetric, lake-survey, and land-survey data were 

collected at Upper Lake Mary to determine area and storage 

capacity relations (fig. 2). Bathymetric data were collected 

from a boat over all navigable areas of the lake by using a 

survey-grade, single-beam fathometer for water-depth data, 

and DGPS was used to collect corresponding position data. 

Lake-survey data were collected from non-navigable areas of 

the lake—areas that were either too shallow or had dense areas 

of submerged vegetation—by using real-time kinematic DGPS 

receivers (hereafter referred to as RTK GPS) for position 

and elevation data. Land-survey data were collected from the 

water’s edge to a location on land slightly above the spillway 

elevation by using RTK GPS for position and elevation data.

Figure 2. Map showing locations of three data-collection methods used at 

Upper Lake Mary: bathymetric data, lake-survey data, and land-survey data.

Lake Mary

Road

111°30'

35°04'

0 0.5 1 MILES

0 0.5 1 KILOMETERS

111°31'

111°29'

111°28'

35°03'

111°32' Spillway

Dam

Boat Ramps

Boat Ramp

EXPLANATION

Bathymetric data

Lake-survey data

Land-survey data

Edge-of-water at time of bathymetric survey

(mean water-surface elevation during survey

was 6,813.8 feet)

Universal Transverse Mercator projection,

Zone 12
4 Bathymetric Survey and Storage Capacity of Upper Lake Mary

Bathymetric data were collected from navigable areas 

of Upper Lake Mary. Water-depth data were collected using 

a Reson, Incorporated, model 210 single-beam fathometer, or 

echosounder, and a 200-kilohertz transducer with a 2.7-degree 

beam width. Manufacturer specifications state an accuracy 

of +/-0.4 in. (Reson Incorporated, 2002); however, actual 

accuracy may be less because of wave action introducing tilt, 

roll, and pitch errors. The lake was relatively calm during the 

bathymetric data-collection effort, and therefore errors introduced because of boat instability are assumed to be small.

The transducer was mounted to a bracket on the boat 

with the transducer face at a depth of 0.2 ft to 1.0 ft below 

the water surface. Distance from the water surface to the face 

of the transducer was manually measured daily and added to 

the echosounder depth to obtain the total depth (lake bottom 

to water surface). Before the bathymetric data were collected 

each day, water depth was manually measured at a location 

and used to calibrate the echosounder. The water-surface 

elevation for each day was determined by measuring the 

elevation difference between a reference point with a known 

elevation and the water surface, and then subtracting that 

difference from the reference point elevation. This allowed 

for the conversion of depths measured by the echosounder to 

elevation data.

Horizontal-position data (latitude and longitude) were 

collected concurrently and combined with water-depth data. 

The position data were collected using a Trimble AG132 

DGPS receiver. Differentially corrected data collected with a 

DGPS receiver improve the global positioning system (GPS) 

data accuracy by correcting for errors such as those introduced 

through atmospheric delays and satellite-clock errors. The 

manufacturer states an accuracy of less than +/-3.28 ft for the 

AG132 DGPS receiver (Trimble Navigation Limited, 2000). 

The antenna for the DPGS receiver was mounted at a fixed 

location above the transducer. Position data from the DGPS 

receiver were combined with depth data from the echosounder 

as they were being collected in the field by using Hypack 

Max, a hydrographic surveying software package developed 

by Hypack, Incorporated.

Bathymetric data were collected along transects that 

were spaced approximately 180 ft apart and were oriented 

perpendicular to the longitudinal axis of the lake (fig. 2). The 

boat slowly moved along each transect at velocities less than 

3 miles per hour while collecting data in order to maximize the 

number of depth measurements made. The upper end of the 

lake was shallow, with areas of dense, submerged vegetation. 

Distances between transects were greater in this area because 

of boat-navigation difficulties, or because data collected along 

a transect were too noisy, because of submerged vegetation, to 

be useable and therefore were eliminated. 

Raw bathymetric data were processed using Hypack Max 

to eliminate points that were outliers (a point that was much 

higher or lower than nearby points, points that showed zero 

depth, vegetation-affected points from which the bottom could 

not be determined, or points that may have been affected by 

boat roll/pitch errors). The resulting data were exported from 

Hypack Max as an x, y, z (latitude, longitude, elevation) file 

and then imported into a geographic information system database for postprocessing.

The second type of data collected was lake-survey data. 

These data were collected from areas in the lake that either 

were too shallow to safely navigate the boat or where there 

was dense, submerged vegetation, causing noisy and therefore 

unusable echosounder data (fig. 2). Lake-survey position and 

elevation data were collected using the following RTK GPS 

systems: the Trimble RTK R8 GNSS, the Trimble 5700, and 

the Trimble R7. These systems, for kinematic surveys, have 

a horizontal accuracy of +/-0.4 in. and a vertical accuracy of 

+/-0.8 in. (Trimble Navigation Limited, 2006).

Lake-survey data were collected either by wading across 

the lake or by using a boat for those areas with deeper water 

that had dense, submerged vegetation. In areas of the lake 

that were shallow enough to wade, measurements were taken 

along transects, with more frequent measurements taken in 

areas with rapidly changing slopes. In water too deep to wade, 

measurements were collected from a boat by slowly moving 

across the lake and stopping frequently to take RTK GPS measurements. Again, more frequent measurements were made in 

areas of rapidly changing slopes. These areas were determined 

by manually checking the lake bottom with a pole for slope 

changes as the boat traversed a transect.

Raw position and elevation data were processed using a 

standard surveying software package called Trimble Geomatics Office (TGO) made by Trimble Navigation Limited. Data 

were corrected with reference to the local geoid and quality 

assured for outliers. The corrected data were exported from 

TGO as an x, y, z (latitude, longitude, elevation) file and then 

imported into the geographic information system database for 

postprocessing.

The final type of data collected was land-survey data. 

Position and elevation data were collected using the same RTK 

GPS systems described above for lake-survey data. Data were 

collected from the water’s edge and at several points along a 

transect moving away from the lake, until an elevation slightly 

above spillway elevation was reached (fig. 2). These transects 

were spaced approximately 220 ft apart, with larger intervals 

in the upper part of the lake. In some cases, it was not possible to reach the spillway elevation along a transect because 

trees interfered with the RTK GPS signal reception. In those 

instances, the spillway elevation was estimated using nearby 

data. Raw position and elevation data were processed as 

described in the lake-survey section.

Data Postprocessing

The bathymetric, lake-survey, and land-survey elevation 

and position data were imported into the ArcGIS 9.1 software 

package (Environmental Systems Research Institute, 2007a) 

in x, y, z format for additional processing. The data were 

first inspected in a 3-D environment to aid in identifying and 

deleting any outliers not apparent during the initial processing 
Results 5

of the data. The data were then processed into a preliminary 

triangulated irregular network (TIN) surface model. A TIN 

is a network of adjacent, nonoverlapping triangles generated 

from irregularly spaced points that have x, y coordinates 

and z values. The triangles are created so that all points are 

connected using their two nearest neighbors to form the 

triangles and the resulting triangulation satisfies the Delaunay 

triangle criterion (Environmental Systems Research Institute, 

2005). This triangulated network forms a continuous faceted 

surface, where each triangle describes the behavior of a 

portion of the surface.

Preliminary elevation contours were generated from 

the initial TIN surface model by using the TIN contouring 

function. The contours were inspected for the accurate 

surface representation of linear features such as stream 

channels, steep slopes, and the tops of the dam and spillway. 

The surface model (and consequently the contours) may 

not accurately represent these features because the distance 

between transects can be large enough that the feature is not 

interpolated appropriately between transects. Adding linear 

enforcement data to the surface model forces a more accurate 

representation of linear features. To add linear-enforcement 

data for stream channels and other linear features identified 

in the 3-D environment, lines were drawn to connect the 

linear features between transects. The nodes at the ends of 

the lines, where lines intersect with data points on a transect, 

were attributed with the surveyed elevations of the data 

points. Additional vertices were added along the lines, and 

the elevations for these vertices were interpolated using the 

known elevations of the end nodes. The line vertices were 

then converted to points.

A secondary TIN was generated using the edited 

elevation data and the linear-enforcement point data 

representing the stream channels and the tops of the dam and 

the spillway. From this TIN, a secondary set of contours was 

generated using the TIN contouring function. Because of 

the strictly numerical interpretation of the data, the contour 

lines in some areas appeared jagged. The contouring function 

interpolates straight lines across each triangle to produce 

an exact linear interpretation of the surface. Although this 

interpretation is numerically correct, it does not match the 

cartographic interpretation (smooth contour lines typically 

shown on maps) of the data. To more closely match the 

cartographic interpretation, the contours were edited manually 

by reshaping contour lines using the edited elevation data as 

a guide. 

The necessity for reshaping the contours using the 

edited elevation data as a guide indicated that the nonuniform 

change in slope along the north shore of the lake was not 

accurately represented in the secondary TIN surface model. 

Therefore, linear-enforcement data in the form of constant 

elevation breaklines based on the edited contours were used 

to linearly enforce the slope and shape of the north shore of 

the lake in the secondary TIN. The final bathymetric TIN 

surface model was generated using the edited elevation data, 

the linear enforcement point data representing the stream 

channels and the tops of the dam and spillway, and the northshore breaklines.

Area and storage capacity were calculated for specific 

water-surface elevations using the final TIN surface model 

with the ArcGIS 3D Analyst extension (Environmental 

Systems Research Institute, 2007b). Each triangle in the TIN 

was examined to determine its contribution to the area and 

volume at the given elevation.

Results 

At full pool (spillway elevation of 6,828.5 ft), Upper 

Lake Mary has a storage capacity of 16,300 acre-ft, a surface 

area of 939 acres, a mean depth of 17.4 ft, and a depth near the 

dam of 39 ft. It is 5.6 mi long and varies in width from 308 ft 

near the central, narrow portion of the lake to 2,630 ft in the 

upper portion.

The edited contour map created in ArcGIS is shown 

in figure 3. Although vertical accuracy using the National 

Standard for Spatial Data Accuracy (NSSDA) method was not 

checked for this contour map, the survey was completed using 

processing methods that usually obtain a vertical accuracy 

of approximately 2.78 ft at the 95-percent confidence level 

for lakes of this size (Wilson and Richards, 2006). Figure 3 

represents lakebed elevations when the lake is at full pool or 

at the spillway elevation of 6,828.5 ft. The blue shading is the 

approximate edge-of-water (mean water-surface elevation of 

6,813.8 ft) at the time of the bathymetric survey. The contours 

are at 5-ft intervals. At this resolution, it is possible to see an 

old channel of Walnut Creek meandering through the lake. 

The locations of aerators that were installed in the lake to keep 

the lake well mixed also are shown in figure 3.

Table 1 shows area and storage-capacity information 

calculated from the final TIN surface model using ArcGIS for 

Upper Lake Mary, starting from near the lake bottom to 1.1 ft 

above full-pool capacity, allowing for backwater conditions. 

Although vertical accuracy using the NSSDA method was 

not checked for this bathymetric surface, the survey was 

completed using processing methods that usually obtain a 

vertical accuracy of approximately 1.62 ft at the 95-percent 

confidence level (Wilson and Richards, 2006). Table 1 was 

generated at 0.1-ft increments in order to match the area 

and storage-capacity table currently in use at the Lake Mary 

Water Treatment Plant (LMWTP). The table also relates lake 

elevation data to a relative datum used by personnel at the 

LMWTP.

Upper Lake Mary was last surveyed in the early 1950s 

(J. Rathjen, Utilities Department—Water Production, City 

of Flagstaff, oral commun., 2007). Results from that survey 

showed a full-pool storage capacity of 15,620 acre-ft at the 

spillway elevation, a maximum surface area of 876 acres, a 

mean depth of 17.9 ft, and a depth near the dam of 40 ft. The 

lake was determined to be 5.5 mi long and 300 to 2,000 ft wide 

(Blee, 1987). Table 2 compares results from the two surveys.
Figure 3. Contour map showing lakebed elevations up to the spillway elevation for Upper Lake Mary. A, West (lower) part. B, East (upper) part.

35°04'

0 0.5 MILES

0 0.5 KILOMETERS

111°31'

111°32'

Spillway

Dam

Boat Ramps

Boat Ramp

EXPLANATION

Bathymetric contour—Shows elevation of the Contour interval 5 feet. Although vertical accuStandard for Spatial Data Accuracy method wcontour map, this survey was completed using that usually obtain a vertical accuracy of approthe 95-percent confidence level.Edge-of-water at time of bathymetric survey (elevation during survey was 6,813.8 feet).Location of aeration systems Map not for navigational use

UniversZone 1Vertica

Lake 

Mary 

Road 

6795

6800

6805 6810 6815

6820 6825

6830

6800

6790

A
0 0.5 MILES

0 0.5 KILOMETERS

111°29'

111°28'

35°03'

Universal Transverse Mercator projection,Zone 12Vertical datum is NGVD 29

B

Lake

Mary

Road

6830

6825

6820

6815

6820

6810

6810

6805

6810

6820

Figure 3. Contour map showing lakebed elevations up to the spillway elevation for Upper Lake Mary–Continued.
8 Bathymetric Survey and Storage Capacity of Upper Lake Mary

Table 1. Elevation-area and elevation-storage capacity information for Upper Lake Mary

[This is an operational table that will be used by personnel at the Lake Mary Water Treatment Plant (LMWTP); the beginning and ending elevations are the 

same as those currently in use by personnel at the LMWTP; the base elevation used for this study was monument 27 located on the spillway with an elevation 

of 6,828.548 feet as documented by the City of Flagstaff; the spillway elevation used by the LMWTP is 6,828.5 feet, which corresponds to full capacity for 

Upper Lake Mary; elevation is referenced to the National Geodetic Vertical Datum of 1929; personnel at the LMWTP use a relative datum for measurements, 

which also is shown on this table; although vertical accuracy using the National Standard for Spatial Data Accuracy method was not checked for the bathymetric 

surface from which this table was generated, this survey was completed using processing methods that usually obtain a vertical accuracy of approximately 1.62 

feet at the 95-percent confidence level]

Water-surface 

elevation (feet)

Surface area 

(acres)

Volume

(acre-feet)

Volume

(million gallons)

Relative datum - 

measured up from 

lake bottom (feet)

Relative datum - 

measured down 

from tower (feet)

Percent capacity

(percent)

6,790.0 0.009 0.001 0.000 0.0 39.6 0.0

6,790.1 0.013 0.002 0.001 0.1 39.5 0.0

6,790.2 0.019 0.004 0.001 0.2 39.4 0.0

6,790.3 0.027 0.006 0.002 0.3 39.3 0.0

6,790.4 0.037 0.009 0.003 0.4 39.2 0.0

6,790.5 0.052 0.013 0.004 0.5 39.1 0.0

6,790.6 0.076 0.020 0.006 0.6 39.0 0.0

6,790.7 0.118 0.029 0.009 0.7 38.9 0.0

6,790.8 0.192 0.044 0.014 0.8 38.8 0.0

6,790.9 0.304 0.069 0.022 0.9 38.7 0.0

6,791.0 0.454 0.106 0.035 1.0 38.6 0.0

6,791.1 0.639 0.161 0.052 1.1 38.5 0.0

6,791.2 0.868 0.236 0.077 1.2 38.4 0.0

6,791.3 1.10 0.334 0.109 1.3 38.3 0.0

6,791.4 1.34 0.456 0.149 1.4 38.2 0.0

6,791.5 1.61 0.604 0.197 1.5 38.1 0.0

6,791.6 1.92 0.779 0.254 1.6 38.0 0.0

6,791.7 2.28 0.988 0.322 1.7 37.9 0.0

6,791.8 2.70 1.24 0.403 1.8 37.8 0.0

6,791.9 3.19 1.53 0.499 1.9 37.7 0.0

6,792.0 3.75 1.88 0.612 2.0 37.6 0.0

6,792.1 4.38 2.28 0.744 2.1 37.5 0.0

6,792.2 5.15 2.76 0.898 2.2 37.4 0.0

6,792.3 5.88 3.31 1.08 2.3 37.3 0.0

6,792.4 6.62 3.93 1.28 2.4 37.2 0.0

6,792.5 7.36 4.63 1.51 2.5 37.1 0.0

6,792.6 8.10 5.41 1.76 2.6 37.0 0.0

6,792.7 8.90 6.26 2.04 2.7 36.9 0.0

6,792.8 9.89 7.20 2.35 2.8 36.8 0.0

6,792.9 11.0 8.24 2.68 2.9 36.7 0.1

6,793.0 12.1 9.39 3.06 3.0 36.6 0.1

6,793.1 13.3 10.7 3.47 3.1 36.5 0.1

6,793.2 14.8 12.1 3.93 3.2 36.4 0.1

6,793.3 16.1 13.6 4.43 3.3 36.3 0.1

6,793.4 17.5 15.3 4.98 3.4 36.2 0.1

6,793.5 18.8 17.1 5.57 3.5 36.1 0.1
Results 9

Water-surface 

elevation (feet)

Surface area 

(acres)

Volume

(acre-feet)

Volume

(million gallons)

Relative datum - 

measured up from 

lake bottom (feet)

Relative datum - 

measured down 

from tower (feet)

Percent capacity

(percent)

6,793.6 20.1 19.0 6.21 3.6 36.0 0.1

6,793.7 21.4 21.1 6.88 3.7 35.9 0.1

6,793.8 22.7 23.3 7.60 3.8 35.8 0.1

6,793.9 24.0 25.7 8.36 3.9 35.7 0.2

6,794.0 25.3 28.1 9.17 4.0 35.6 0.2

6,794.1 26.6 30.7 10.0 4.1 35.5 0.2

6,794.2 27.9 33.4 10.9 4.2 35.4 0.2

6,794.3 29.4 36.3 11.8 4.3 35.3 0.2

6,794.4 31.0 39.3 12.8 4.4 35.2 0.2

6,794.5 32.7 42.5 13.9 4.5 35.1 0.3

6,794.6 34.6 45.9 14.9 4.6 35.0 0.3

6,794.7 36.7 49.4 16.1 4.7 34.9 0.3

6,794.8 39.0 53.2 17.3 4.8 34.8 0.3

6,794.9 41.5 57.2 18.6 4.9 34.7 0.4

6,795.0 44.2 61.5 20.0 5.0 34.6 0.4

6,795.1 46.9 66.1 21.5 5.1 34.5 0.4

6,795.2 49.6 70.9 23.1 5.2 34.4 0.4

6,795.3 52.4 76.0 24.8 5.3 34.3 0.5

6,795.4 55.3 81.4 26.5 5.4 34.2 0.5

6,795.5 58.0 87.0 28.4 5.5 34.1 0.5

6,795.6 60.6 93.0 30.3 5.6 34.0 0.6

6,795.7 63.4 99.2 32.3 5.7 33.9 0.6

6,795.8 66.3 106 34.4 5.8 33.8 0.7

6,795.9 69.2 112 36.6 5.9 33.7 0.7

6,796.0 71.9 120 38.9 6.0 33.6 0.7

6,796.1 74.4 127 41.3 6.1 33.5 0.8

6,796.2 76.7 134 43.8 6.2 33.4 0.8

6,796.3 78.9 142 46.3 6.3 33.3 0.9

6,796.4 81.2 150 48.9 6.4 33.2 0.9

6,796.5 83.6 158 51.6 6.5 33.1 1.0

6,796.6 86.4 167 54.4 6.6 33.0 1.0

6,796.7 89.3 176 57.3 6.7 32.9 1.1

6,796.8 92.3 185 60.2 6.8 32.8 1.1

6,796.9 95.0 194 63.2 6.9 32.7 1.2

6,797.0 97.8 204 66.4 7.0 32.6 1.3

6,797.1 101 214 69.6 7.1 32.5 1.3

6,797.2 103 224 73.0 7.2 32.4 1.4

6,797.3 106 234 76.4 7.3 32.3 1.4

6,797.4 109 245 79.9 7.4 32.2 1.5

6,797.5 111 256 83.5 7.5 32.1 1.6

6,797.6 114 267 87.1 7.6 32.0 1.6

Table 1. Elevation-area and elevation-storage capacity information for Upper Lake Mary—Continued
10 Bathymetric Survey and Storage Capacity of Upper Lake Mary

Water-surface 

elevation (feet)

Surface area 

(acres)

Volume

(acre-feet)

Volume

(million gallons)

Relative datum - 

measured up from 

lake bottom (feet)

Relative datum - 

measured down 

from tower (feet)

Percent capacity

(percent)

6,797.7 117 279 90.9 7.7 31.9 1.7

6,797.8 119 291 94.8 7.8 31.8 1.8

6,797.9 121 303 98.7 7.9 31.7 1.9

6,798.0 123 315 103 8.0 31.6 1.9

6,798.1 125 327 107 8.1 31.5 2.0

6,798.2 128 340 111 8.2 31.4 2.1

6,798.3 130 353 115 8.3 31.3 2.2

6,798.4 132 366 119 8.4 31.2 2.2

6,798.5 134 379 124 8.5 31.1 2.3

6,798.6 136 393 128 8.6 31.0 2.4

6,798.7 138 407 132 8.7 30.9 2.5

6,798.8 140 420 137 8.8 30.8 2.6

6,798.9 141 434 142 8.9 30.7 2.7

6,799.0 143 449 146 9.0 30.6 2.8

6,799.1 144 463 151 9.1 30.5 2.8

6,799.2 146 478 156 9.2 30.4 2.9

6,799.3 147 492 160 9.3 30.3 3.0

6,799.4 148 507 165 9.4 30.2 3.1

6,799.5 150 522 170 9.5 30.1 3.2

6,799.6 151 537 175 9.6 30.0 3.3

6,799.7 153 552 180 9.7 29.9 3.4

6,799.8 154 567 185 9.8 29.8 3.5

6,799.9 155 583 190 9.9 29.7 3.6

6,800.0 156 598 195 10.0 29.6 3.7

6,800.1 157 614 200 10.1 29.5 3.8

6,800.2 158 630 205 10.2 29.4 3.9

6,800.3 159 646 210 10.3 29.3 4.0

6,800.4 160 662 216 10.4 29.2 4.1

6,800.5 161 678 221 10.5 29.1 4.2

6,800.6 162 694 226 10.6 29.0 4.3

6,800.7 163 710 231 10.7 28.9 4.4

6,800.8 164 727 237 10.8 28.8 4.5

6,800.9 165 743 242 10.9 28.7 4.6

6,801.0 166 760 248 11.0 28.6 4.7

6,801.1 167 777 253 11.1 28.5 4.8

6,801.2 168 793 259 11.2 28.4 4.9

6,801.3 169 810 264 11.3 28.3 5.0

6,801.4 171 827 270 11.4 28.2 5.1

6,801.5 172 844 275 11.5 28.1 5.2

6,801.6 173 862 281 11.6 28.0 5.3

6,801.7 174 879 286 11.7 27.9 5.4

Table 1. Elevation-area and elevation-storage capacity information for Upper Lake Mary—Continued
Results 11

Table 1. Elevation-area and elevation-storage capacity information for Upper Lake Mary—Continued

Water-surface 

elevation (feet)

Surface area 

(acres)

Volume

(acre-feet)

Volume

(million gallons)

Relative datum - 

measured up from 

lake bottom (feet)

Relative datum - 

measured down 

from tower (feet)

Percent capacity

(percent)

6,801.8 176 896 292 11.8 27.8 5.5

6,801.9 177 914 298 11.9 27.7 5.6

6,802.0 178 932 304 12.0 27.6 5.7

6,802.1 179 950 309 12.1 27.5 5.8

6,802.2 180 968 315 12.2 27.4 5.9

6,802.3 181 986 321 12.3 27.3 6.0

6,802.4 182 1,000 327 12.4 27.2 6.1

6,802.5 183 1,020 333 12.5 27.1 6.3

6,802.6 184 1,040 339 12.6 27.0 6.4

6,802.7 185 1,060 345 12.7 26.9 6.5

6,802.8 187 1,080 351 12.8 26.8 6.6

6,802.9 188 1,100 357 12.9 26.7 6.7

6,803.0 189 1,120 363 13.0 26.6 6.9

6,803.1 190 1,130 370 13.1 26.5 6.9

6,803.2 191 1,150 376 13.2 26.4 7.1

6,803.3 192 1,170 382 13.3 26.3 7.2

6,803.4 193 1,190 388 13.4 26.2 7.3

6,803.5 195 1,210 395 13.5 26.1 7.4

6,803.6 196 1,230 401 13.6 26.0 7.5

6,803.7 197 1,250 407 13.7 25.9 7.7

6,803.8 198 1,270 414 13.8 25.8 7.8

6,803.9 199 1,290 420 13.9 25.7 7.9

6,804.0 201 1,310 427 14.0 25.6 8.0

6,804.1 202 1,330 433 14.1 25.5 8.2

6,804.2 203 1,350 440 14.2 25.4 8.3

6,804.3 205 1,370 447 14.3 25.3 8.4

6,804.4 206 1,390 453 14.4 25.2 8.5

6,804.5 207 1,410 460 14.5 25.1 8.7

6,804.6 209 1,430 467 14.6 25.0 8.8

6,804.7 210 1,450 474 14.7 24.9 8.9

6,804.8 212 1,470 481 14.8 24.8 9.0

6,804.9 214 1,500 487 14.9 24.7 9.2

6,805.0 215 1,520 494 15.0 24.6 9.3

6,805.1 217 1,540 502 15.1 24.5 9.4

6,805.2 219 1,560 509 15.2 24.4 9.6

6,805.3 221 1,580 516 15.3 24.3 9.7

6,805.4 222 1,600 523 15.4 24.2 9.8

6,805.5 224 1,630 530 15.5 24.1 10.0

6,805.6 226 1,650 538 15.6 24.0 10.1

6,805.7 228 1,670 545 15.7 23.9 10.2

6,805.8 230 1,700 552 15.8 23.8 10.4
12 Bathymetric Survey and Storage Capacity of Upper Lake Mary

Table 1. Elevation-area and elevation-storage capacity information for Upper Lake Mary—Continued

Water-surface 

elevation (feet)

Surface area 

(acres)

Volume

(acre-feet)

Volume

(million gallons)

Relative datum - 

measured up from 

lake bottom (feet)

Relative datum - 

measured down 

from tower (feet)

Percent capacity

(percent)

6,805.9 232 1,720 560 15.9 23.7 10.6

6,806.0 234 1,740 568 16.0 23.6 10.7

6,806.1 236 1,770 575 16.1 23.5 10.9

6,806.2 239 1,790 583 16.2 23.4 11.0

6,806.3 241 1,810 591 16.3 23.3 11.1

6,806.4 243 1,840 599 16.4 23.2 11.3

6,806.5 246 1,860 607 16.5 23.1 11.4

6,806.6 248 1,890 615 16.6 23.0 11.6

6,806.7 251 1,910 623 16.7 22.9 11.7

6,806.8 253 1,940 631 16.8 22.8 11.9

6,806.9 256 1,960 639 16.9 22.7 12.0

6,807.0 259 1,990 648 17.0 22.6 12.2

6,807.1 262 2,010 656 17.1 22.5 12.3

6,807.2 264 2,040 665 17.2 22.4 12.5

6,807.3 267 2,070 673 17.3 22.3 12.7

6,807.4 270 2,090 682 17.4 22.2 12.8

6,807.5 273 2,120 691 17.5 22.1 13.0

6,807.6 277 2,150 700 17.6 22.0 13.2

6,807.7 280 2,180 709 17.7 21.9 13.4

6,807.8 284 2,200 718 17.8 21.8 13.5

6,807.9 289 2,230 728 17.9 21.7 13.7

6,808.0 294 2,260 737 18.0 21.6 13.9

6,808.1 299 2,290 747 18.1 21.5 14.0

6,808.2 303 2,320 757 18.2 21.4 14.2

6,808.3 307 2,350 767 18.3 21.3 14.4

6,808.4 312 2,380 777 18.4 21.2 14.6

6,808.5 316 2,410 787 18.5 21.1 14.8

6,808.6 320 2,450 797 18.6 21.0 15.0

6,808.7 323 2,480 808 18.7 20.9 15.2

6,808.8 327 2,510 818 18.8 20.8 15.4

6,808.9 331 2,540 829 18.9 20.7 15.6

6,809.0 334 2,580 840 19.0 20.6 15.8

6,809.1 337 2,610 851 19.1 20.5 16.0

6,809.2 341 2,640 862 19.2 20.4 16.2

6,809.3 344 2,680 873 19.3 20.3 16.4

6,809.4 347 2,710 884 19.4 20.2 16.6

6,809.5 350 2,750 896 19.5 20.1 16.9

6,809.6 354 2,780 907 19.6 20.0 17.1

6,809.7 357 2,820 919 19.7 19.9 17.3

6,809.8 360 2,860 930 19.8 19.8 17.5

6,809.9 363 2,890 942 19.9 19.7 17.7
Results 13

Table 1. Elevation-area and elevation-storage capacity information for Upper Lake Mary—Continued

Water-surface 

elevation (feet)

Surface area 

(acres)

Volume

(acre-feet)

Volume

(million gallons)

Relative datum - 

measured up from 

lake bottom (feet)

Relative datum - 

measured down 

from tower (feet)

Percent capacity

(percent)

6,810.0 366 2,930 954 20.0 19.6 18.0

6,810.1 370 2,960 966 20.1 19.5 18.2

6,810.2 373 3,000 978 20.2 19.4 18.4

6,810.3 376 3,040 990 20.3 19.3 18.7

6,810.4 379 3,080 1,000 20.4 19.2 18.9

6,810.5 383 3,110 1,020 20.5 19.1 19.1

6,810.6 387 3,150 1,030 20.6 19.0 19.3

6,810.7 391 3,190 1,040 20.7 18.9 19.6

6,810.8 396 3,230 1,050 20.8 18.8 19.8

6,810.9 401 3,270 1,070 20.9 18.7 20.1

6,811.0 405 3,310 1,080 21.0 18.6 20.3

6,811.1 410 3,350 1,090 21.1 18.5 20.6

6,811.2 415 3,390 1,110 21.2 18.4 20.8

6,811.3 419 3,440 1,120 21.3 18.3 21.1

6,811.4 424 3,480 1,130 21.4 18.2 21.3

6,811.5 428 3,520 1,150 21.5 18.1 21.6

6,811.6 433 3,560 1,160 21.6 18.0 21.8

6,811.7 438 3,610 1,180 21.7 17.9 22.1

6,811.8 444 3,650 1,190 21.8 17.8 22.4

6,811.9 450 3,700 1,200 21.9 17.7 22.7

6,812.0 456 3,740 1,220 22.0 17.6 22.9

6,812.1 462 3,790 1,230 22.1 17.5 23.3

6,812.2 468 3,830 1,250 22.2 17.4 23.5

6,812.3 475 3,880 1,260 22.3 17.3 23.8

6,812.4 481 3,930 1,280 22.4 17.2 24.1

6,812.5 488 3,980 1,300 22.5 17.1 24.4

6,812.6 494 4,030 1,310 22.6 17.0 24.7

6,812.7 500 4,080 1,330 22.7 16.9 25.0

6,812.8 505 4,130 1,340 22.8 16.8 25.3

6,812.9 511 4,180 1,360 22.9 16.7 25.6

6,813.0 517 4,230 1,380 23.0 16.6 26.0

6,813.1 523 4,280 1,390 23.1 16.5 26.3

6,813.2 529 4,330 1,410 23.2 16.4 26.6

6,813.3 534 4,390 1,430 23.3 16.3 26.9

6,813.4 538 4,440 1,450 23.4 16.2 27.2

6,813.5 543 4,490 1,460 23.5 16.1 27.5

6,813.6 547 4,550 1,480 23.6 16.0 27.9

6,813.7 552 4,600 1,500 23.7 15.9 28.2

6,813.8 558 4,660 1,520 23.8 15.8 28.6

6,813.9 568 4,710 1,540 23.9 15.7 28.9

6,814.0 573 4,770 1,550 24.0 15.6 29.3
14 Bathymetric Survey and Storage Capacity of Upper Lake Mary

Table 1. Elevation-area and elevation-storage capacity information for Upper Lake Mary—Continued

Water-surface 

elevation (feet)

Surface area 

(acres)

Volume

(acre-feet)

Volume

(million gallons)

Relative datum - 

measured up from 

lake bottom (feet)

Relative datum - 

measured down 

from tower (feet)

Percent capacity

(percent)

6,814.1 579 4,830 1,570 24.1 15.5 29.6

6,814.2 584 4,890 1,590 24.2 15.4 30.0

6,814.3 589 4,950 1,610 24.3 15.3 30.4

6,814.4 594 5,010 1,630 24.4 15.2 30.7

6,814.5 599 5,060 1,650 24.5 15.1 31.0

6,814.6 604 5,130 1,670 24.6 15.0 31.5

6,814.7 609 5,190 1,690 24.7 14.9 31.8

6,814.8 614 5,250 1,710 24.8 14.8 32.2

6,814.9 619 5,310 1,730 24.9 14.7 32.6

6,815.0 624 5,370 1,750 25.0 14.6 32.9

6,815.1 628 5,430 1,770 25.1 14.5 33.3

6,815.2 631 5,500 1,790 25.2 14.4 33.7

6,815.3 635 5,560 1,810 25.3 14.3 34.1

6,815.4 639 5,620 1,830 25.4 14.2 34.5

6,815.5 642 5,690 1,850 25.5 14.1 34.9

6,815.6 646 5,750 1,870 25.6 14.0 35.3

6,815.7 650 5,820 1,900 25.7 13.9 35.7

6,815.8 653 5,880 1,920 25.8 13.8 36.1

6,815.9 657 5,950 1,940 25.9 13.7 36.5

6,816.0 661 6,010 1,960 26.0 13.6 36.9

6,816.1 665 6,080 1,980 26.1 13.5 37.3

6,816.2 669 6,150 2,000 26.2 13.4 37.7

6,816.3 673 6,210 2,020 26.3 13.3 38.1

6,816.4 677 6,280 2,050 26.4 13.2 38.5

6,816.5 681 6,350 2,070 26.5 13.1 39.0

6,816.6 685 6,420 2,090 26.6 13.0 39.4

6,816.7 689 6,490 2,110 26.7 12.9 39.8

6,816.8 694 6,560 2,140 26.8 12.8 40.2

6,816.9 698 6,620 2,160 26.9 12.7 40.6

6,817.0 703 6,690 2,180 27.0 12.6 41.0

6,817.1 707 6,770 2,200 27.1 12.5 41.5

6,817.2 711 6,840 2,230 27.2 12.4 42.0

6,817.3 715 6,910 2,250 27.3 12.3 42.4

6,817.4 720 6,980 2,270 27.4 12.2 42.8

6,817.5 724 7,050 2,300 27.5 12.1 43.3

6,817.6 727 7,120 2,320 27.6 12.0 43.7

6,817.7 730 7,200 2,350 27.7 11.9 44.2

6,817.8 733 7,270 2,370 27.8 11.8 44.6

6,817.9 736 7,340 2,390 27.9 11.7 45.0

6,818.0 739 7,420 2,420 28.0 11.6 45.5

6,818.1 741 7,490 2,440 28.1 11.5 46.0
Results 15

Table 1. Elevation-area and elevation-storage capacity information for Upper Lake Mary—Continued

Water-surface 

elevation (feet)

Surface area 

(acres)

Volume

(acre-feet)

Volume

(million gallons)

Relative datum - 

measured up from 

lake bottom (feet)

Relative datum - 

measured down 

from tower (feet)

Percent capacity

(percent)

6,818.2 744 7,570 2,470 28.2 11.4 46.4

6,818.3 747 7,640 2,490 28.3 11.3 46.9

6,818.4 749 7,710 2,510 28.4 11.2 47.3

6,818.5 752 7,790 2,540 28.5 11.1 47.8

6,818.6 754 7,870 2,560 28.6 11.0 48.3

6,818.7 757 7,940 2,590 28.7 10.9 48.7

6,818.8 759 8,020 2,610 28.8 10.8 49.2

6,818.9 762 8,090 2,640 28.9 10.7 49.6

6,819.0 764 8,170 2,660 29.0 10.6 50.1

6,819.1 767 8,250 2,690 29.1 10.5 50.6

6,819.2 770 8,320 2,710 29.2 10.4 51.0

6,819.3 772 8,400 2,740 29.3 10.3 51.5

6,819.4 775 8,480 2,760 29.4 10.2 52.0

6,819.5 778 8,550 2,790 29.5 10.1 52.5

6,819.6 780 8,630 2,810 29.6 10.0 52.9

6,819.7 783 8,710 2,840 29.7 9.9 53.4

6,819.8 785 8,790 2,860 29.8 9.8 53.9

6,819.9 787 8,870 2,890 29.9 9.7 54.4

6,820.0 790 8,950 2,920 30.0 9.6 54.9

6,820.1 793 9,030 2,940 30.1 9.5 55.4

6,820.2 795 9,100 2,970 30.2 9.4 55.8

6,820.3 797 9,180 2,990 30.3 9.3 56.3

6,820.4 799 9,260 3,020 30.4 9.2 56.8

6,820.5 801 9,340 3,040 30.5 9.1 57.3

6,820.6 803 9,420 3,070 30.6 9.0 57.8

6,820.7 805 9,500 3,100 30.7 8.9 58.3

6,820.8 807 9,590 3,120 30.8 8.8 58.8

6,820.9 809 9,670 3,150 30.9 8.7 59.3

6,821.0 811 9,750 3,180 31.0 8.6 59.8

6,821.1 812 9,830 3,200 31.1 8.5 60.3

6,821.2 814 9,910 3,230 31.2 8.4 60.8

6,821.3 816 9,990 3,260 31.3 8.3 61.3

6,821.4 818 10,100 3,280 31.4 8.2 62.0

6,821.5 820 10,200 3,310 31.5 8.1 62.6

6,821.6 822 10,200 3,340 31.6 8.0 62.6

6,821.7 824 10,300 3,360 31.7 7.9 63.2

6,821.8 826 10,400 3,390 31.8 7.8 63.8

6,821.9 827 10,500 3,420 31.9 7.7 64.4

6,822.0 829 10,600 3,440 32.0 7.6 65.0

6,822.1 831 10,600 3,470 32.1 7.5 65.0

6,822.2 833 10,700 3,500 32.2 7.4 65.6
16 Bathymetric Survey and Storage Capacity of Upper Lake Mary

Table 1. Elevation-area and elevation-storage capacity information for Upper Lake Mary—Continued

Water-surface 

elevation (feet)

Surface area 

(acres)

Volume

(acre-feet)

Volume

(million gallons)

Relative datum - 

measured up from 

lake bottom (feet)

Relative datum - 

measured down 

from tower (feet)

Percent capacity

(percent)

6,822.3 835 10,800 3,520 32.3 7.3 66.3

6,822.4 836 10,900 3,550 32.4 7.2 66.9

6,822.5 838 11,000 3,580 32.5 7.1 67.5

6,822.6 840 11,100 3,610 32.6 7.0 68.1

6,822.7 842 11,200 3,630 32.7 6.9 68.7

6,822.8 844 11,200 3,660 32.8 6.8 68.7

6,822.9 845 11,300 3,690 32.9 6.7 69.3

6,823.0 847 11,400 3,720 33.0 6.6 69.9

6,823.1 849 11,500 3,740 33.1 6.5 70.6

6,823.2 851 11,600 3,770 33.2 6.4 71.2

6,823.3 853 11,700 3,800 33.3 6.3 71.8

6,823.4 854 11,700 3,830 33.4 6.2 71.8

6,823.5 856 11,800 3,860 33.5 6.1 72.4

6,823.6 858 11,900 3,880 33.6 6.0 73.0

6,823.7 860 12,000 3,910 33.7 5.9 73.6

6,823.8 861 12,100 3,940 33.8 5.8 74.2

6,823.9 863 12,200 3,970 33.9 5.7 74.8

6,824.0 865 12,300 4,000 34.0 5.6 75.5

6,824.1 866 12,300 4,020 34.1 5.5 75.5

6,824.2 868 12,400 4,050 34.2 5.4 76.1

6,824.3 870 12,500 4,080 34.3 5.3 76.7

6,824.4 872 12,600 4,110 34.4 5.2 77.3

6,824.5 873 12,700 4,140 34.5 5.1 77.9

6,824.6 875 12,800 4,170 34.6 5.0 78.5

6,824.7 877 12,900 4,190 34.7 4.9 79.1

6,824.8 879 13,000 4,220 34.8 4.8 79.8

6,824.9 880 13,000 4,250 34.9 4.7 79.8

6,825.0 882 13,100 4,280 35.0 4.6 80.4

6,825.1 884 13,200 4,310 35.1 4.5 81.0

6,825.2 886 13,300 4,340 35.2 4.4 81.6

6,825.3 887 13,400 4,370 35.3 4.3 82.2

6,825.4 889 13,500 4,400 35.4 4.2 82.8

6,825.5 891 13,600 4,420 35.5 4.1 83.4

6,825.6 892 13,700 4,450 35.6 4.0 84.0

6,825.7 894 13,800 4,480 35.7 3.9 84.7

6,825.8 896 13,800 4,510 35.8 3.8 84.7

6,825.9 897 13,900 4,540 35.9 3.7 85.3

6,826.0 899 14,000 4,570 36.0 3.6 85.9

6,826.1 901 14,100 4,600 36.1 3.5 86.5

6,826.2 902 14,200 4,630 36.2 3.4 87.1

6,826.3 904 14,300 4,660 36.3 3.3 87.7
Results 17

Table 1. Elevation-area and elevation-storage capacity information for Upper Lake Mary—Continued

Water-surface 

elevation (feet)

Surface area 

(acres)

Volume

(acre-feet)

Volume

(million gallons)

Relative datum - 

measured up from 

lake bottom (feet)

Relative datum - 

measured down 

from tower (feet)

Percent capacity

(percent)

6,826.4 906 14,400 4,690 36.4 3.2 88.3

6,826.5 907 14,500 4,720 36.5 3.1 89.0

6,826.6 909 14,600 4,750 36.6 3.0 89.6

6,826.7 910 14,700 4,780 36.7 2.9 90.2

6,826.8 912 14,700 4,810 36.8 2.8 90.2

6,826.9 914 14,800 4,840 36.9 2.7 90.8

6,827.0 915 14,900 4,870 37.0 2.6 91.4

6,827.1 917 15,000 4,900 37.1 2.5 92.0

6,827.2 919 15,100 4,930 37.2 2.4 92.6

6,827.3 920 15,200 4,960 37.3 2.3 93.3

6,827.4 922 15,300 4,990 37.4 2.2 93.9

6,827.5 923 15,400 5,020 37.5 2.1 94.5

6,827.6 925 15,500 5,050 37.6 2.0 95.1

6,827.7 927 15,600 5,080 37.7 1.9 95.7

6,827.8 928 15,700 5,110 37.8 1.8 96.3

6,827.9 930 15,800 5,140 37.9 1.7 96.9

6,828.0 931 15,900 5,170 38.0 1.6 97.5

6,828.1 933 15,900 5,200 38.1 1.5 97.5

6,828.2 935 16,000 5,230 38.2 1.4 98.2

6,828.3 936 16,100 5,260 38.3 1.3 98.8

6,828.4 938 16,200 5,290 38.4 1.2 99.4

6,828.5 939 16,300 5,320 38.5 1.1 100.0

6,828.6 941 16,400 5,350 38.6 1.0 100.6

6,828.7 943 16,500 5,380 38.7 0.9 101.2

6,828.8 944 16,600 5,410 38.8 0.8 101.8

6,828.9 946 16,700 5,440 38.9 0.7 102.5

6,829.0 948 16,800 5,470 39.0 0.6 103.1

6,829.1 949 16,900 5,500 39.1 0.5 103.7

6,829.2 951 17,000 5,530 39.2 0.4 104.3

6,829.3 953 17,100 5,570 39.3 0.3 104.9

6,829.4 954 17,200 5,600 39.4 0.2 105.5

6,829.5 956 17,300 5,630 39.5 0.1 106.1

6,829.6 958 17,400 5,660 39.6 0.0 106.7
18 Bathymetric Survey and Storage Capacity of Upper Lake Mary

Table 2. Comparison of summary lake statistics between surveys for Upper Lake Mary

[1950s survey results summarized in Blee, 1987; 2006 survey results, this paper. Values based on full-pool capacity at spillway 

elevation of 6,828.5 feet above mean sea level referenced to National Geodetic Vertical Datum of 1929]

Lake Statistic 1950s Survey (a) 2006 Survey (b) Percent Change 

[((b-a)/a)x100]

Storage capacity (acre-feet) 15,620 16,300 4.4

Surface area (acres) 876 939 7.2

Mean depth (feet) 17.9 17.4 -2.8

Depth near dam (feet) 40 39 -2.5

Lake length (miles) 5.5 5.6 1.8

Lake width range (feet) 300 - 2,000 308 - 2,630 2.7 - 31.5

The small differences in storage capacity (4.4 percent), 

surface area (7.2 percent), mean depth (-2.8 percent), and 

depth near the dam (-2.5 percent) between the last survey 

and this one indicate that lake geometry has remained fairly 

stable over this period. The large difference in lake width 

(31.5 percent) is probably because measurements were taken 

at different locations in the lake for the earlier survey (it is 

not known where the measurements were made) and this 

survey. The reservoir capacity calculated from this recent 

survey is 4.4 percent larger than the capacity reported from the 

earlier survey. This apparent difference in storage capacity is 

probably a result of differences in surveying methods and the 

development and use of more accurate surveying equipment, 

as well as better processing capabilities in terms of both 

software algorithms and computing technology since the 

earlier survey was conducted. Decreases in area and storage 

capacity as a result of sedimentation in Upper Lake Mary 

are not apparent in comparisons between the two surveys. In 

conclusion, the area and storage capacity of Upper Lake Mary 

has remained fairly stable over time. 

References Cited

Blee, J.W.H., 1987, Determination of evaporation and seepage losses, Upper Lake Mary near Flagstaff, Arizona: U.S. 

Geological Survey Water-Resources Investigations Report 

87-4250, 39 p.

City of Flagstaff Utilities Department, 2004, Report to the 

Water Commission, Water and Wastewater Operation Plan 

Year 2004: Flagstaff, Arizona, City of Flagstaff Utilities 

Department, 70 p.

Environmental Systems Research Institute, 2005 ArcGIS 

Desktop 9.1 Help: Redlands, Calif.

Environmental Systems Research Institute, 2007a, ArcGIS: 

[http://www.esri.com/software/arcgis/index.html, last 

accessed March 28, 2007].

Environmental Systems Research Institute, 2007b, ArcGIS: 

[http://www.esri.com/software/arcgis/extensions/3danalyst/

index.html, last accessed March 28, 2007].

National Geodetic Survey, 2006, On-line positioning user 

service: [http://www.ngs.noaa.gov/OPUS/, last accessed 

September 8, 2006].

National Oceanic and Atmospheric Administration, 2006, 

Local climatological data annual summary with comparative data, Flagstaff, Arizona: Asheville, N.C., National 

Climate Data Center, ISSN 0198-0564, 8 p.

Pellatz, R., 2006, Upper Lake Mary annual report 2005, 

prepared for Arizona Dept. of Water Resources Dam Safety 

Section: City of Flagstaff, Arizona, 52 p.

Reson, Incorporated, 2002, NaviSound 200/400 series singlebeam echosounders operator’s guide, issue 1.5, version 3: 

Goleta, Calif., Reson Inc., 126 p.

Trimble Navigation Limited, 2000, AgGPS 124/132 operation 

manual, revision C: Overland Park, Kan., Trimble Precision 

Agricultural Systems, 216 p.

Trimble Navigation Limited, 2006, Trimble R7 GPS receiver, 

Trimble R8 GNSS receiver user guide, revision A: Dayton, 

Ohio, Trimble Engineering & Construction Group, 164 p.

Wilson, G.L., and Richards, J.M., 2006, Procedural documentation and accuracy assessment of bathymetric maps and 

area/capacity tables for small reservoirs: U.S. Geological 

Survey Scientific Investigations Report 2006-5208, 24 p. 

plus oversize figs.
Results 19

Inside back cover
20 Bathymetric Survey and Storage Capacity of Upper Lake Mary

Hornewer and Flynn—Bathymetric Survey and Storage Capacity of Upper Lake Mary— U.S. Geological Survey Open-File Report 2008–1098