YELLOWTAIL AFTERBAY

2000 SURVEY

FOR THE

RFLOJ -

U.S. Department of the Interior

Bureau of Reclamation
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I. AGENCY USE ONLY (Leave Blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED

April 2003 Final _______________________________

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

Yellowtail Afterbay PR

2000 Survey

6. AUTHOR(S)

Ronald L. Ferrari ____________________________

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION

Bureau of Reclamation, Technical Service Center, Denver CO 80225-0007 REPORT NUMBER

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING

Bureau of Reclamation, Denver Federal Center, PU Box 25007, AGENCY REPORT NUMBER

Denver CO 80225-0007

__________________________________________________________________ DIBR

11. SUPPLEMENTARY NOTES

Hard copy available at Bureau of Reclamation Technical Service Center, Denver, Colorado

12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE

Available from the National Technical Information Service,

Operations Division, 5285 Port Royal Road, Springfield VA 22161 ____________________________

13. ABSTRACT (Maximum 200 words)

The Bureau of Reclamation (Reclamation) surveyed Yellowtail Afterbay on June 14th of 2000 to develop a topographic map and

compute a present storage-elevation relationship (area-capacity tables). The underwater survey was conducted near water surface

elevation 3,186 feet (NGVD29). The underwater survey used sonic depth recording equipment interfaced with a global positioning

system (GPS) that gave continuous sounding positions throughout the underwater portions of the reservoir covered by the survey

vessel. The above-water topography was determined from elevation 3190.0 and above from an aerial survey conducted in the fall

of 1997. The new topographic map of Yellowtail Afterbay was developed from the combined 1997 aerial and 2000 underwater

measured topography. The 2000 underwater survey was conducted using a flat bottom raft that allowed collection in the shallow

portions of the reservoir, but did not have the power to collect any closer then 1,400 feet downstream of the dam. As part of the

analysis, underwater contours in this portion of the underwater area were projected.

As of June 2000, at water surface elevation (feet) 3,192.0, the surface area was 176 acres with a projected total capacity of 2,877

acre-feet.

14. SUBJECT TERMS 15. NUMBER OF PAGES

reservoir area and capacity! sedimentation! reservoir surveys! sonar! sediment distribution! ________________________

contour areal reservoir area! sedimentation survey/global positioning system 16. PRICE CODE

17. SECURITY 18. SECURITY 19. SECURITY CLASSIFICATION 20. LIMITATION OF

CLASSIFICATION CLASSIFICATION ABSTRACT

OF REPORT OF ABSTRACT

OF ThIS PAGE

UL UL UL

UL _______________________ ____________________

NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89)

Prescribed by ANSi Std. 239.18

298- 102
Yellowtail Afterbay

2000 Survey

By

Ronald L. Ferrari

Sedimentation and River Hydraulics Group

Water Resources Services

Technical Service Center

Denver, Colorado

July 2003
A CKNOWLEDGMENTS

The Bureau of Reclamations (Reclamation) Sedimentation and River Hydraulics Group of the

Technical Service Center (TSC) prepared and published this report. Ronald Ferrari and

Stephanie Schwinghamnier of the TSC conducted the hydrographic survey. Ronald Ferrari

completed the data processing needed to generate the new topographic map and area-capacity

tables. Sharon Nuanes of the TSC completed the final map development. Kent Collins of

TSC performed the technical peer review of this documentation.

Mission Statements

The mission of the Department of the Interior is to protect and provide access to our Nation's

natural and cultural heritage and honor our trust responsibilities to Indian tribes and our

commitments to island communities.

The mission of the Bureau of Reclamation is to manage, develop, and protect water and

related resources in an environmentally and economically sound manner in the interest of the

American public.

The information contained in this report regarding commercial products or firms may not be

used for advertising or promotional purposes and is not to be construed as an endorsement of

any product or firm by Reclamation.

The information contained in this report was developed for the Bureau of Reclamation; no

warranty as to the accuracy, usefulness, or completeness is expressed or implied.
CONTENTS

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Page

Introduction 1

Hydrographic Survey Equipment and Method I

Reservoir Area and Capacity 3

2000 Storage Capacity 4

References 5

TABLES

Table

1 Summary of 2000 survey results 6

2 Yellowtail Afterbay area and capacity tables 7

FIGURES

Figure

1 Survey vessel with mounted hydrographic equipment 2

2 Yellowtail Afterbay topographic map 13

3 2000 area and capacity curves 15

111
INTRODUCTION

Yellowtail Afterbay Dam and Reservoir are located 2.2 miles below Yellowtail Dam near Fort

Smith, Montana. The Yellowtail Afterbay Dam and Reservoir are used to smooth out fluctuating

discharges from the Yellowtail Powerplant and as a diversion structure to the Bighorn Canal.

The original reported storage for the reservoir was around 3,130 acre-feet at elevation 3,192.0

feet'.

The primary objectives of the June 2000 survey were to gather data needed to develop reservoir

topography and compute area-capacity relationships for the Yellowtail Afterbay reservoir. Prior

to the underwater survey, a 1997 ground and aerial photography survey was conducted at the Fort

Smith government camp. The survey covered the Yellowtail Afterbay at water surface elevation

3,190.0 and above. The 1997 established global positioning system (GPS) control points were

used as the control network for the 2000 underwater survey. The horizontal control was

established in a local coordinate system that was tied to Montana State plane coordinates in the

North American Datum of 1983 (NAD83). The vertical control was in the National Geodetic

Vertical Datum of 1929 (NGVD29). The detailed contours were developed with the local

horizontal coordinates that required a shifting of the 2000 underwater survey data points to match

the 1997 survey.

The bathymetric survey was run using sonic depth recording equipment interfaced with a

differential GPS capable of determining sounding locations within the reservoir. The system

continuously recorded depth and horizontal coordinates of the survey vessel as it was navigated

around Yellowtail Afterbay. Water surface elevations recorded by a Reclamation gauge during

the time of collection and measured by the GPS system were used to convert the sonic depth

measurements to true reservoir bottom elevations.

Table 1 contains a summary of the 2000 Yellowtail Afterbay Reservoir survey. The 2000 survey

determined that the reservoir has a total storage capacity of 2,877 acre-feet and a surface area of

around 176 acres at reservoir elevation 3,192.0.

HYDROGRAPHIC SURVEY EQUIPMENT AND METHOD

The hydrographic survey equipment was mounted on an 18-foot raft with an outboard motor

(figure 1). The hydrographic system included a GPS receiver with a built-in radio, a depth

sounder, a helmsman display for navigation, a computer, and hydrographic system software for

collecting the underwater data. On-board batteries supplied power to all the equipment. The

shore equipment included a second GPS receiver with an external radio. The GPS receiver and

antenna were mounted on a survey tripod over a known datum point and a 12-volt battery

provided the power for the shore unit.

Elevation levels are shown in feet and are based on the National Geodetic Vertical Datum of 1929 (NGVD29).
Figure 1 - Survey vessel with mounted hydrographic equipment

The Sedimentation and River Hydraulics Group uses Real-time Kinematic (RTK) GPS with the

major benefit being the ability to measure precise heights in real time to monitor the water

surface elevation changes. The basic outputs from an RTK receiver are precise 3D coordinates in

latitude, longitude, and height with accuracies in the order of 2 centimeters horizontally and 3

centimeters vertically. This output was on the GPS datum of WGS-84 that the hydrographic

collection software converted into Montana's NAD83 state plane coordinate system. The RTK

GPS system employs two receivers that track the same satellites simultaneously just like with

differential GPS. The shore base unit was placed over the 1997 aerial survey point labeled "12"

located upstream of the left abutment of the afterbay dam with the following coordinates:

Montana's State Plane in NAD 1983 (Grid North)

North 119,826.22 meters

East 723,625.27 meters

Local Ground Feet (True North)

North 393,147.00

East 2,374,873.78

Elevation 3,204.27

2
The bearings were referenced to True North based on UPS observations and rotated about

(+) 1.1403 degrees from the grid bearings.

The underwater data were collected by a depth sounder that was calibrated by lowering a 25-foot

survey rod below the sounders transducer. This was accomplished by tying the survey vessel at

several locations along the buoy line just upstream of the dam. The depth sounder was calibrated

by adjusting the speed of sound, which can vary with density, salinity, temperature, turbidity, and

other conditions to match the known bottom depth. The collected data were digitally transmitted

to the computer collection system via a RS-232 port. The depth sounder also produced an analog

hard-copy chart of the measured depths. These graphed analog charts were printed for all survey

lines as the data were collected and recorded by the computer. The charts were analyzed during

post-processing, and when the analog charted depths indicated a difference from the recorded

computer bottom depths, the computer data files were modified. The water surface elevations at

the dam recorded by a Reclamation gage at 15-minute intervals and the RTK UPS elevation

measurements were used to convert the sonic depth measurements to true lake-bottom elevations.

These vertical measurements were absolutely critical for this study since the water surface

fluctuated continuously throughout the survey.

The small flat bottom survey vessel allowed collection in the shallow portions of the reservoir,

but due to limited power of the survey vessel and underwater turbulence conditions the collection

ended about 1,400 feet below Yellowtail Dam. Even if the vessel could have progressed safely

further upstream, the dam would have eventually hindered the collection of the UPS

measurements and the underwater turbulence from the power releases would have prevented the

depth sounder from obtaining good bottom depth readings.

RESERVOIR AREA AND CAPACITY

Using ARC/INFO the topography of Yellowtail Afterbay was developed from the 1997 aerial

data and the 2000 underwater data set. ARC/INFO is a software package for development and

analysis of geographic information system (GIS) layers and development of interactive GIS

applications that provided a means of organizing and interpreting these data sets. The 1997 data

was provided in a digital format, but the contour of the reservoir water surface, elevation 3,190.0,

was not a complete contour and did not provide all the island details as illustrated on the hard

copy maps. For the purpose of this study, the 3190 contour was digitized from the several maps

that represented the reservoir. The aerial contours were projected to a local coordinate system

that had ties to Montana's NAD 1983 state plane coordinates. The resulting enclosed 3,190.0

contour provided a surface area at this elevation and was also used to provide a clip or boundary

around the edge of the underwater data set such that interpolation was not allowed to occur

outside of this boundary. This clip was performed using the hardclip option of the ARC/INFO

CREATETIN command. This clip was selected because it was the closest available contour

elevation to the reservoir water surface during the underwater collection that was conducted near

reservoir elevation 3,186.

3
Using the ARCEDIT command the underwater data and the digitized 3190 contour layers were

plotted. Since the underwater data were in Montana's state plane coordinates they needed to be

shifted to match the local coordinated system of the aerial contour data. Shifting the underwater

data points 17.2 feet north and 779.9 feet east and rotating the data set, using point 12 as the

pivot point, 1.1403 degrees, completed this. A plot of the adjusted underwater data set found all

points within the 3190 contour boundary along the banks and around the islands.

Contours for elevations 3,190.0 and below were computed from the 2000 underwater data set

using the triangular irregular network (TIN) surface-modeling package within ARC/INFO. The

2000 contour surface areas for Yellowtail Afterbay were computed at 1-foot increments, from

elevation 3,144.0 to 3,190.0, using the developed TIN. The 2000 survey measured the minimum

reservoir elevation at 3,143.3. These calculations were performed using the ARC/INFO

VOLUME command that computes areas at specified elevations directly from the TIN taking

into consideration all regions of equal elevation.

Due to the lack of 2000 underwater data points from the dam to about 1400 feet downstream,

some judgment was used to add points in this area to develop contours and resulting surface

areas in this portion of the reservoir. These points were added using the 3190 clip and the 2000

upper data points as a guide. The surface areas and resulting capacity from the 2000 survey data

and the modified data set are listed on table 1. The contour topography at 2-foot intervals is

presented on figure 2.

2000 Storage Capacity

The storage-elevation relationships based on the measured surface areas were developed using

the area-capacity computer program ACAP85 (Bureau of Reclamation, 1985). The 2000

measured surface areas at 1-foot contour intervals from minimum reservoir elevation 3,145.0 (no

area reported at this elevation) to elevation 3,186.0 and the surface areas of aerial data from

elevation 3,190.0 to elevation 3,210.0 were used as the control parameters for computing the

reservoir capacity. The program can compute an area and capacity at elevation increments 0.0 1-

to 1.0-foot by linear interpolation between the given contour surface areas. The program begins

by testing the initial capacity equation over successive intervals to ensure that the equation fits

within an allowable error limit that was set at 0.000001. The initial capacity equation is used

over the full range of intervals fitting within this allowable error limit. For the first interval at

which the initial allowable error limit is exceeded, a new capacity equation (integrated from a

basic area curve over that interval) is utilized until it exceeds the error limit. Thus, the capacity

curve is defined by a series of curves, each fitting a certain region of data. Final area equations

are derived by differentiating the capacity equations, which are of second order polynomial form:

y = a1 + a2x + a3x

where:

y = capacity

x = elevation above a reference base

a1 = intercept

a2 and a = coefficients

4
Results of the 2000 Yellowtail Afterbay Reservoir area and capacity computations are listed in

table 1 and 2 and the area-capacity curves plotted on figure 3. As of June 2000, at elevation

3,197.5, crest elevation of embankments, the surface area was 202 acres with a total capacity of

3,902 acre-feet.

REFERENCES

Bureau of Reclamation, 1981. Project Data, Denver Office, Denver CO.

Bureau of Reclamation, 1985. Surface Water Branch, ACAP85 User's Manual, Technical

Service Center, Denver CO.

Environmental Systems Research Institute , Inc. (ESRI), 1992. ARC Command References.
Elevations 2000 Survey 2000 Survey

Adjusted Adjusted

Area Capacity

(feet) (acres) (acre-feet)

3,210.0 258.4 6,813

3,200.0 218.4 4,429

3,198.0 206.7 4,004

3,197.5 202.0 3,902

3,196.0 189.7 3,608

3,194.0 182.3 3,236

3,192.0 176.4 2,877

3,190.0 167.2 2,533

3,186.0 149.7 1,899

3,184.0 144.4 1,605

3,182.0 138.8 1,322

3,180.0 132.0 1,051

3,178.0 120.3 799

3,176.0 103.5 575

3,174.0 82.9 389

3,172.0 56.8 249

3,170.0 39.7 153

3,168.0 28.8 84

3,166.0 16.4 39

3,164.0 6.9 16

3,162.0 2.1 6

3,160.0 1.1 3

3,158.0 0.4 2

3,156.0 0.3 1

3,154.0 0.2 1

3,152.0 0.1 0

3,150.0 0.1 0

3,148.0 0.0 0

3,146.0 0.0 0

3,145.0 0.0 0

Table 1 - Summary of 2000 survey results

6
UNITED STATES

DEPARTMENT OF TIlE INTERIOR

BUREAU OF RECLAMATION

GREAT PLAINS REGION

YELLOWTAIL UNIT

YELLOWTAIL AFTERBAY

WYOMING

AREA AND CAPACITY TABLES

J

tFY FOR

OFTS

U.S. Department of the Interior

Bureau of Reclamation

June 2000
EQUATIONS --> AREA = A2 + X*(A3 + A3)

2

CAPACITY = A3*X + A2*X + Al

WHERE X = THE DIFFERENCE BETWEEN THE BASE

ELEVATION AND A GIVEN ELEVATION.

AREA IS IN ACRES AND CAPACITY IS

IN ACRE-FEET

YELLOWTAIL AFTERBAY - MONTANA

2000 AREA-CAPACITY TABLES

EQUATION ELEVATION CAPACITY COEFFICIENT COEFFICIENT COEFFICIENT

NUNBER BASE BASE A1(INTERCEPT) A2(1ST TERM ) A3(2ND TERN

1 3145.00 0 .0000 .0000 .0050

2 3146.00 0 .0050 .0100 .0050

3 3148.00 0 .0450 .0300 .0075

4 3150.00 0 .1350 .0600 .0150

5 3152.00 0 .3150 .1200 .0225

6 3156.00 1 1.1550 .3000 .0275

7 3158.00 1 1.8650 .4100 .1625

8 3160.00 3 3.3350 1.0600 .2600

9 3162.00 6 6.4950 2.1000 1.2050

10 3164.00 15 15.5150 6.9200 2.3650

11 3166.00 38 38.8150 16.3800 3.1100

12 3168.00 84 84.0150 28.8200 2.7300

13 3170.00 152 152.5750 397400 4.2600

14 3172.00 249 249.0950 56.7800 6.5400

15 3174.00 388 388.8150 82.9400 5.1400

16 3176.00 575 575.2550 103.5000 4.1900

17 3178.00 799 799.0150 120.2600 2.9350

18 3180.00 1051 1051.2750 132.0000 1.6925

19 3182.00 1322 1322.0450 138.7700 1.4175

20 3184.00 1605 1605.2550 144.4399 1.3250

21 3186.00 1899 1899.4351 149.7400 2.1825

22 3190.00 2533 2533.3149 167.2000 2.3000

23 3192.00 2876 2876.9151 176.3999 1.4750

24 3194.00 3235 3235.6150 182.3000 1.8500

25 3196.00 3607 3607.6150 189.7001 4.2499

26 3198.00 4004 4004.0149 206.7001 2.9250

27 3200.00 4429 4429.1147 218.4000 2.0000

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ELEV. FEET 0

3185 147.

3186 150.

3187 154.

3188 158.

3189 163.

3190 167.

3191 172.

3192 176.

3193 179.

3194 182.

3195 186.

3196 190.

3197 198.

3198 207.

3199 213.

3200 218.

3201 222.

3202 226.

3203 230.

3204 234.

3205 238.

3206 242.

3207 246.

3208 250.

3209 254.

3210 258.

YELLOWTAIL AFTERBAY - MONTANA

2000 AREA-CAPACITY TABLES

.1 .2 .3 .4

147. 148. 148. 148

150. 151. 151. 151

155. 155. 155. 156

159. 159. 160. 160

163. 164. 164. 165

168. 168. 169. 169

172. 173. 173. 174

177. 177. 177. 178

180. 180. 180. 181

183. 183. 183. 184

186. 187. 187. 187

191. 191. 192. 193

199. 200. 201. 202

207. 208. 208. 209

213. 214. 214. 215

219. 219. 220. 220

223. 223. 224. 224

227. 227. 228. 228

231. 231. 232. 232

235. 235. 236. 236

239. 239. 240. 240

243. 243. 244. 244

247. 247. 248. 248

251. 251. 252. 252

255. 255. 256. 256

10

(ACAP92) COMPUTED

4/ 8/2003

10:25:28

THE ELEVATION INCREMENT IS IN ONE TENTH FOOT

.5 .6 .7 .8

148. 149. 149. 149

152, 152. 153. 153

156. 157. 157. 158

161. 161. 162. 162

166. 165. 166. 166

170. 170. 170. 171

174. 175. 175. 175

178. 178. 178. 179

181. 181. 181. 182

184. 185. 185. 185

188. 188. 189. 189

194. 195. 196. 196

202. 203. 204. 205

210. 210. 211. 211

215. 216. 217. 217

220. 221. 221. 222

224. 225. 225. 226

228. 229. 229. 230

232. 233. 233. 234

236. 237. 237. 238

240. 241. 241. 242

244. 245. 245. 246

248. 249. 249. 250

252. 253. 253. 254

256. 257. 257. 258

9

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YELLOWTAIL AFTERBAY - MONTANA

2000 AREA-CAPACITY TABLES

THE CAPACITY TABLE IS IN ACRE FEET

ELEV. FEET 0 .1 .2 .3 .4 .5

3185 1751. 1766. 1780. 1795. 1810. 1825,

3186 1899. 1914. 1929. 1945. 1960. 1975

3187 2051. 2067. 2082. 2098. 2113. 2129

3188 2208. 2224. 2239. 2255. 2271. 2287

3189 2368. 2385. 2401. 2417. 2434. 2450

3190 2533. 2550. 2567. 2584. 2601. 2617

3191 2703. 2720. 2737. 2755. 2772. 2789

3192 2877. 2895. 2912. 2930. 2948. 2965

3193 3055. 3073. 3091. 3109. 3127. 3145

3194 3236. 3254. 3272. 3290. 3309. 3327

3195 3420. 3438. 3457. 3476. 3494. 3513

3196 3608. 3627. 3646. 3665. 3684. 3704

3197 3802. 3821. 3841. 3861. 3882. 3902

3198 4004. 4025. 4045. 4066. 4087. 4108

3199 4214. 4235. 4256. 4278. 4299. 4321

3200 4429. 4451. 4473. 4495. 4517. 4539

3201 4650. 4672. 4694. 4716. 4739. 4761

3202 4874. 4897. 4919. 4942. 4965. 4988

3203 5102. 5125. 5148. 5172. 5195. 5218

3204 5335. 5358. 5382. 5405. 5429. 5452

3205 5571. 5595. 5619. 5643. 5667. 5691

3206 5812. 5836. 5860. 5884. 5909. 5933

3207 6056. 6081. 6105. 6130. 6155. 6180

3208 6304. 6329. 6354. 6380. 6405. 6430

3209 6557. 6582. 6608. 6633. 6659. 6684

3210 6813.

(ACAP92) COMPUTED

4/ 8/2003

1 0:25:28

THE ELEVATION INCREMENT IS ONE TENTH FOOT

.6 .7 .8 .9

1840. 1855. 1870. 1884.

1990. 2005. 2021. 2036.

2145. 2160. 2176. 2192.

2304. 2320. 2336. 2352.

2467. 2483. 2500. 2517.

2634. 2651. 2669. 2686.

2807. 2824. 2842. 2859.

2983. 3001. 3019. 3037.

3163. 3181. 3199. 3217.

3346. 3364. 3383. 3401.

3532. 3551. 3570. 3589.

3723. 3742. 3762. 3782.

3922. 3942. 3963. 3983.

4129. 4150. 4171. 4192.

4342. 4364. 4386. 4407.

4561. 4583. 4605. 4627.

4784. 4806. 4829. 4851.

5010. 5033. 5056. 5079.

5241. 5265. 5288. 5311.

5476. 5500. 5524. 5547.

5715. 5739. 5763. 5787.

5958. 5982. 6007. 6031.

6204. 6229. 6254. 6279.

6455. 6481. 6506. 6531.

6710. 6736. 6762. 6787.

12
N

'if'

a '

ci

Horizontal datum based on 1997

ground and aera1 survey

Local coordinate system stn ties

to 1ontana State Plane (NAOB3)

Vertical datum baSeS North American

Otum of 1929

p/-4M4'/Sp2I #4a/!fl*vzW

)EZLaPIA/L lifT -

)'eI/afc// Af/ercy

Tapo/agy

_____- T&'W/CAL AKOMt_______

__ ___________

Osnr,r, co/arado 4'7?

13

Figure 2 - Yellowtail Afterbay topographic map
Area-Capacity Curves for Yellowtail Afterbay

Area (acre)

260 234 208 182 156 130 104 78 52 26 0

3,210.0

3205.0

3200.0

3195.0

3190.0

3185.0

3,180.0

3,175.0

3,170.0

3,165,0

3,160.0

3,155.0

3,150.0

3,145.0

Capacity

Area

0 700 1400 2100 2800 3500 4200 4900 5600 6300

CapacIty (acre-feet)

Figure 2 - 2000 area and capacity curves

15

- 3,,Iu.u

- 3,205.0

- 3,200.0

- 3,195.0

- 3,190.0

- 3,185.0

- 3,180.0

- 3,175.0

- 3,170.0

- 3,165.0

- 3,160.0

- 3,155.0

- 3,150.0

- 3,145.0

7000