U.S. Department of the Interior

U.S. Geological Survey

Prepared in cooperation with the

U.S. Army Corps of Engineers

Scientific Investigations Map 3409

Bathymetric Contour Map, Surface Area and Capacity Table, and Bathymetric Difference Map for Clearwater Lake near Piedmont, Missouri, 2017

By 

Joseph M. Richards and Richard J. Huizinga

2018

Introduction

Clearwater Lake, on the Black River near Piedmont in Reynolds 

County, Missouri, (fig. 1) was constructed in 1948 and is operated by 

the U.S. Army Corps of Engineers (USACE) for flood-risk reduction, 

recreation, and fish and wildlife habitat (U.S. Army Corps of Engineers, [n.d.]). The lake area is about 1,800 acres with about 34 miles 

of shoreline at the conservation pool elevation of 498 feet (ft). Since 

the completion of the lake in 1948, sedimentation likely has caused the 

storage capacity of the lake to decrease gradually. The loss of storage 

capacity can decrease the effectiveness of the lake to mitigate flooding, 

and excessive sediment accumulation also can reduce aquatic habitat 

in some areas of the lake. Many lakes operated by the USACE have 

periodic bathymetric and sediment surveys to monitor the status of the 

lake. The U.S. Geological Survey completed one such survey of Clearwater Lake in 2008 during a period of high lake level using bathymetric 

surveying equipment consisting of a multibeam echosounder (MBES), 

a singlebeam echosounder, 1/3 arc-second National Elevation Dataset data (used outside the MBES survey extent; https://nationalmap.

gov/elevation.html), and the waterline derived from 2008 aerial light 

detection and ranging (lidar) data (Richards, 2013). In May 2017, the 

U.S. Geological Survey, in cooperation with the USACE, surveyed the 

bathymetry of Clearwater Lake to prepare an updated bathymetric map 

and a surface area and capacity table. The 2008 survey was contrasted 

with the 2017 survey to document the changes in the bathymetric surface of the lake.

Methods

A bathymetric survey was done from May 3 to 11, 2017, at Clearwater Lake using similar methods to the previous survey completed in 

2008 (Richards, 2013). The average water-surface elevation of the lake 

during the 2017 survey was 559.77 ft. A bathymetric surface, a bathymetric contour map, and a difference map were created from the survey 

data.

Bathymetric Data Collection

Bathymetric data (water depths and positions) were collected 

(fig. 2) using a high-resolution multibeam mapping system (MBMS). 

The various components of the MBMS used for this study are described 

in more detail in reports about studies on the Missouri and Mississippi 

Rivers in Missouri (for example, see Huizinga, 2010, 2017; Huizinga 

and others, 2010) and for the City of Cameron water supply lakes (Huizinga, 2014). The survey methods used to obtain the data for Clearwater 

Lake were similar to these other studies, as were the methods used to 

ensure data quality. A brief description of the equipment and methods 

follows.

An MBMS is an integration of several individual components: the 

MBES, an inertial navigation system (INS), and a data-collection and 

data-processing computer. The INS provides position in three-dimensional space and measures the heave, pitch, roll, and heading of the 

vessel (and, thereby, the MBES) to accurately position the data received 

by the MBES.

Real-time navigation during the survey used a Differential Global 

Position System (DGPS) solution; however, the navigation information 

from the Clearwater Lake survey was postprocessed using the POSPacTM Mobile Mapping Suite (MMSTM) software (Applanix Corporation, 2009) to mitigate the effects of the degraded positional accuracy 

of the vessel from the DGPS solution. POS-PacTM MMSTM provides 

tools to identify and compensate for sensor and environmental errors 

and computes an optimally blended navigation solution from the Global 

Navigation Satellite Systems (GNSS) and inertial measurement unit raw 

data from the INS. The location solution was further enhanced by collecting static GNSS data with a GNSS base receiver set up over a documented benchmark at the dam, using techniques detailed in Rydlund and 

Densmore (2012). The blended navigation solution (called a “smoothed 

best estimate of trajectory” or “SBET” file) generated by postprocessing the daily navigation data was applied to the respective day of data 

collection in the survey.

Bathymetric data within the conservation pool area of Clearwater Lake (fig. 3) were collected with the MBES sound navigation and 

ranging (sonar) head oriented horizontally. However, along the banks in 

the conservation pool area and in the area above the conservation pool, 

the MBES head was tilted at 30 degrees to port to enhance acquisition 

of bathymetric data in the shallow areas near the banks, in coves, and 

in the upper reaches of the lake arms and to cover a wider swath of the 

bottom compared to when the head was not tilted.

The bathymetric data were collected along transect lines oriented 

longitudinally in the main lake area. In the conservation pool area, the 

transect lines were spaced to create about 10- to 25-percent overlap of 

the survey swaths to attempt to ensure complete coverage of the lake 

bottom and minimize sonic shadows. In the areas above the conservation pool, the transect lines were about 250 ft apart, resulting in partial 

lake-bottom coverage in these areas because it was shallower, had less 

bathymetric relief, and had more surface obstructions to navigation. 

Shoreline data were collected by travelling along the edge of the data 

collected along the longitudinal survey lines to ensure overlap of the 

shoreline data with the main body data. Cove data were collected by 

navigating into a cove along the approximate centerline of the cove 

as far as practical (usually, the point at which forward progress was 

blocked by thick timber, or water depth decreased to less than about 

3 ft), pivoting the boat 180 degrees, and egressing the cove along the 

ingress line.

In a lake, it is not unusual for the speed of sound in the water to 

change over time and to vary spatially. The speed of sound also can 

vary over the water column because of water temperature variations 

with depth. Although sound velocity data are collected at the MBES 

head throughout the survey to mitigate these variations near the water 

surface, the changes in the speed of sound with depth needs to be known 

to accurately determine the depths acquired by the MBES. Therefore, 

sound velocity profiles were measured at various locations throughout 

each survey day and applied during postprocessing in the HYPACK®/

HYSWEEP® software.

Preparation for the bathymetric survey was done in HYPACK®/

HYSWEEP® (HYPACK, Inc., 2015). To collect the survey data, a 

computer onboard the survey vessel ran HYPACK®/HYSWEEP® data 

acquisition software. After completing the surveys, the acquired depth 

data were processed further to apply sound velocity profiles and to 

remove data spikes and other spurious points in the MBES swath trace, 

georeferenced using the navigation and position solution data from the 

SBET file from POS-PacTM MMSTM, and visualized in HYPACK®/

HYSWEEP® as a triangulated irregular network (TIN) surface or a point 

cloud. The georeferenced data were output to a comma-delimited file 

that was filtered and reduced to a 3.28-ft data resolution.

Bathymetric Surface and Contour Map Creation

The data collected by the 2017 MBES survey represented about 

56 percent of the flood pool lake area (fig. 2), whereas the 2008 survey 

represented about 40 percent. About 19,000,000 data points (Richards 

and Huizinga, 2018), spaced 3.28-ft horizontally, were exported from 

the raw data collected in the 2017 survey. The vertical datum for the survey was the North American Vertical Datum of 1988, and the horizontal 

datum was the North American Datum of 1983. Geographic information 

system (GIS) software was used to filter the 3.28-ft spaced bathymetric 

data points so that the points would be no closer than about 16.4 ft apart. 

The data reduction retained about 715,000 surveyed data points from the 

2017 MBES survey.

Data for the remaining 44 percent of the flood pool area (fig. 2), 

where direct surveying with the MBES was not possible (for example, 

where wooded or too shallow), was obtained from the 2008 bathymetric surface and sampled at a 16.4-ft spacing (about 581,000 points). In 

addition, about 600 additional points were added to the dataset based on 

surrounding 2017 data values using the linear enforcement techniques 

described in Wilson and Richards (2006). These data were added to 

anchor the surface in areas of sparse data such as in the upper ends of 

coves and along near vertical bluffs where the 16.4-ft spacing could not 

constrain the steep elevation change.

These three point datasets, in combination with the water-surface 

elevation line derived from 2008 lidar data, were used to produce a 

three-dimensional TIN surface of the lake-bottom elevations. A surface area and capacity table was produced from the three-dimensional 

TIN surface showing surface area and capacity at specified lake watersurface elevations (table 1). The surface was contoured at a 5-ft interval 

using GIS software, and the contours were cartographically smoothed 

and edited to create a bathymetric contour map (fig. 2) using the techniques of Wilson and Richards (2006).

Bathymetric Difference Map Creation

The bathymetric difference map (fig. 3) was computed as the difference between the 2008 and 2017 bathymetric surfaces. The 2008 

map was based on a 16.4-ft gridded set of points, and the 2017 map 

was based on a similar spacing of data. To compute the bathymetric 

difference, 16.4-ft raster surfaces were interpolated linearly from the 

bathymetric TIN surfaces for each survey, and then the 2008 16.4-ft 

raster surface was subtracted from the 2017 16.4-ft raster surface. The 

bathymetric difference map was limited to the intersection of the 2008 

and 2017 MBES survey extents so that only data that were surveyed 

by the MBES were compared. Because the uncertainty is larger and 

vertical accuracy of the MBES typically is worse in areas of steep slope 

(see “Uncertanty Estimation” section, fig. 4; and “Bathymetric Surface 

and Contour Map Quality Assurance” section, fig. 5) and bathymetric 

change was assumed to be minor in these areas, raster cells that had a 

2017 slope greater than 16.6 degrees (about 5 percent of the 2017 slope 

values) also were removed from the map.

Bathymetric Data Collection Quality 

Assurance

For the MBMS, the principal quality-assurance measures were 

assessed in real time during the survey. The MBMS operator continuously assessed the quality of the data collected during the survey by 

making observations of across-track swaths (such as convex, concave, 

or skewed bed returns in flat, smooth bottoms), noting data quality 

flags and alarms from the MBES and the INS, and inspecting comparisons between adjacent overlapping swaths. In addition to the real-time 

quality-assurance assessments during the survey, beam angle checks and 

a suite of patch tests were done on May 3 before the survey to ensure 

quality data were acquired from the MBMS. These tests were completed 

in the deepest part of Clearwater Lake near Clearwater Lake Dam. Additional patch tests were completed on May 4, after a substantial strike of 

the MBES head on a submerged stob, and on May 8, at the beginning of 

a new survey week with a different boat operator.

Beam Angle Check

A beam angle check is used to determine the accuracy of the depth 

readings obtained by the outer beams (greater than 25 degrees from 

nadir [vertical]) of the MBES (U.S. Army Corps of Engineers, 2013), 

which may change with time because of inaccurate sound velocities, 

physical configuration changes, and water depth. On the first day of 

surveying on May 3, a beam angle check was done, and the results were 

within the recommended performance standards used by the U.S. Army 

Corps of Engineers for hydrographic surveys for all the representative angles below 50 degrees (U.S. Army Corps of Engineers, 2013), 

permitting the use of the central 100 degrees of the sonar swath with 

confidence.

Patch Tests

Patch tests are a series of dynamic calibration tests that are used to 

check for subtle variations in the orientation and timing of the MBES 

with respect to the INS and real-world coordinates. The patch tests are 

used to determine timing offsets caused by latency between the MBES 

and the INS, and angular offsets to roll, pitch, and yaw caused by the 

alignment of the transducer head (Huizinga, 2017). These offsets have 

been observed to be essentially constant for a given survey, barring 

an event that causes the mount to change such as striking a floating or 

submerged object (see Huizinga, 2017). The offsets determined in the 

patch test are applied when processing the data collected during a survey. Patch tests were completed on May 3, 4, and 8, 2017, at Clearwater 

Lake, and angular offsets were updated in the data collection software as 

appropriate. For this study, there was no measured timing offset, which 

is consistent with latency test results for this boat and similar equipment 

configurations used in other surveys (Huizinga, 2010, 2017; Huizinga 

and others, 2010).

Uncertainty Estimation

Similar to the previous studies of bathymetry in Missouri (Huizinga, 2010, 2017), uncertainty in the survey was estimated by computing the total propagated uncertainty (TPU) for each 3.28-ft survey-grid 

cell in the surveyed area using the Combined Uncertainty and Bathymetric Estimator (CUBE) method (Calder and Mayer, 2003). The CUBE 

method allows all random system component uncertainties and resolution effects to be combined and propagated through the data processing 

steps, which provides a robust estimate of the spatial distribution of 

possible uncertainty within the survey area (Czuba and others, 2011). 

Thus, the TPU of a point is a measure of the accuracy to be expected 

for such a point when all relevant error sources are taken into account 

(Czuba and others, 2011).

Most of the TPU values (93 percent) were less than 0.50 ft, which 

is within the specifications for a “Special Order” survey, the moststringent survey standard of the International Hydrographic Organization (International Hydrographic Organization, 2008). The median TPU 

value of the data was about 0.20 ft. The largest TPU in this survey was 

about 2.69 ft; however, TPU values of this magnitude typically are 

found near high-relief features, such as the nearly vertical banks that 

exist on some parts of the lake (fig. 2). The TPU values were larger 

near moderate-relief features (steep banks and submerged channels 

and ridges; fig. 2). The TPU values also were sometimes larger (1.00 ft 

or greater) in the outermost beam extents of the MBES swath in the 

overlap with an adjacent swath, particularly when the MBES head was 

tilted for the survey lines along the banks or in the upper extent of the 

lake (fig. 4).

Bathymetric Surface and Contour Map 

Quality Assurance

Accuracy of the bathymetric surface and contours is a function of 

the survey data accuracy, density of the survey data, and the processing steps involved in the surface and contour creation. The process of 

data reduction done to obtain the 3.28-ft gridded dataset from the raw 

survey data likely degraded the accuracy of the 3.28-ft gridded dataset 

relative to the raw data. Four areas of the lake were surveyed twice 

(fig. 2) to collect a dataset that could be used to estimate the accuracy 

of the 3.28-ft gridded dataset used to produce the bathymetric surface. 

The four areas had a combined total of about 2,930,000 raw survey 

points. Raw points that were within a horizontal distance of 0.33 ft of 

a 3.28-ft gridded point were selected as quality-assurance data points, 

and the elevation values of these points were compared to the 3.28-ft 

gridded points. The 93,361 selected raw points were compared to 3.28-ft 

gridded points, and the data tested at a vertical accuracy of 0.77 ft at 

a 95-percent confidence level; the median absolute vertical error was 

about 0.23 ft.

The quality-assurance dataset used to evaluate the bathymetric 

surface included about 910,000 data points selected at random from the 

about 19,000,000, 3.28-ft data points. Points that were used to create the 

bathymetric surface were not included as quality-assurance points. The 

three-dimensional bathymetric surface was tested against the qualityassurance dataset to determine the vertical accuracy of the surface using 

methods described in Wilson and Richards (2006). The surface tested 

at a vertical accuracy of 1.33 ft at the 95-percent confidence level; the 

median absolute vertical error was about 0.12 ft. The three-dimensional 

bathymetric surface was used as the source for the computation of the 

surface area and capacity values in table 1, the source for the development of the bathymetric contour map (fig. 2), and the source for the 

bathymetric difference map (fig. 3).

The process of smoothing and cartographic editing of the bathymetric contours to produce an aesthetic map degrades the positional 

and vertical accuracy of the contours; however, the contours are used 

primarily for visualization of the surface in an illustration, so some 

accuracy degradation is expected. The bathymetric contours (fig. 2) 

were tested with the same quality-assurance dataset used to evaluate the 

bathymetric surface. A point was considered a contour elevation evaluation point if it was within a horizontal distance of 0.66 ft of a given contour line. Of the about 910,000 quality-assurance points, 18,607 points 

were selected as evaluation points for the contour lines, and the contour 

vertical accuracy was computed to be 5.85 ft at the 95-percent confidence level; the median absolute vertical error was about 0.92 ft.

Bathymetry, Capacity, and Bathymetric 

Change

A bathymetric surface was created from the current (2017) surveyed data and used to produce a bathymetric contour map (fig. 2). The 

bathymetric map is similar to the map produced from the 2008 survey 

(appendix of Richards, 2013). The lake bathymetric contours show that 

the submerged Black River channel and the tributary stream channels 

are still present and are still well-defined in some areas at and below the 

500-ft contour (fig. 2). There is evidence of the Black River channel, 

although somewhat muted, all the way to Clearwater Lake Dam (fig. 2).

A surface area and capacity table (table 1) was computed from the 

bathymetric surface. At the conservation pool elevation of 498 ft, the 

surface area of the lake is 1,800 acres and the capacity is 26,800 acrefeet (table 1). The area and capacity table is similar to the previous 

2008 survey; however, on average, the survey areas shown on table 1 

are about 2 percent larger and capacities are about 1 percent larger than 

the survey completed in 2008. The differences in the table may exist, in 

part, because a somewhat larger area of the lake was surveyed in 2017 

because the lake level was higher in 2017 than in 2008, and because 

parts of the lake were surveyed with the MBES head tilted that allowed 

greater MBES data collection in shallow water where values were estimated in 2008.

The area of bathymetric change below the tested accuracy of the 

2017 bathymetric surface (1.33 ft) is shown as a light tan color on the 

map (fig. 3). This large area of the bathymetric difference map indicated 

change below the tested accuracy of the 2017 bathymetric surface, so 

the changes in these areas may or may not be the result of deposition 

and erosion or a survey or data processing artifact. The bathymetric 

difference map shows some erosional and depositional areas along the 

Black River and some of the tributary channels along the upper reaches 

of the conservation pool elevation of about 498 ft. Areas of erosion and 

deposition on the map, particularly in the upper reaches of the lake and 

along the edge of the bathymetric difference map extent, that are collocated with areas of greater survey uncertainty (fig. 4) and in areas of 

larger vertical accuracy differences (fig. 5), are less likely to represent 

real change between the 2008 and 2017 surveys and more likely to be 

the result of some survey or data processing artifacts.

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user guide, rev. 4: Richmond Hill, Ontario, Canada, PUBS–MAN–

001768, 523 p.

Calder, B.R., and Mayer, L.A., 2003, Automatic processing of highrate, high-density multibeam echosounder data: Geochemistry, 

Geophysics, Geosystems (G3), v. 4, no. 6, 22 p. [Also available at 

https://doi.org/10.1029/2002GC000486.]

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Garcia, M.H., and Ashmore, P., 2011, Bed morphology, flow structure, and sediment transport at the outlet of Lake Huron and in the 

Upper Saint Clair River: Journal of Great Lakes Research, v. 37, 

no. 3, p. 480–493. [Also available at https://doi.org/10.1016/j.

jglr.2011.05.011.]

Huizinga, R.J., 2010, Bathymetric surveys at highway bridges crossing the Missouri River in Kansas City, Missouri, using a multibeam 

echo sounder, 2010: U.S. Geological Survey Scientific Investigations 

Report 2010–5207, 61 p. [Also available at https://pubs.usgs.gov/

sir/2010/5207/.]

Huizinga, R.J., 2014, Bathymetric surveys and area/capacity tables of 

water-supply reservoirs for the city of Cameron, Missouri, July 2013: 

U.S. Geological Survey Open-File Report 2014–1005, 15 p. [Also 

available at https://doi.org/10.3133/ofr20141005.]

Huizinga, R.J., 2017, Bathymetric and velocimetric surveys at highway bridges crossing the Missouri and Mississippi Rivers near St. 

Louis, Missouri, May 23–27, 2016: U.S. Geological Survey Scientific Investigations Report 2017–5076, 102 p. [Also available at 

https://doi.org/10.3133/sir20175076.]

Huizinga, R.J., Elliott, C.M., and Jacobson, R.B., 2010, Bathymetric and velocimetric survey and assessment of habitat for pallid 

sturgeon on the Mississippi River in the vicinity of the proposed 

Interstate 70 Bridge at St. Louis, Missouri: U.S. Geological Survey 

Scientific Investigations Report 2010–5017, 28 p. [Also available at 

https://pubs.usgs.gov/sir/2010/5017/.]

HYPACK, Inc., 2015, HYPACK® hydrographic survey software user 

manual: Middletown, Conn., HYPACK, Inc., 2,041 p.

International Hydrographic Organization, 2008, IHO standards for 

hydrographic surveys (5th ed.): Monaco, International Hydrographic 

Bureau, Special publication no. 44, 27 p.

Richards, J.M., 2013, Bathymetric surveys of selected lakes in 

Missouri—2000–2008: U.S. Geological Survey Open-File 

Report 2013–1101, 9 p. with appendix. [Also available at 

https://pubs.usgs.gov/of/2013/1101.]

Richards, J.M., and Huizinga, R.J., 2018, Bathymetric data for Clearwater Lake near Piedmont, Missouri, 2017: U.S. Geological Survey data 

release, https://doi.org/10.5066/F7DN44BJ.

Rydlund, P.H., Jr., and Densmore, B.K., 2012, Methods of practice and 

guidelines for using survey-grade global navigation satellite systems 

(GNSS) to establish vertical datum in the United States Geological 

Survey: U.S. Geological Survey Techniques and Methods, book 11, 

chap. D1, 102 p. with appendixes.

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manual no. EM 1110–2–1003, 560 p.

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at https://www.swl.usace.army.mil/Missions/Recreation/Lakes/

Clearwater-Lake/Dam-and-Lake-Information/.

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2006–5208, 24 p. 

REYNOLDS

COUNTY

MISSOURI

Clearwater Lake

0 1 2 MILES

0 1 2 KILOMETERS

90°50’ 90°45’ 90°40’

37°20’

37°15’

37°10’

CLEARWATER LAKE DAM

Base from U.S. Geological Survey digital data, 1:250,000, 1990

Universal Transverse Mercator Projection, zone 15

North American Datum of 1983

Figure 1. Location of Clearwater Lake near Piedmont, Missouri.

90°48’

90°51’

37°18’

37°15’

37°12’

37°09’

90°51’

90°48’

37°12’

EXPLANATION

0 1 2 MILES

0 1 2 KILOMETERS

Water surface contour—Shows approximate 

water-surface elevation of the flood pool 

from the light detection and ranging (lidar) 

survey (559.77 feet, table 1). Datum is North 

American Vertical Datum of 1988

460

480

500

520

540

Bathymetric contour—Shows elevation of the lake 

bottom. Principal contour interval 20 feet. Supplemental 

contour (grey) interval 5 feet. Datum is North American 

Vertical Datum of 1988

Area of resurvey for point to point 

quality-assurance data collection

CLEARWATER LAKE DAM

Figure 2. Bathymetric contours for Clearwater Lake near Piedmont, Missouri, resulting from survey made May 3–11, 2017.

Table 1. Surface area and capacity at specified 

water surface elevations for Clearwater Lake near 

Piedmont, Missouri, May 3–11, 2017.

[Conservation pool elevation is about 498 feet (fig. 3); the 

approximate flood-pool water-surface elevation during the 

survey was 559.77 feet (fig. 2)]

Water surface

 elevation1, in feet

Surface area, 

in acres

Capacity,2

in acre-feet

458.0 30.2 32.8

460.0 60.5 126

462.0 73.9 262

464.0 84.9 421

466.0 102 607

468.0 118 826

470.0 159 1,090

472.0 258 1,500

474.0 335 2,100

476.0 428 2,860

478.0 538 3,820

480.0 642 5,000

482.0 761 6,400

484.0 885 8,050

486.0 1,020 9,950

488.0 1,170 12,100

490.0 1,300 14,600

492.0 1,390 17,300

494.0 1,500 20,200

496.0 1,650 23,400

498.0 1,800 26,800

500.0 1,970 30,600

502.0 2,160 34,700

504.0 2,360 39,200

506.0 2,570 44,200

508.0 2,750 49,500

510.0 2,950 55,200

512.0 3,150 61,300

514.0 3,340 67,800

516.0 3,550 74,600

518.0 3,770 82,000

520.0 3,980 89,700

522.0 4,190 97,900

524.0 4,400 106,000

526.0 4,620 116,000

528.0 4,850 125,000

530.0 5,080 135,000

532.0 5,320 145,000

534.0 5,540 156,000

536.0 5,790 167,000

538.0 6,040 179,000

540.0 6,300 192,000

542.0 6,580 205,000

544.0 6,930 218,000

546.0 7,260 232,000

548.0 7,610 247,000

550.0 7,960 263,000

552.0 8,250 279,000

554.0 8,530 296,000

556.0 8,830 313,000

558.0 9,260 331,000

559.77 9,630 348,000

1

Elevations are referenced to the North American Vertical 

Datum of 1988.

2

Capacities were calculated from surface testing at 1.33-foot 

vertical accuracy at a 95-percent confidence level.

EXPLANATION

0 0.2 0.4 0.6 0.8 1 MILE

0 0.2 0.4 0.6 0.8 1 KILOMETER

Water-surface contour (elevaton 559.77 feet)

Conservation pool (elevation 498 feet)

>1.33 to 5.00

>5.00

0 to 1.33

>1.33 to 5.00

>5.00

Erosion Deposition

Bathymetric difference between the 2008 and 2017 

 bathymetric surfaces, in feet [>, greater than]

90°50’ 90°48’ 90°46’

37°12’

37°10’

37°08’

CLEARWATER LAKE DAM

Figure 3. Bathymetric difference between the 2008 survey and the 2017 survey of Clearwater Lake near Piedmont, Missouri.

EXPLANATION

Water-surface contour 

 (elevaton 559.77 feet)

Total propogated uncertainty,

 in feet [>, greater than]

0 to 0.16

>0.16 to 0.26

>0.26 to 0.39

>0.39 to 0.53

>0.53 to 0.66

>0.66

0 1 2 MILES

0 1 2 KILOMETERS

90°54’ 90°51’ 90°48’ 90°45’

37°18’

37°15’

37°12’

37°09’

Figure 4. Total propagated uncertainty of bathymetric data from the survey of 

Clearwater Lake near Piedmont, Missouri, 2017.

90°54’ 90°51’ 90°48’ 90°45’

37°18’

37°15’

37°12’

37°09’

0 to 0.25

>0.25 to 0.50

>0.50 to 1.0

>1.0 to 5.0

>5.0

EXPLANATION

Water-surface contour 

 (elevaton 559.77 feet)

Bathymetric surface vertical accuracy, 

 in feet [>, greater than]

0 1 2 MILES

0 1 2 KILOMETERS

Figure 5. Vertical accuracy of the bathymetric surface of Clearwater Lake near 

Piedmont, Missouri, 2017.

Any use of trade, firm, or product names is for 

descriptive purposes only and does not imply 

endorsement by the U.S. Government.

Suggested citation:

Richards, J.M., and Huizinga, R.J., 2018, Bathymetric contour map, surface area and capacity table, 

and bathymetric difference map for Clearwater Lake 

near Piedmont, Missouri, 2017: U.S. Geological 

Survey Scientific Investigations Map 3409, 1 sheet, 

https://doi.org/10.3133/sim3409.

For more information about this publication, 

contact

Director, USGS Central Midwest Water Science 

Center, Missouri Office

1400 Independence Road

Rolla, MO 65401

(573) 308–3667

For additional information visit 

https://mo.water.usgs.gov

ISSN 2329-132X (online)

http://doi.org/10.3133/sim3409