Tributary Reservoir Regulation Activities

2015 Annual Report (October 2014 – September 2015)

Pactola Dam near its record peak pool of 4589.4 ft, June 29, 2015

Chatfield Dam near its record peak pool of 5448.5 ft June 19, 2015

Salt Creek Dam No. 2, Olive Creek Lake, near its record peak pool of 1345.6 ft, May 7, 2015.

Salt Creek Dam No. 2 peaked less than 4.5 ft below its emergency spillway crest (left)

Water Control and Water Quality Section Hydrologic Engineering Branch Engineering Division Omaha District March 2016 2015 ANNUAL REPORT TRIBUTARY RESERVOIR REGULATION ACTIVITIES (OCTOBER 2014 – SEPTEMBER 2015) NORTHWESTERN DIVISION OMAHA DISTRICT

CHAPTER 1 - INTRODUCTION ...... 1-1

CHAPTER 2 – RESERVOIRS IN THE OMAHA DISTRICT ...... 2-1 a. Reservoirs with Storage ...... 2-1 b. Reservoirs without Flood Control Storage ...... 2-3

CHAPTER 3 – TRIBUTARY AND RUNOFF CONDITIONS ...... 3-1 a. General Hydrologic Conditions ...... 3-1 i. Long-Term Trends ...... 3-1 ii. Mountain Snow Conditions ...... 3-5 iii. Plains Snowpack ...... 3-10 b. Precipitation and Temperature Summary ...... 3-14 i. October-November-December 2014 ...... 3-14 ii. January-February-March 2015 ...... 3-17 iii. April-May-June 2015 ...... 3-21 iv. July-August-September 2015 ...... 3-26 c. Flooding Concerns ...... 3-31 d. Snow Surveys ...... 3-35

CHAPTER 4 – RESERVOIR ACCOMPLISHMENTS ...... 4-1 a. Flood Damages Prevented ...... 4-1 b. Recreation Usage ...... 4-5

CHAPTER 5 – RESERVOIR REGULATION ...... 5-1 a. Previous Year Operations ...... 5-2 i. Corps of Engineers Dams ...... 5-2 ii. Bureau of Reclamation Dams ...... 5-2 b. Proposed Operations ...... 5-3 i. Corps of Engineers ...... 5-3 (1) ...... 5-3 (2) ...... 5-3 (3) ...... 5-4 (4) ...... 5-4 ii. Bureau of Reclamation ...... 5-4 (1) Canyon Ferry ...... 5-4 (2) Keyhole ...... 5-5 (3) Pactola ...... 5-5

i CHAPTER 6 – MAJOR REGULATION ISSUES ...... 6-1 a. Water Quality ...... 6-1 b. Downstream Channel Capacity ...... 6-1 c. Potential Hazardous Conditions ...... 6-4 d. Dam Safety Issues ...... 6-5 i. Corps of Engineers Dams ...... 6-5 (1) Bear Creek Dam ...... 6-5 (2) ...... 6-5 (3) ...... 6-6 (4) Salt Creek Dams ...... 6-6 (5) Papillion Creek Dams ...... 6-6 ii. Bureau of Reclamation Dams ...... 6-7 (1) ...... 6-7 (2) ...... 6-7 (3) ...... 6-7 (4) ...... 6-7 (5) ...... 6-7 (6) ...... 6-7 (7) ...... 6-8 (8) Keyhole Dam ...... 6-8 (9) ...... 6-8 (10) ...... 6-8 (11) Glendo Dam ...... 6-8

CHAPTER 7 – WATER CONTROL MANUALS ...... 7-1 a. Current Manual Status ...... 7-1 b. Work Priorities ...... 7-2

CHAPTER 8 – DATA COLLECTION PROGRAM AND PROCEDURES ...... 8-1 a. Water Control Data Collection ...... 8-1 i. Sources ...... 8-1 ii. Data Storage ...... 8-1 iii. Data Collection Equipment ...... 8-1 b. Cooperative Hydrologic Programs ...... 8-2 c. Water Quality ...... 8-3 d. Sediment ...... 8-4 i. Bed and Suspended Sediment Sampling ...... 8-4 ii. Sedimentation Surveys ...... 8-5 iii. MRB Sediment Memoranda Reports ...... 8-5 CHAPTER 9 – OTHER WATER CONTROL ACTIVITIES ...... 9-1 a. Water Control Initiatives ...... 9-1 i. River Region Water Control Data System Master Plan ...... 9-1 ii. Model Development ...... 9-1 b. Personnel ...... 9-2 c. Training ...... 9-3

ii LIST OF TABLES

2-1 Corps of Engineers Tributary Reservoirs, Omaha District ...... 2-1 2-2 Bureau of Reclamation Tributary Reservoirs, Omaha District ...... 2-2 3-1 2015 Water Year Observations/Departures from Normal ...... 3-2 3-2 Mountain Snowpack Moisture as a Percent of Normal ...... 3-6 3-3 Monthly Snowfall Reports in Inches ...... 3-13 3-4 Snow Surveys ...... 3-34 4-1 Omaha District Projects Flood Damages Prevented ...... 4-1 4-2 Bureau of Reclamation Projects Flood Damages Prevented ...... 4-4 4-3 Flood Damages Prevented by State, Omaha District ...... 4-5 4-4 Recreation Visitation Hours ...... 4-5 5-1 Tributary Reservoir Flood Control Operation and Runoff ...... 5-1 5-2 Utilization of Exclusive Flood Control Zone ...... 5-3 6-1 Water Quality Issues and Concerns ...... 6-2 6-2 Bureau of Reclamation Dam Safety Information ...... 6-7 7-1 Schedule for Revision of Water Control Manuals ...... 7-2 8-1 Cost of USGS Cooperative Program ...... 8-2 8-2 Tributary Projects Sampled and Types of Sampling ...... 8-4 8-3 Sediment Sampling Stations ...... 8-5 8-4 Area-Capacity Tables Updated ...... 8-5 9-1 CWMS Model Development ...... 9-2 9-2 List of Personnel ...... 9-3 9-3 Training Attended ...... 9-4 X X

LIST OF FIGURES

1-1 Tributary Reservoir Projects ...... 1-3 3-1 Fall 2014 U.S. Drought Monitor; NOAA ...... 3-3 3-2 Winter 2015 U.S. Drought Monitor; NOAA ...... 3-4 3-3 Spring 2015 U.S. Drought Monitor; NOAA ...... 3-4 3-4 Summer 2015 U.S. Drought Monitor; NOAA ...... 3-5 3-5 Mountain Snowpack as of 1 February (left) and 1 March (right); NRCS ...... 3-7 3-6 Mountain Snowpack as of 1 April (left) and 1 May (right); NRCS ...... 3-8 3-7 Time Series Snowpack Summary for the Platte River Basins ...... 3-9 3-8 Time Series Snowpack Summary for the Basin ...... 3-10 3-9 Modeled Inches of SWE on January 1, 2015; NOHRSC ...... 3-11 3-10 Modeled Inches of SWE on February 1, 2015; NOHRSC ...... 3-12 3-11 Modeled Inches of SWE on March 1, 2015; NOHRSC ...... 3-12 3-12 October-December 2014 Percent of Normal Precipitation; HPRCC ...... 3-16 3-13 October-December 2014 Departure from Normal Temperature; HPRRC ...... 3-17 3-14 January-March 2015 Percent of Normal Precipitation; HPRRC ...... 3-19 3-15 January-March 2015 Departure from Normal Temperature; HPRRC ...... 3-20 3-16 April-June 2015 Percent of Normal Precipitation; HPRCC ...... 3-23

iii 3-17 April-June 2015 Departure from Normal Temperature; HPRCC ...... 3-26 3-18 July-September 2015 Percent of Normal Precipitation; HPRCC ...... 3-28 3-19 July-September 2015 Departure from Normal Temperature; HPRCC ...... 3-29 8-1 USGS Cooperative Funding since 1971 for the Omaha District ...... 8-3 X X

APPENDICES

APPENDIX A – COE PROJECT PERTINENT DATA SHEETS Bear Creek Reservoir ...... A-1 Bowman-Haley Dam and Lake ...... A-1 Bull Hook – Scott Coulee Dams ...... A-1 Cedar Canyon Dam (Red Dale Gulch) ...... A-1 Chatfield Reservoir ...... A-1 Cherry Creek Reservoir ...... A-2 Cold Brook Dam and Lake ...... A-2 Cottonwood Springs Dam and Lake ...... A-2 Kelly Road Dam ...... A-2

Papillion Creek Dams Dam No. 11 – Glenn Cunningham Dam and Lake ...... A-3 Dam No. 16 – Standing Bear Dam and Lake ...... A-3 Dam No. 18 – Zorinsky Dam and Lake ...... A-3 Dam No. 20 – Wehrspann Dam and Lake ...... A-3

Salt Creek Dams Dam No. 2 – Olive Creek Dam and Lake ...... A-4 Dam No. 4 – Bluestem Dam and Lake ...... A-4 Dam No. 8 – Wagon Train Dam and Lake ...... A-4 Dam No. 9 – Stagecoach Dam and Lake ...... A-4 Dam No. 10 – Yankee Hill Dam and Lake ...... A-4 Dam No. 12 – Conestoga Dam and Lake ...... A-5 Dam No. 13 – Twin Lakes Dam and Lake ...... A-5 Dam No. 14 – Pawnee Dam and Lake ...... A-5 Dam No. 17 – Antelope Creek Dam and Holmes Park Lake ...... A-5 Dam No. 18 – Branched Oak Dam and Lake ...... A-5 and Lake ...... A-6 Snake Creek Dam and Lake Audubon ...... A-6 Spring Creek Dam and Lake Pocasse ...... A-6 Westerly Creek Dam ...... A-6 Spring Gulch Dam ...... A-6 and Lake ...... A-7 and ...... A-7 and Lake ...... A-7 and ...... A-7 iv and ...... A-7 and Lewis & Clark Lake ...... A-7

APPENDIX B – COE PROJECT OPERATION SUMMARIES B1-Bear Creek Reservoir ...... B1-1 B2-Bowman-Haley Dam and Lake ...... B2-1 B3-Bull Hook – Scott Coulee – Cedar Canyon Dams ...... B3-1 B4-Chatfield Reservoir ...... B4-1 B5-Cherry Creek Reservoir ...... B5-1 B6-Cold Brook Dam and Lake ...... B6-1 B7-Cottonwood Springs Dam and Lake ...... B7-1 B8-Kelly Road Dam ...... B8-1 B9-Westerly Creek Dam ...... B9-1

Papillion Creek Dams B10-Dam No. 11 – Glenn Cunningham Dam and Lake ...... B10-1 B11-Dam No. 16 – Standing Bear Dam and Lake ...... B11-1 B12-Dam No. 18 – Zorinsky Dam and Lake ...... B12-1 B13-Dam No. 20 – Wehrspann Dam and Lake ...... B13-1 B14-Pipestem Dam and Lake ...... B14-1

Salt Creek Dams B15-Dam No. 2 – Olive Creek Dam and Lake ...... B15-1 B16-Dam No. 4 – Bluestem Dam and Lake ...... B16-1 B17-Dam No. 8 – Wagon Train Dam and Lake ...... B17-1 B18-Dam No. 9 – Stagecoach Dam and Lake ...... B18-1 B19-Dam No. 10 – Yankee Hill Dam and Lake...... B19-1 B20-Dam No. 12 – Conestoga Dam and Lake ...... B20-1 B21-Dam No. 13 – Twin Lakes Dam and Lake ...... B21-1 B22-Dam No. 14 – Pawnee Dam and Lake ...... B22-1 B23-Dam No. 17 – Antelope Creek Dam and Holmes Park Lake...... B23-1 B24-Dam No. 18 – Branched Oak Dam and Lake ...... B24-1 B25-Snake Creek Dam and Lake Audubon ...... B25-1 B26-Spring Creek Dam and Lake Pocasse ...... B26-1 B27-Spring Gulch Creek Dam ...... B27-1

APPENDIX C – USBR PROJECT PERTINENT DATA SHEETS Boysen Dam and Reservoir ...... C-1 Canyon Ferry Dam and Reservoir ...... C-1 Clark Canyon Dam and Reservoir ...... C-1 Glendo Dam and Reservoir ...... C-1 Heart Butte Dam and Reservoir (Lake Tschida) ...... C-2 Jamestown Dam and Reservoir ...... C-2 Keyhole Dam and Reservoir ...... C-2 Pactola Dam and Reservoir ...... C-2 Shadehill Dam and Reservoir ...... C-3

v Tiber Dam and Reservoir () ...... C-3 Yellowtail Dam and Reservoir (Bighorn Lake) ...... C-3

APPENDIX D – USBR PROJECT OPERATION SUMMARIES D1-Boysen Dam and Reservoir ...... D1-1 D2-Canyon Ferry Dam and Reservoir ...... D2-1 D3-Clark Canyon Dam and Reservoir ...... D3-1 D4-Glendo Dam and Reservoir ...... D4-1 D5-Heart Butte Dam and Reservoir (Lake Tschida) ...... D5-1 D6-Jamestown Dam and Reservoir ...... D6-1 D7-Keyhole Dam and Reservoir ...... D7-1 D8-Pactola Dam and Reservoir ...... D8-1 D9-Shadehill Dam and Reservoir ...... D9-1 D10-Tiber Dam and Reservoir (Lake Elwell) ...... D10-1 D11-Yellowtail Dam and Reservoir (Bighorn Lake) ...... D11-1

vi CHAPTER 1 INTRODUCTION

The Omaha District is within the jurisdiction of the Northwestern Division, Corps of Engineers. Annually, the Omaha District provides pertinent information about the operation and activities of its reservoirs on tributaries to the Missouri River. This annual report summarizes significant tributary reservoir regulation activities and tributary flooding within the geographic boundaries of the Omaha District (Figure 1-1) for the period covered by this report. This period is October 1, 2014 through September 30, 2015 and is referred throughout the report as “the reporting period.” This period matches the USGS Water Year period.

Topics in this report include general information about the reservoirs, significant weather events, and runoff into the reservoirs during the reporting period. Additional chapters discuss the accomplishments of the reservoirs, including the flood damages prevented and recreation uses. Operational data from the reporting period and an outlook for next year is also included. Final chapters of this report discuss topics pertinent to tributary reservoir regulation activities such as major regulation issues, water control manuals, data collection program and procedures, water control initiatives, and personnel information.

The following references were used in the development of this Annual Report:

• ER 1110-2-1400, September 30, 1993. • ER 1110-2-240, October 8, 1982. • Missouri River Division Letter, October 1, 1970, Subject: Reservoir Regulation Reports.

Operational reports for all tributary reservoirs with authorized flood control storage are included as appendices to this report. The information contained in the appendices includes pertinent data sheets, operational summaries, historical as well as reporting period minimum and maximum data, and plots detailing flow and discharge data.

1-1 CHAPTER 1 INTRODUCTION

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1-2

CHAPTER 1 INTRODUCTION

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1-4 CHAPTER 2 RESERVOIRS IN THE OMAHA DISTRICT

The Omaha District, Corps of Engineers, civil works boundaries include 414,900 square miles that comprise the Missouri River watershed upstream of Rulo, Nebraska (Figure 1-1). This chapter is divided into two parts. One part describes the reservoirs that are within this watershed with flood storage and the other part describes those reservoirs without flood storage.

a. Reservoirs with Flood Control Storage. This report presents information for 39 tributary reservoirs with allocated flood control storage, including 24 Corps of Engineers dams, 4 dams built by the Corps but turned over to a local sponsor, and 11 Bureau of Reclamation dams. The Corps of Engineers and locally sponsored dams are listed on Table 2-1. Bureau of Reclamation dams are listed in Table 2-2. The locations of the tributary reservoirs are shown in Figure 1-1, and pertinent data for the tributary reservoirs are presented in Appendices A and C of this report.

In the original design and construction of the Corps dams, elevations on design drawings and reservoir levels referenced the Sea Level Datum of 1929, commonly referred to as “feet above mean sea level”. In 1973 the Sea Level Datum of 1929 was renamed the National Geodetic Vertical Datum of 1929 (NGVD29). The NGVD29 datum was subsequently replaced by the North American Vertical Datum of 1988 (NAVD88) as the current vertical reference datum used by the National Oceanic and Atmospheric Administration (NOAA). As specified in ER 1110-2-8160, long-term efforts shall be programmed to transition from older datums to NAVD88. In this annual report, elevations for Corps reservoir levels and project drawings are based on the Project Datums (PD), which for some projects is very close to the NGVD29.

Table 2-1 Corps of Engineers Tributary Reservoirs, Omaha District Exclusive Flood Drainage Area Control Storage Name of Dam Location River Date of Closure (sq. miles) (ac-ft) 1. Bear Creek , CO Bear Creek July 1977 236 28,514 2. Bowman-Haley Haley, ND N. Fork Grand August 1966 446 72,696 3. Bull Hook and Scott Havre, MT Bull Hook Creek October 1955 54 6,200 Coulee1 and Scott Coulee 4. Cedar Canyon2 Rapid City, SD Deadman Gulch September 1959 0.4 123 5. Chatfield Denver, CO South Platte August 1973 3,018 205,985 6. Cherry Creek Denver, CO Cherry Creek October 1948 386 79,294 7. Cold Brook Hot Springs, SD Cold Brook September 1952 70.5 6,711 8. Cottonwood Springs Hot Springs, SD Cottonwood Cr May 1969 26 7,752 9. Kelly Road3 Denver, CO Westerly Creek November 1953 11 360 10. Papillion No. 11 (Glenn Omaha, NE Knight Creek August 1974 18 13,573 Cunningham Dam) 11. Papillion No. 16 Omaha, NE Big Papio Creek October 1972 6 3,532 (Standing Bear Dam) 12. Papillion No. 18 Omaha, NE Boxelder Creek July 1984 16 7,476 (Zorinsky Dam) 13. Papillion No. 20 Omaha, NE S. Br. Papio September 1982 13 6,203 (Wehrspann Dam) Creek 14. Pipestem Jamestown, ND Pipestem Creek July 1973 594 135,040 15. Salt Creek No. 2 (Olive Lincoln, NE S. Olive Branch September 1963 8 3,857 Creek Dam) 2-1 CHAPTER 2 RESERVOIRS IN THE OMAHA DISTRICT

Table 2-1 Corps of Engineers Tributary Reservoirs, Omaha District Exclusive Flood Drainage Area Control Storage Name of Dam Location River Date of Closure (sq. miles) (ac-ft) 16. Salt Creek No. 4 Lincoln, NE N. Olive Branch September 1962 17 7,134 (Bluestem Dam) 17. Salt Creek No. 8 Lincoln, NE N. Hickman September 1962 16 6,595 (Wagon Train Dam) Branch 18. Salt Creek No. 9 Lincoln, NE S. Hickman August 1963 10 4,413 (Stagecoach Dam) Branch 19. Salt Creek No. 10 Lincoln, NE Cardwell Branch October 1965 8 5,839 (Yankee Hill Dam) 20. Salt Creek No. 12 Lincoln, NE Holmes Creek September 1963 15 7,607 (Conestoga Dam) 21. Salt Creek No. 13 Lincoln, NE Middle Creek September 1965 11 5,028 (Twin Lakes Dam) 22. Salt Creek No. 14 Lincoln, NE N. Middle Creek July 1964 36 20,097 (Pawnee Dam) 23. Salt Creek No. 17 Lincoln, NE Antelope Creek September 1962 5 5,870 (Antelope Creek Dam) 24. Salt Creek No. 18 Lincoln, NE Oak Creek August 1967 89 71,671 (Branched Oak Dam) 25. Westerly Creek4 Denver, CO Westerly Creek July 1991 9 4,150 26. Spring Creek Dam Pollock, SD Spring Creek 1961 660 0 (Lake Pocasse) 27. Snake Creek Dam Riverdale, ND Snake Creek 1952 250 0 (Lake Audubon) 28. Spring Gulch Creek Denver, CO Spring Gulch 1973 2 0 Dam 1 Havre, MT is the local sponsor for Bull Hook and Scott Coulee Dams. 2 Rapid City, SD is the local sponsor for Cedar Canyon Dam. 3 20,600 ac-ft. of exclusive flood control storage at Chatfield Reservoir will be reallocated to a joint-use flood control and water supply storage zone. The phased implementation of this new joint-use zone will begin on October 9, 2017. 4 Aurora, CO is the local sponsor for Kelly Road Dam. 5 Urban Drainage and Flood Control District is the local sponsor for Westerly Creek Dam.

Table 2-2 Bureau of Reclamation Tributary Reservoirs, Omaha District Exclusive Flood Drainage Area Control Storage Name of Dam Location River Date of Closure (sq. miles) (ac-ft) 1. Boysen Thermopolis, WY Wind October 1951 7,710 150,632 2. Canyon Ferry Helena, MT Missouri March 1953 15,900 101,089 3. Clark Canyon Dillon, MT Beaverhead August 1964 2,320 22,621 4. Glendo Glendo, WY North Platte June 1956 14,330 271,017 5. Heart Butte Glen Ullin, ND Heart August 1949 1,710 147,027 6. Jamestown Jamestown, ND James May 1953 1,300 190,502 7. Keyhole Moorcroft, WY Belle Fourche March 1952 1,950 140,463 8. Pactola Rapid City, SD Rapid Creek August 1956 319 43,063 9. Shadehill Shadehill, SD Grand July 1950 3,120 230,004 10. Tiber Chester, MT Marias October 1950 4,850 403,075 11. Yellowtail Hardin, MT Bighorn December 1966 19,626 258,323

2-2 CHAPTER 2 RESERVOIRS IN THE OMAHA DISTRICT

The Corps of Engineers Missouri River mainstem reservoir system is a multipurpose system serving both flood control and water supply functions. The flood control storage space provided in the system was developed on the basis that no upstream storage space was in existence. Continuing analysis of inflows into the mainstem system and into tributary reservoirs constructed upstream from the system has indicated that in certain instances, particularly when inflows are distinctly seasonal in nature, storage space provided in upstream reservoirs could effectively replace a portion of the annual flood control and multiple-use space initially provided in the mainstem system. Reclamation and the Corps coordinate forecasts and project releases to best utilize the storage provided by the upstream reservoirs. This upstream storage has been designated as "replacement flood control storage space."

In years when utilization of a major portion of the flood control and multiple-use storage space within the downstream Fort Peck Reservoir is anticipated, Canyon Ferry, Clark Canyon, and Tiber Reservoirs will assist in flood control along the Missouri River below Fort Peck by storing inflows to withhold flood water from Fort Peck Reservoir.

b. Reservoirs without Flood Control Storage. Three Corps of Engineers tributary reservoirs without allocated flood control storage are included in this report. Two of them are subimpoundments of the Missouri River mainstem projects and were formed by the construction of relocations for transportation facilities and utilities. Lake Audubon, a subimpoundment of Lake Sakakawea, is located just northeast of Riverdale, North Dakota, and is part of the Lake Sakakawea flood control area- calculations. Lake Pocasse, a subimpoundment of , is located near Pollock, South Dakota, and is not part of the Lake Oahe flood control area-calculations. Both Lake Audubon and Lake Pocasse are used for fish, wildlife and recreational purposes. The third project is the Spring Gulch Creek Dam. This dam was constructed as part of the Chatfield Dam project. The three reservoirs are included in Table 2-1 and the pertinent data are presented in Appendix A. The locations of Lake Audubon and Lake Pocasse are shown on Figure 1-1.

2-3 CHAPTER 2 RESERVOIRS IN THE OMAHA DISTRICT

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2-4 CHAPTER 3 TRIBUTARY AND RUNOFF CONDITIONS

The following chapter gives a description of weather related events that occurred in the District during the reporting period. It is useful to understand previous weather events, since they affect the activities of the Water Control personnel and how they regulate the tributary reservoirs. a. General Hydrologic Conditions

i. Long-Term Trends

The Climate Prediction Center (CPC) issued their final La Niña Advisory on May 3, 2012 for the most recent La Niña episode. At that time, a transition to ENSO-neutral conditions had occurred and was expected to continue through the Northern Hemispheric summer of 2012. While an El Niño Alert was issued on July 5, 2012 followed by an upgrading to an El Niño Watch on August 8, 2012, a cooling of those same waters during the first half of fall 2012 resulted in a discontinuation of the El Niño Watch on November 8, 2012. ENSO-neutral conditions persisted through the remainder of 2013.

Following consistent predictions from a variety of global climate models for a warming of the waters in the eastern equatorial Pacific Ocean, the CPC issued an El Niño Watch on March 6, 2014. At that time, the CPC forecasted a continuation of ENSO-neutral conditions through the Northern Hemisphere spring 2014, with about a 50% chance of El Niño developing during the summer or fall. While the ENSO-neutral conditions persisted through summer 2014, the CPC maintained an El Niño Watch as part of the ENSO Alert System as an El Niño was favored by nearly all computer models to begin by late November and last into the Northern Hemisphere spring 2015.

During February 2015, weak El Niño conditions were observed across the western and central equatorial Pacific and were forecasted by the CPC to have an approximately 50%-60% chance of continuing through Northern Hemisphere summer 2015. As sea surface temperatures (SSTs) continued to warm across the eastern equatorial Pacific during the spring of 2015, the CPC issued an El Niño Advisory and forecasted on May 14, 2015 a greater than 80% chance of El Niño conditions continuing through the remainder of the calendar year. The El Niño Advisory was still in effect by the end of Water Year 2014 with the CPC forecasting “an approximately 95% chance that El Niño will continue through Northern Hemisphere winter 2015-16, gradually weakening through spring 2016.”

As opposed to 12-months prior, the beginning of Water Year 2015 saw very little drought conditions (Figure 3-1) observed across the Missouri River basin. The only areas experiencing moderate to severe drought were found in far western with only isolated locations designated as being abnormally dry. This was a direct result of the copious amounts, in some cases record setting, of precipitation that fall across much of the basin during summer 2014. Much of the Plains, however, received below normal moisture during winter 2014-15 particularly across the Dakotas. This lack of

3-1 CHAPTER 3 TRIBUTARY AND RUNOFF CONDITIONS moisture resulted in an area of abnormally dry soil conditions to develop and expand throughout the eastern half of the Dakotas by late February 2015 (Figure 3-2).

By late spring 2015 (Figure 3-3), drought conditions had decreased in both areal coverage and intensity throughout the Missouri River basin. This was the product of unusually heavy rainfall that most locations had received during the month of May. In fact, by that time drought conditions were confined to southeastern South Dakota, northeastern Nebraska and northwestern Kansas. A steady stream of precipitation continued across the lower portion of the Missouri River basin through early summer 2015, but the Northern Rockies was generally much drier than normal. As a result, drought areas began to develop and expand (Figure 3-4) by late summer over much of western .

Table 3-1 2015 Water Year Observations/Departures from Normal Precipitation (inches) State City Observed Departure Colorado Denver 15.58 1.28 Montana Billings 11.68 -1.98 Glasgow 11.32 -0.34 Great Falls 13.53 -1.22 Helena 10.48 -0.74 Nebraska Lincoln 38.41 9.46 North Platte 19.67 -0.56 Omaha 40.34 9.72 North Dakota Bismarck 16.29 -1.07 Jamestown 21.33 2.94 Williston 10.94 -2.81 South Dakota Aberdeen 18.84 -2.88 Pierre 21.27 1.26 Rapid City 23.94 4.15 Falls 27.40 1.02 Cheyenne 16.12 0.18 Lander 15.48 2.82 Riverton 10.05 0.62 Sheridan 16.13 1.97

Most of the lower portion of the Missouri River basin received above average precipitation throughout Water Year 2015 (Table 3-1), with the largest anomalies observed in eastern Nebraska at Omaha (131% of normal) and Lincoln (133% of normal). Above normal precipitation was also reported in the Black Hills (121% of normal at Rapid City) and of central Wyoming (122% of normal at Lander).

Below normal precipitation was most predominantly located in the same regions of abnormally dry conditions, in particular across western Montana. Negative anomalies were greatest at Billings (85% of normal) and Great Falls (92% of normal). Further

3-2 CHAPTER 3 TRIBUTARY AND RUNOFF CONDITIONS east, more significant deficits were observed in the Dakotas at Williston (79% of normal) and Aberdeen (87% of normal).

Figure 3-1 Fall 2014 U.S. Drought Monitor; NOAA

3-3 CHAPTER 3 TRIBUTARY AND RUNOFF CONDITIONS

Figure 3-2 Winter 2015 U.S. Drought Monitor; NOAA

Figure 3-3 Spring 2015 U.S. Drought Monitor; NOAA

3-4 CHAPTER 3 TRIBUTARY AND RUNOFF CONDITIONS

Figure 3-4 Summer 2015 U.S. Drought Monitor; NOAA

ii. Mountain Snow Conditions

The mountain snowpack for the entire Missouri River basin ranged from near normal to well below average throughout the cold season of 2014-2015. The basin was the closest to average as northeastern Colorado was the beneficiary of multiple late season winter storms. Elsewhere, mountain snowpack was significantly lower than both the climatological average as well as recent years. At their peaks, the snowpack moisture levels as measured by snow water equivalent (SWE) ranged from 70% to 75% of the climatological average for the Missouri basin headwaters, Yellowstone River, and Belle Fourche River basins (Table 3-2). The Platte River basin was markedly different between the North and South Platte River watersheds. The former had a peak SWE that was only 62% of the climatological average while the latter rose to 88% of normal by the beginning of May. Of greatest significance was the unusually late snowmelt, where the each had 151% and 331%, respectively, of normal SWE by the beginning of June.

3-5 CHAPTER 3 TRIBUTARY AND RUNOFF CONDITIONS

Table 3-2 Mountain Snowpack Moisture as a Percent of Normal (values are % year-to-date & % of median peak) Missouri basin Yellowstone Belle Fourche North Platte South Platte Date Headwaters River basin basin River basin River basin 01-Nov-14 26/2 19/2 * 20/2 20/1 01-Dec-14 100/23 104/26 132/27 82/18 99/21 01-Jan-15 106/44 110/46 100/43 93/36 111/40 01-Feb-15 100/58 105/61 101/62 77/43 96/49 01-Mar-15 94/69 105/75 82/72 82/59 106/72 01-Apr-15 73/67 79/71 4/4 68/62 88/76 15-Apr-15 75/70 76/71 0/0 58/55 80/73 01-May-15 61/55 70/61 0/0 62/56 96/88 15-May-15 46/35 59/45 * 64/45 115/86 01-Jun-15 39/15 68/25 * 151/27 333/70 *incomplete data

Mountain snowfall during the late fall was generally light to moderate, with the first significant storm impacting the Colorado Rockies November 9-11. Snowfall totals were generally 3 to 6 inches around Denver and 6-12 inches in the higher elevations west of Boulder and Fort Collins. Heavier amounts were observed in the Northern Rockies from a couple of systems at the end of November that brought 4 to 8 inch totals around Billings and Livingston along with 10 to 14 inch amounts in the higher elevations from near Lake Yellowstone to the Big Horn Mountains.

The next couple of weeks were relatively quiet, followed by an area of low pressure December 13-15 that produced generally 6 to 12 inches of snowfall in the higher elevations of central Wyoming. Highest amounts were reported at Cloud Peak Reservoir SNOTEL (13 inches), Ten Sleep (12 inches), Casper (7-10 inches), and Thermopolis (8.5 inches). Heavy mountain snowfall December 20-23 was located from Yellowstone National Park southward to the upper North Platte River basin, with mostly 10 to 15 inch totals and localized amounts up to 2 feet. Even greater localized snowfall was measured around the Black Hills in South Dakota with 24 inches at Lead and 14 inches at Deadwood, combined with 3 to 4 foot drifts resulting from the gusty winds associated with the front.

The last several days of December 2014 brought more snow to the Northern Rockies, as an Arctic front became draped along the Front Range and initiated upslope conditions at the higher elevations. Snowfall totals included 7.7 inches at Great Falls and 6inches at Livingston, with lesser amounts further south of 4 inches at Torrington in Wyoming and 4.5 inches at Boulder in Colorado.

No major winter storms impacted the Northern and Central Rockies during January 2015, with only periods of light to moderate snowfall in the higher elevations. These were mostly the result of occasional upslope conditions on the back side of cold fronts and, as a result, were generally limited in moisture availability. As a result, the mountain snowpack was near to below average by the beginning of February (Figure

3-6 CHAPTER 3 TRIBUTARY AND RUNOFF CONDITIONS

3.5, left) with the greatest negative anomaly (only 77% of the climatological average) found within the North Platte River basin.

Figure 3-5 Mountain Snowpack as of 1 February (left) and 1 March (right); NRCS

A succession of Pacific based systems moved across the Northern Rockies during the first half of February 2015, bringing periods of light to localized moderate snowfall to the Missouri River Headwaters region as well as the upper Yellowstone River basin. While none of these storms produced unusually large amounts of snowfall, they enabled the mountain snowpack within these regions to remain near to slightly below normal as compared to the climatological average.

By far, the most significant mountain snowfall during February 2015 was observed across central Wyoming (particularly within the Wind River Range) and in the Colorado Rockies. A winter storm at the beginning of the month produced 6 to 10 inches of snowfall in the Cherry Creek basin with 7 inches at Cherry Creek Dam and 8.1 inches at Parker. Totals of 4 to 8 inches were also common in the foothills west of Denver, especially around Boulder and Golden. The next round of significant snowfall to move through the Central Rockies was February 14-17 as a result of upslope conditions on the backside of a series of Arctic cold fronts that had swept through the adjacent Plains days earlier. Snowfall totals included 8.1 inches at Golden, 10.2 inches at Nederland, 10.6 inches at Lakewood, and 14.5 inches at Jamestown.

Days later on February 20-21, another round of moderate to heavy snowfall impacted the Denver metropolitan area with 8-14 inch totals common from Aurora and Cherry Creek Reservoir to Boulder and Estes Park. The final winter storm in the area for the month involved a narrower strip of 6 to 12 inches of snowfall February 24-26 with observations of 7.2 inches at Lakewood and 10.9 inches at Boulder. These frequent

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winter storms in the Central Rockies resulted in an above average mountain snowpack for the South Platte River basin by the beginning of March 2015, although the North Platte River basin had not been the beneficiary of as much snowfall (Figure 3-5, right).

Figure 3-6 Mountain Snowpack as of 1 April (left) and 1 May (right); NRCS

March 2015 could be easily summed up as having been unusually, if not unprecedentedly, quiet with regards to snow storms across the Northern and Central Rockies. The only storms to produce even light to moderate snowfall were generally located in the upper North Platte and South Platte River basins. Two to 4 inch totals were observed from Fort Collins to Estes Park March 3-4 with a rain/snow mix from Aurora to Castle Rock March 18-19. The mountain snowpack, not surprisingly, was well below normal across the Missouri River basin by the beginning of April (Figure 3-6, left). Snowpack in the Missouri River Headwaters region was generally 50%-70% of normal, in the Yellowstone River basin 60%-80% of normal, and in the Platte River basin 60%- 80% of normal.

For parts of the Northern and Central Rockies, some of the greatest snowfall for the 2014-2015 season occurred during the month of April. One system April 6-9 brought heavy snowfall to the higher elevations of the northern and central . Overall moisture amounts, however, were not significant and were generally less than 0.75 inches. A much different scenario arrived mid-month as snowfall totals of 12 to 24 inches were common in the higher elevations of northeastern Colorado and extended into the upper North Platte and South Platte River basins. Lesser totals of 6 to 12 inches were observed further north in the Yellowstone River and Wind River basins in northern and central Wyoming. SWE amounts from this storm were much more impressive and ranged from 1 to 3 inches in Wyoming and Colorado. The remainder of

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the month was active as well, although the bulk of the moisture fell in the form of rainfall or wet snow in the higher elevations of the Central Rockies.

Figure 3-7: Time Series Snowpack Summary for the North Platte (left) and South Platte (right) River basins; NRCS

Additional snow fell during the month of May, however, particularly across the Central Rockies within the South Platte River basin. This resulted in the region with above normal mountain snowpack at the beginning of the month (Figure 3-6, right) to have near record amounts of SWE by the beginning of June. The lower portion of the North Platte River basin also picked up additional snowfall during May, although its totals were still much less than further south across Colorado.

Within the Platte River watershed, the seasonal snowpack varied significantly from Wyoming into Colorado (Figure 3-7). While the peak of the mountain snowpack in the North Platte basin was earlier than normal and occurred on March 28th, the peak within the South Platte basin was nearly two months later on May 24th. In addition, the former was well below normal (only 72% of the climatological average) and the latter was above normal (103% of the 30-year climatological average).

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Figure 3-8 Time Series Snowpack Summary for the Missouri River basin above Fort Peck (left) and from Fort Peck to Garrison (right); NRCS / MRBWMD

The snowpack for the Missouri River above Fort Peck Dam (Figure 3-8, left) peaked at 72% the normal peak on March 9. This was more than a month earlier than the normal peak of April 15. The mountain snowpack that flows into the Missouri River main stem reservoirs between Fort Peck Dam and Garrison Dam (Figure 3-8, right) also peaked much earlier than normal on both March 9 and again on March 14. Similarly, this peak was well below average and represented just 78% of the normal peak.

iii. Plains Snowpack

While several storm systems moved across the Plains during the final months of 2014, unseasonably mild temperatures in December resulted in much of the precipitation falling as moderate to heavy rainfall across Nebraska and . Nevertheless, snowfall was observed in this region on multiple occasions. The first round of snow was November 2-4, with 2 to 4 inches across southeastern Wyoming and the Nebraska panhandle. This was followed about a week later with a swath of 4 to 8 inches that was widespread from eastern Montana eastward along the North and South Dakota border and into the upper Midwest. Three to 6 inch totals were reported from near Mobridge to Aberdeen along with 6 to 12 inch totals in the upper Big Sioux River basin. This front was followed by another round November 14-16 that produced 2 to 4 inch amounts across much of Nebraska and western Iowa.

Heavy mountain snow developed in mid-December; but as the system worked eastward into the plains, much less amounts were observed including 4 to 6 inches from Ainsworth to Valentine in Nebraska and 2 to 4 inches around Sioux Falls in South Dakota. While no major storm systems moved through the plains during the latter half of the month, unusually cold temperatures ensured the maintenance of the snowpack from winter storms December 24-26 (4-8 inches around the Denver metropolitan area

3-10 CHAPTER 3 TRIBUTARY AND RUNOFF CONDITIONS and 2 to 4 inches from northern Nebraska to near Sioux Falls) and December 29-31 (2 to 4 inches from eastern Wyoming through the Nebraska panhandle).

Figure 3-9 Modeled inches of SWE on January 1, 2015; NOHRSC

The greatest SWE amounts for plains snowpack on January 1, 2015 (Figure 3-9) were found in the High Plains of Wyoming and the Nebraska panhandle, with 1 to 2 inches common in those areas. Much of eastern Montana and the Dakotas had less than an inch of SWE at that time, with the exception of the White River basin in South Dakota which had slightly higher SWE depths. These amounts were much less than a year earlier in the upper portion of the basin, as the lower Yellowstone River and much of North Dakota had 1 to 3 inches of SWE at that time.

With the exception of Glasgow and Sioux Falls, which received 275% and 127% respectively of their climatological averages, January 2015 produced below normal snowfall across the Plains. While a couple of clipper systems, one January 4-6 and the other January 24-26, delivered 1 to 3 inches of snowfall each to the eastern Dakotas, the largest storm arrived at the end of the month with snowfall totals of 4 to 8 inches extending from Nebraska and northern Kansas into Iowa and northern Missouri. Some of the highest totals, generally 6 to 10 inches, were observed around the Omaha metropolitan area. As a result, the only portion of the plains within the Missouri River basin to have any significant snowpack at the beginning of February 2015 (Figure 3-10) was in the upper James River basin, where 1 to 2 inches of SWE was observed at that time.

The pattern of below normal precipitation across the Plains continued into the following month. Light to localized moderate snowfall along an Arctic cold front February 2-4 was typical with only 2 to 4 inch totals in eastern Nebraska and western Iowa and the higher amounts of 4 to 8 inches located further west along the front range of the Rockies and

3-11 CHAPTER 3 TRIBUTARY AND RUNOFF CONDITIONS adjacent High Plains. For the remainder of the month, this is where the bulk of the plains snowfall was observed primarily from near Cheyenne and Denver eastward into the Nebraska panhandle with SWE across the plains less than an inch by the beginning of March 2015 (Figure 3-11) except in the upper James River basin.

Figure 3-10 Modeled inches of SWE on February 1, 2015; NOHRSC

Figure 3-11 Modeled inches of SWE on March 1, 2015; NOHRSC

The dearth of snowfall was most obvious across South Dakota. Monthly snowfall totals in Pierre, Watertown, Huron, and Aberdeen were 25%, 36%, 54%, and 75% respectively, of the climatological average. Similar conditions were evident further north at Glasgow (68% of normal), Bismarck (67% of normal), and Mobridge (73% of normal).

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The first half of March 2015 was unseasonably warm and generally free of any significant winter storms across the region. By the middle of the month, little to no plains snowpack remained across the Missouri River basin. The remainder of the month provided little additional snowfall to the plains, with the exception of light to localized moderate snowfall March 23-25 that extended from the foothills of the Northern Rockies eastward into the High Plains of Montana. Totals were not very significant with some of the highest observations including 6 inches near Billings and 2.5 inches at Red Lodge. Combined with ususually warm weather, no plains snowpack existed by the beginning of April 2015.

Snowfall totals for the entire month of March were well below normal throughout the Dakotas, although some locations were even drier than others. Monthly snowfall totals in Pierre at 4.8 inches and Watertown at 4.4 inches were some of the highest observed and represented 80% and 71%, respectively, of the climatological average. The most extreme conditions were located further north at Aberdeen (1.7 inches of snow; 24% of normal), Bismarck (0.8 inches of snow; 9% of normal), and Mobridge (Trace of snow; 0% of normal). Similar conditions were observed within the lower James River and Big Sioux River basins at Huron (1.2 inches of snow; 13% of normal) and Sioux Falls (1.7 inches of snow; 20% of normal).

Table 3-3 Monthly Snowfall Reports in Inches (December 2014-April 2015); NOAA/NWS Season December January February March April Location Totals (normal) (normal) (normal) (normal) (normal) (normal) 0.2 20.5 3.0 2.8 5.3 43.2 Glasgow, MT (8.0) (8.0) (4.4) (4.7) (1.9) (34.8) 2.4 7.2 5.4 0.8 2.2 23.9 Bismarck, ND (9.3) (8.9) (8.1) (9.1) (4.2) (51.3) 2.8 4.3 4.1 Trace Trace 18.7 Mobridge, SD (5.7) (5.2) (5.6) (7.7) (3.6) (33.4) 10.2 1.4 1.5 4.8 0.0 27.1 Pierre, SD (4.9) (4.7) (5.9) (6.0) (4.1) (31.9) 0.7 4.6 5.1 1.7 0.0 20.2 Aberdeen, SD (6.9) (6.4) (6.8) (7.2) (3.1) (38.4) 3.8 4.0 2.7 4.4 Trace 25.3 Watertown, SD (7.1) (5.3) (7.4) (6.2) (3.3) (35.9) 5.4 4.3 4.0 1.2 Trace 22.8 Huron, SD (8.0) (7.3) (7.4) (8.9) (4.0) (43.9) 5.9 9.8 6.2 1.7 Trace 31.9 Sioux Falls, SD (8.2) (7.7) (6.9) (8.4) (4.6) (44.5)

With the exception of a system in early April 2015 that brought light snowfall to portions of the High Plains, the remainder of the season saw little to no wintry precipitation across the Dakotas, Nebraska, and Iowa. As a result these locations continued to have no snowpack.

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The totals for the 2014-2015 snow season at selected locations across the Plains are given below (Table 3-3). With the exceptions of Glasgow and Mobridge, every location received below normal snowfall for the second consecutive season. The former was the only to have above normal snowfall for the most recent winter, with 124% of the normal totals, while Mobridge saw a decrease from 44.3 inches to 18.7 inches year-to- year (or from 133% of normal to 56% of normal).

Elsewhere in the Dakotas, the seasonal snowfall totals were well below the 30-year climatological average. At Bismarck, 23.9 inches represented 47% of normal. Similar percentages were observed further south within the James (53% of normal at Aberdeen and 52% of normal at Huron) and Big Sioux River basins (70% of normal at Watertown and 72% of normal at Sioux Falls). b. Precipitation and Temperature Summary

i. October-November-December 2014

Water Year 2015 began with localized flooding during the first week of October 2014 across southern Nebraska and southwestern Iowa due to heavy rainfall along and ahead of a strong cold front that dropped southward through the Missouri River basin. Rainfall totals of 2 to 3 inches were widespread within this region with the greatest totals in Nebraska of 7.15 inches near Lincoln, 5.29 inches at Roca, 5.10 inches at Crete, 3.52 inches at Gretna, and 3.20 inches at Offutt AFB and in Iowa of 4.09 inches at Oakland, 3.60 inches at Glenwood, and 3.05 inches at Council Bluffs. Heavy rainfall, while not quite as widespread, continued further downstream around the Kansas City metropolitan area with totals of 4.51 inches at Kansas City (Kansas), 4.09 inches at Kansas City (Missouri), and 2.98 inches at KCI Airport.

Moderate to localized heavy rainfall occurred across the lower portion of the basin again October 8-10 from near Omaha downstream into Missouri as a surface low formed along the lee of the Southern Rockies before lifting northeastward into the region. Rainfall amounts were enhanced by the remnant moisture from Hurricane Simon in the eastern Pacific and extended from Colorado (2.25 inches at Boulder and 1.03 inches at Fort Collins) into southern Nebraska (1.88 inches at Falls City and 1.04 inches at Beatrice), Kansas (1.84 inches at Topeka and 1.17 inches at Lawrence), and Missouri (3.21 inches at KCI Airport and 2.30 inches at St. Joseph). This was closely followed by areas of moderate to heavy rainfall October 11-14 across the lower portion of the basin along and ahead of a cold front that dropped out of the Northern Plains. Rainfall with this system was greatest in southwestern Iowa (1.26 inches at Clarinda and 1.01 inches at Red Oak), northeastern Kansas (1.55 inches at Leavenworth and 1.00 inch at Overland Park), and northwestern Missouri (1.72 inches at Platte City, 1.57 inches at Maryville, and 1.39 inches at St. Joseph).

While areas of low pressure continued to slide eastward through the Missouri River basin ahead of Pacific frontal systems through the remainder of the month, most contained only light amounts of precipitation with limited areal coverage. The only one

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with any significant moisture occurred October 21-23 with the highest totals once again observed in the lower portion of the basin, particularly across Nebraska (1.14 inches at York and 1.02 inches at Omaha), Iowa (0.83 inches at Council Bluffs), and Kansas (1.44 inches at Topeka and 0.95 inches at Manhattan). With the exception of this region, October 2014 was unusually dry for the Missouri River basin.

November 2014 was unusually dry as well for most of the Missouri River basin, with the exception of the Northern Rockies and a few isolated locations, such as near Cheyenne in southeastern Wyoming and Garrison in western North Dakota. The driest conditions were found in the lower portion of the basin from the Central Plains eastward with less than 25 percent of normal precipitation for the month observed across much of Nebraska, Kansas, and western Iowa.

Most of the month was colder than normal, which began friged early on as a powerful area of low pressure moved along the U.S.-Canadian border November 2-4, pulling a cold front southeastward through the Plains. This resulted in thundershowers from the Central Rockies eastward into the Plains and wintry precipitation across parts of Montana and North Dakota. Cold enough air on the back-side of the front produced 2 to 4 inches of snowfall across southeastern Wyoming and the Nebraska panhandle.

This was followed November 9-11 by a strong cold front that plunged south out of Canada into the Missouri River basin and brought the coldest temperatures of the season thus far along with moderate to localized heavy wind-driven snowfall from Montana eastward through the Dakotas. Snowfall totals of 4 to 8 inches are widespread from eastern Montana eastward along the North-South Dakota border and into the upper Midwest. The greatest totals, 6 to 12 inches, were located in the upper Big Sioux River basin. Upslope conditions on the back-side of the front combined with an active jet stream to produce moderate to heavy snowfall in the Colorado Rockies, with 3 6 inches around Denver and 6 to 12 inches in the higher elevations west of Boulder and Fort Collins. Totals in Montana included 9 inches at Red Lodge, 5.7 inches at Plevna, 5.4 inches at Fort Smith, 4 inches at Billings and in Wyoming 9.5 inches at Story, 4 inches at Sheridan. A reinforcing shot of Arctic air pushed southward on the eastern edge of the Rockies a few days late and produced moderate to localized heavy snowfall in the higher elevations of the Rockies along with light snow further south that extended eastward across the Plains. The heaviest snowfall totals in the Northern Rockies were near the Bighorn Mountains with 7 inches at Buffalo, in the Black Hills with 3 to 5 inches at Custer and Hot Springs, and in the Central Rockies with 3 to 5 inches around the Denver metropolitan area at Castle Rock, Franktown, and Aurora. Totals eastward in Nebraska were generally 2 to 4 inches.

A powerful winter storm moved across the far upper portion of the basin November 25- 27 and brought heavy snowfall to the higher elevations of the Northern Rockies, particularly in western Montana, while a clipper system dropped across North Dakota. Snowfall totals of 6 to 10 inches were common from near Butte and Helena in Montana to the Bighorn Mountains in northern Wyoming. This storm was closely followed by a strong cold front dropping south out of Canada, which produced east to northeasterly

3-15 CHAPTER 3 TRIBUTARY AND RUNOFF CONDITIONS winds that created upslope conditions in the Northern Rockies. The result was 2 to 4 inches of snowfall across a wide swath of Montana with greater amounts at the higher elevations. The greatest totals included 14 inches at Fort Smith, 11 inches at Red Lodge, 9.5 inches at Lodge Grass, 6.5 inches at Livingston, and 4.4 inches at Billings in Montana with 9.1 inches at Cody, 5.5 inches at Dayton, and 5 inches at Sheridan in Wyoming.

Figure 3-12 October-December 2014 Percent of Normal Precipitation; HPRCC

While November 2014 was unusually cold across the Missouri River basin, the following month was warmer than the climatological average and resulted in much of the month’s precipitation falling in the form of rainfall. An area of low pressure that moved out of the Southern Rockies December 4-5 brought 0.50 to 1 inch of rainfall across northern Kansas. This was followed a week later by a stronger system that had a greater amount of moisture to work with as it followed along a similar path. Rainfall totals were significant by December standards and in Nebraska included 1.25 inches at Papillion, 0.94 inches at Offutt AFB, and 0.73 inches at Omaha.

Leading up to Christmas, cooler temperatures December 20-23 brought a mix of precipitation from the High Plains of Wyoming eastward into the plains along with another round of rainfall for the lower portion of the basin. The heaviest amounts were less than an inch of rain again located in eastern Nebraska and western Iowa. The following days saw bands of snow developing from the Colorado Rockies to the Nebraska panhandle, with 4 to 8 inches around the Denver metropolitan area. A weaker system with generally 2 to 4 inch totals moved through the same region December 29-31.

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With the exception of a few locations, most notably the Big Horn Mountains and Nebraska panhandle, the final three months of 2014 were drier than normal across the Missouri River basin (Figure 3-12). The driest conditions were found in the Northern High Plains eastward into the Dakotas and central Nebraska. Much of these regions received less than 70% of normal moisture for that time period. Some of the most extreme dry conditions were located in the upper James River basin, which received less than 50% of normal precipitation.

For the October through December 2014 time period, the average temperatures were near average compared to the 30-year climatological average (Figure 3-13). This is a result of an unusally cold November being followed by an abnormally warm December. The lower portion of the basin, due to frequest storm systems late in the year, was the coolest overall for those 3 months. Conversely, the Rockies and adjacent High Plains which were generally not as cold in November averaged around 2 degrees warmer than normal for the same season.

Figure 3-13 Oct-Dec 2014 Departure from Normal Temperature (°F); HPRCC

ii. January-February-March 2015

January 2015 was much drier than normal for almost the entire Missouri River basin, with unseasonably warm condition expanding eastward from the Rockies into the Plains by mid-month. The year did start off quite cold, however, as an Arctic front dropped southward across the Northern Rockies and Dakotas January 2-6 with a swath of moderate snowfall for the region. Further south, an area of low pressure moved

3-17 CHAPTER 3 TRIBUTARY AND RUNOFF CONDITIONS through the far lower portion of the basin and brought rain showers to central Missouri. As the cold air surged into the Central Plains, that precipitation changed over to snowfall and expanded eastward from Nebraska into Iowa in advance of a follow-on clipper system out of southern Canada. Precipitation amounts were generally less than 0.50 inches with 3 to 6 inches of snowfall around Livingston and Red Lodge in Montana, 4 to 6 inches of snowfall from Aurora to Castle Rock in Colorado, and 2 to 4 inches of snowfall around Watertown in far eastern South Dakota.

The next clipper system to move through the upper portion of the basin didn’t arrive until nearly 3 weeks later, January 24-26, and dropped light to localized moderate snowfall across the Dakotas, Iowa, and northern Missouri. Snowfall totals were generally only 1 to 3 inches with moisture amounts less than 0.25 inches. The greatest amounts of precipitation arrived at the end of the month, beginning with moderate snowfall on January 28 from Cody to Casper in Wyoming. Better moisture inflow to the system arrived over the next several days as an upper level low swung out of the Southern Rockies and into the Central Plains.

Across the upper portion of the basin, most locations picked up 1 to 3 inches along the edge of the Arctic cold front. These amounts were exceeded considerably from the Central Rockies eastward. Snowfall totals of 4 to 6 inches were common around Denver, particularly within the Cherry Creek basin. Moisture availability rose with precipitation amounts exceeding an inch from Kansas (1.45 inches at Lawrence and 1.25 inches at Manhattan) and Missouri (1.32 inches at Mound City and 1.26 inches at St. Joseph) northward into Nebraska (1.22 inches at Lincoln and 1.15 inches at ) and Iowa (1.21 inches at Council Bluffs). Snowfall amounts of 6 to 10 inches were common from Hastings eastward into Iowa, with 9 inches at Fremont and 10 inches at Papillion.

February 2015 was generally tranquil precipitation-wise across the Missouri River basin, as cold fronts frequently dropped Arctic cold conditions southward but contained limited moisture for any significant snowfall totals. Light to localized moderate snowfall spread across the basin February 2-4 along one of those fronts, although the totals of 5 to 10 inches were generally limited to the High Plains region from near Cheyenne into the Nebraska panhandle including 8 inches at Guernsey in Wyoming and 5 inches at Ogallala in Nebraska. This was followed by a series of powerful Pacific based storm systems that rode along the northern periphery of the basin and brought light snowfall to parts of northern Montana and North Dakota February 5-9. Again, moisture availability was limited with these systems.

Much more significant snowfall, with moderate to localized heavy totals, was observed February 14-17 in the Northern Rockies from upslope conditions on the backside of a series of Arctic cold fronts that moved southward through the basin. Totals of note included 11 inches at Red Lodge in southern Montana and 8 to 14 inches around the Denver metropolitan area. A similar set-up occurred February 19-22 with 9 inches of snowfall at Red Lodge and 6 to 10 inch totals in the foothills of the Colorado Rockies west of Denver.

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A clipper system February 24-26 brought a stripe of light snowfall southward from the Dakotas into northern Nebraska and Iowa with localized heavier amounts further west. Totals from this system included 3 to 6 inches in the northern Black Hills and an additional 6 to 10 inches in the foothills of the Colorado Rockies.

Despite the arrival of a Polar front that stalled across the Central Plains during the first several days of March that provided a focus for precipitation as areas of low pressure moved along it as they developed in the Southern Rockies, the month was even drier than the previous two for almost the entire Missouri River basin. Parts of the Central Rockies picked up moderate snowfall with 4 to 8 inches around Casper, Wyoming and 4 to 6 inches from Fort Collins to Estes Park in Colorado March 3-4, but the next round of precipitation wouldn’t arrive until 2 weeks later.

Figure 3-14 January-March 2015 Percent of Normal Precipitation; HPRCC

Only localized moderate precipitation was observed until the final week of the month with 1.63 inches at St. Mary in Montana on March 15 and 0.50 to 0.82 inches from Cherry Creek Dam to Castle Rock on March 18. A taste of springtime thundershowers arrived in the Missouri River basin March 23-25 with the season’s first round of moderate to localized heavy rainfall across the Central Plains. Rainfall totals of 0.50 to 1 inch were common in southeastern Nebraska and northwestern Missouri with 1.48 inches at Mound City and 1.26 inches at Maryville. Meanwhile, a Pacific weather system combined with a Canadian cold front to bring snowfall to the mountains and foothills of the Northern Rockies. Most of the activity was relatively light in this region with 6 inches of snow at Billings from 0.36 inches of moisture. Light rain and snow fell

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across much of North Dakota March 26-30 with 0.25 to 0.50 inches of precipitation from Bismarck and Garrison to Jamestown.

With the exception of a few locations, the entire Missouri River basin was drier than normal (Figure 3-14) for the first quarter of 2015. The only areas that received above normal precipitation were in the lower Milk River basin (150%-300%), Wind River basin (100%-140%), and upper South Platte River basin (110%-200%). While the Northern Rockies and North Platte River basin were unusually dry, the most blatantly arid conditions were spread across the Plains. Almost all of South Dakota, Nebraska, Kansas, Iowa, and Missouri along with regions in surrounding states received 70% or less of normal precipitation from January through March with parts of central South Dakota along with the region along the Nebraska-Kansas border picking up less than 25% of normal.

Figure 3-15 Jan-Mar 2015 Departure from Normal Temperature (°F); HPRCC

Multiple strong Arctic cold fronts moved across the Missouri River basin during January and February 2015, especially from the Plains and southeastward. Nevertheless, the relatively limited snowpack combined with periodic Pacific airmasses ensured that the seasonal temperatures were above normal for most of the basin through March (Figure 3-15). Temperatures were generally 2 to 4 degrees above normal from the western Plains through the Rockies with cooler conditions eastward. Negative temperature anomalies were greatest in the far lower portion of the basin, 1 to 2 degrees below normal, from near Nebraska City downstream through Missouri. Near to slightly below normal temperatures were also found in the upper portion of the James River basin.

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iii. April-May-June 2015

While the region received below normal snowfall during April 2015, the weather patterns changed significantly and many locations began to receive much needed moisture in the form of showers and occasional thunderstorms. This was most evident from the Central Rockies eastward into Nebraska, Kansas, and Missouri. During the first couple of days of the month, strong to severe thunderstorms rolled across the lower portion of the Missouri River basin along and ahead of a cold front sliding southeastward through the Northern and Central Plains. While these storms did produce localized severe weather in Nebraska with inch diameter hail in the eastern part of the state and a 73 mph wind gust near Red Cloud, the most significant impact was heavy rainfall. Totals were greatest at De Witt (2.00 inches), Tecumseh (1.33 inches), Mead (1.32 inches), and Omaha (1.10 inches). Similar totals were observed in western Iowa (1.32 inches at Underwood and 1.12 inches at Council Bluffs) and northwestern Missouri (1.08 inches at Mound City at 0.81 inches at Maryville). Moisture amounts of 0.50 to 0.75 inches were common in the foothills of the Rockies west of Denver along with heavy wet snowfall of 5.8 inches at Nederland and 8 inches at Estes Park.

A series of low pressure systems moving eastward April 6-9 from the Central Rockies pulled moisture northward with rain and light snow from eastern Montana and the Dakotas southward through Nebraska and Iowa. On the tail end of the storm, heavy snowfall was observed in the higher elevations of the northern and central Bighorn Mountains. Moisture totals in the Plains were generally 0.75 inches or less in South Dakota, Nebraska, and Kansas.

A bit more moisture was available for the next system April 12-13 as an area of low pressure moved out of the Rockies into the lower portion of the basin and brought a line of strong to severe thunderstorms through the region. Once again, the severe weather reports were localized to Nebraska with baseball sized hail (2.75 inch diameter) near Columbus and golf ball sized hail (1.75 inch diameter) near Bellwood. Those storms produced 1.22 inches of rainfall at Clarkson, 0.86 inches at Bellwood, and 0.79 inches at Columbus. Much greater precipitation occurred around the Kansas City metropolitan area with 2.42 inches at Lenexa, 2.02 inches at Olathe, and 1.48 inches at Kansas City.

Mother Nature hadn’t given up on the mountain snowpack in the Rockies quite yet, as a follow-on area of low pressure April 15-19 combined with a strong cold front to bring heavy, wet snow to the higher elevations with 12 to 24 inch totals common in northeastern Colorado. This was in conjunction with 1 to 3 inch rainfall totals extending from the High Plains of Wyoming and Colorado eastward into the Plains. Totals further north weren’t quite as great with 0.50 to 1 inch of moisture in Montana, along with snowfall amounts of 12.3 inches at Red Lodge, 9.5 inches at Bozeman, and 4 inches at Livingston. The heaviest precipitation on April 15 was in these locations before the higher totals were observed in subsequent days further south.

Along with heavy snowfall on April 16, the moisture amounts were quite significant in Wyoming (1.23 inches at Burns), Colorado (2.36 inches at Nederland, 2.11 inches at

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Boulder, 1.90 inches at Aurora, 1.87 inches at Chatfield Dam, and 1.43 inches at Denver), Nebraska (1.21 inches at Doniphan), and Kansas (1.88 inches at Goodland). The region of rainfall expanded the following day, but the heaviest amounts were generally in many of the same locations in Wyoming (2.00 inches at Yoder, 1.42 inches at Pine Bluffs, and 1.06 inches at Cheyenne), Colorado (2.00 inches at Evergreen, 1.05 inches at Fort Collins, and 0.93 inches at Denver), South Dakota (1.15 inches at Martin), Nebraska (2.07 inches at Sidney, 1.75 inches at Mullen, and 1.49 inches at Scottsbluff), and Kansas (0.52 inches at Goodland). As the moisture tapered off April 18-19 in the Central Rockies (1.22 inches at Glenrock in Wyoming and 0.64 inches at Evergreen in Colorado), it intensified across eastern Nebraska (1.43 inches at Omaha, 1.34 inches at Plattsmouth, and 1.28 inches at Offutt AFB), Iowa (1.77 inches at Sidney and 1.59 inches at Shenandoah), and Missouri (2.03 inches at Rockport and 1.69 inches near Mound City).

An area of low pressure April 23-25 formed along the lee side of the Central Rockies and spread a swath of moderate rainfall (0.25 to 0.50 inches) from the front range eastward across southern Nebraska and Kansas. These storms did produce isolated severe weather in Colorado (tornado at Haxtun and 1.75 inch diameter hail at Holly), South Dakota (inch diameter hail at Cottonwood and Kadoka), and Nebraska (59 mph wind gust at Chadron). A follow-on surface low April 26-28 developed in eastern Colorado, with southeasterly winds pulling moisture northward and increasing precipitation rates in the Central Rockies due to orographic uplift. Moderate to localized heavy rainfall then expanded eastward across southern Nebraska and Kansas into Iowa and Missouri. Many of the same locations that received heavy rainfall a week prior were impacted again from this system.

Outside of inch diameter hail in South Dakota (at Mitchell, Loomis, and Corsica) and Nebraska (near Taylor and at Brewster) on April 24, this was clearly defined as a heavy precipitation event. Totals of note included 1.33 inches at Astoria and 0.92 inches at Mitchell in South Dakota, 1.94 inches at Aurora, 1.67 inches at Blue Hill, 1.52 inches at Fremont, and 1.43 inches at Hastings in Nebraska, 1.25 inches at Sidney in Iowa, and 1.14 inches at Concordia in Kansas. Heavier precipitation was observed the following day further west in the High Plains of Colorado (2.33 inches at Bennett, 2.22 inches at Sterling, and 1.42 inches at Fort Morgan), and Nebraska (1.51 inches at Sidney, 1.47 inches near Hay Springs, and 1.20 inches at Kimball). As the system wrapped up on April 26, the greatest precipitation was centered in the foothills of the Colorado Rockies and adjacent Plains with 1.56 inches at Castle Rock, 1.27 inches at Fort Morgan, 1.12 inches at Chatfield Dam, and 1.04 inches at Boulder. The month of April finished with a cool front dropping southward through the basin with light to moderate rainfall and thundershowers from the Central Rockies eastward into the Plains. This front produced precipitation totals generally less than 0.25 inches.

May was unusually wet across almost the entire Missouri River basin, with record monthly rainfall reported at Lincoln, Nebraska with 10.90 inches. The active weather pattern began during the first week of the month as a front stalled across the Central Plains. This enabled a series of systems to move from west to east as moisture was

3-22 CHAPTER 3 TRIBUTARY AND RUNOFF CONDITIONS drawn northward into the basin. The wide swath of moderate to localized heavy rainfall was spread from the High Plains eastward into the Midwest as the front gradually lifted northward into the Dakotas. Heaviest totals May 1-5 were concentrated in Nebraska (3.95 inches at Johnson, 3.12 inches at Cook, 2.11 inches at Weeping Water and 1.97 inches at Western), northwestern Missouri (2.48 inches near Rockport), and Kansas (4.22 inches at Manhattan and 2.25 inches at Leavenworth). While heavy rainfall impacted locations further north on May 6 (1.64 inches at Garrison in North Dakota and 1.57 inches at Rapid City in South Dakota), many of the same locations would receive near to record rainfall on that day. Totals of significance in Nebraska included 10.91 inches near Hebron, 9.85 inches at Wilber, 9.50 inches at Western, 6.65 inches at Lincoln, 4.49 inches at Elkhorn, 3.84 inches at Gretna, 3.38 inches at Fort Calhoun, 2.49 inches at Omaha, and 1.71 inches at Offutt Air Force Base. Just across the border in the Hawkeye State, reports included 3.37 inches at Missouri Valley and 1.89 inches at Schleswig.

Figure 3-16 April-June 2015 Percent of Normal Precipitation; HPRCC

The following day, moderate showers were common across the front range of the Central Rockies, which were an indication of the onset of frequent rain storms to arrive in that region as well. From May 8-11, an area of low pressure that formed on the lee side of the Central Rockies pulled moisture northward and brought a wide area of moderate to localized heavy rainfall from eastern Wyoming and Colorado through the Black Hills and adjacent Plains. In addition to the rainfall, unusually heavy late season snow was observed in the Central Rockies and Black Hills with accumulations of 12 to 24 inches at the higher elevations.

3-23 CHAPTER 3 TRIBUTARY AND RUNOFF CONDITIONS

Precipitation totals May 8-9 included in Colorado 3.92 inches at Fort Morgan, 3.37 inches at Fort Collins, and 3.13 inches at Loveland; in Wyoming 2.97 inches at Carpenter and 2.62 inches at Cheyenne; in South Dakota 2.37 inches at Pine Ridge and 2.18 inches at White River; and in Nebraska 3.84 inches at Gering, 3.42 inches at Sidney, 3.36 inches at Scottsbluff, 3.12 inches at Kimball, and 1.80 inches at Chadron. Heavier precipitation on May 10 shifted to the northeast in South Dakota with 3.18 inches at Mansfield, 2.41 inches at Mobridge, and 2.11 inches at Aberdeen. The next round of precipitation arrived May 13-17 after a front stalled temporarily across the lower portion of the Missouri River basin. This enabled an area of low pressure to form, which resulted in the surging of moisture northward out of the Gulf of Mexico. As the system developed, heavy precipitation broke out in the upper portion of the basin from the Northern Rockies eastward into the Dakotas while severe storms were widespread in the Central Plains. While parts of Montana saw heavy rainfall, with 2.57 inches at Big Timber, 1.76 inches at Red Lodge, and 1.61 inches at Lewistown, the highest totals were generally further south from the lower Big Sioux River basin into Missouri. Totals of note included 2.58 inches near Slayton and 2.00 inches at Edgerton in far southwestern Minnesota, 2.88 inches at Pawnee City in Nebraska, and 2.65 inches at St. Joseph and 2.10 inches at Tarkio in northwestern Missouri.

Periods of showers and thunderstorms again moved across the Missouri River basin May 18-20, while record flooding was ongoing across much of the Southern Plains in Oklahoma and Texas. 1 to 2 inch totals were common around the Denver metropolitan area with 2.03 inches at Fort Collins and 1.72 inches at Boulder and similar amounts within the James River basin in North Dakota including 2.08 inches at Carrington, 1.80 inches at Jamestown, and 1.32 inches at Grace City. Flooding concerns became more widespread across the basin May 21-25 as an inverted upper level trough slowly moved through the central and drew copious amounts of moisture northward out of the Gulf of Mexico with localized heavy rainfall from the Central Rockies eastward into the Plains. The heaviest rainfall totals extended from Wyoming (3.20 inches near Big Horn, 2.77 inches at Buffalo, 2.63 inches at Manville, 2.50 inches at Ten Sleep, and 1.71 inches at Thermopolis) to western South Dakota (4.89 inches at Midland, 2.39 inches at Rapid City, and 1.85 inches at Hot Springs).

As a soggy month came to a close, another cold front slid southward through the Missouri River basin May 28-30 and brought moderate to localized heavy rainfall with isolated strong thunderstorms to multiple locations. The most heavily impacted regions from these storms were in central South Dakota (1.95 inches at Fort Pierre and 1.14 inches at Chamberlain) and western Nebraska (1.34 inches at Lisco and 1.29 inches at Mullen).

The stormy pattern continued into June 2015, as several storm systems rode over a weakening ridge positioned along the spine of the Rockies during the first week of the month with localized heavy rainfall moving from the front range eastward across the Plains. Rainfall was heaviest in western North Dakota (2.77 inches at Hazen, 2.47 inches at Killdeer, and 1.53 inches at Williston) and Nebraska (1.55 inches near McCook and 1.51 inches at Western) with the first round of storms, but was much

3-24 CHAPTER 3 TRIBUTARY AND RUNOFF CONDITIONS heavier June 3-4 in Wyoming (3.77 inches at Buffalo and 2.11 inches at Sheridan), Nebraska (6.31 inches at Western, 5.90 inches at Falls City, 5.60 inches at Hastings, 4.80 inches at Steele City, and 3.81 inches at Hebron), Kansas (4.11 inches at Topeka and 3.33 inches at Salina), and Missouri (7.23 inches at Plattsburg and 3.36 inches at Kansas City). The following day shifted the heavier totals further north to parts of Montana (3.31 inches near Ismay and 2.94 inches at Glendive), North Dakota (2.29 inches at Garrison and 1.24 inches at Bowman), and South Dakota (3.16 inches at Hill City, 2.41 inches at Madison, and 2.32 inches at Flandreau).

Moderate to localized heavy precipitation slid eastward from the Rockies across the Plains and into Iowa and Missouri along and ahead of a cold front June 10-14. This produced widespread flooding to regions with unusually high levels of soil moisture. While 1 to 2 inch totals were common in southern Montana and northern Wyoming, particularly in the Big Horn Mountains, much greater rainfall was observed at the onset in southeastern Nebraska (4.12 inches at Denton, 3.88 inches at Crete, and 3.02 inches at Lincoln), southwestern Iowa (3.65 inches at Sidney and 3.63 inches at Shenandoah), and northwestern Missouri (3.10 inches at Maryville and 2.88 inches at Mound City). At the same time, northeastern Colorado was being inundated with 3.84 inches at Castle Rock, 3.12 inches at Parker, and 2.50 inches at Denver. The lower portion of the basin received the heaviest rainfall June 14 with 2.68 inches at Western and 2.26 inches at Omaha in Nebraska along with 2.44 inches at Sidney and 1.55 inches at Atlantic in Iowa.

A low pressure system June 15-17 slid along the underside of an area of high pressure centered in south-central Canada and brought a swath of moderate to localized heavy rainfall across a large portion of the Dakotas from west to east. Some of the most persistent heavier rainfall with this system was found in the Black Hills region of South Dakota. Totals of note included 2.35 inches at Presho, 2.07 inches at Oacoma, 1.92 inches at Hot Springs, and 1.64 inches at Edgemont. An upper level ridge built over the Central Rockies June 18-24 and forced the primary storm path northward across the Dakotas. Totals during that time period included 1.21 inches at Bismarck and 1.02 inches at Jamestown in North Dakota and 3.11 inches at Fort Pierre, 0.91 inches at Rapid City, 0.81 inches at Hill City, and 0.58 inches at Kadoka in South Dakota.

A stationary front June 23-25 oriented in a generally northwest to southeast direction from the Black Hills into central Iowa enabled a series of nocturnal storms during that time period to produce localized heavy rainfall and isolated severe weather. Unfortunately, some of this fell in already rain-soaked locations in South Dakota (3.21 inches at Hot Springs and 2.85 inches at Rapid City), Colorado (2.45 inches at Denver), and Nebraska (1.95 inches near Hay Springs and 1.26 inches at Loup City). The remainder of the month saw only isolated thunderstorms across the Missouri River basin, as a typical summertime pattern became established, with heaviest rainfall totals in South Dakota (1.39 inches at Highmore) and Missouri (1.65 inches at Mound City).

The nearly continuous onslaught of rainfall from the Central Rockies into the adjacent Plains during late spring and early summer 2015 brought flooding to many area streams

3-25 CHAPTER 3 TRIBUTARY AND RUNOFF CONDITIONS and rivers. Precipitation during April through June (Figure 3-16) exceeded 200% of the climatological average for much of Wyoming, Colorado, the Black Hills region of South Dakota, and the Nebraska panhandle. This combined with an unusually high level of mountain snowpack within the Platte River basin maintained flooding conditions along the lower North Platte, South Platte, and upper Platte Rivers along with the creeks surrounding Rapid City. Interestingly, the entire basin was not the recipient of extreme rainfall during this time period. Much of Montana and the Missouri River valley from near Fort Randall Dam to Sioux City were drier than normal and received less than 75% of typical moisture.

Figure 3-17 Apr-Jun 2015 Departure from Normal Temp. (°F); HPRCC

Not surprisingly, the regions with the heaviest rainfall and most frequent thunderstorm activity tended to be cooler than normal (Figure 3-17). Temperatures averaged 1 to 2 degrees below normal in northeastern Colorado, western South Dakota, and the Nebraska panhandle. Above normal temperatures of 1 to 3 degrees were located along the Yellowstone River, Big Horn and Wind River Mountains, and James River basin during April-June 2015.

iv. July-August-September 2015

Drought conditions remained at bay for most of the Missouri River basin into the summer months as periods of storms, some containing heavy rainfall, rolled across the region. The heaviest activity July 1-4 was confined to the lower portion of the basin from central South Dakota downstream into Missouri with 2.45 inches near Gettysburg, 1.50 inches at Mobridge, and 1.44 inches at Hill City in South Dakota, 1.73 inches at

3-26 CHAPTER 3 TRIBUTARY AND RUNOFF CONDITIONS

York and 1.33 inches at Beaver City in Nebraska, and 2.05 inches at Lawrence in Kansas.

A cold front during the next week produced even higher rainfall totals, particularly from central South Dakota into northwestern Iowa. Totals included 1.69 inches at Madison and 1.13 inches at Marion in South Dakota on July 4, 4.20 inches at Bridgewater, 2.22 inches at Marion, and 2.02 inches at Dell Rapids in South Dakota, 4.10 inches at Edgerton and 2.00 inches at Slayton in Minnesota, and 2.63 inches at Logan and 1.88 inches at Schleswig in Iowa the following day. The axis of rainfall shifted further south on 6 July with 2.72 inches at Shubert and 1.61 inches at Pawnee City in Nebraska, 4.31 inches at Topeka and 2.92 inches at Lawrence in Kansas, and 2.70 inches at St. Joseph and 2.07 inches at Kansas City in Missouri.

A typical summertime pattern developed during the second week of July and persisted for the remainder of the month, with periods of isolated thunderstorms and periodic systems rotating counter-clockwise over an upper level ridge across the western half of the continental U.S. Occasionally, localized heavy rainfall was observed with these systems including 4.07 inches at Rathbun Reservoir in southern Iowa July 10-11. This same location picked up an additional 2.15 inches of precipitation July 15-16 with 4.35 inches at Bedford and 2.77 inches at Creston. That latter system also produced 6.87 inches at Maryville, 2.93 inches at Mound City, and 2.23 inches at Tarkio in far northwestern Missouri. Just 3 days later on July 19, northwestern Missouri received more heavy rainfall with 3.40 inches at Mound City, 2.45 inches at St. Joseph, 1.35 inches at Maryville, and 1.11 inches at Tarkio.

More periods of localized heavy rainfall continued through the final week of July in Nebraska (2.45 inches at Doniphan and 2.10 inches at Harvard on the July 24), South Dakota (2.03 inches at Flandreau and 1.57 inches at Sioux Falls on July 25), Minnesota (2.93 inches at Slayton on July 25) as well as parts of the upper portion of the basin (2.90 inches at Sacajawea, 2.10 inches at Rocky Boy, and 1.89 inches at Glendive in Montana on July 27). Mostly, however, many of the same locations picked up periods of thunderstorms and heavy rainfall in Iowa (4.26 inches at Bedford, 4.24 inches at Creston, and 2.26 inches at Rathbun Reservoir on July 27-28) and northwestern Missouri (2.11 inches at Mound City, 2.04 inches at Maryville, and 1.70 inches at Tarkio on July 28.

A typical summertime pattern continued across the region during August 2015, with localized late day storms and generally near-average temperatures. Only occasional storms moved through the basin with the heaviest rainfall located in the lower portion of the basin, particularly across parts of Nebraska. Totals in the Cornhusker State during the first week of the month included 3.75 inches at Republican City, 3.70 inches near Lodgepole, and 2.73 inches at Albion.

Another line of storms developed August 7-8 with heavy rainfall in Nebraska (4.17 inches at Champion and 2.27 inches at North Platte) and southern Iowa (5.25 inches at Sidney and 3.20 inches at Bedford). Otherwise, the only other portion of the basin to

3-27 CHAPTER 3 TRIBUTARY AND RUNOFF CONDITIONS receive significant rainfall during the second week of the month was in eastern South Dakota (2.11 inches at De Smet, 1.34 inches at Mitchell, and 1.29 inches at Brooking) and far southwestern Minnesota (3.47 inches at Edgerton).

Figure 3-18 July-September 2014 Percent of Normal Precipitation; HPRCC

The region extending from eastern South Dakota into far northwestern Missouri received the bulk of the rainfall activity through the remainder of the month. In some locations, precipitation was intense enough to produce brief periods of minor localized flooding on smaller tributaries. A frontal boundary on August 16 brought rainfall totals of 2.75 inches at Worthing, 1.98 inches at Brookings, and 1.75 inches at Sioux Falls in South Dakota, 3.19 inches at Edgerton in Minnesota, and 3.21 inches at Orange City, 2.71 inches at Schleswig, and 1.92 inches at Lake Park in northwestern Iowa. The Omaha metro picked up even heavier amounts the following day with 4.79 inches in Millard, 2.83 inches at Chalco, and 2.61 inches at Eppley Airfield. A follow-on front August 18 produced more heavy rainfall for northeastern South Dakota with 3.99 inches at De Smet, 3.09 inches at Huron, 2.04 inches at Brookings, and 2.01 inches at Aberdeen.

The last round of significant rainfall to impact the basin in August 2015 persisted from August 27 through 29. Some of the same locations that were inundated in the previous weeks were recipients again in South Dakota (4.05 inches at Centerville, 3.82 inches at Sioux Falls, 3.81 inches at Harrisburg, and 1.98 inches at Marion), Nebraska (2.50 inches at Neligh, 2.27 inches at Pierce, and 1.24 inches at Millard), and Iowa (2.65 inches at Orange City and 2.46 inches at Schleswig).

3-28 CHAPTER 3 TRIBUTARY AND RUNOFF CONDITIONS

Figure 3-19 July-Sept 2014 Departure from Normal Temp. (°F); HPRCC

September 2015 was generally much drier across the Missouri River basin compared to the previous 6 months, although localized pockets of heavy rainfall were still observed from the Dakotas southward across Nebraska and into northern Missouri. The month began with 1.43 inches at Slayton Minnesota and 1.06 inches at Mound City in Missouri and was followed by an area of much needed rainfall (1.39 inches at Cut Bank) in Montana on September 4.

More significant precipitation rolled across the basin September 5-10 with multiple locations receiving greater than 3 inches of rainfall. The highest totals were found in North Dakota on September 5 (2.34 inches near Williston and 1.62 inches at Garrison) with a band of heavy rainfall the next day in southeastern Nebraska (2.68 inches at Lincoln) and southern Iowa (4.50 inches at Rathbun Reservoir, 2.43 inches at Glenwood, and 1.98 inches at Sidney). The region of heavy precipitation expanded significantly during the following 48 hours in South Dakota (2.16 inches at Scotland and 1.30 inches at Sioux Falls), Nebraska (4.00 inches at York, 2.70 inches at Geneva, 2.52 inches at Dannebrog, 2.21 inches at Sterling, and 1.96 inches at Friend), and Iowa (2.00 inches at Bedford, 1.91 inches at Oakland, and 1.68 inches at Hamburg). Even heavier amounts were reported in northeastern Kansas (7.76 inches at Topeka, 3.40 inches at Lawrence, and 1.97 inches at Manhattan) and northwestern Missouri (4.01 inches at Rock Port, 3.48 inches at Tarkio, and 2.56 inches at Kansas City) September 7-10 and resulted in the observation of localized flooding along several tributaries.

Conditions were much more tranquil for most of the basin the following week, although another round of needed moisture traversed western Montana with 2.80 inches at West

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Yellowstone and 2.00 inches at Sacajawea. Parts of the Nebraska panhandle (1.02 inches at Alliance) received precipitation September 17-18 along with southwestern Iowa (1.95 inches at Creston and 1.22 inches at Sidney), northeastern Kansas (1.55 inches at Topeka), and northwestern Missouri (1.10 inches at Platte City and 1.03 inches at Kansas City).

The final week of Water Year 2015 brought a multi-day heavy rain event September 22- 25 that included, in some locations around the Omaha metro area, record to near record precipitation. The 24-hour totals, in particular, for September 23 were 6 to 8 inches near and south of Council Bluffs in Iowa and 5.74 inches at Omaha’s Eppley Airfield. The latter was the fourth highest daily rainfall on record for Omaha.

While significant rainfall was observed on the Colorado front-range, with 3.87 inches at La Junta, the heaviest amount was clearly focused on South Dakota, Nebraska, and Iowa. Rainfall in central South Dakota included 5.95 inches near Reliance, 4.03 inches at Oacoma, 3.17 inches at Chamberlain, 3.09 inches at Tyndall, 2.09 inches at Wagner, and 1.58 inches at Huron. 1.69 inches of rainfall was observed at Sioux Falls, with totals in the surrounding area including 2.49 inches at Vermillion, 1.95 inches at Dell Rapids, 1.61 inches at Gayville, 1.50 inches at Marion, and 1.14 inches at Brookings along with 1.05 inches near Slayton in far southeastern Minnesota.

Of course, the much heavier rainfall was located further south in eastern Nebraska and western Iowa and produced brief flash flooding along several tributaries within this region. Some of the minor flooding was within the Elkhorn River basin and Omaha Creek in northeastern Nebraska with near minor flooding within the Papillion Creek watershed throughout the Omaha metro. Rainfall totals, in addition to that 7.41 inches observed at Eppley Airfield for the entire duration of the multi-day event, included 5.69 inches at Tekamah, 5.51 inches at Wakefield, 4.10 inches at Blair, 3.74 inches at Valley, 3.58 inches at Valentine, 3.55 inches at Clarkson, 3.31 inches at Wayne, and 3.11 inches at Bennington. While heavy amounts were reported in downtown Council Bluffs, only 3.98 inches were measured at the airport on the eastern side of town. Elsewhere in western Iowa, storm rainfall totals included 6.03 inches at Blencoe, 5.75 inches at Audubon, 5.51 inches at Missouri Valley, 5.11 inches at Logan, 3.34 inches at Mondamin, 2.39 inches at Atlantic, and 2.22 inches at Red Oak.

For the season of July through September 2015, the heaviest rainfall was observed in the far lower portion of the Missouri River basin, with 150%-300% of the normal precipitation observed from near Fort Randall Dam southeastward to near Sioux City and across much of western Iowa and far northwestern Missouri (Figure 3-18). Drier than normal conditions were most extreme in central and eastern Wyoming as well as the far upper portion of the James River basin in southeastern North Dakota, with less than 50% of normal precipitation observed in both region.

Most of the Missouri River basin observed above normal temperatures (Figure 3-19) during the same 3-month period. Temperatures from the Central Rockies eastward into the adjacent High Plains were generally 2 to 4 degrees above normal in this region, with

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similar anomalies reported from eastern Montana into North Dakota as well as in central Nebraska. Elsewhere, average temperature departures varied within a degree Fahrenheit of the climatological average.

c. Flooding concerns

Heavy rainfall at the beginning of Water Year 2015 in southeastern Nebraska (4 to 7 inches around Lincoln) and southwestern Iowa (widespread 2 to 4 inch totals) produced flooding along Salt Creek from Lincoln to Ashland, with a peak stage of 25.84 feet (29,800 cfs) near Greenwood on October 1 which exceeded major flood stage by nearly 2 feet. Additional flooding occurred along the East Nishnabotna River (minor flooding from Red Oak to Riverton October 1-2), West Nishnabotna River (minor flooding from Henderson to Riverton October 1-2), and Nishnabotna River at Hamburg with a peak stage of 25.65 feet (20,500 cfs) on October 2. These increased flows resulted in minor flood stage being exceeded along the Missouri River at Nebraska City, Brownville, and Rulo with a peak flow at the latter of 105,000 cfs on October 2.

An early onset of unusually cold weather resulted in minor flooding from local ice jamming along the North Platte River at Lewellen November 12-17 and November 19- 23. These issues would persist with additional ice jam flooding in the same area December 27-30, January 3-15, and January 19-21. Significant ice jamming was observed on the other end of the Cornhusker State January 26-29 along the Platte River near Two Rivers State Park in western Douglas County. The only other winter flooding issues of note were brief ice jamming along the Platte River near Grand Island on February 7 and minor flooding along Big Muddy Creek near Antelope (Montana) March 12-14 due to a combination of melting snow and a thawing of the frozen ground.

The next round of significant flooding occurred in a fairly close proximity to that witnessed at the beginning of the Water Year as an extreme storm produced a large area of 3 to 6 inches of rainfall across southeastern Nebraska with totals as high as 10.91 inches near Hebron, 9.85 inches at Wilber, 8.10 inches at Hallam, and 6.65 inches at Lincoln. Significant flooding was observed along Wahoo Creek at Ashland (peak stage of 20.43 feet on May 8 approaching the record of 20.50 feet established on June 15, 1991), but the most extreme flooding was along Salt Creek from Lincoln downstream to the Platte River. Tributaries along Lincoln that flooded included Stevens Creek, Middle Creek (record peak stage of 23.11 feet on May 7 exceeding the previous record of 17.39 feet established on May 5, 2007), and Little Salt Creek (record peak stage of 20.58 feet on May 7 with a flow in excess of 9,960 cfs that exceeded the previous record of 20.58 feet established on July 24, 1993).

Along Salt Creek, flooding was observed May 7-9 at Roca (10,900 cfs), Lincoln- Pioneers Boulevard (record stage of 30.05 feet on May 7 exceeding the previous record of 22.92 feet from July 20, 1996), Lincoln-Fairgrounds (record stage of 35.38 feet on May 7 exceeding the previous record of 27.70 feet from May 6, 2007), Greenwood (33,800 cfs with a record stage of 27.24 feet on May 7 exceeding the previous record of 26.08 feet from July 24, 1993), and near Ashland. These flows produced contributed to

3-31 CHAPTER 3 TRIBUTARY AND RUNOFF CONDITIONS minor flooding along the Missouri River May 8-9 at Brownville and Rulo (peak flow of 87,500 cfs).

The onset of above normal precipitation to the Central Rockies combined with an unseasonably high mountain snowpack within the upper South Platte River basin to produce an extended period of flooding issues in northeastern Colorado and western Nebraska from mid-May into June 2015. The initial concerns were minor flooding along the Cache La Poudre River near Greeley May 10-14 (peak flow of 4,090 cfs on May 11) and extended to the South Platte River near Kersey (May 9-16; peak flow of 17,500 cfs on May 16), near Weldona (May 11-14; peak flow of 19,000 cfs on May 12), at Fort Morgan (May 11-13; peak flow of 15,300 cfs on May 11), near Balzac (May 11-14; peak flow 12,800 cfs on May 13), at Atwood (May 13; peak flow 13,400 cfs on May 13), and at Roscoe. The latter would remain in minor flood stage from May 13 through June 25 due to the continuation of the aforementioned mountain snowpack and periodic heavy rainfall. Elsewhere, minor flooding was observed along the White River at the South Dakota/Nebraska state line (May 13-14; peak flow 1,510 cfs on May 13) and near Oglala (May 13-14) and was a harbinger of future events in the western half of South Dakota during the remainder of spring and early summer months.

Flooding issues became more widespread and severe across the upper Platte River basin over the next week and began to impact additional tributaries including the Laramie River near Fort Laramie which peaked at 8.97 feet (4,750 cfs) on May 25 and exceeded flood stage (7 feet) May 21 through June 3. The Cache La Poudre near Greeley returned to flood stage with a peak flow of 3,890 cfs on May 24. These flows brought the South Platte River back above flood stage near Kersey (May 20-28; peak flow 14,900 cfs on May 25), near Weldona (May 22-27; peak flow 13,700 cfs on May 22), and near North Platte (May 27-31). As a result of the continued high flows, the Platte River downstream of North Platte also rose into flood stage at Brady (May 16-29), near Cozad (off and on from May 29 through June 23), near Kearney (May 18 to June 29; peak flow 12,900 cfs on June 4), and near Grand Island (off and on from May 22 through June 27 with a peak flow of 15,900 cfs on June 5). Above normal flows were also developing along the middle James River by mid-May and exceeded flood stage (13 feet) from May 18 through July 9, with a peak stage of 15.06 feet (1,740 cfs) on June 3 near Columbia in South Dakota.

The accelerated melt of the mountain snowpack by the end of May raised multiple tributaries above flood stage. Included among those were the North Platte River near Henry (May 27-31; peak flow of 5,990 cfs on May 29), near Mitchell (off and on from May 26 through June 18 with a peak flow of 7,010 cfs on May 30), at Lisco (May 29 to June 2), and at Lewellen (May 24 to July 3). In northern Wyoming, record flooding was observed along the Powder River at Sussex (peak stage of 15.63 feet exceeding the previous record of 15.16 feet established on May 19, 1978) with a peak flow of 26,400 cfs on May 25, moderate flooding along Little Goose Creek at Big Horn (May 24 to June 2), and minor flooding along Goose Creek at Sheridan (May 25 to June 3; peak flow 4,830 cfs on May 25). Minor flooding was occurring concurrently along the Tongue

3-32 CHAPTER 3 TRIBUTARY AND RUNOFF CONDITIONS

River near Birney (Montana) from May 27-28 and again May 31 to June 9 with a peak flow of 3,940 cfs on June 5.

The flooding concerns expanded across western South Dakota toward the end of May, in particular around the Black Hills region. The White River near Oglala returned to flood stage May 25-27 with a peak flow of 2,140 cfs while the South Fork of the Bad River near Cottonwood exceeded flood stage May 25-26 with a peak flow of 4,550 cfs. Around Rapid City, Elk Creek exceeded flood stage 25-26 May with a peak flow of 813 cfs on May 25, Battle Creek at Hermosa exceeded flood stage May 24-26 with a peak flow of 1,390 cfs on May 24, and Spring Creek near Rockerville exceeded flood stage May 24-31 with a peak flow of 647 cfs on May 26. Rapid Creek rose above flood stage at multiple locations including above Johnson Siding (May 27 to July 24), above Victoria Creek (May 24 to July 8; peak flow 948 cfs on June 24), and below Sewage Treatment Plant (May 24-25; peak flow 1,650 cfs on May 25).

Continued mountain snowmelt combined with persistent bouts of localized heavy rainfall to produce widespread minor flooding during the month of June. Brief minor flooding was observed in Montana along the Boulder River at Big Timber (peak flow of 5,210 cfs on June 2) and in Wyoming along the Wind River near Dubois (peak flow of 1,520 on June 2) and at Riverton (peak flow of 5,830 cfs on June 3). Near Rapid City, Elk Creek returned to flood stage with peak flows of 2,850 cfs on June 2 and 792 cfs on June 5. The White River near Interior also briefly exceeded minor flood stage (14 feet) on June 5.

By the second week of June, flooding concerns widened further. In northeastern Colorado, these were centered on the peak of the melting of the mountain snowpack with flooding along the Cache La Poudre near Greeley (June 2-20; peak flow 4,900 cfs on June 13) and South Platte River at Henderson (briefly on June 5 with a peak flow of 8,850 cfs), near Kersey (June 4-20; peak flow 16,100 cfs on June 14), near Weldona (June 7-16; peak flow 15,100 cfs on June 8), at Fort Morgan (June 8-15; peak flow 14,700 cfs on June 15), and at Balzac (June 9-16; peak flow 14,400 cfs on June 16). While not as dynamic or widespread, minor flooding along the James River expanded to Stratford on June 5 and continued at that location through July 21. Minor flooding also returned along the Wind River at Riverton (June 8-15; peak flow 8000 cfs on June 12) and Laramie River at Laramie (June 6-20; peak flow 1,620 cfs on June 15). Minor flooding (22 feet) along the Missouri River at Williston was observed June 6-11 and June 13-19 with peak stages of 22.48 feet and 22.3 feet, respectively.

In addition to northeastern Colorado, the other main region of widespread flooding during the first half of June was in the southwestern corner of South Dakota and included many locations that had already experienced minor flooding during the previous weeks. In the Black Hills region, flood stage was exceeded along Spring Creek near Rockerville (June 6-9; peak flow 661 cfs on June 7), Battle Creek at Hermosa (June 6-7; peak flow 1,150 cfs on June 7), Reno Gulch near Hill City (June 6), Grizzly Bear Creek near Keystone (June 6), and Hat Creek near Edgemont. Larger rivers and streams in the region exceeding flood stage included the White River at

3-33 CHAPTER 3 TRIBUTARY AND RUNOFF CONDITIONS

South Dakota/Nebraska state line (June 7-9), near Oglala (June 6-12, June 21-22), and near Oacoma (June 7; peak flow 15,600 cfs). These flows brought the Cheyenne River near Plainview above flood stage June 9-11 and June 21-23, with a peak flow of 23,500 cfs on June 10. Elsewhere, localized heavy rainfall in eastern Nebraska contributed to the Platte River near Venice exceeding minor flood stage on June 7 with a peak flow of 54,900 cfs.

As the melting of the mountain snowpack wound down, minor flood stage was briefly exceeded along the South Fork of the Shoshone River near Valley (June 8-11; peak flow 4,760 cfs), Wind River below Diversion Dam (June 11; peak flow 767 cfs), and Little Goose Creek at Big Horn (June 10-11; peak flow 1,980 cfs). Ongoing flooding along the South Platte River was accompanied by minor flooding downstream of Denver at Henderson (June 12; peak flow 10,100 cfs) and near the mouth at North Platte (June 21-22). Another basin with recent flooding issues (Salt Creek) returned above flood stage with Middle Creek at Lincoln (June 15; peak flow 5,400 cfs), Haines Branch at Lincoln (June 11; peak flow 3,660 cfs), Stevens Creek near Lincoln (June 11; peak flow 2,830 cfs), and Salt Creek near Greenwood (June 11; peak flow 19,400 cfs).

Heavy rainfall from the latter contributed to tributary flooding in western Iowa, including Maple Creek near Nickerson (June 11), West Nishnabotna River near Riverton (June 12-16), East Nishnabotna River near Coburg (June 15-16) and at Riverton (June 13- 17), and Nishnabotna River at Hamburg (June 16; peak stage of 25.39 feet with minor flood stage of 25 feet). The high flows in eastern Nebraska and southwestern Iowa brought minor to moderate flooding along the Missouri River at Nebraska City (June 12; peak flow 84,500 cfs), Brownville (June 11-18), and Rulo (June 11-15, peak flow 118,000 cfs; June 15-19, peak flow 111,000 cfs).

Additional flooding concerns during June and July were generally focused along the South Platte River and in the Black Hills region of South Dakota. The former exceeded minor flood stage June 14-20 at South Platte with a peak flow of 4,250 cfs. This would represent the final push of melting mountain snowpack for this basin with stages gradually decreasing during the subsequent weeks. In and around Rapid City, Rapid Creek briefly exceeded flood stage at St. Patrick Street (June 18), below Sewage Treatment Plant (June 18) and near Farmingdale (June 18; with a record peak stage of 12.53 feet exceeding the previous record of 10.76 established on October 14, 2013) with a peak flow of 5,320 cfs. Additional flooding from the same storm system was observed along the White River at South Dakota/Nebraska state line June 18-20 (peak flow 1,900 cfs) and South Fork of the Bad River near Cottonwood (June 18-19; peak flow 3,470 cfs).

Similar slow moving thunderstorms the following week impacted Rapid City and Denver. These produced additional flooding along Rapid Creek at Big Bend (June 24-26) and near Farmingdale (June 24-25; peak stage of 11.85 feet with a peak flow of 3,730 cfs) and Spring Creek near Rockerville (June 23 to July 4; peak flow 716 cfs on June 25). The South Platte River briefly exceeded flood stage on June 24 at Denver (peak flow 15,000 cfs) and Henderson (peak flow 9,540 cfs).

3-34 CHAPTER 3 TRIBUTARY AND RUNOFF CONDITIONS

After a couple of active months in May and June, stages along rivers and streams throughout the Missouri River basin gradually decreased with no further flooding issues developing until the second week of August. Localized thunderstorms in western Iowa resulted in briefly minor flooding along the West Nishnabotna River near Riverton (August 9) and the West Fork Ditch at Moville (August 18-19) and near Hornick (August 18-19). With the exception of brief localized flash flooding events, particularly those in urban and small stream locations, no additional flooding was observed within the boundaries of the Omaha District during the remainder of Water Year 2015.

d. Snow surveys

The Omaha District typically conducts snow surveys as needed in northeastern Montana, the Big Sioux River basin, and the upper James River basin. During late winter/early spring 2014, these surveys were primarily conducted within the upper James River basin above Pipestem Reservoirs, with seven snow observations taken during this time period. These measurements were conducted by personnel from the Pipestem Project and were performed in a grassy area approximately 5 miles north of Jamestown, North Dakota.

Table 3-4 Snow Surveys (completed in late winter and early spring) Snowpack SWE SWE - 2014 SWE - 2013 Date (inches) (inches) (inches) (inches) January 6, 2015 5.6 0.94 1.32 0.43 January 20, 2015 5.2 0.90 1.75 0.68 February 2, 2015 4.8 1.19 1.79 1.15 February 13, 2015 5.4 1.11 2.13 1.79 February 27 2015 7.6 1.49 2.39 2.13 March 11, 2015 0.0 0.0 0.0 2.82 April 1, 2015 0.0 0.0 1.19 2.82

The snowpack, as measured by snow water equivalent SWE, was significantly lower at the beginning of 2015 than the previous year and remained below normal through the entire winter. The combination of well below normal snowpack and above normal temperatures resulted in an early melting with no snowpack remaining by the second week of March.

In addition to the snow surveys conducted by the Omaha District, a cooperative plains snow survey has been spearheaded by the Missouri River basin Water Management Division. This survey is conducted by local cooperators who take measurements every 2 weeks. Previous results submitted by volunteers in Montana, North Dakota, South Dakota, and Nebraska as well as snow survey instructions can be obtained in an interactive map format from the U.S. Army Corps of Engineers Northwestern Division website at www.nwd-mr.usace.army.mil/rcc/snowsurvey/snowsurvey.html.

3-35 CHAPTER 3 TRIBUTARY AND RUNOFF CONDITIONS

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3-36 CHAPTER 4 RESERVOIR ACCOMPLISHMENTS

The Omaha District had some substantial flood damages prevented during localized rainfall events during this reporting period. The Corps projects continue to be popular for recreation usage by the general public. This chapter documents the accomplishments for all reservoirs in the District.

a. Flood Damages Prevented. Flood damages prevented in Fiscal Year 2015 (FY15) by Corps of Engineers mainstem reservoirs, tributary reservoirs and local protection projects are summarized in Table 4-1. Flood damages prevented in FY15 by Bureau of Reclamation projects are summarized in Table 4-2. Flood damages prevented in FY15 for each state are shown in Table 4-3. Rounding errors may be present.

Table 4-1 Omaha District Projects Flood Damages Prevented FY15 Local and Mainstem Reductions Cum Thru Cum Thru Omaha District Loca- FY14 Oct-Mar April May June July Aug-Sep Total FY15 FY15 Projects tion ($1,000) ($1,000) ($1,000) ($1,000) ($1,000) ($1,000) ($1000) ($1,000) ($1,000) Missouri River Mainstem NWO 7,011,880.2 559.5 0.0 66,615.7 262,654.9 0.0 0.0 329,830.1 7,341,710.3 Reservoirs Tributary Reservoir Projects Aurora, Kelly Road/ CO 10,701.1 0.0 10,701.1 Westerly Ck Dams Bear Creek Dam CO 2,220.9 1,198.6 1,198.6 3,419.5 Bowman-Haley Dam ND/SD 15,124.0 0.0 15,124.0 Chatfield Dam CO 5,552.5 95.7 95.7 5,648.2 Cottonwood Springs SD 62.9 0.0 62.9 Dam Cherry Creek Dam CO 169,944.3 2,875.9 2,875.9 172,820.2 Cold Brook Dam SD 916.5 0.0 916.5 Papillion Ck Dams NE 20,113.7 2,605.9 2,605.9 22,719.6 Papillion Ck NE 42,643.5 2,870.3 2,870.3 45,513.8 Pipestem Dam ND 100,789.3 18.9 5.3 24.2 100,813.5 Salt Creek Dams NE 78,087.7 75,816.2 75,816.2 153,903.9 Salt Creek Levees NE 77,785.8 9,406.0 9,406.0 87,191.8 Subtotal: 523,942.2 0.0 0.0 90,717.3 4,175.5 0.0 0.0 94,892.8 618,835.0 Missouri River System L-601 IA 205,923.6 0.0 0.0 4,946.6 3,374.4 0.0 0.0 8,321.0 214,244.6 L-594 IA 145,894.6 0.0 0.0 3,497.9 2,386.1 0.0 0.0 5,884.0 151,778.6 L-575 IA/MO 114,665.3 0.0 0.0 2,281.1 3,288.4 0.0 0.0 5,569.5 120,234.8 L-561/L-550 MO 92,648.0 0.0 0.0 1,949.0 2,809.7 0.0 0.0 4,758.7 97,406.7 L-536 MO 28,457.9 0.0 0.0 533.5 769.1 0.0 0.0 1,302.7 29,760.6 R-613 NE 45,071.2 0.0 0.0 1,086.5 741.2 0.0 0.0 1,827.7 46,898.9 R-573 NE 5,245.8 0.0 0.0 98.0 141.3 0.0 0.0 239.3 5,485.1 R-562 NE 15,609.5 0.0 0.0 304.9 439.5 0.0 0.0 744.4 16,353.9

4-1 CHAPTER 4 RESERVOIR ACCOMPLISHMENTS

Table 4-1 Omaha District Projects Flood Damages Prevented FY15 Local and Mainstem Reductions Cum Thru Cum Thru Omaha District Loca- FY14 Oct-Mar April May June July Aug-Sep Total FY15 FY15 Projects tion ($1,000) ($1,000) ($1,000) ($1,000) ($1,000) ($1,000) ($1000) ($1,000) ($1,000) R-548 NE 11,356.6 0.0 0.0 212.3 306.1 0.0 0.0 518.4 11,875.0 R-520 NE 3,310.6 0.0 0.0 65.3 94.2 0.0 0.0 159.5 3,470.1 Subtotal: 668,183.1 0.0 0.0 14,975.3 14,349.9 0.0 0.0 29,325.3 697,508.4 Local Protection Projects Antelope Creek, NE 38,058.6 23,054.1 8,166.8 31,220.9 69,279.5 Lincoln Belle Fourche R. @ SD 379.6 0.0 379.6 Belle Fourche Big Sioux R. @ IA 70,700.9 0.0 70,700.9 Sioux City Blackbird Creek @ NE 5,113.1 0.0 5,113.1 Macy Broken Bow, Mud NE 5,463.4 0.0 5,463.4 Creek Clarkson, Maple Ck. NE 3,566.8 0.0 3,566.8 Columbus, Loup R. NE 17,298.8 0.0 17,298.8 Council Bluffs, IA 1,695,083.1 0.0 0.0 0.0 30,073.3 0.0 0.0 30,073.3 1,725,156.4 Missouri R. Deadman Gulch @ SD 20,731.8 0.0 20,731.8 Sturgis Denison, E. Boyer R IA 3,379.4 0.0 3,379.4 Emerson, Indian Ck IA 7,541.3 0.0 7,541.3 Floyd R., Sioux City IA 91,442.3 0.0 91,442.3 Forsyth, MT 6,787.8 0.0 6,787.8 Yellowstone R. Gering Valley NE 4,671.7 0.0 4,671.7 Glasgow, Milk R. MT 2,933.0 0.0 2,933.0 Grand Island, Wood NE 25,647.6 0.0 25,647.6 River Great Falls, Sun R. MT 874.3 0.0 874.3 Greybull, Bighorn R. WY 15,229.7 744.3 744.3 15,974.0 Hamburg, Ditch 6 IA 28,159.3 0.0 28,159.3 Hamburg, IA 353,784.6 6,025.8 6,117.1 803.4 12,946.3 366,730.9 Nishnabotna R. Havre, Bull Hook/ MT 4,487.8 0.0 4,487.8 Scott Coulee Dams Hawarden, Dry Ck. IA 1,407.2 0.0 1,407.2 Herreid, Spring Ck. SD 2,632.5 0.0 2,632.5 Hooper, Elkhorn R. NE 5,352.1 0.0 5,352.1 Hot Springs, Fall R. SD 350.8 0.0 350.8 Howells, E. Fork of NE 5,384.9 0.0 5,384.9 Maple Ck. Ida Grove, Maple R. IA 3,159.7 455.4 29.9 485.3 3,645.0 and Odebolt Ck.

4-2 CHAPTER 4 RESERVOIR ACCOMPLISHMENTS

Table 4-1 Omaha District Projects Flood Damages Prevented FY15 Local and Mainstem Reductions Cum Thru Cum Thru Omaha District Loca- FY14 Oct-Mar April May June July Aug-Sep Total FY15 FY15 Projects tion ($1,000) ($1,000) ($1,000) ($1,000) ($1,000) ($1,000) ($1000) ($1,000) ($1,000) Kenslers Bend SD/NE 54,605.7 457.0 457.0 55,062.7 Little Papillion Ck. NE 22,273.4 0.0 22,273.4 @ Omaha Little Sioux River IA 269,679.8 3,731.2 571.7 4,302.9 273,982.7 Lodgepole Ck. @ NE 69,247.0 0.0 69,247.0 Sidney Lost Ck, Columbus NE 4,567.8 0.0 4,567.8 Madison, Union Ck. NE 10,034.8 0.0 10,034.8 Malta, Milk River MT 0.0 0.0 0.0 , Heart R. ND 97,989.6 55.8 55.8 98,045.4 Marmarth, Little ND 10,645.7 0.0 10,645.7 Missouri R. Meadow Grove, NE 3,619.9 0.0 3,619.9 Buffalo Ck. Milk R Levee, Havre MT 51,858.1 0.0 51,858.1 Norfolk, Elkhorn R. NE 66,345.0 0.0 66,345.0 Omaha, Missouri R. NE 1,548,222.2 0.0 0.0 1,595.3 25,399.8 0.0 0.0 26,995.1 1,575,217.3 Pebble Ck, Scribner NE 21,405.2 0.0 21,405.2 Pender, Logan Ck. NE 0.0 0.0 0.0 Pierce, North Fork NE 1,040.1 0.0 1,040.1 Elkhorn R. Rapid City, Rapid SD 344.5 0.0 344.5 Creek Rapid City, Cedar SD 250.0 0.0 250.0 Canyon Dam Red Oak, East IA 70,796.4 2,177.3 2,856.6 40.0 5,073.9 75,870.3 Nishnabotna R. Saco, Beaver Ck. MT 1,392.4 0.0 1,392.4 Schuyler, Lost Ck./ NE 6,339.6 0.0 6,339.6 Platte River Scranton, Buffalo Ck ND 584.0 0.0 584.0 Scribner, Elkhorn R. NE 10,270.8 0.0 10,270.8 Sheridan, Goose Ck WY 7,077.0 0.0 7,077.0 Shields R. @ Clyde MT 156.2 0.0 156.2 Park Sioux City, Perry Ck IA 30,672.5 0.0 30,672.5 Sioux Falls, Big SD 37,262.5 111.5 111.5 37,374.0 Sioux R. Thurman-Hamburg, IA 1,549.9 0.0 1,549.9 Missouri R. Van Bibber Creek, CO 14,026.5 0.0 14,026.5 Arvada Vaughn, Sun R. MT 986.8 0.0 986.8 Waterloo, Elkhorn R NE 2,108.5 0.0 2,108.5

4-3 CHAPTER 4 RESERVOIR ACCOMPLISHMENTS

Table 4-1 Omaha District Projects Flood Damages Prevented FY15 Local and Mainstem Reductions Cum Thru Cum Thru Omaha District Loca- FY14 Oct-Mar April May June July Aug-Sep Total FY15 FY15 Projects tion ($1,000) ($1,000) ($1,000) ($1,000) ($1,000) ($1,000) ($1000) ($1,000) ($1,000) W. Glendive, MT 23,264.4 0.0 23,264.4 Yellowstone R. West Point, Elkhorn NE 44,862.8 0.0 44,862.8 R. Western Sarpy/ NE 13,971.9 0.0 13,971.9 Clear Creek Subtotal: 4,917,073.1 31,257.2 0.0 9,762.1 65,246.9 4,186.6 2,013.5 112,466.3 5,029,539.4 Other Projects McCook Lake SD 0.0 0.0 0.0 Total Corps NWO 13,121,078.6 31,816.7 0.0 182,070.5 346,427.2 4,186.6 2,013.5 566,514.4 13,687,593.0 Projects:

Table 4-2 Bureau of Reclamation Projects Flood Damages Prevented FY15 Local and Mainstem Reductions Cum Thru Total Cum Thru Loca- FY14 Oct-Mar April May June July Aug-Sep FY15 FY15 River Basin Project tion ($1,000) ($1,000) ($1,000) ($1,000) ($1,000) ($1,000) ($1,000) ($1,000) ($1,000) Big Horn R. Boysen WY 118,855.8 131.3 3,037.3 3,168.6 122,024.4 Buffalo Bill WY 30,502.4 1,156.7 1,156.7 31,659.1 Bull Lake WY 3,378.6 101.2 101.2 3,479.8 Yellowtail MT 165,282.3 67.8 5,204.9 5,272.8 170,555.1 Subtotal: 318,019.1 0.0 0.0 199.1 9,500.1 0.0 0.0 9,699.3 327,718.4 Cheyenne R. Angostura SD 22.6 0.0 22.6 Keyhole WY/SD 4,626.9 16.0 60.2 76.3 4,703.2 Pactola SD 3,600.3 10.5 155.5 165.9 3,766.2 Subtotal: 8,249.8 0.0 0.0 26.5 215.7 0.0 0.0 242.2 8,492.0 Grand River Shadehill SD 12,690.4 8.6 71.2 79.8 12,770.2 Heart River Heart Butte ND 16,169.4 3.7 3.7 16,173.1 James River Jamestown ND 208,512.0 0.0 208,512.0 Marias River Tiber MT 95,694.9 53.7 606.7 660.3 96,355.2 Milk River Fresno MT 15,500.9 0.0 15,500.9 Canyon Missouri River MT 231,811.4 114.7 5,933.3 6,048.1 237,859.5 Ferry North Platte R. Pathfinder WY 17,307.7 687.1 687.1 17,994.8 Alcova WY 1,633.8 92.0 92.0 1,725.8 Seminoe WY 46,920.0 778.5 778.5 47,698.5 Guernsey WY 434.0 0.0 434.0 Glendo WY/NE 95,500.5 6,974.1 6,974.1 102,474.6 Subtotal: 161,796.0 0.0 0.0 0.0 0.0 8,531.7 0.0 8,531.7 170,327.7 Sun River Gibson MT 3,085.6 0.0 3,085.6

4-4 CHAPTER 4 RESERVOIR ACCOMPLISHMENTS

Table 4-2 Bureau of Reclamation Projects Flood Damages Prevented FY15 Local and Mainstem Reductions Cum Thru Total Cum Thru Loca- FY14 Oct-Mar April May June July Aug-Sep FY15 FY15 River Basin Project tion ($1,000) ($1,000) ($1,000) ($1,000) ($1,000) ($1,000) ($1,000) ($1,000) ($1,000) Threeforks Clark MT 16,068.6 1.8 57.3 59.1 16,127.7 Basin Canyon St. Mary River Sherburne MT 10,412.0 0.0 10,412.0 Total Bureau 1,098,010.1 0.0 0.0 408.2 16,384.3 8,531.7 0.0 25,324.3 1,123,334.4 Projects:

Table 4-3 Flood Damages Prevented by State Omaha District, FY15 Corps Mainstem Corps Local Corps Mainstem Non- USBR USBR Local Protection Supported Mainstem Urban Urban Dams Dams Protection Channels Emergency Dams Levees Levees (Mainstem) (Local) Dams and Levees Operations Total State ($1,000) ($1,000) ($1,000) ($1,000) ($1,000) ($1000) ($1,000) ($1,000) ($1,000) CO 4,170.2 4,170.2 IA 87,202.8 30,073.3 19,161.9 22,808.4 159,246.4 MO 15,753.2 6,674.0 22,427.2 MT 7,021.9 11,738.8 301.5 19,062.2 NE 102,545.3 26,995.1 3,489.3 5,579.3 78,422.1 43,725.7 260,756.8 ND 80,409.8 3.7 24.2 55.8 80,493.5 SD 36,897.0 150.3 133.6 340.0 37,520.9 WY 2,928.0 4,489.1 744.3 8,161.4

Total: 329,830.0 57,068.4 29,325.2 14,820.8 10,503.5 82,616.5 67,674.2 0.0 591,838.6

b. Recreation Usage. Visitation hours for each Corps of Engineers project for FY08 through FY13 are tabulated in Table 4-4. A new system began development in FY13, implementation and development is expected to be finished in FY16. When new surveys are completed and new load‐factors are applied to meter readings that were reported during the transition period, FY13, FY14 and FY15 numbers will be generated and completed. At that time the interim visitation estimates from FY13 will be replaced by estimates based on actual meter readings and the new load-factors.

Table 4-4 Recreation Visitation Hours Project Name FY 08 FY 09 FY 10 FY 11 FY 12 FY 133 Bowman-Haley 387,985 338,038 623,089 300,152 600,863 450,507 Cottonwood Springs 166,087 157,333 157,690 140,665 192,540 166,603 Cold Brook 91,881 141,006 153,297 123,547 124,551 124,049 Pipestem 185,393 162,811 155,269 166,000 193,235 179,617 Papillion Creek No. 11 Glenn Cunningham 01 938,535 126,708 808,087 779,345 793,716 Dam

4-5 CHAPTER 4 RESERVOIR ACCOMPLISHMENTS

Table 4-4 Recreation Visitation Hours Project Name FY 08 FY 09 FY 10 FY 11 FY 12 FY 133 Papillion Creek No. 16 235,022 206,181 103,668 239,099 230,191 234,645 Standing Bear Dam Papillion Creek No. 18 801,453 788,538 329,757 779,546 777,270 778,408 Zorinsky Dam Papillion Creek No. 20 781,101 735,954 308,417 621,701 745,591 683,646 Wehrspann Dam Papillion Creek 1,817,576 2,669,208 868,550 2,470,671 2,532,397 2,490,415 Subtotal: Chatfield 9,002,848 7,674,116 7,459,1122 3,692,4992 2,156,2192 2,924,359 Cherry Creek 8,576,514 10,136,930 10,145,1122 4,066,4142 1,998,2582 3,032,336 Bear Creek 1,394,814 1,661,908 1,776,0162 758,7702 550,7822 654,776 Tri-Lakes Subtotal: 18,974,176 19,472,954 19,380,2402 8,517,6832 4,705,2592 6,611,471 Salt Creek No. 2 95,150 81,236 12,119 68,138 83,888 76,013 Olive Creek Salt Creek No. 4 71,278 91,084 17,504 64,126 93,203 78,665 Blue Stem Salt Creek No. 8 83,919 92,262 18,308 67,174 90.262 33,632 Wagon Train Salt Creek No. 9 69,036 96,212 16,654 77,178 70,903 74,041 Stagecoach Salt Creek No. 10 36,862 33,676 18,075 29,180 34,141 31,661 Yankee Hill Salt Creek No. 12 200,010 237,890 47,731 191,667 260,682 226,175 Conestoga Salt Creek No. 13 47,159 38,402 18,994 27,526 34,902 31,214 Twin Lakes Salt Creek No. 14 682,851 614,643 139,322 579,374 676,948 628,161 Pawnee Salt Creek No. 17 1,013,596 959,961 334,544 729,732 764,248 746,990 Holmes Lake Salt Creek No. 18 1,228,106 1,130,097 220,647 887,017 1,152,257 1,019,637 Branched Oak Lake Salt Creek Subtotal: 3,527,967 3,375,463 843,898 2,721,112 3,261,434 2,946,189 Total: 25,151,065 28,893,088 21,092,688 11,238,795 11,610,279 12,968,851 Notes: 1 Drained in FY06 for lake restoration 2 The Tri-Lakes method of calculating recreation visitation hours has changed from FY10 to FY12 resulting in reduced numbers. 3Visitation was estimated for FY13 until the new system is completed and implemented. No estimates have been generated for FY14 and FY15.

4-6 Table 5-1 Tributary Reservoir Flood Control Operation & Runoff (Water Year 2015) Days in Max Date POR2 Max Max Inflow POR POR Ave Inflow FC1 FC Pool Of Max Max FC Stor Max Max Out Volume Inflow Inflow % Name of Dam Pool (ft) Pool (ft) Pool Pool (Year) (af) % FC In (cfs) (cfs) (af) Vol (Year) Vol (af) Norm Corps of Engineers Reservoirs Bear Creek 5558.0 365 5602.7 May 26 5607.8 (13) 10,293 36% 1,183 509 84,135 91,900 (83) 34,927 241% Bowman-Haley 2754.8 0 2753.7 Jun 26 2762.7 (78) 0 0% 211 119 32,811 89,064 (11) 24,405 134% Chatfield 5432.0 231 5448.5 Jun 19 5448.5 (15) 29,910 15% 3,896 3,067 398,692 450,000 (83) 150,368 265% Cherry Creek 5550.0 331 5555.3 Jun 17 5565.8 (73) 4,807 6% 1,231 262 27,689 30,900 (84) 11,893 233% Cold Brook 3585.0 352 3585.7 Jul 27 3585.8 (14) 24 0.4% 7 7 1,954 2,481 (11) 761 257% Cottonwood Spr 3875.0 0 3859.3 Sep 30 3872.7 (00) 0 0% 2 0 81 300 (99) 39 208% Papio Dam 11 1121.0 348 1122.4 May 8 1125.3 (99) 474 4% 159 48 8,628 18,700 (80) 6,630 130% Papio Dam 16 1104.0 257 1108.2 May 7 1108.6 (08) 596 17% 277 53 4,213 5,377 (08) 1,684 250% Papio Dam 18 1110.0 352 1115.0 May 7 1116.8 (93) 1,432 19% 684 117 8,836 11,000 (93) 5,208 170% Papio Dam 20 1095.8 292 1098.0 May 7 1103.2 (93) 551 9% 249 56 3,650 9,710 (93) 2,429 150% Pipestem 1442.5 218 1452.4 May 31 1492.2 (09) 11,277 8% 557 161 27,132 303,263 (11) 56,601 48% Salt Cr Dam 2 1335.0 56 1345.3 May 7 1345.3 (15) 2,324 60% 813 133 5,272 12,500 (87) 2,201 240% Salt Cr Dam 4 1307.4 101 1316.3 May 7 1316.5 (73) 3,568 50% 1,501 277 9,927 15,500 (93) 4,429 224% Salt Cr Dam 8 1287.8 152 1294.9 May 7 1295.5 (08) 2,608 40% 1,237 249 9,249 15,632 (10) 5,229 177% Salt Cr Dam 9 1271.1 171 1278.9 May 7 1279.7 (08) 1,990 45% 897 133 6,002 10,400 (87) 3,235 186% Salt Cr Dam 10 1244.9 228 1253.5 May 7 1253.5 (15) 2,354 40% 896 138 8,287 16,600 (93) 4,702 176% Salt Cr Dam 12 1232.9 35 1239.9 Jun 11 1241.1 (87) 1,926 25% 1,053 162 13,220 25,000 (84) 4,628 286% Salt Cr Dam 13 1341.0 102 1345.1 Jun 15 1346.9 (83) 1,092 22% 515 134 5,016 13,300 (93) 3,487 144% Salt Cr Dam 14 1244.3 267 1246.2 Jun 15 1249.1 (93) 1,454 7% 577 139 5,853 23,300 (87) 6,721 87% Salt Cr Dam 17 1242.4 308 1249.2 May 7 1250.0 (93) 1,064 18% 300 115 6,226 11,100 (93) 3,272 190% Salt Cr Dam 18 1284.0 322 1286.1 May 8 1287.9 (87) 4,029 6% 1,568 228 23,443 74,400 (83) 24,682 95%

Bureau of Reclamation Reservoirs RESERVOIR REGULATION Boysen3 4725.0 28 4728.3 Jun 18 4730.8 (67) 66,993 45% 11,006 7,539 1,200,379 1,476,000 (97) 997,401 120% Canyon Ferry 3797.0 0 3796.8 Jun 19 3800.0 (55) 0 0% 13,486 5,681 2,891,929 5,786,000 (97) 3,726,239 78% Clark Canyon 5546.1 0 5534.9 Apr 30 5564.7 (84) 0 0% 723 812 142,901 718,000 (84) 250,929 57% Glendo 4635.0 41 4639.9 Jun 4 4650.9 (73) 63,025 23% 3,983 7,998 900,056 2,476,411 (11) 1,164,090 77% Heart Butte 2064.5 75 2066.5 Feb 12 2086.2 (52) 6,855 5% 1,281 819 96,762 307,000 (82) 90,734 107% Jamestown 1431.0 30 1431.8 May 25 1454.1 (09) 2,016 1% 1,183 304 26,719 500,005 (11) 59,379 45% Keyhole 4099.3 22 4099.6 Jun 27 4100.4 (78) 2,465 2% 4,077 117 44,820 100,000 (78) 18,470 243% Pactola 4580.2 75 4589.4 Jun 29 4589.4 (15) 8,284 19% 720 514 111,586 111,586 (15) 37,829 295% CHAPTER 5 Shadehill 2272.0 0 2271.9 Oct 5 2297.9 (52) 0 0% 871 251 73,832 413,504 (09) 78,199 94% Tiber 2993.0 0 2993.0 Jun 15 3011.4 (11) 0 0% 2,445 913 476,380 1,150,000 (75) 592,549 80% Yellowtail 3640.0 53 3647.9 Jun 20 3656.4 (67) 109,729 43% 19,225 14,287 2,771,984 3,838,936 (11) 2,364,771 117% 1Flood Control 5-1 2Period of Record 3If a project has a joint use or replacement storage pool, storage in the joint use and replacement storage zones are not counted as flood control in this table. Refer to Appendix B and Appendix D for more detailed flood control operations and runoff descriptions. CHAPTER 5 RESERVOIR REGULATION

Actual operations for the past year and proposed operations through water year 2015 are briefly discussed in the following sections. Individual project operation summaries are contained in Appendices B and D for Corps of Engineers projects and Bureau of Reclamation projects, respectively. Table 5-1 above summarizes the tributary reservoir flood control operation and runoff for the 2015 water year.

a. Previous Year Operations (October 1, 2014 through September 30, 2015). A tabulation of the number of cases the exclusive flood control zones in the 36 Omaha District tributary reservoirs have been filled to 25, 50, 75, and 100 percent is shown in Table 5-2.

Table 5-2 Utilization of Exclusive Flood Control Zone, Omaha District Tributary Projects Percent of Flood Control Storage

Total of 25% 50% 75% 100% Total of 25% 50% 75% 100% Tributary or or or or Tributary or or or or Year Projects More More More More Year Projects More More More More 1967 26 3 2 2 0 1992 36 0 0 0 0 1968 27 0 0 0 0 1993 36 12 0 0 0 1969 27 1 0 0 0 1994 36 2 0 0 0 1970 28 2 2 0 0 1995 36 6 3 0 0 1971 28 2 1 0 0 1996 36 6 1 0 0 1972 28 1 0 0 0 1997 36 6 3 0 0 1973 28 6 2 1 0 1998 36 3 1 1 0 1974 31 1 1 0 0 1999 36 5 2 0 0 1975 32 6 2 1 1 2000 36 1 0 0 0 1976 32 2 1 0 0 2001 36 2 0 0 0 1977 32 0 0 0 0 2002 36 0 0 0 0 1978 33 5 1 0 0 2003 36 0 0 0 0 1979 33 1 0 0 0 2004 36 2 0 0 0 1980 33 2 1 0 0 2005 36 1 1 0 0 1981 33 2 1 1 0 2006 36 0 0 0 0 1982 33 2 1 0 0 2007 36 0 0 0 0 1983 34 5 1 1 0 2008 36 3 1 0 0 1984 35 7 2 1 1 2009 36 6 5 2 1 1985 35 0 0 0 0 2010 36 5 4 1 0 1986 35 5 0 0 0 2011 36 7 6 5 0 1987 35 3 0 0 0 2012 36 2 0 0 0 1988 35 0 0 0 0 2013 36 3 0 0 0 1989 36 0 0 0 0 2014 36 1 0 0 0 1990 36 0 0 0 0 2015 36 7 2 0 0 1991 36 2 1 0 0 TOTAL 138 48 16 3

i. Corps of Engineers Dams. Deviation from the approved water control plan was obtained at Salt Creek 12. All other Corps tributary projects within the Omaha District were regulated in accordance with the water control plan during this report period. Detailed operation reports for each project are included in Appendix B.

ii. Bureau of Reclamation Dams. Deviation from the approved water control plan was obtained at Keyhole and Pactola Reservoirs. Reservoir operations at the other nine Bureau of Reclamation projects in the Omaha District were carried out in accordance with the water control plan during this reporting period.

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Coordination with Reclamation takes place throughout the year. Monthly inflow volume forecasts are prepared and coordinated with Reclamation from January through June for the following projects that receive a portion of their runoff from mountain snowmelt: Boysen (WY), Clark Canyon (MT), Canyon Ferry (MT), Glendo (WY), Tiber (MT), and Yellowtail (MT). These forecasts are shared with the appropriate Reclamation Area office as well as with the Regional office. Reclamation and the Natural Resources Conservation Service also prepare a monthly runoff forecast for these reservoirs, and all agencies discuss any large discrepancies. In 2011, the USACE runoff forecast regression equations were updated with current data by the Cold Regions Research and Engineering Laboratory (CRREL). In subsequent years, these equations have been updated with current data by Omaha District personnel.

Weekly and daily coordination was conducted as necessary throughout the events related to each project. Reclamation spreadsheet models were used for forecasting specific events. Detailed operation reports for each project are included in Appendix D.

b. Proposed Operations. With the exception of Bear Creek, Cherry Creek, Chatfield, and Pipestem, all Corps of Engineers tributary dams have ungated service outlets and no gate operations are normally required except for occasional opening of low-level outlets for various purposes. Releases to meet downstream water rights can be expected at Bowman-Haley, Cold Brook, Chatfield, Cherry Creek, Bear Creek, and Salt Creek No. 18. Evacuation of stored floodwater in these projects is scheduled as soon as practicable after each flood event.

i. Corps of Engineers.

(1) Colorado. Chatfield Dam releases are generally set based on water rights which are administered by the State of Colorado unless large flood inflows are observed. During the Colorado water use season, the Water Control and Water Quality Section and the State Engineer will calculate inflows to Cherry Creek Reservoir on a daily basis and releases will be balanced on a weekly basis to comply with State water rights. A formal small sedimentation flush was planned for mid-May, but instead was done during the flood control regulation while 250 cfs was being released. Flushes will not be scheduled during the December through March period or if there is downstream flooding. The flushing schedule utilizes approximately 250 to 300 ac-ft of water in a yearly flush with a larger flush every third year. At Bear Creek Reservoir, the low-level gate will be opened, if requested and practical, during the June through August period when the lake typically stratifies to assist in the improvement of lake water quality. If the lake falls below elevation 5558.0 ft, releases from the low level gates may be needed in order to satisfy downstream water rights requests. All other operations of the Colorado reservoirs will be made in accordance with the projects’ water control plans.

(2) Nebraska. At Salt Creek Dam 18, releases of inflows up to a total of 11.6 cfs may be made for water rights calls from downstream landowners. Releases up to 3 cfs will be made when required to satisfy downstream water rights. Low-level releases

5-3 CHAPTER 5 RESERVOIR REGULATION

will be made when practicable from the Papillion Creek projects to allow water to be discharged from lower elevations in an attempt to improve lake water quality. A deviation request was submitted and approved late in FY13 to lower Conestoga Reservoir and hold it at the low level gate invert elevation of 1228.0 ft for a lake rehab and outlet works modification. The gate was opened on October 1, 2013 and has remained open all of FY14 and FY15. The reservoir operated in fill and spill mode near the low-level gate invert elevation throughout the report period. A second deviation request was submitted and approved late in FY15 to lower Conestoga Reservoir to an elevation of 1217.0 ft completely evacuating the pool. It is expected to take one month for the Nebraska Games and Parks Department to pump the water out of the lake to elevation 1217 ft and an additional 3 to 4 weeks to modify the intake structure. When the intake structure modification is complete, the gates will be closed and the pool will be refilled. Work on the outlet works is expected to begin in late 2015, and the lake rehabilitation is expected to be completed in 2016 calendar year. All other operations of the Nebraska reservoirs will be done in accordance with the individual reservoir water control plan.

(3) North Dakota. Flood releases from Pipestem Dam will be coordinated with those from Reclamation's Jamestown Dam in accordance with the water control plan update that was approved in 2008. In early 2013, North Dakota Game and Fish found low dissolved oxygen (DO) levels in Pipestem Lake. To mitigate low oxygen levels and prevent a large fish kill, releases were initiated out of the low level gate at Pipestem in April 2013. As the ice melted off the lake, fish were found that had died over the winter due to low DO concentrations. A small low level release has since been initiated over the winter months to draw anoxic water from the bottom of the reservoir for water quality purposes. At Bowman-Haley Reservoir, the water quality improvement program calls for releases from the low-level drawdown tube during periods of pronounced lake stratification that typically occur in late winter and again in late summer around mid-July. If the local sponsor concurs and winter downstream conditions permit, water will be evacuated from the lower elevations of the reservoir each year starting in early February.

(4) South Dakota. At Cold Brook, Larive Lake Resort holds a water right to inflows into the reservoir up to 1.1 cfs. The resort may request a release of up to 1.1 cfs from the reservoir.

ii. Bureau of Reclamation. As in the past, Reclamation will continue to operate their reservoirs to meet project objectives and to coordinate operations with other interests to achieve optimum use of water resources. Generally, all reservoirs will be operated as close to the top of their conservation pools as possible in order to provide water for authorized purposes. Boysen, Canyon Ferry, Clark Canyon, Tiber, and Yellowtail Reservoirs require evacuation and refill of joint-use storage for flood control based on mountain runoff inflow forecasts.

(5) Canyon Ferry. Northwestern Energy will try to limit releases from Hebgen Reservoir to keep Canyon Ferry’s pool level below elevation 3794.0 ft after

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December 1. A pool level below elevation 3794.0 ft prior to the winter freeze is desired to prevent ice jam problems at the upper end of the lake.

(6) Keyhole. A deviation was approved on June 5 in anticipation of entering the flood control pool to increase releases at 0.5 foot increments instead of 0.1 foot increments as specified in the water control plan. The deviation specified holding a release near 100 cfs until the pool reached an elevation of 4100 feet. The deviation was coordinated with the Reclamation Dakotas Area Office.

(7) Pactola. Following above normal inflow during the fall of 2014 and winter of 2015, a deviation from the Pactola Reservoir water control plan to store up to 5% in the flood control pool to allow the reservoir to control the release to accommodate downstream construction was approved on March 4th with the following caveats

1. If drastic rises in mountain snowpack were to occur during the last two months of snowpack accumulation in 2015, more aggressive releases may have been determined necessary to avoid large flood control releases at Pactola Reservoir 2. Releases will be increased to evacuate the flood control storage space as soon as the downstream construction is complete and downstream conditions permit so as to not induce flooding. The deviation was coordinated with the Reclamation Dakotas Area Office.

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5-6 CHAPTER 6 MAJOR REGULATION ISSUES

There are several areas where major regulation issues may arise. This chapter will detail the regulation issues dealing with water quality, downstream channel capacity, potential hazardous conditions and dam safety.

a. Water Quality. The Omaha District has identified the following four general water quality priorities that have relevance to the tributary projects:

• Evaluate surface water quality conditions and trends at District projects.

• Identify existing and potential surface water quality problems at District projects, and develop and implement appropriate solutions.

• Provide water quality information to support Corps reservoir regulation elements for effective surface water quality and aquatic habitat management.

• Provide water quality information and technical support to the Tribes and States in the development of their Section 303(d) lists and development and implementation of Total Maximum Daily Load (TMDLs) at District Projects.

Water quality data were collected at the tributary projects identified in Table 8-2. Water quality data are assessed by the District's Water Quality Unit to identify any surface water quality concerns, including compliance with State water quality standards, at the tributary projects. Other water quality information, including State 303(d) and 305(b) Reports, is also reviewed for indications of water quality concerns at the projects. Table 6-1 provides a summary of water quality issues and concerns at each of the tributary projects based on Omaha District monitoring and a review of current State water quality reports.

b. Downstream Channel Capacity. Inadequate or reduced channel capacity is a problem below many of the tributary reservoirs. This was caused by several factors, including natural plant growth during extended low flow periods, flood deposits, human construction, and agriculture practices. In some cases, downstream channel capacity is significantly less than is needed for flood control releases.

In Montana, the Beaverhead River downstream of Clark Canyon has a safe channel capacity up to 1200 cfs to Barrets, MT and 750 cfs through Dillon, MT. During periods of high flows as much as 900 cfs has been passed through Dillon, MT with no reported damages. The Missouri River below Canyon Ferry has a safe channel capacity of 25,000 cfs through the city of Great Falls, MT. Great Falls, MT experienced flows of 27,000 cfs in 2011 with no reported damages. The Bighorn River channel capacity below Yellowtail is 10,000 cfs during most years. During higher flow years, Yellowtail releases of 12,000 cfs have been made with minimal damages reported. During 2011, 15,000 cfs was released from Yellowtail Dam. A release of 15,000 cfs threatened some rural residential properties.

6-1 CHAPTER 6 MAJOR REGULATION ISSUES

Table 6-1 Water Quality Issues and Concerns Fish Consumption Other TMDL Considerations* Advisories Concerns On 303(d) Impaired Pollutant/Stressor TMDL Advisory Identified Impacting Project List Uses Status*** in Effect Contaminant Water Quality Colorado: Coldwater Chlorophyll a TBD Yes Aquatic Life Phosphorus Bear Creek Res. No Urbanization Coldwater To Be Yes** Low dissolved oxygen** Aquatic Life Monitored Chatfield Res. No No Urbanization Cherry Creek Res. No No Urbanization Nebraska: Aquatic Life Nutrients Bluestem Res. Yes TBD Yes Mercury Aesthetics Sediment Branched Oak Res. Yes Aquatic Life Nutrients TBD No Recreation Algae Toxins Conestoga Res. Yes Aquatic Life Nutrients TBD No Aesthetics Sediment East Twin Res. Yes Aquatic Life Nutrients TBD No Nutrients Completed**** Ed Zorinsky Res. Yes Aquatic Life Yes Mercury Urbanization Mercury (Fish Tissue) TBD Glen Cunningham Res. No***** No Urbanization Nutrients Completed**** Holmes Res. Yes Aquatic Life Yes Mercury Urbanization High pH TBD Nutrients, Ammonia Olive Creek Res. Yes Aquatic Life Arsenic, High pH TBD No Low Dissolved Oxygen Yes Recreation Algae Toxins Completed**** Pawnee Res. Aquatic Life Nutrients No TBD Aesthetics Arsenic, Sediment Stagecoach Res. Yes Aquatic Life Nutrients TBD Yes Mercury Aesthetics Sediment Aquatic Life Nutrients, Sediment Completed**** Standing Bear Res. Yes Yes Mercury Urbanization Aesthetics Mercury (Fish Tissue) TBD Nutrients, Arsenic, Completed**** Wagon Train Res. Yes Aquatic Life Yes Mercury Mercury (Fish Tissue) TBD Nutrients Wehrspann Res. Yes Aquatic Life TBD Yes Mercury Urbanization Mercury (Fish Tissue) West Twin Res. Yes Aquatic Life Nutrients, Ammonia TBD No Completed**** Yankee Hill Res. No***** No TBD North Dakota: Bowman-Haley Res No Yes Mercury Nutrients/Eutrophication Pipestem Res. Yes Recreation TBD Yes Mercury Biological Indicators South Dakota: Cold Brook Res. Coldwater Water Temperature Yes TBD No Fishery (Natural Sources) Cottonwood Springs Low Water No No Res. Levels * Information taken from published state Total Maximum Daily Load (TMDL) 303(d) reports and listings. ** Identified as a Category 2 water – additional dissolved oxygen data is needed to assess aquatic life use support. *** TBD = To Be Developed. **** TMDLs completed: Ed Zorinsky 2002 (Dissolved Oxygen, Nutrients, and Sediment); Holmes 2003 (Nutrients and Sediment); Pawnee 2001 (Sediment); Standing Bear 2003 (Dissolved Oxygen, Nutrients, and Sediment); Wagon Train 2002 (Dissolved Oxygen, Nutrients, and Sediment – Arsenic Naturally Occurring); and Yankee Hill 2003 (Nutrients and Sediment). ***** Category 4R – Water body data exceeds the impairment threshold however a TMDL may not be needed. The category will only be used for nutrient assessments in new or renovated lakes and reservoirs. Newly filled reservoirs usually go through a period of trophic instability – a trophic upsurge followed by the trophic decline. Erroneous water quality assessments are likely to occur during this period. To account for this, all new or renovated reservoirs will be placed in this category for a period not to exceed eight years following the fill or re-fill process. After the eighth year monitoring data will be assessed and the water body will be appropriately placed into category 1, 2, or 5.

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In Wyoming, the Bighorn River channel capacity below Boysen Reservoir has not been tested in recent years. 12,000 cfs releases were made in 1991 with no known damages. Releases have not exceeded 7600 cfs since 1995. It is assumed channel capacity is near 10,000 cfs. The channel capacity downstream of Glendo Reservoir on the North Platte River has been improved after the 2010 and 2011 events when high flows were seen on the river from Glendo Reservoir to Lewellen, NE. During those events, the channel could not contain much above 7000 cfs without overbank flooding along the river.

In Colorado, the reservoir design routings for Chatfield, Bear Creek, and Cherry Creek Reservoirs were made independently of each other. Each Water Control Plan sets a target flow of 5,000 cfs at the South Platte River at Denver streamgage, but the individual routings did not account for releases from the other two dams or for incremental runoff below the dams. This constraint impacts the regulation of the Tri- Lakes reservoir system. A study was initiated at the end of FY15 to determine the risks associated with removing the Denver streamgage flow target during an extreme flood at Cherry Creek Dam to allow for additional flood storage evacuation. The study includes two phases, a coincident flow study to be complete mid-January and a water control plan modification study to be complete summer of 2016. The goal is to ensure 5000 cfs can be released from Cherry Creek Dam during an extreme flood event at Cherry Creek Dam no matter the condition at the Denver streamgage. The study will achieve this by further refining a new reservoir release pool elevation trigger at Cherry Creek Dam that was first developed during the concurrent Cherry Creek Dam Safety Modification Study (DSMS). The Bear Creek and Chatfield system evacuation plans will also be adjusted to ensure no increased flood risk below Bear Creek and Chatfield. The Chatfield Reallocation Study was initiated in 1996 and included coordination between many agencies and the public. The study analyzed the risks of transferring 20,600 ac-ft of exclusive flood control storage to a new joint use flood control and water supply storage zone at Chatfield Reservoir. In May 2013 the Chatfield, Cherry Creek, and Bear Creek proposed Water Control Plans (WCPs) including the newly reallocated Chatfield Reservoir joint use storage zone were approved by the Northwest Division Missouri River Basin Water Management (MRBWM) office, contingent on reallocation implementation. The Record of Decision was signed May 29, 2014 approving the reallocation of flood control storage at Chatfield. The Chatfield Reallocation Study was completed following the October 9, 2014 execution of the Water Storage Agreement. The mitigation based Chatfield Reallocation implementation phase began in FY15. The impacts of Chatfield Reallocation on flood control benefits included evaluation of impacts at Chatfield Reservoir as well as impacts at Bear Creek Reservoir and Cherry Creek Reservoir, and on the South Platte River from Chatfield to Julesburg, Colorado. The primary flood risk management purpose of Chatfield Reservoir was not impacted. During small flood events, the reallocation of storage at Chatfield slightly increases system evacuation releases and affects the timing and duration of releases made from Cherry Creek and Bear Creek Reservoirs though the primary flood risk management purpose is not affected. The target flow past the South Platte River at Denver, Colorado stream gage of 5,000 cfs was unchanged, thus there is no net effect past Henderson and Julesburg, Colorado.

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In North Dakota, on the James River below Pipestem and Jamestown Reservoirs the channel has some additional capacity due to high flows that have scoured the channel in 2009, 2010, and 2011. In 2009, emergency levees were designed and built by the Corps of Engineers to pass a 4000 cfs combined release in the event this release was needed to safely evacuate the flood storage. Only 3200 cfs was released from the reservoirs because of problems associated with high river stages and city infrastructure. The emergency levees were removed after the flood event. In 2010, the high runoff forecast was not realized and the maximum combined release was 1800 cfs. In 2011, initially a combined release of 1800 cfs was made necessitating some sandbag levees installed by the city of Jamestown. Because of several late summer rainfall events, combined releases were increased to 2400 cfs, and additional sandbag levees were installed by the city of Jamestown. These levees were removed after the flood event. A feasibility study took began in 2012 on the James River in North Dakota; structural and non-structural alternatives were assessed to reduce flooding damages. The study was completed in FY14. No alternatives were found to be feasible, though some smaller alternatives were recommended for assessment under the Section 205 program. The Corps has not yet received a formal request letter from the City of Jamestown for the Section 205 assessment, but since the project is transitioning from the feasibility study, Corps Headquarters has given approval and funding to initiate the assessment during FY16.

In South Dakota, changing groundwater conditions have caused Cold Brook reservoir releases to become more frequent. Numerous years with no releases allowed residents to fill the channel with homes, trailers, and outbuildings. To resolve this problem, a channel restoration project was initiated in 1999. Deviations for a 3 to 5 foot drawdown were approved from 1999 to 2012 as the downstream channel conditions were improved. The channel restoration on Corps land was completed in 2008, and the City of Hot Springs completed restoring the channel through town in 2009. In FY12 the Corps funded the construction of a culvert on the county portion of the channel. These projects have increased the channel capacity to 1,500 cfs through most of the impacted reach. Work to clear rocks, remove sloughing and enlarge driveway culverts remains in the Fall River County portion of the channel. Other than a short drawdown for maintenance and repair purposes in 2013, the drawdown has not been conducted since 2012, and subsequent season-long drawdowns are not planned unless required for the restoration of the county portion of the channel. On Rapid Creek downstream from Pactola Dam, complaints are received when routine flood control releases of around 500 cfs are made from the reservoir. The James River in South Dakota has large agricultural impacts with high James River flows especially in the Aberdeen area.

c. Potential Hazardous Conditions. A potential problem exists if water is released through project spillways where the land downstream of the project has been developed into urban areas. A hazard-to-life condition exists if a significant flow of water is discharged through the spillways at these projects.

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d. Dam Safety Issues. There is also a hazard-to-life condition if a flood event occurs that causes overtopping of the dam embankment. Dams located above populated areas are normally designed to safely pass a Probable Maximum Flood (PMF) without overtopping the embankment. The PMF is estimated using probable maximum precipitation (PMP) estimates developed by the National Weather Service. Recent studies indicate that seventeen Corps of Engineers and nine Bureau of Reclamation tributary reservoirs in the Omaha District cannot safely pass the PMF without being overtopped. Following is information on each of these projects along with the status of potential corrective actions.

i. Corps of Engineers Dams. Corps dams are being screened and assigned a safety classification rating. This Dam Safety Action Classification (DSAC) system classifies dams into five classes with class I having the highest priority for attention and class V the lowest priority. Part of the screening process for Corps dams with a DSAC rating of I, II or III is to identify interim measures to reduce safety risks while long-term solutions are being pursued. These measures are called Interim Risk Reduction Measures (IRRM) and could be structural or non-structural.

(1) Bear Creek Dam. The Probable Maximum Flood (PMF) was updated in September 2015 resulting in an increased inflow volume. The PMF update has been through an Agency Technical Review (ATR) and is now awaiting approval by the Northwestern Division Missouri River Basin Water Management (MRBWM) office. The 1970’s design inflow volume of 84,950 ac-ft was increased to 93,300 ac-ft. Assuming a starting pool of 5635.5 feet (top of the flood control pool) at the start of the PMF, the pool elevation is within 3 feet of the maximum pool for a duration of 2 hours. Due to this duration, the required minimum freeboard is 3 feet according to ER 1110-8-2(FR), Inflow Design Floods for Dams and Reservoirs. It is recommended that a new maximum pool elevation of 5689.3 ft be adopted, which provides 0.9 ft of freeboard. To meet the minimum freeboard requirement of 3 feet the dam would need to be raised by 2.1 ft. The main embankment of Bear Creek Dam received a Dam Safety Action Classification (DSAC) IV rating while the south embankment received a DSAC III. A Periodic Assessment is scheduled for the summer of FY16 at which time the DSAC rating will be re-evaluated.

(2) Cherry Creek Dam. Corps of Engineers design guidance for dams located above populated areas states they should store and pass the PMF without overtopping the embankment. The most recent precipitation estimate prepared by the National Weather Service for this area indicates that the reservoir could safely pass no more than 66% of the PMF under existing development with a freeboard allowance of 5.0 ft, and can contain 77% of the PMF at the existing minimum top of dam elevation of 5644.4 ft LPD. Cherry Creek Dam has received a Dam Safety Action Classification (DSAC) II rating because of the amount of development below the dam and the PMF studies that have identified a potential for an extreme precipitation event that could fill the reservoir and possibly overtop the dam. Interim Risk Reduction Measures (IRRM) were developed in response to the DSAC rating. Some of the interim measures being implemented for Cherry Creek Dam are an improved flood warning system, updating

6-5 CHAPTER 6 MAJOR REGULATION ISSUES response procedures with emergency managers, evaluating the capacities of the downstream channel and emergency spillway, as well as evaluating the vulnerability to seepage and earthquakes. The IRRM Plan has undergone an Agency Technical Review (ATR) and the comments were addressed in FY14. The document was approved in July 2014. With the approval of the Issue Evaluation Study (IES) and confirmed DSAC II rating by the Senior Oversight Group in March 2011, the scoping for the Dam Safety Modification Study (DSMS) was initiated in 2011. Several geotechnical and hydrologic studies were started in FY 2012 and were completed in FY13. The DSMS Baseline Risk Assessment was developed and completed in FY14. The DSMS Notice of Intent (NOI) was placed in the Federal Registrar early in FY14. The Future without Action Condition (FWAC) was completed by the end of FY14. Following a public meeting on the study in January of 2015, measures that address the risk at the dam were developed in FY15. The measures were then combined into alternatives to address the overtopping deficiency towards the end of FY15. The alternatives will go through a screening phase early in FY16 based on cost and non-breach risk. The final array of alternatives will be further developed in FY16. The study is scheduled to be complete at the end of 2017 with scheduled completion of the design and construction phase at the end of 2020.

(3) Cold Brook Dam. On August 11, 1993, the revised draft reconnaissance report for the Cold Brook Dam hydrologic improvement assessment was completed. The report concluded that the Cold Brook project was hydrologically deficient as it could safely pass only 48 percent of the PMF with adequate freeboard. A dam safety evaluation study was initiated in FY 2000 to determine optimal solutions to the hydrologic inadequacy of Cold Brook Dam. Cold Brook Dam has received a DSAC IV rating. As a result of this rating, the hydrologic capacity issue at Cold Brook Dam will be carried forward and included as part of the Corps’ risk-based approach to dam safety and prioritized on a national level. As that process continues, interim measures to reduce safety risks are being implemented while long-term solutions are being pursued. Some of the measures being considered for Cold Brook are an improved flood warning system and updating response procedures with emergency managers.

(4) Salt Creek Dams. Freeboard amounts at Salt Creek Dams 2, 4, 8, 9, 10, 12, 13, 14, 17, and 18 are all less than what was required by updated criteria discussed in ER 1110-8-2(FR), Inflow Design Floods for Dams and Reservoirs, due to changes in required antecedent conditions. A study to update the PMF for the Salt Creek Dams and determine the available freeboard was completed in draft form in FY 2013, and initial review was completed in FY 2014. The study indicated that, based on the new criteria for the development of the PMF, these ten dams do not have adequate freeboard, and many will be overtopped by the PMF.

(5) Papillion Creek Dams. Freeboard amounts at Papio Dams 11, 16, 18, and 20 are all less than required by updated criteria discussed in ER 1110-8-2. A study to update the PMF for the Papillion Creek Dams and determine the available freeboard based on new criteria was completed in draft form in FY 2013, and initial review was completed in FY 2014. The study indicated that, based on the new criteria for the

6-6 CHAPTER 6 MAJOR REGULATION ISSUES

development of the PMF, these four dams do not have adequate freeboard, and two will be overtopped by the PMF.

ii Bureau of Reclamation Dams. Table 6-2 summarizes PMF information for the Bureau of Reclamation Reservoirs; additional information can be found in the following paragraphs

Table 6-2 Bureau of Reclamation Dam Safety Information Peak Inflow Volume Length of % PMF to Date of Name of Dam (cfs) (ac-ft) Volume Overtop Study Clark Canyon Dam 166,800 506,000 30-day 58% 1985 Canyon Ferry Dam 506,000 2,035,000 15-day 99% 1985 Tiber Dam 695,926 1,433,000 15-day 59% 1989 Boysen Dam 865,000 3,061,000 15-day 48% 2008 Yellowtail Dam 887,000 4,700,000 15-day 31% 1988 Heart Butte Dam 236,000 700,000 5-day * 1990 Jamestown Dam 243,900 589,500 15-day 85% 1986 Keyhole Dam 513,600 785,800 5-day 75% 1985 Pactola Dam 344,000 214,000 41-hr * 2005 Shadehill Dam 423,200 1,324,900 15-day 77% 1986 Glendo Dam 457,000 2,800,000 15-day 40% 1990 *These projects were modified in 1987 to safely pass the PMF.

(1) Clark Canyon Dam. Maximum depth of overtopping is 3.7 ft for a duration of 32 hours. Overtopping of the dam embankment would likely result in failure of the dam. The 2005 Flood Frequency Analysis for Clark Canyon Dam estimates the return period of the threshold flood for overtopping is approximately 100,000 years.

(2) Canyon Ferry Dam. Maximum depth of overtopping is 0.48 ft for a 4-hour duration. Overtopping would not likely cause failure of the dam.

(3) Tiber Dam. The PMF is characterized by a peak inflow of 695,926 cfs and a 15-day volume of 1,433,000 ac-ft. Tiber Dam would be overtopped by floods exceeding 59 percent of the PMF. The values are from the last PMF study dated 1989.

(4) Boysen Dam. The maximum depth of overtopping is 18 ft for a duration of 187 hours. Boysen Dam would likely fail upon overtopping. The CFR indicates the return period of the flood which overtops Boysen Dam is approximately 800,000 to 900,000 years based upon the results of the 2004 Flood Frequency Analysis.

(5) Yellowtail Dam. Failure of the concrete arch dam as a result of overtopping is very unlikely. The PMF is estimated to be a 10,000,000-year event with an estimated overtopping depth of 26 feet. Despite the potential for significant overtopping of the dam, the risk estimates for this potential failure mode are relatively low due to the remote probability of the overtopping flood events and the low estimated probability of erosion of the foundation rock to the extent necessary to fail the dam.

(6) Heart Butte Dam. A peak inflow of 236,000 cfs and a 5-day volume of

6-7 CHAPTER 6 MAJOR REGULATION ISSUES

700,000 ac-ft characterize the PMF. Heart Butte Dam was modified in 1987 to safely pass the PMF. The values are from the last PMF study dated 1990 contained in the 2011 Comprehensive Facility Review report, Bureau of Reclamation, Technical Service Center, Denver, CO; November 2011.

(7) Jamestown Dam. The PMF, developed in 1986, is characterized by a peak inflow of 243,900 cfs and a 15-day volume of 589,500 ac-ft. PMF routing indicates the dam overtops to a maximum depth of 1.9 ft for approximately 92 hrs at 85% of the PMF.

(8) Keyhole Dam. Flood Frequency Analysis completed for the 2010 Comprehensive Facility Review indicates the return period of an overtopping threshold flood is extremely remote. The PMF would overtop the dam by 4.5 ft. for 57 hours.

(9) Pactola Dam. The new values are for a general storm for the Pactola area and the required flow releases through Deerfield Dam. Pactola Dam was modified in 1985-87 to safely pass the PMF.

(10) Shadehill Dam. Flood Frequency Analyses completed for the 2007 CFR indicate the return periods for floods resulting in overtopping of Shadehill Dam are extremely remote.

(11) Glendo Dam. The original inflow design flood used during the design of Glendo Dam had a peak inflow of 180,000 cfs with a 15-day volume of 849,000 ac-ft. The current Probable Maximum Flood (PMF) study completed in 1990 has a peak flow of 457,000 cfs and a 15-day volume of 2,800,000 ac-ft and is based on a 72-hour, June Probable Maximum Precipitation (PMP) general rainstorm centered over the North Platte River Basin between Seminoe and Pathfinder Dams, with concurrent floods occurring in the Seminoe Reservoir basin and the intervening between Pathfinder and Glendo Dams. From 2011 thru 2015, Glendo Dam was modified by constructing a new auxiliary spillway and increasing surcharge capacity by three feet, Glendo dikes were raised and modified to address risk associated with internal erosion, and Guernsey Dam was modified by repairing one drum gate at the South Spillway, replacing the other drum gate at the South Spillway with a weir, installing a filter at the embankment contact with the North Spillway, and installing a parapet wall on the crest of the dam. Glendo Dam can now safely pass floods up to the 100,000 year event. Modifications to Guernsey will allow for safe passage of larger operational spills from Glendo.

6-8 CHAPTER 7 WATER CONTROL MANUALS

A responsibility of the Water Control and Water Quality Section is to update the water control manuals for each project on a periodic basis. During the reporting period, work progressed on several Water Control Manual updates. This chapter details the current status of updates as well as the schedule for updating the balance of the project manuals.

a. Current Manual Status. Water control manual updates for the Chatfield, Cherry Creek, and Bear Creek projects were initiated in FY1995. During the public involvement process, most of the public comment involved issues of reallocation of a portion of the Chatfield flood control storage to multipurpose storage, including water supply storage. Since this type of reallocation of storage was beyond the scope of a water control manual update, a General Investigation (GI) funded reallocation study at Chatfield Reservoir was initiated in conjunction with the state of Colorado. Other issues developed related to the ongoing Cherry Creek Dam Safety Modification Study and potential impacts on the water control plan for Cherry Creek reservoir. As a result, completion of the water control manual updates was delayed pending completion of the Chatfield Reallocation Study and the Cherry Creek Dam Safety Modification Study. In May 2013, the Chatfield, Cherry Creek, and Bear Creek proposed Water Control Plans (WCPs) including the newly reallocated Chatfield Reservoir joint use storage zone were approved by the Northwestern Division Missouri River Basin Water Management (MRBWM) office, contingent on reallocation implementation. The contingent WCPs for Chatfield, Cherry Creek, and Bear Creek Dams have been included in the draft water control manuals as exhibits. The existing WCPs will be active until the Chatfield Reallocation has been implemented. The water control manual updates, which were partially updated in FY14 and FY15, will be completed following the final approval by MRBWM, planned for in FY16. The Cherry Creek Dam Safety Modification Study began in 2011. A final array of alternatives will be developed in FY16. Interim Risk Reduction Measures (IRRMs) have been put in place to reduce risk while the dam safety study is underway. Reference Chapter 6 for further information on the reallocation study, IRRMs and dam safety study.

The water control manuals for Jamestown and Pipestem Reservoirs were last updated in 2008. Due to several years of unusually high inflows, funding was received in FY 2012 to update the hydrology and to conduct agency coordination concerning an update of the Pipestem water control manual. The updated water control manual was approved in FY14, and the Jamestown water control manual is scheduled to be updated in FY16. The Cold Brook water control manual update is in progress.

For Bureau of Reclamation owned and operated Section 7 reservoirs, the updated Pactola and Canyon Ferry water control manuals are in the review process. For the other nine Section 7 reservoirs, an effort has been initiated to develop information used in updating each of the water control manuals. Starting in FY11, funding was provided to Reclamation to prepare a write-up of operational constraints in reservoir areas upstream of dam, at dam and outlet works facilities, and in downstream locations; to prepare a write-up of reservoir inflow forecasting procedures; and to prepare a write-up of procedures for simulation of reservoir operations.

7-1 CHAPTER 7 WATER CONTROL MANUALS

In FY13, a draft updated water control manual for Clark Canyon, Tiber and Keyhole Reservoirs was initiated. In FY15, a draft updated water control manual for Yellowtail Reservoir was developed. The existing the water control plans will be reviewed for adequacy and will be updated if deemed necessary.

b. Work Priorities. Water control manuals will typically be updated on an approximate 10-year cycle. If funds are not available for a comprehensive review and update of a water control manual, at a minimum "baseline" O&M funds will be used to update area-capacity curves, rating curves, stage-damage curves, historical records, and documentation of large runoff events. Table 7-1 lists the current status of all water control manuals.

Table 7-1 Schedule for Revision of Water Control Manuals FY 2016 – FY 2026 Date of Scheduled Type of Manual Completion Revision - Estimated or Last Date of Next Manual (M) Total Cost Dam/Reservoir Name Stream Owner District Revision Revision or Plan (P) $1000 Bear Creek Bear Creek CE NWO Mar 77 FY 2016 M/P 40

Chatfield South Platte River CE NWO Apr 73 FY 2016 M/P 50

Cherry Creek Cherry Creek CE NWO Oct 71 FY 2016 M/P 60

Canyon Ferry Missouri River BR NWO Apr 95 FY 2016 M 60

Jamestown James River BR NWO Oct 08 FY 2016 M 15

Pactola Rapid Creek BR NWO Feb 77 FY 2016 M 60

Tiber Marias River BR NWO Sep 87 FY 2016 M 120

Cold Brook Cold Brook CE NWO Aug 54 FY 2017 M 40

Boysen Wind River BR NWO Dec 66 FY 2017 M/P 80

Yellowtail Bighorn River BR NWO Jan 74 FY 2017 M/P 120

Keyhole Belle Fourche River BR NWO Jun 69 FY 2018 M/P 60

Lake Audubon Snake Creek CE NWO Dec 92 FY 2018 M 40

Clark Canyon Beaverhead River BR NWO Jun 76 FY 2018 M 60

Cottonwood Springs Cottonwood Springs CE NWO Sep 73 FY 2019 M 30

Heart Butte Heart River BR NWO Feb 51 FY 2019 M 60

Shadehill Grand River BR NWO Nov 51 FY 2019 M 60

Salt Creek Dams (10) Salt Creek/Tribs CE NWO Dec 78 FY 2019 M 120

Lake Pocasse Spring Creek CE NWO Jun 89 FY 2019 M 30

Papillion Creek Dams (4) Papillion Creek/Tribs CE NWO Oct 98 FY 2020 M 60

Bull Hook/Scott Coulee Bull Hook Creek CE NWO Mar 91 FY 2020 M 30

7-2 CHAPTER 7 WATER CONTROL MANUALS

Table 7-1 Schedule for Revision of Water Control Manuals FY 2016 – FY 2026 Date of Scheduled Type of Manual Completion Revision - Estimated or Last Date of Next Manual (M) Total Cost Dam/Reservoir Name Stream Owner District Revision Revision or Plan (P) $1000 Cedar Canyon Deadman's Gulch CE NWO Jan 71 FY 2020 M 30

Bowman-Haley N Fork Grand River CE NWO Mar 87 FY 2021 M 40

Kelly Rd/Westerly Creek Westerly Creek CE NWO Dec 92 FY 2022 M 30

Glendo North Platte River BR NWO Dec 97 FY 2022 M 60

Pipestem Pipestem Creek CE NWO Jul 14 FY 2024 M 35

7-3 CHAPTER 7 WATER CONTROL MANUALS

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7-4 CHAPTER 8 DATA COLLECTION PROGRAM AND PROCEDURES

The Omaha District data collection program is responsible for collecting tributary and reservoir data within the district boundaries. This chapter describes the manner in which the data is collected and who collects the data. In addition, a brief summary of other data that is being collected, including water quality and sedimentation, is included.

a. Water Control Data Collection.

i. Sources. Data from hydrologic gages for water management are obtained from various sources including contract observers, project offices, National Weather Service (NWS), U.S. Geological Survey (USGS), Bureau of Reclamation, state offices and data collection platforms (DCPs) operated by the Omaha District. The NWS provides current weather conditions, one to five day forecasts, precipitation reports, river level data and special hydrologic forecasts including flood warnings. Products available on various websites range from raw data (i.e. precipitation and temperature) to upper air maps and forecast products containing "value-added" graphics. In addition to DCP data, other data streams have been added to the database for both redundancy and improved information. These additions include the SNOTEL sites maintained by the Natural Resources Conservation Service (NRCS).

ii. Data Storage. The Corps Water Management System (CWMS) is the Omaha District’s primary data management system. CWMS was developed by the Hydrologic Engineering Center (HEC) and utilizes an Oracle database to store river, reservoir, snow, and weather data. Another feature of CWMS utilized by this office is the ability to collect data from the Kansas City District office. This provides redundancy/backup for the Omaha District and the Kansas City District offices.

iii. Data Collection Equipment. Remote site, satellite data transmissions are utilized for water management. Satellite collection equipment being used by the district was purchased from Sutron Corporation and Design Analysis. The equipment is installed and maintained by Water Control and Water Quality Section personnel and/or by the USGS. Currently there are 16 DCPs in Montana, 3 in Wyoming, 9 in Colorado, 25 in North Dakota, 28 in South Dakota, 41 in Nebraska, and 19 in Iowa for a total of 141 sites funded by the Omaha District. The DCPs in the district transmit real-time river and reservoir levels, precipitation, wind, and water and air temperature data. This hourly data collected by these remote sensors is transmitted to Wallops Island, VA. Wallops Island then retransmits to ground receiving sites called Local Readout Ground Stations (LRGS), one of which is located at Omaha District headquarters. This information is currently transmitted via the GOES-west satellite located at 135 degrees west longitude. At the end of FY14, new satellite dishes were procured for the Omaha District and Kansas City District locations. These dishes are Low Rate Information Transmission (LRIT) dishes that will be compatible with a new GOES-west satellite in the future. In FY15 Kansas City District installed and implemented their LRIT satellite. Omaha District has installed their LRIT satellite and expects to implement it in FY16. All of the Omaha District DCPs are high data rate that transmit data every hour on channel 58.

8-1 CHAPTER 8 DATA COLLECTION PROGRAM AND PROCEDURES

b. Cooperative Hydrologic Programs. Omaha District personnel complete the District’s stream gaging program with assistance from the USGS. The USGS’ activities are funded through the Cooperative Streamgaging Program (FC-33) executed by the Water Control and Water Quality Section. The Cooperative Streamgaging Program provides financial support to seven USGS Water Science Centers within the Omaha District footprint for operation and maintenance of multiple streamgaging stations. The USGS Water Science Centers are Colorado, Iowa, Montana and Wyoming, Nebraska, North Dakota, and South Dakota (note that the Montana and Wyoming Water Science Centers combined on October 1, 2013). Collection and publication of data such as stage, discharge, sediment and water quality records are the primary functions of this program. Table 8-1 shows the cost for these programs. A total of 107 streamgages are funded by these programs. Of the 107 streamgages, 78 streamgages are fully funded by operation and maintenance (O&M) funds, one streamgage is fully funded by Construction General (CG) funds, and two streamgages are fully funded by Headquarters General Coverage (HGC) funds. Twenty-eight streamgages are funded partially by these programs. Over half of these streamgages are used in the Missouri River Mainstem Reservoir forecasts and for the threatened and endangered species program. Figure 8-1 shows the funding trend over time since 1971.

Table 8-1 Cost of USGS Cooperative Program O&M CG HGC Fiscal Year District Funded Funded Funded Total 2014 Omaha $1,317,240 $10,080 $29,000 $1,356,320 2015 Omaha $1,346,190 $10,280 $29,000 $1,385,470

8-2 CHAPTER 8 DATA COLLECTION PROGRAM AND PROCEDURES

Figure 8-1. USGS cooperative program funding since 1971 for Omaha District

c. Water Quality. The Omaha District’s Water Quality Unit operates a water quality monitoring program for Corps projects in the District. Water quality monitoring goals, objectives, and data collection approaches are defined in the document, “Program Management Plan for Implementing the Omaha District’s Water Quality Management Program” (USACE, 2015). In general, water quality data collection consists of long-term fixed station ambient monitoring, intensive surveys, special studies, and investigative monitoring.

Long-term fixed station ambient monitoring is intended to provide information that will allow the Omaha District to determine the status and trends of surface water quality at District projects. This type of sampling consists of systematically collecting samples at the same location over a long period of time (e.g., collecting monthly water samples at the same site for several years).

Intensive surveys are intended to provide more detailed information regarding the water quality conditions at District projects. They typically will include more sites sampled over a shorter timeframe than long-term fixed station monitoring. Intensive surveys will provide the detailed water quality information needed to thoroughly understand water quality conditions at a project.

8-3 CHAPTER 8 DATA COLLECTION PROGRAM AND PROCEDURES

Special studies are conducted to address specific water quality information needs. Special studies may be undertaken to collect the information needed to “scope-out” a specific water quality problem; apply water quality models; design and engineer modifications at projects; or evaluate the effectiveness of implemented surface water quality enhancement measures.

Investigative monitoring is typically initiated in response to an immediate need for surface water quality information at a District project. This may be in response to an operational situation, the occurrence of a significant pollution event, public complaint, or a report of a fish kill. Any District response to a pollution event or fish kill would need to be coordinated with the appropriate Tribal, State, and Local authorities. The type of sampling that is done for investigative purposes is highly specific to the situation under investigation.

Water quality data collection conducted in the reporting period (October 1, 2014 to September 30, 2015) at Omaha District Tributary Projects is summarized in Table 8-2.

Table 8-2 Tributary Projects Sampled and Types of Sampling (1-Oct-14 to 30-Sep-15) Samples Project Type of Sampling* Collected By** Watershed Tri-Lakes (CO) LTFS, SS Authority

Papillion Creek Reservoirs (NE) LTFS WQU • Reservoir Sites (Near-dam, Mid-Lake, and Upper-Lake) LTFS WQU • Inflow Sites (Runoff Conditions) Salt Creek Reservoirs (NE) • Reservoir Sites (Near-dam, Mid-Lake, and Upper-Lake) LTFS WQU • Inflow Sites (Runoff Conditions) LTFS WQU

LTFS South Dakota Reservoirs – Cold Brook and Cottonwood Springs (3-Yr Rotation, WQU • Reservoir Sites (Near-dam and Mid-Lake) Sampled in 2015) LTFS, SS North Dakota Reservoirs – Bowman-Haley and Pipestem (3-Yr Rotation, WQU • Reservoir Sites (Near-dam and Mid-Lake) sampled in 2015) * LTFS = Long-Term Fixed Station. SS = Special Study. ** WQU = Omaha District Water Quality Unit. Watershed Authority = Local Watershed Authorities established for Cherry Creek, Chatfield, and Bear Creek Lakes.

d. Sediment.

i. Bed and Suspended Sediment Sampling. The Omaha District operated six sediment sampling stations under the Cooperative Stream Gaging Agreement with the United States Geological Survey (USGS). Three of these stations are multipurpose stations which gather bed and suspended sediment data and flow velocity data on the Missouri River, while the other three are suspended sediment sampling stations on tributaries to the Missouri River. Data is collected on a rotating schedule at the Omaha, Nebraska City, and Sioux City gages. The USGS monitors, maintains, and publishes

8-4 CHAPTER 8 DATA COLLECTION PROGRAM AND PROCEDURES

the data from these stations under a cooperative stream-gaging program with USACE, Omaha. Table 8-3 lists the stations and their locations.

Table 8-3 Sediment Sampling Stations River City State USGS Published Data Yellowstone Suspended sediment concentration Station No. 06329500 Sidney Montana Suspended sediment discharge Bad Suspended sediment concentration Station No. 06441500 Fort Pierre South Dakota Suspended sediment discharge White Suspended sediment concentration Station No. 06452000 Oacoma South Dakota Suspended sediment discharge Missouri Station No. 06486000 Sioux City Iowa Multipurpose Missouri Station No. 06610000 Omaha Nebraska Multipurpose Missouri Station No. 06807000 Nebraska City Nebraska Multipurpose

ii. Sedimentation Surveys. A tributary sedimentation survey was completed in 2015 at Cold Brook Lake near Hot Springs, South Dakota. New reservoir surface area and storage capacity tables are pending for Cold Brook (2015 data), Pipestem (2014 data), Salt Creek #09 – Stagecoach Lake (2014 data), and Salt Creek #12 – Conestoga Lake (2006 data). These tables will be updated when resources are available.

Table 8-4 Area-Capacity Tables Updated Storage Area Curve Curve Reservoir Updated Updated No reservoir curves were updated during FY15.

iii. MRB Sediment Memoranda Reports. The Missouri River Basin (MRB) Sediment Memoranda Program is a comprehensive basin-wide reporting program for coordination of studies of sedimentation problems in the Omaha District as well as for continuity and perspective in the planning and design of individual projects. Two MRB Sediment Memoranda Reports were published in 2015:

• MRB Sediment Memorandum #15c – Lake Oahe Aggradation Study, 1958-2012.

• MRB Sediment Memorandum #31 – Lake Sharpe Aggradation Study, 1963-2012.

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8-6 CHAPTER 9 OTHER WATER CONTROL ACTIVITIES

In addition to the information previously discussed, the Omaha District Water Control and Water Quality Section routinely reports on other activities. The following is a brief synopsis of these activities.

a. Water Control Initiatives.

i. Missouri River Region Water Control Data System Master Plan. The Water Control and Water Quality Section has been using the Corps Water Management System (CWMS) since February 2001. In August 2007, a regional CWMS database was implemented with the Missouri River Basin Water Management Division using CWMS version 1.5. An upgrade to CWMS version 2.0 was scheduled for 2010 but implementation was delayed due to lack of functionality of the system. An upgrade to CWMS version 2.1 was initiated in 2012. During FY15 the water control staff made major progress in moving towards a regional CWMS 2.1 database between the Omaha District, the Kansas City District, and the Missouri River Water Management Office. The Water Control and Water Quality Section began using CWMS version 2.1 as the production database beginning November 2012. The T5140 servers were upgraded to M3000 servers, which were installed in FY13. Initial setup work was completed midway through the fiscal year. The Omaha District and Missouri River Basin Water Management moved to the new servers in October 2014. In October 2014, CWMS servers were upgraded to version 3.0 in anticipation of a new client. In November 2014, beta testing of a CWMS 3.0 client began, and the full CWMS 3.0 client is scheduled to be released in FY16.

ii. Model Development. The CWMS software integrates with Hydrologic Engineering Center (HEC) models to provide real-time forecasting. In 2010, HEC oversaw a national initiative for CWMS model development in which portions of the South Platte, Fall, and James Rivers were modeled. These models were integrated into the CWMS 2.0 database, but have not been used in real-time because CWMS 2.0 was not used as the production database. Through the CWMS National Implementation process, a suite of models were developed in the South Platte River Basin by the Modeling, Mapping and Consequences (MMC) Production Center’s virtual team. In January 2014, the MMC’s virtual team completed and handed off the model suite to the Omaha District for testing and implementation. The WCWQ staff has not fully implemented the South Platte River Basin modeling suite due to challenges with the CWMS CAVI implementation. With the beta testing of CWMS 3.0 software, the Omaha District has begun the process of moving other existing stand alone models into the CWMS database to be used for real-time forecasting once CWMS version 3.0 is fully operational.

Table 9-1 shows a list of the developed water control models and those desired at each of the Omaha District reservoirs and USBR Section 7 projects. The majority of these base models still need to be integrated into the CWMS CAVI to be used in real-time operations. Eventually, it is desired to model each reservoir watershed with the Hydrologic Modeling System (HMS) to simulate the precipitation-runoff processes, the River Analysis System (RAS) for calculating water surface profiles for river reaches

9-1 CHAPTER 9 OTHER WATER CONTROL ACTIVITIES

downstream of the reservoirs, and the Flood Impact Analysis (FIA) model to compute flood damages for regulated flow. In addition, it is desired to develop the Reservoir Simulation (ResSim) model for the gated reservoirs (non-fill and spill) to perform reservoir operation modeling for a variety of operational goals and constraints. The goal of the CWMS National Implementation Plan is to address these modeling needs on a nationwide level. Future model development and CWMS implementation will be performed either by the WCWQ staff or through a national initiative as part of the USACE MMC’s virtual team. The James River and Big Horn River Basins are scheduled to be implemented in FY16.

Table 9-1 CWMS Model Development Project Size Implementation Watershed Type (mi2) of CWMS Models Desired

USBR Canyon Ferry-Missouri River, MT Section 7 15900 ResSim HMS, HMS-snowmelt, RAS, FIA USBR Clark Canyon-Beaverhead River, MT Section 7 2320 * ResSim HMS, HMS-snowmelt, RAS, FIA USBR Tiber-Marias River, MT Section 7 4850 ResSim HMS, HMS-snowmelt, RAS, FIA USBR Yellowtail-Bighorn River, MT Section 7 19626 ResSim HMS, HMS-snowmelt, RAS, FIA USBR Boysen-Wind River, WY Section 7 7710 * ResSim HMS, HMS-snowmelt, RAS, FIA USBR Heart Butte-Heart River, ND Section 7 1710 None HMS, HMS-snowmelt USBR HMS, HMS-snowmelt, Jamestown-James River, ND Section 7 1790 ResSim, RAS FIA HMS, HMS-snowmelt, Pipestem-Pipestem Creek, ND USACE 594 * ResSim, RAS FIA USBR Shadehill-Grand River, SD Section 7 3120 None HMS, HMS-snowmelt, RAS, FIA USBR Keyhole-Belle Fourche River, WY Section 7 1950 None HMS, RAS, FIA USBR HMS, HMS-snowmelt, ResSim, Pactola-Rapid Creek, SD Section 7 319 None RAS, FIA USBR Glendo-North Platte River, WY Section 7 14330 ResSim HMS, HMS-snowmelt, RAS, FIA Bowman Haley-Grand River, ND USACE 446 None HMS HMS, RAS d/s Cold Cold Brook and Cottonwood-Fall River, SD USACE 136 Brook FIA 4 Papio Creek Reservoirs-Papio Creek, NE USACE 384 None HMS, RAS, FIA 10 Salt Creek Reservoirs-Salt Creek, NE USACE 1050 None HMS, RAS, FIA HMS, HMS-snowmelt, Chatfield, Cherry Creek and Bear Creek-CO** USACE 3640 ResSim, RAS** FIA Note: Many of the existing models are not on the CWMS server, but have been developed. Developed models may need additional calibration before using in a real-time environment. Watershed areas are a combination of the contributing area above the reservoirs or the area above a gage of interest. * Clark Canyon watershed size is included in Canyon Ferry watershed size. Boysen watershed size is included in Yellowtail watershed size. Pipestem watershed size is included in Jamestown watershed size. ** Through the national CWMS Implementation process, a suite of models was developed in the South Platte River Basin and were given to the Omaha District for implementation into the CWMS-CAVI in January 2014.

b. Personnel. The Water Control and Water Quality Section consists of Hydraulic Engineers, a Hydrologic Engineering Technician, a Water Quality Specialist, Biologists, an Administrative Support Assistant, and student trainees. Table 9-2 shows a complete listing of the personnel who were in the section during the reporting period. A student 9-2 CHAPTER 9 OTHER WATER CONTROL ACTIVITIES

9-5 CHAPTER 9 OTHER WATER CONTROL ACTIVITIES

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9-6 APPENDIX A – COE PROJECT PERTINENT DATA SHEETS

Bear Creek Reservoir ...... A-1 Bowman-Haley Dam and Lake ...... A-1 Bull Hook – Scott Coulee Dams ...... A-1 Cedar Canyon Dam (Red Dale Gulch) ...... A-1 Chatfield Reservoir ...... A-1 Cherry Creek Reservoir...... A-2 Cold Brook Dam and Lake ...... A-2 Cottonwood Springs Dam and Lake ...... A-2 Kelly Road Dam ...... A-2

Papillion Creek Dams Dam No. 11 – Glenn Cunningham Dam and Lake ...... A-3 Dam No. 16 – Standing Bear Dam and Lake ...... A-3 Dam No. 18 – Zorinsky Dam and Lake ...... A-3 Dam No. 20 – Wehrspann Dam and Lake...... A-3

Salt Creek Dams Dam No. 2 – Olive Creek Dam and Lake ...... A-4 Dam No. 4 – Bluestem Dam and Lake ...... A-4 Dam No. 8 – Wagon Train Dam and Lake ...... A-4 Dam No. 9 – Stagecoach Dam and Lake ...... A-4 Dam No. 10 – Yankee Hill Dam and Lake ...... A-4 Dam No. 12 – Conestoga Dam and Lake...... A-5 Dam No. 13 – Twin Lakes Dam and Lake ...... A-5 Dam No. 14 – Pawnee Dam and Lake ...... A-5 Dam No. 17 – Antelope Creek Dam and Holmes Park Lake ...... A-5 Dam No. 18 – Branched Oak Dam and Lake ...... A-5

Pipestem Dam and Lake ...... A-6 Snake Creek Dam and Lake Audubon ...... A-6 Spring Creek Dam and Lake Pocasse ...... A-6 Westerly Creek Dam ...... A-6 Spring Gulch Dam ...... A-6 Fort Peck Dam and Lake ...... A-7 Garrison Dam and Lake Sakakawea ...... A-7 Oahe Dam and Lake ...... A-7 Big Bend Dam and Lake Sharpe ...... A-7 Fort Randall Dam and Lake Francis Case ...... A-7 Gavins Point Dam and Lewis & Clark Lake ...... A-7

APPENDIX A - COE PROJECTS PERTINENT DATA

SUMMARY OF ENGINEERING DATA ITEM SUBJECT BEAR CREEK BOWMAN-HALEY BULL HOOK- CEDAR CANYON CHATFIELD NO SCOTT COULEE GENERAL 1 Location of dam 3 mi. S W of Denver, CO 6 mi. W of Haley, ND 1 mi. S of Havre, MT 3.5 mi. W of Rapid City, SD 2 mi. S of Denver, CO 2 River and river mile Bear Creek R M 8 N. Fk. Grand R M 100 Bull Hook Cr.-Scott Coulee Deadman's Gulch South Platte River R M 321 3 Drainage area (sq. mi.) 236 446 54 0.4 3,018 4 Reservoir length (mi.) 0.5 mi. at el. 5558 2.5 mi. at el. 2755 Normally dry Normally dry 2.0 mi. at el. 5430 5 Location of Damtender At Chatfield Dam Garrison Dam Ft. Peck Dam Oahe Dam On site 6 Travel time to Missouri River 2 weeks 1 day to Shadehill Dam - - 2 weeks 7 Max. discharge of record 8600 cfs Jul 1896 14,100 cfs Apr 1952 - 440 cfs Aug 1949 110,000 cfs Jun 1965 8 Max. pool of record (ft) PD (1) 5607.8 Sep 2013 2762.7 Mar 1978 - Not available 5447.6 May 1980 9 Project cost (2) $61,700,000 $4,372,200 $1,837,200 $122,600 (4) $101,130,000 DAM AND EMBANKMENT 10 Top of dam – ft 5689.5 2794 2613.3 (BH) 2613.3 (SC) 3554 5527 11 Length of dam – ft. 5300-main 2100-south 5730 1900 (BH) 1500 (SC) 1320 13,136 12 Height of dam – ft. 179.5-main 65-south 79 73 (BH) 53 (SC) 42 147 13 Stream bed – ft 5510 2715 2540 (BH) 2560 (SC) 3512 5380 14 Abutment formation Clay,shale,siltstone,sandstone Ludlow, sandy clay, silty sand Glacial till, lean clay Minnekahta limestone Sandy overburden-Dawson F. 15 Type of fill Rolled earth Rolled earth Rolled earth Rolled earth Rolled earth 16 Fill quantity in cu. yds. 11,346,000-main 770,000-so. 1,750,000 1,300,000 150,000 14,650,000 17 Date of closure July 1977 August 1966 October 1955 September 1959 August 1973 18 Date of initial fill (base F.C.) May 1979 March 1969 - - June 1979 SPILLWAY *Notch in BH to 2583 19 Discharge capacity – cfs 153,500 cfs at el. 5684.5 62,970 cfs at el. 2789 25,200 cfs at el. 2605 1,400 cfs at el. 3550.6 188,000 cfs at el. 5521.6 20 Crest elevation – ft 5667 2777 2593.0 (BH)* 2586.0 (SC) 3545 5500 21 Width – ft. 800 650 - 60 500 22 Gates, number, size, type Ungated earth channel Ungated earth notch (3) Ungated earth channels Ungated rock channel Ungated converging chute RESERVOIR ELEV AND AREA (ac) (2009 data) (2010 data) Total - (BH & SC) (2010 data) 23 Maximum pool 5684.5 (4) 1,215 2789.0 8,048 2605.0 384 3550.6 16 5521.6 5,987 24 Top of flood control pool 5635.5 711 2777.0 5,136 2593.0 283 3545.0 11 5500.0 4,782 25 Top of multipurpose pool 5558.0 107 2754.8 1,762 none none 5432.0 1,412 26 Top of inactive pool 5528.0 16 2740.0 507 none 3526.0 3 5385.0 10 STORAGE ZONES, ELEV - CAP (af) (2009 data) (2010 data) Total - (BH & SC) (2010 data) 27 Surcharge 5635.5 – 5684.5 46,955 2777.0 - 2789.0 77,276 2593.0 - 2605.0 3,600 3545.0 - 3550.6 74 5500.0 – 5521.6 116,392 28 Flood Control 5558.0 – 5635.5 28,514 2754.8 - 2777.0 72,696 2540.0 - 2593.0 6,200 3526.0 - 3545.0 123 5432.0 – 5500.0 205,985 29 Multipurpose 5528.0 – 5558.0 1,771 2740.0 - 2754.8 15,196 none none 5385.0 – 5432.0 27,060 30 Inactive 5510.0 – 5528.0 53 2715.0 - 2740.0 2,436 none 3512.0 - 3526.0 13 5377.0 – 5385.0 16 31 Gross (top of flood control pool) 30,338 af 90,329 af 6,400 af 136 af 233,061 af OUTLET WORKS 32 Number and size – conduits 1 – 7 ft. circular – upstream 1 - 10 ft. circular conduit 1 - 30 in. RCP - (BH) 1 - 24 in. C. M. P. 2 – 11 x 16 ft. oval conduit 1 – 7 x 10.5 ft. – downstream 1 - 30 in. RCP - (SC) 33 Conduit length – ft. 1690 ft. 341 ft. 393 ft. - (BH) 230 ft. 1280 ft. 286 ft. - (SC) 34 Disch Cap of Conduit - cfs 49 cfs at el. 3545 35 Gated outlets (No - size - invert elev) 2 – 3 x 6 ft. hydraulic slide 2 - 30 in. valves - el. 2740.0 1 - 24 in. valve, (BH) 2 – 6 x 13.5 ft. hydraulic slide 2 – 36” K-flo Butterfly 1 - 30 in. interior gate valve 1 - 24 in. valve, (SC) 2 – 2 x 2 ft. slide-gate on gate 1 - 30 in. interior slide gate 1 – 72 in. butterfly 36 Disch Cap of gated outlets - cfs 2169 cfs at el. 5667 Glory Hole-3206cfs at el 2789 123 cfs at 2593- (BH) 8400 cfs at el. 5500.0 30 in. valve-140cfs at el 2755 103 cfs at 2593- (SC) 37 Ungated Outlets (No - size - invert elev) Ungated drop inlet – el. 5558 Ungated Glory Hole-el 2754.8 Ungated inlet - el. 3526

(1) Project Datum

A-1 (2) Costs are as of September 30, 1980. (3) Bowman-Haley sillway equipped with fuse plug (crest elevation 2780.7 ft) (4) Costs are as of May 3, 1988 (5) Area Table only goes to Elevation 5680 for the 2009 surveyed data A-2 APPENDIX A - COE PROJECTS PERTINENT DATA

SUMMARY OF ENGINEERING DATA ITEM SUBJECT CHERRY CREEK COLD BROOK COTTONWOOD KELLY ROAD NO SPRINGS GENERAL 1 Location of dam 10 mi. S E of Denver, CO 1 mi. N of Hot Springs, SD 4.5 mi. W of Hot Springs, SD Lowry ac-ftB., Denver, CO 2 River and river mile Cherry Creek R M 11.4 Cold Brook R M 1 Cottonwood Springs Creek Westerly Creek 3 Drainage area (sq. mi.) 386 70.5 26 10.84 4 Reservoir length (mi.) 1.5 mi.at el. 5550 1.2 at el. 3646.5 0.6 mi. at el. 3875 Normally dry 5 Location of Damtender At Chatfield Dam On site At Cold Brook Dam Rocky Mt. Area 6 Travel time to Missouri River 2 weeks - - 2 weeks 7 Max. discharge of record 58,000 cfs Jun 1965 8400 cfs Sep 1938 - Not available 8 Max. pool of record (ft) PD 5565.8 Jun 1973 3585.8 Aug 2014 3872.7 Mar 2000 Not available 9 Project cost (1) $14,670,000 $1,571,000 (5) $2,885,000 (5) $232,000 (Original Cost) DAM AND EMBANKMENT 10 Top of dam – ft 5644.5 3675 3955 5372 5363 West Emb. 11 Length of dam – ft. 14,300 925 1190 4700 12 Height of dam – ft. 141 127 123 32 13 Stream bed – ft 5504 3545 3832 5340 14 Abutment formation Sandstone, clay, silt Sandstone, shale, limestone Minnekahta limestone Overburden-sandy clay 15 Type of fill Rolled earth Rolled earth Rolled earth Rolled earth 16 Fill quantity in cu. yds. 13,000,000 1,072,000 950,000 200,000 17 Date of closure October 1948 September 1952 May 1969 November 1953 Rehab 1978 18 Date of initial fill (base F.C.) March 1960 June 1963 (3584.7) - Dry Pool SPILLWAY 19 Discharge capacity – cfs 17,600 cfs at el. 5636.2 80,600 cfs at el. 3667.2 39,600 cfs at el. 3950.3 3600 cfs at el. 5366.8 20 Crest elevation – ft 5610.6 (3) 3647 3936 5362 21 Width – ft. 67 200 275 120 22 Gates, number, size, type Ungated earth channel Ungated sharp crested weir Ungated broad weir Uncontrolled concrete U wall and chute RESERVOIR ELEV AND AREA (ac) (1988 data) (1966 data) (1971 data) (1993 data) 23 Maximum pool 5645.0 (2) 4,820 3667.2 280 3950.0 240 5366.8 43 24 Top of flood control pool 5598.0 2,638 3651.4 202 3936.0 221 5362.0 38 25 Top of multipurpose pool 5550.0 844 3585.0 37 3875.0 44 none 26 Top of inactive pool none none 3868.0 30 none STORAGE ZONES, ELEV - CAP (af) (2006-07 data) (1966 data) (1971 data) (1993 data) 27 Surcharge 5598.0 - 5645.0 181,942 (3)(4) 3651.4 - 3667.2 3,723 3936.0 - 3950.0 3,221 5362.0 - 5366.8 200 28 Flood Control 5550.0 – 5598.0 79,294 (3) 3585.0 - 3651.4 6,711 3875.0 - 3936.0 7,752 5342.0 - 5362.0 360 29 Multipurpose 5504.0 – 5550.0 12,558 3548.0 - 3585.0 520 3868.0 - 3875.0 257 none 30 Inactive none none 3832.0 - 3868.0 406 none 31 Gross (top of flood control pool) 91,852 af (3) 7,231 af 8,414 af 360 af OUTLET WORKS 32 Number and size – conduits 2 – 8 x 12 ft. oval conduit 1 - 6.67 ft. conduit 1 - 48 in. concrete 1 - 5.5 ft. circular conduit 1 – 12 ft. circular conduit 1 - 8 in. supply line 1 - 30 in. CMP 33 Conduit length – ft. 679.5 ft. 907 ft. 580 ft. 260 ft.

34 Disch Cap of Conduit - cfs 1540 cfs at el. 3651.4 560 cfs at el. 3936.0 35 Gated outlets (No - size - invert elev) 5 – 6 x 9 ft. – hydraulic slide 3 - 12 in. gate valves el. 3548 1 - 3 x 3 ft. gate - el. 3868 Gated inlet - el. 5342.0 2 – 18 in. bypass gates 1 - 8 in. valve

36 Disch Cap of gated outlets - cfs 8100 cfs at el. 5598.0 570 cfs at el. 5362.0 (two outside tunnels) 37 Ungated Outlets (No - size - invert elev) Ungated drop inlet - el. 3585 Ungated drop inlet - el. 3875 Ungated drop inlet-el. 5358.4 (1) Costs are as of September 30, 1980. (2) Due to updated Hydrological Improvement Assessment for Cherry Creek Reservoir, with the maximum pool the dam would be overtopped. (3) Top of Flood Control Pool is elevation 5598.0 which was original spillway crest elevation. Due to sloughing of spillway side slopes, spillway crest elevation is 5610.6 ft. (4) The 2006-07 Cherry Creek survey did not include the top five feet of storage in the surcharge zone. The curve was linearly interpolated to obtain the entire zone's storage capacity. APPENDIX A - COE PROJECTS PERTINENT DATA

SUMMARY OF ENGINEERING DATA ITEM SUBJECT PAPIO DAM NO. 11 PAPIO DAM NO. 16 PAPIO DAM NO. 18 PAPIO DAM NO. 20 NO (Glenn Cunningham Lake) (Standing Bear Lake) (Zorinsky Lake) (Wehrspann Lake) GENERAL 1 Location of dam 93rd State Street 132nd and Fort Street 156th and "F" Street 156th and Giles Road 2 River and river mile Knight Creek - Tributary Big Papio - Boxelder Creek - Trib. South Branch Papio- 3 Drainage area (sq. mi.) 17.8 6 16.4 13.1 4 Reservoir length (mi.) 2.5 1 1.5 1.5 5 Location of Damtender Missouri River Project Office Missouri River Project Office Missouri River Project Office Missouri River Project Office 6 Travel time to Missouri River 5 - 10 Hours 5 - 10 Hours 5 - 10 Hours 5 - 10 Hours 7 Max. discharge of record 157 cfs Aug 1999 65 cfs Jun 1984 142 cfs Jul 1993 124 cfs Jul 1993 8 Max. pool of record (ft) PD 1125.3 Aug 1999 1108.6 Jun 2008 1116.8 Jul 1993 1103.2 Jul 1993 9 Project cost (1) $11,800,000 $4,500,000 $20,656,000 $14,934,000 DAM AND EMBANKMENT 10 Top of dam – ft 1152 1130 1143.5 1131 11 Length of dam – ft. 1940 1460 1400 1810 12 Height of dam – ft. 67 70 64 59 13 Stream bed – ft 1085 1060 1079.5 1069 14 Abutment formation Lean clay Lean clay loess Lean clay loess Lean clay loess 15 Type of fill Rolled earth Rolled earth Rolled earth Rolled earth 16 Fill quantity in cu. yds. 656,000 481,000 1,263,000 767,450 17 Date of closure August 1974 October 1972 July 1984 September 1982 18 Date of initial fill (base F.C.) September 1977 October 1977 April 1992 May 1987 SPILLWAY 19 Discharge capacity – cfs 18,700 9500 30,000 12,000 20 Crest elevation – ft 1142 1121 1128.2 1113.1 21 Width – ft. 700 250 400 600 22 Gates, number, size, type Ungated earth channel Ungated earth channel Ungated earth channel Ungated earth channel RESERVOIR ELEV AND AREA (ac) (2009 data) (2009 data) (2007 data) (2009 data) 23 Maximum pool 1147.0 1,111 1127.0 378 1138.2 853 1125.8 765 24 Top of flood control pool 1142.0 959 1121.0 305 1128.2 601 1113.1 495 25 Top of multipurpose pool 1121.0 337 1104.0 123 1110.0 247 1095.83 (2) 236 26 Top of inactive pool none none none none STORAGE ZONES, ELEV - CAP (af) (2009 data) (2009 data) (2007 data) (2009 data) 27 Surcharge 1142.0 - 1147.0 5,397 1121.0 - 1127.0 2,051 1128.2 - 1138.2 7,273 1113.1 - 1125.8 7,980 28 Flood Control 1121.0 - 1142.0 13,573 1104.0 - 1121.0 3,532 1110.0 - 1128.2 7,476 1095.83 - 1113.1 6,203 29 Multipurpose 1085.0 - 1121.0 3,015 1060.0 - 1104.0 1,141 1060.5 - 1110.0 2,781 1069.0 - 1095.83 2,309 30 Inactive none none none none 31 Gross (top of flood control pool) 16,588 af 4,673 af 10,257 af 8,512 af OUTLET WORKS 32 Number and size – conduits 1 - RCP - 54" Dia. 1 - RCP - 36" Dia. 1 - RCP - 48" Dia. 1 - RCP - 48" Dia. 33 Conduit length – ft. 680 736 782 656 34 Disch Cap of Conduit - cfs 570 160 460 490 35 Lower weir Design Elev (Surveyed) - ft. 1121.0 (1120.7) (3) 1104.0 (1104.0) 1110.0 (1110.0) 1096.0 (1095.9) 36 Gated outlets (No - size - invert elev) 1 - 30" x 30" 1096 1 - 30" x 30" 1080 1 - 30" x 30" 1090 1 - 30" x 30" Dia. 1077 1 - 6" diameter 1104.25 1 - 6" diameter 1090 37 Disch Cap of gated outlets - cfs 90 90 140 140 38 Ungated Outlets (No - size - invert elev) 2 - 2.0' x 4.0' 1121 2 - 1.0' x 2.5' 1104 2 - 1.5' x 3.5' 1110 2 - 1.25' x 3.5' 1095.83 2 - 2.5' x 9.0' 1127.5 2 - 2.0' x 6.0' 1109 2 - 3.15' x 8.0' 1117.6 2 - 3.67' x 8.0' 1103.4 A-3

(1) Costs as of May 3, 1988 (2) Based on a survey from July 1987 the elevation of the overflow lip was changed from 1096 ft to 1095.83 ft. A-4 APPENDIX A - COE PROJECTS PERTINENT DATA

SUMMARY OF ENGINEERING DATA ITEM SUBJECT SALT CR. DAM NO. 2 SALT CR. DAM NO. 4 SALT CR. DAM NO. 8 SALT CR. DAM NO. 9 SALT CR. DAM NO. 10 NO (Olive Creek Lake) (Bluestem Lake) (Wagon Train Lake) (Stagecoach Lake) (Yankee Hill Lake) GENERAL 1 Location of dam 1.5 mi. W of Sprague 2.5 mi. W of Sprague 1.5 mi. N of Holland 1 mi. S of Hickman 3.5 mi. N of Denton 2 River and river mile S Trib. of Olive Br. RM 12 N. Trib. of Olive Br. RM 9.5 N. Trib. of Hickman Br. RM .8 S. Trib. of Hickman Br. RM 1 Cardwell Br. RM 4 3 Drainage area (sq. mi.) 8.2 16.6 15.6 9.7 8 4 Reservoir length (mi.) 1.2 1.6 1.8 1.4 0.7 5 Location of Damtender Missouri River Project Office Missouri River Project Office Missouri River Project Office Missouri River Project Office Missouri River Project Office 6 Travel time to Missouri River 23 hrs. 13 hrs. 14 hrs. 8 hrs. 3 hrs. 7 Max. discharge of record 188 cfs May 2004 342 cfs Oct 1973 334 cfs Jul 1993 193 cfs Jun 2008 145 cfs Oct 1973 8 Max. pool of record (ft) PD 1345.3 May 2015 1316.5 Oct 1973 1295.5 Jun 2008 1279.7 Jun 2008 1253.5 May 2015 9 Project cost (1) (1) (1) (1) (1) (1) DAM AND EMBANKMENT 10 Top of dam design elev (Surveyed) – ft 1359.0 (1359.0) 1334.0 (1332.7) 1312.0 (1311.2) 1294.0 (1294.2) 1270.0 (1270.2) 11 Length of dam – ft. 3020 2460 1650 2250 3100 12 Height of dam – ft. 45 57 52 48 52 13 Stream bed – ft 1314 1277 1260 1246 1218 14 Abutment formation Clay - sand - silt Clay - sand Clay Clay - sand Clay - sand 15 Type of fill Rolled earth Rolled earth Rolled earth Rolled earth Rolled earth 16 Fill quantity in cu. yds. 312,000 471,000 376,000 374,000 502,000 17 Date of closure September 1963 September 1962 September 1962 August 1963 October 1965 18 Date of initial fill (base F.C.) June 1965 July 1963 June 1963 May 1965 June 1967 SPILLWAY 19 Discharge capacity – cfs 15,875 at el. 1357.1 22,925 at el. 1331.7 23,210 at el. 1309.8 17,565 at el. 1291.6 12,100 at el. 1267.8 20 Crest design elevation (Surveyed) – ft 1350.0 (1350.0) 1322.5 (1322.8) 1302.0 (1301.2) 1285.0 (1284.9) 1262.0 (1262.5) 21 Width – ft. 340 340 430 430 400 22 Gates, number, size, type Ungated earth channel Ungated earth channel Ungated earth channel Ungated earth channel Ungated earth channel RESERVOIR ELEV AND AREA (ac) (1993 data) (1993 data) (1993 data) (1990 data) (1994 data) 23 Maximum pool 1357.1 459 1331.7 938 1309.8 909 1291.6 621 1267.8 627 24 Top of flood control pool 1350.0 359 1322.5 647 1302.0 644 1285.0 464 1262.0 495 25 Top of multipurpose pool none 1307.4 309 1287.8 265 none 1244.9 211 26 Top of sediment pool 1335.0 162 1306.1 282 1284.6 185 1271.1 195 1241.9 170 STORAGE ZONES, ELEV - CAP (af) (1993 data) (1993 data) (1993 data) (1990 data) (1994 data) 27 Surcharge 1350.0 - 1357.1 2,907 1322.5 - 1331.7 7,227 1302.0 - 1309.8 5,947 1285.0 - 1291.6 3,578 1262.0 - 1267.8 3,225 28 Flood Control 1335.0 - 1350.0 3,857 1307.4 - 1322.5 7,134 1287.8 - 1302.0 6,595 1271.1 - 1285.0 4,413 1244.9 - 1262.0 5,839 29 Multipurpose none 1306.1 - 1307.4 386 1284.6 - 1287.8 710 none 1241.9 - 1244.9 571 30 Sediment 1314.0 -1335.0 1,100 1277.0 - 1306.1 2,146 1260.0 - 1284.6 1,070 1246.0 - 1271.1 1,451 1218.0 - 1241.9 1,058 31 Gross (top of flood control pool) 4,957 af 9,666 af 8,375 af 5,864 af 7,468 af OUTLET WORKS 32 Number and size – conduits 1 - CMP - 48" Dia. 1 - CMP - 60" Dia. 1 - CMP - 60" Dia. 1 - CMP - 48" Dia. 1 - CMP - 42" Dia. With 30" RCP lining With 42" RCP lining With 42" RCP lining With 30" RCP lining With 30" RCP lining 33 Conduit length – ft. 280 313 299 280 300 34 Lower weir design elev (Surveyed) - ft. 1335.0 (1334.9) (2) 1307.6 (1307.3) 1288.0 (1287.9) 1271.0 (1270.9) 1245.0 (1245.0) 35 Gated outlets (No - size - invert elev) 1 - 36" x 36" Lift gate- 1330.0 1 - 36" x 36" Lift gate- 1303.0 1 - 36" x 36" Lift gate- 1283.5 1 - 36" x 36" Lift gate- 1261.0 1 - 30" x 42" Lift gate-1237 36 Ungated outlets (openings - size - elev.) 2 - 24" x 72" - 1340.9 2 - 30" x 96" - 1313.5 2 - 30" x 96" - 1292.4 2 - 24" x 72" - 1277.1 2 - 18" x 63" - 1250.0 2 - 12" x 30" - 1335.0 2 - 12" x 54" - 1307.4 2 - 12" x 54" - 1287.8 2 - 12" x 30" - 1271.1 2 - 12" x 30" - 1244.9 37 Disch cap - cfs at base of FC 85 @ 1335.0 85 @ 1307.4 85 @ 1287.8 85 @ 1271.1 110 @ 1244.9

(1) Total project financial cost including all Salt Creek dams = $12,075,000 (Costs are as of September 30, 1980). APPENDIX A - COE PROJECTS PERTINENT DATA

SUMMARY OF ENGINEERING DATA ITEM SUBJECT SALT CR. DAM NO. 12 SALT CR. DAM NO. 13 SALT CR. DAM NO. 14 SALT CR. DAM NO. 17 SALT CR. DAM NO. 18 NO (Conestoga Lake) (Twin Lakes) (Pawnee Lake) (Holmes Lake) (Branched Oak Lake) GENERAL 1 Location of dam 1.5 mi. N of Denton 2 mi. NW of Pleasantdale 2 mi. NW of Emerald SE edge of Lincoln 4 mi. W of Raymond 2 River and river mile Holmes Cr. RM 1 Middle Cr. RM 12.8 N Middle Cr. RM 1 Antelope Cr. RM 6.1 Oak Cr. RM 17.3 3 Drainage area (sq. mi.) 15.1 11 35.9 5.4 89 4 Reservoir length (mi.) 1.4 1.5 3 0.7 3.7 5 Location of Damtender Missouri River Project Office Missouri River Project Office Missouri River Project Office Missouri River Project Office Missouri River Project Office 6 Travel time to Missouri River 8 hrs. 13 hours 7 hrs. 3 hrs. 6 hrs. 7 Max. discharge of record 185 cfs Mar 1987 168 cfs Jun 1983 420 cfs Jul 1993 187 cfs Jun 1983 774 cfs Jul 1993 8 Max. pool of record (ft) PD 1241.1 Mar 1987 1346.9 Jun 1983 1249.1 Jul 1993 1250.0 Jul 1993 1287.9 Aug 1987 9 Project cost (1) (1) (1) (1) (1) (1) DAM AND EMBANKMENT 10 Top of dam design elev (Surveyed) – ft 1260.0 (1260.2) 1364.0 (1363.6) 1271.0 (1270.6) 1273.0 (1271.3) 1320.0 (1318.2) 11 Length of dam – ft. 3000 2075 5000 7700 5200 12 Height of dam – ft. 63 58 65 55 70 13 Stream bed – ft 1197 1306 1206 1218 1250 14 Abutment formation Clay - sand Clay - sand - silt Clay - sand Clay - sand Clay - sand - silt 15 Type of fill Rolled earth Rolled earth Rolled earth Rolled earth Rolled earth 16 Fill quantity in cu. yds. 658,000 610,000 870,000 900,000 246,000 17 Date of closure September 1963 September 1965 July 1964 September 1962 August 1967 18 Date of initial fill (base F.C.) May 1965 March 1969 June 1967 June 1965 January 1973 SPILLWAY 19 Discharge capacity – cfs 27,220 at el. 1258.2 25,200 at el. 1361.6 19,875 at el. 1269.1 800 at el. 1269.7 7825 at el. 1317.5 20 Crest design elevation (Surveyed) – ft 1252.0 (1251.9) 1355.0 (1354.9) 1263.5 (1263.4) 1266.0 (1267.2) 1311.0 (1311.6) 21 Width – ft. 750 400 700 50 200 22 Gates, number, size, type Ungated earth channel Ungated earth channel Ungated earth channel Ungated earth channel Ungated earth channel RESERVOIR ELEV AND AREA (ac) (1996 data) (1994 data) (1991 data) (1993 data) (1991 data) 23 Maximum pool 1258.2 689 1361.6 628 1269.1 1,674 1269.7 423 1317.3 4,187 24 Top of flood control pool 1252.0 578 1355.0 498 1263.5 1,398 1266.0 381 1311.0 3,655 25 Top of multipurpose pool none 1341.0 236 none 1242.4 120 1284.0 1,847 26 Top of sediment pool 1232.9 214 1337.4 177 1244.3 725 1240.0 102 1275.7 1,225 STORAGE ZONES, ELEV - CAP (af) (1996 data) (1994 data) (1991 data) (1993 data) (1991 data) 27 Surcharge 1252.0 - 1258.2 3,927 1355.0 - 1361.6 3,721 1263.5 - 1269.1 8,549 1266.0 - 1269.7 1,490 1311.0 - 1317.3 24,714 28 Flood Control 1232.9 - 1252.0 7,607 1341.0 - 1355.0 5,028 1244.3 - 1263.5 20,097 1242.4 - 1266.0 5,870 1284.0 - 1311.0 71,671 29 Multipurpose none 1337.4 - 1341.0 747 none 1240.0 - 1242.4 220 1275.7 - 1284.0 12,724 30 Sediment 1197.0 - 1232.9 1,808 1306.0 - 1337.4 1,414 1206.0 - 1244.3 7,500 1218.0 - 1240.0 538 1250.0 - 1275.7 12,364 31 Gross (top of flood control pool) 9,415 af 7,189 af 27,597 af 6,628 af 96,759 af OUTLET WORKS 32 Number and size – conduits 1 - CMP - 60" Dia. 1 - CMP - 42" Dia. 1 - CMP - 60" Dia. 1 - CMP - 60" Dia. 1 - CMP - concrete With 42" RCP lining With 30" RCP lining With 42" RCP lining With 42" RCP lining Lined - 72" Dia. 33 Conduit length – ft. 318 335 382 320 370 34 Lower weir design elev (Surveyed) - ft. 1233.0 (1233.0) 1341.0 (1340.8) 1244.5 (1244.2) 1242.5 (1242.5) 1284.0 (1284.0) 35 Gated outlets (No - size - invert elev) 1 - 36" x 36" Lift gate- 1228.0 1 - 42" x 54" Lift gate- 1333.0 1 - 42" x 60" Lift gate- 1236.0 1 - 36" x 36" Lift gate- 1231.0 1 - 48" x 72" Lift gate - 1274.0 36 Ungated outlets (openings - size - elev.) 2 - 30" x 96" - 1242.3 2 - 24" x 63" - 1341.0 2 - 34" x 120" - 1244.3 2 - 30" x 96" - 1249.0 1 - 10" Dia. slide gate- 1276.3

A-5 2 - 12" x 54" - 1232.9 - - 2 - 12" x 36" - 1242.5 2 - 42" x 144" - 1283.95 37 Disch cap - cfs at base of FC 85 @ 1232.9 190 @ 1341.0 210 @ 1244.3 85 @ 1242.4 300 @ 1284.0

(1) Total project financial cost including all dams = $12,075,000 (Costs are as of September 30, 1980). A-6 APPENDIX A - COE PROJECTS PERTINENT DATA

SUMMARY OF ENGINEERING DATA ITEM SUBJECT PIPESTEM SNAKE CREEK (2) SPRING CREEK (3) WESTERLY CREEK SPRING GULCH NO LAKE AUDUBON LAKE POCASSE GENERAL 1 Location of dam 3 mi. N W Jamestown, ND 12 mi. NE of Garrison Dam Pollock, SD Lowry B., Denver, CO Right abutment of Chatfield Dam 2 River and river mile Pipestem Creek R M 3 Snake Creek Spring Creek Westerly Creek Spring Gulch Creek 3 Drainage area (sq. mi.) 594 250 660 9.29 2 4 Reservoir length (mi.) 5.5 at elevation 1442.4 Normally dry Normally dry 5 Location of Damtender On site Garrison Dam Oahe Dam Rocky Mt. Area At Chatfield Dam 6 Travel time to Missouri River 8 weeks - - 2 weeks - 7 Max. discharge of record 1,422 cfs Apr 2009 - - Not available Not available 8 Max. pool of record (ft) PD 1492.2 Apr 2009 1849.5 Jun 2011 1625.0 Mar 1987 Not available Not available 9 Project cost (1) $9,277,500 Not available Not available Not available Not available DAM AND EMBANKMENT 10 Top of dam – ft 1507.5 1865 1625 5434.5 5603 11 Length of dam – ft. 4000 12,900 3200 9100 3600 12 Height of dam – ft. 107.5 85 40 45.5 68 13 Stream bed – ft 1400 1780 1585 5389 5535 14 Abutment formation Sandy overburden-P. shale Not available Not available Not available Not available 15 Type of fill Rolled earth Rolled Earth Rolled earth Rolled earth Rolled earth 16 Fill quantity in cu. yds. 1,990,000 Not available Not available Not available Not available 17 Date of closure July 1973 1952 1961 July 1991 1973 18 Date of initial fill (base F.C.) May 1974 September 1975 Between 1961 and 1964 Dry Pool Dry Pool SPILLWAY 19 Discharge capacity – cfs 56,200 cfs at el. 1502.8 none Not available 46,900 cfs at el. 5431.4 Not available 20 Crest elevation – ft 1496.3 1617 5419 5600 21 Width – ft. 1500 72 400 200 22 Gates, number, size, type Ungated earth channel Ungated box culverts Uncontrolled grass lined, earth cut Uncontrolled grass lined, earth cut RESERVOIR ELEV AND AREA (ac) (2002 data) 23 Maximum pool 1502.8 5,861 1850.0 20,620 1625.0 2,560 5431.4 375 5600.0 24 Top of flood control pool 1496.3 4,721 none none 5419.0 275 none 25 Top of multipurpose pool 1442.5 823 1847.0 18,780 1617.0 1,520 none none 26 Top of inactive pool 1415.0 10 1810.0 1,450 1602.0 60 none none STORAGE ZONES, ELEV - CAP (af) (2002 data) 27 Surcharge 1496.3 - 1502.8 34,305 1847.0 - 1850.0 59,130 1617.0 - 1625.0 15,000 5419.0 - 5431.4 3,950 none 28 Flood Control 1442.5 - 1496.3 135,040 none none 5389.0 - 5419.0 4,150 none 29 Multipurpose 1415.0 - 1442.5 8,354 1810.0 - 1847.0 323,690 1585.0 - 1617.0 11,000 none none 30 Inactive 1400.0 - 1415.0 0 1780.0 - 1810.0 13,180 none none none 31 Gross (top of flood control pool) 143,394 af 396,000 af 11,000 af 4,150 af 1,800 af OUTLET WORKS 32 Number and size – conduits 1 - 8 ft. circular conduit 1 - 7 x 10 ft. reinforced 1 - 5 ft. CMP 1 - 4 ft. prestressed concrete 1-42 in. concrete cylinder pipe concrete conduit cylinder pipe 33 Conduit length – ft. 675 ft. 907 ft. 462 ft. 34 Gated outlets (No - size - invert elev) 2 - 4 x 7 ft. hydraulic slide 1 - 7 x 10 ft. sluice gate 5 x 5 ft sluice gate el. 1602 1 - 48 x 24 inches hand 1 - 36 in valve, 1-3 x 3 ft slide 5 x 12 ft overflow roller operated sluice gate el. 1609 35 Disch Cap of gated outlets - cfs 2,300 cfs at el. 1496.3 2,300 cfs at 15 ft. head 98 cfs at el. 5431.4 36 Ungated Outlets (No - size - invert elev) Ungated drop inlet-el. 1442.5 differential 1-9' x 9' - 5535

(1) Costs are as of September 30, 1980. (2) Subimpoundment of Garrison Reservoir – no authorized flood control (3) Subimpoundment of Oahe Reservoir – no authorized flood control Summary of Engineering Data - Missouri River Main Stem System Item Subject Garrison Dam - Oahe Dam - Big Bend Dam - Fort Randall Dam - Gavins Point Dam - Total Item Remarks No. Lake Sakakawea Lake Oahe Lake Sharpe Lake Francis Case Lewis & Clark Lake No. 1 Location of Dam Near Glasgow, Montana Near Garrison, ND Near Pierre, SD 21 miles upstream Chamberlain, Near Lake Andes, SD Near Yankton, SD 1 (1) Includes 4,280 square 2 River Mile - 1960 Mileage Mile 1771.5 Mile 1389.9 Mile 1072.3 Mile 987.4 Mile 880.0 Mile 811.1 2 miles of non-contributing 3 Total & incremental drainage 57,500 181,400 (2) 123,900 243,490 (1) 62,090 249,330 (1) 5840 263,480 (1) 14,150 279,480 (1) 16,000 3 areas. areas in square miles (2) Includes 1,350 square 4 Approximate length of full 134, ending near Zortman, MT 178, ending near Trenton, ND 231, ending near Bismarck, ND 80, ending near Pierre, SD 107, ending at Big Bend Dam 25, ending near Niobrara, NE 755 miles 4 miles of non-contributing reservoir (in valley miles) areas. 5 Shoreline in miles (3) 1520 (elevation 2234) 1340 (elevation 1837.5) 2250 (elevation 1607.5) 200 (elevation 1420) 540 (elevation 1350) 90 (elevation 1204.5) 5940 miles 5 (3) With pool at base of flood 6 Average total & incremental 10,200 25,600 15,400 28,900 3300 28,900 30,000 1100 32,000 2000 6 control. inflow in cfs (4) Storage first available for 7 Max. discharge of record 137,000 (June 1953) 348,000 (April 1952) 440,000 (April 1952) 440,000 (April 1952) 447,000 (April 1952) 480,000 (April 1952) 7 regulation of flows. near damsite in cfs (5) Damming height is height 8 Construction started - calendar yr. 1933 1946 1948 1959 1946 1952 8 from low water to maximum 9 In operation (4) cal. yr. 1940 1955 1962 1964 1953 1955 9 operating pool. Maximum Dam and Embankment height is from average 10 Top of dam elevation in ft 2280.5 1875 1660 1440 1395 1234 10 streambed to top of dam. 11 Length of dam in feet 21,026 (excluding spillway) 11,300 (including spillway) 9300 (excluding spillway) 10,570 (including spillway) 10,700 (including spillway) 8,700 (including spillway) 71,596 11 (6) Based on latest available 12 Damming height in feet (5) 220 180 200 78 140 45 863 feet 12 storage data. 13 Maximum height in feet (5) 250.5 210 245 95 165 74 13 (7) River regulation is attained 14 Max. base width, total & w/o 3500, 2700 3400, 2050 3500, 1500 1200, 700 4300, 1250 850, 450 14 by flows over low-crested berms in feet spillway and through 15 Abutment formations ( under dam & Bearpaw shale and glacial fill Fort Union clay shale Pierre shale Pierre shale & Niobrara chalk Niobrara chalk Niobrara chalk & Carlile shale 15 turbines. embankment) (8) Length from upstream face 16 Type of fill Hydraulic & rolled earth fill Rolled earth filled Rolled earth fill & shale berms Rolled earth, shale, chalk fill Rolled earth fill & chalk berms Rolled earth & chalk fill 16 of outlet or to spiral case. 17 Fill quantity, cubic yards 125,628,000 66,500,000 55,000,000 & 37,000,000 17,000,000 28,000,000 & 22,000,000 7,000,000 358,128,000 cu. yds 17 (9) Based on 8th year (1961) 18 Volume of concrete (cubic yards) 1,200,000 1,500,000 1,045,000 540,000 961,000 308,000 5,554,000 cu. yds. 18 of drought drawdown 19 Date of Closure 24 June 1937 15 April 1953 3 August 1958 24 July 1963 20 July 1952 31 July 1955 19 (From study 8-83-1985). Spillway Data (10) Affected by level of Lake 20 Location Right bank - remote Left bank - adjacent Right bank - remote Left bank - adjacent Left bank - adjacent Right bank - adjacent 20 Francis case. Applicable to 21 Crest elevation in ft 2225 1825 1596.5 1385 1346 1180 21 pool at elevation 1350. 22 Width (including piers) in feet 820 gated 1336 gated 456 gated 376 gated 1000 gated 664 gated 22 (11) Spillway crest. 23 No., size and types of gates 16 - 40' x 25' vertical lift gates 28 - 40' x 29' Tainter 8 - 50' x 23.5' Tainter 8 - 40' x 38' Tainter 21 - 40' x 29' Tainter 14 - 40' x 30' Tainter 23 (12) 1967-2006 Average 24 Design discharge capacity, cfs 275,000 at elev 2253.3 827,000 at elev 1858.5 304,000 at elev 1644.4 390,000 at elev 1433.6 620,000 at elev 1379.3 584,000 at elev 1221.4 24 (13) Source: Annual Report on 25 Discharge capacity at maximum 230,000 660,000 80,000 270,000 508,000 345,000 25 Civil Works Activities of the operating pool in cfs Corps of Engineers. Extract Reservoir Data (6) Report Fiscal Year 1999. 26 Max. operating pool elev & area 2250 msl 246,000 a 1854 msl 380,000 a 1620 msl 374,000 a 1423 msl 61,000 a 1375 msl 102,000 a 1210 msl 31,000 a 1,194,000 a 26 27 Max. normal op pool elev & area 2246 msl 240,000 a 1850 msl 364,000 a 1617 msl 360,000 a 1422 msl 60,000 a 1365 msl 95,000 a 1208 msl 28,000 a 1,147,000 a 27 28 Base flood control elev & area 2234 msl 212,000 a 1837.5 msl 307,000 a 1607.5 msl 312,000 a 1420 msl 57,000 a 1350 msl 77,000 a 1204.5 msl 24,000 a 989,000 a 28 29 Min. op. pool elev. & area 2160 msl 90,000 a 1775 msl 128,000 a 1540 msl 117,000 a 1415 msl 51,000 a 1320 msl 38,000 a 1204.5 msl 24,000 a 450,000 a 29 Storage allocation & capacity 30 Exclusive flood control 2250-2246 975,000 ac-ft 1854-1850 1,489,000 ac-ft 1620-1617 1,102,000 ac-ft 1423-1422 60,000 ac-ft 1375-1365 985,000 ac-ft 1210-1208 59,000 ac-ft 4,670,000 ac-ft 30 31 Flood control & multiple use 2246-2234 2,717,000 ac-ft 1850-1837.5 4,222,000 ac-ft 1617-1607.5 3,201,000 ac-ft 1422-1420 117,000 ac-ft 1365-1350 1,309,000 ac-ft 1208-1204.5 90,000 ac-ft 11,656,000 ac-ft 31 32 Carryover multiple use 2234-2160 10,785,000 ac-ft 1837.5-1775 13,130,000 ac-ft 1607.5-1540 13,461,000 ac-ft 1350-1320 1,607,000 ac-ft 38,983,000 ac-ft 32 33 Permanent 2160-2030 4,211,000 ac-ft 1775-1673 4,980,000 ac-ft 1540-1415 5,373,000 ac-ft 1420-1345 1,621,000 ac-ft 1320-1240 1,517,000 ac-ft 1204.5-1160 321,000 ac-ft 18,023,000 ac-ft 33 34 Gross 2250-2030 18,688,000 ac-ft 1854-1673 23,821,000 ac-ft 1620-1415 23,137,000 ac-ft 1423-1345 1,798,000 ac-ft 1375-1240 5,418,000 ac-ft 1210-1160 470,000 ac-ft 73,332,000 ac-ft 34 35 Reservoir filling initiated November 1937 December 1953 August 1958 November 1963 January 1953 August 1955 35 36 Initially reached min. operating pool May 27, 1942 August 7, 1955 April 3, 1962 March 25, 1964 November 24, 1953 December 22, 1955 36 37 Estimated annual sediment inflow 17,700 ac-ft 1030 yrs. 25,900 ac-ft 920 yrs. 19,800 ac-ft 1170 yrs. 5300 ac-ft 430 yrs. 18,400 ac-ft 250 yrs. 2,600 ac-ft 180 yrs. 89,700 ac-ft 37 Outlet Works Data 38 Location Right bank Right Bank Right Bank Left Bank 38 39 Number and size of conduits 2 - 24' 8" diameter (nos. 3 & 4) 1 - 26' dia. and 2 - 22' dia. 6 - 19.75' dia. upstream, 18.25' None (7) 4 - 22' diameter None (7) 39 dia. downstream 40 Length of conduits in feet (8) No. 3 - 6,615, No. 4 - 7,240 1529 3496 to 3659 1013 40 41 No., size, and type of service gates 1 - 28' dia. cylindrical gate 1 - 18' x 24.5' Tainter gate per 1 - 13' x 22' per conduit, vertical 2 - 11' x 23' per conduit, vertical 41 6 ports, 7.6' x 8.5' high (net conduit for fine regulation lift, 4 cable suspension and lift, cable suspension opening) in each control shaft 2 hydraulic suspension (fine regulation) 42 Entrance invert elevation (msl) 2095 1672 1425 1385 (11) 1229 1180 (11) 42 43 Avg. discharge capacity per conduit Elev. 2250 Elev. 1854 Elev. 1620 Elev 1375 43 & total 22,500 cfs - 45,000 cfs 30,400 cfs - 98,000 cfs 18,500 cfs - 111,000 cfs 32,000 cfs - 128,000 cfs 44 Present tailwater elevation (ft) 2032-2036 5000 - 35,000 cfs 1670-1680 ,000- 60,000 cfs 1423-1428 20,000-55,000 c 1351-1355(10) 25,000-100,000 1228-1239 5,000-60,000 cfs 1155-1163 5,000-60,000 cfs 44 Power Facilities and Data 45 Avg. gross head avail in feet (14) 194 161 174 70 117 48 764 feet 45 46 Number and size of conduits No. 1-24'8" dia., No. 2-22'4" dia. 5 - 29' dia., 25' penstocks 7 - 24' dia., imbedded penstocks None: direct intake 8 - 28' dia., 22' penstocks None: direct intake 46 47 Length of conduits in feet (8) No. 1 - 5,653, No. 2 - 6,355 1829 From 3280 to 4005 1074 55,083 47 48 Surge tanks PH#1: 3-40' dia., PH#2: 2-65' dia. 65' dia. - 2 per penstock 70' dia., 2 per penstock None 59' dia, 2 per alternate penstock None 48 49 No., type and speed of turbines 5 Francis, PH#1-2: 128.5 rpm, 5 Francis, 90 rpm 7 Francis, 100 rpm 8 Fixed blade, 81.8 rpm 8 Francis, 85.7 rpm 3 Kaplan, 75 rpm 36 units 49 1-164 rpm , PH#2-2: 128.6 rpm 50 50 Disch. cap. at rated head in cfs PH#1, units 1&3 170', 2-140' 150' 41,000 cfs 185' 54,000 cfs 67' 103,000 cfs 112' 44,500 cfs 48' 36,000 cfs 8,800 cfs, PH#2-4&5 170'-7200 cfs 51 Generator nameplate rating in kW 1&3: 43,500; 2: 18,250; 4&5: 40,000 3 - 121,600, 2 - 109,250 112,290 3 - 67,276, 5 - 58,500 40,000 44,100 51 52 Plant capacity in kW 185,250 583,300 786,030 494,320 320,000 132,300 2,501,200 kw 52 53 Dependable capacity in kW (9) 181,000 388,000 534,000 497,000 293,000 74,000 1,967,000 kw 53 A-7 54 Avg annual energy, million kWh (12) 1,087 2318 2717 1001 1778 740 9,642 million kWh 54 Corps of Engineers, U.S. Army 55 Initial generation, first and last unit July 1943 - June 1961 January 1956 - October 1960 April 1962 - June 1963 October 1964 - July 1966 March 1954 - January 1956 September 1956 - January 1957 July 1943 - July 1966 55 Compiled by 56 Estimated cost September 1999 56 Missouri River Division Completed project (13) $158,428,000 $305,274,000 $346,521,000 $107,498,000 $199,066,000 $49,617,000 $1,166,404,000 January 2007 APPENDIX A – COE PROJECTS PERTINENT DATA

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A-8 APPENDIX B – COE PROJECT OPERATION SUMMARIES

B1-Bear Creek Reservoir ...... B1-1 B2-Bowman-Haley Dam and Lake ...... B2-1 B3-Bull Hook – Scott Coulee – Cedar Canyon Dams ...... B3-1 B4-Chatfield Reservoir ...... B4-1 B5-Cherry Creek Reservoir ...... B5-1 B6-Cold Brook Dam and Lake ...... B6-1 B7-Cottonwood Springs Dam and Lake ...... B7-1 B8-Kelly Road Dam ...... B8-1 B9-Westerly Creek Dam...... B9-1

Papillion Creek Dams B10-Dam No. 11 – Glenn Cunningham Dam and Lake ...... B10-1 B11-Dam No. 16 – Standing Bear Dam and Lake ...... B11-1 B12-Dam No. 18 – Zorinsky Dam and Lake ...... B12-1 B13-Dam No. 20 – Wehrspann Dam and Lake ...... B13-1

B14-Pipestem Dam and Lake ...... B14-1

Salt Creek Dams B15-Dam No. 2 – Olive Creek Dam and Lake...... B15-1 B16-Dam No. 4 – Bluestem Dam and Lake ...... B16-1 B17-Dam No. 8 – Wagon Train Dam and Lake ...... B17-1 B18-Dam No. 9 – Stagecoach Dam and Lake ...... B18-1 B19-Dam No. 10 – Yankee Hill Dam and Lake ...... B19-1 B20-Dam No. 12 – Conestoga Dam and Lake ...... B20-1 B21-Dam No. 13 – Twin Lakes Dam and Lake ...... B21-1 B22-Dam No. 14 – Pawnee Dam and Lake ...... B22-1 B23-Dam No. 17 – Antelope Creek Dam and Holmes Park Lake ...... B23-1 B24-Dam No. 18 – Branched Oak Dam and Lake ...... B24-1 B25-Snake Creek Dam and Lake Audubon ...... B25-1 B26-Spring Creek Dam and Lake Pocasse ...... B26-1 B27-Spring Gulch Creek Dam ...... B27-1

APPENDIX B1-BEAR CREEK DAM

BEAR CREEK DAM AND LAKE SOUTH PLATTE RIVER BASIN, COLORADO 2014-2015 REGULATION

1. Project Description and Water Control Plan. Bear Creek Dam is located in Denver, Colorado on Bear Creek, a tributary to the South Platte River. The dam was completed in 1977 for the authorized purpose of flood control, and later was authorized for general recreation and fish and wildlife recreation. The outlet works consists of a 2-way drop intake structure located at the upstream end of the outlet works conduit. The weir crest of the drop inlet is at elevation 5558.0 ft. The intake structure is followed by a single circular conduit 7.0 feet in diameter and 576.5 feet long under the upstream portion of the embankment. A dome type gated control structure buried under the embankment has two (3ft X 6ft) hydraulically operated slide service gates in each gate passage from which releases are made into one of two oblong conduits which terminate at the exit portal. The downstream oblong conduit is 7.0 feet wide, 10.5 feet high, 1,037 feet long, and sloped so that releases flow under open channel conditions versus pressure flow. The other conduit serves as an access gallery to the gate structure. At one stage in design, it was also planned to use this conduit for installation of an penstock to the Warrior Canal. However, it was ultimately decided to route the Warrior Canal water into the upstream Harriman Ditch and as a result this water flows around the dam rather than through it. The outlet works also have a conventional hydraulic jump type stilling basin with chute blocks and one row of baffles. A discharge channel returns the outlet works releases back into the existing Bear Creek channel. An 11.5 foot drop structure located about 650 feet downstream from the stilling basin is provided for diversion of water into the Pioneer Union Ditch. Table 1 shows the storage zones for Bear Creek Reservoir.

Table 1 Bear Creek Reservoir Storage Allocations, 2009 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) Project Datum (PD) (ac-ft) (ac-ft) Inactive 5510.0-5528.0 53 53 Multipurpose 5528.0-5558.0 1,771 1,824 Flood Control 5558.0-5635.5 28,514 30,338 Surcharge 5635.5-5684.5 46,955 -

Flood control releases are controlled and regulated by the two 3 X 6 foot service gates. The outlet works has a discharge capacity of 2,160 cfs at elevation 5667.0 ft, which is the emergency spillway crest. A gate-within-a-gate is provided on each of the two service gates for fine regulation of low flow releases (less than 70 cfs). Two 3 X 6 foot emergency gates are located 6 feet upstream from the two 3 X 6 foot service gates.

Two low-level 36-inch diameter gated outlets are provided in the intake structure for release of water from the multi-purpose pool. Their invert elevations are at 5528.0 ft and 5538.0 ft. These two low flow outlets have a combined discharge

APPENDIX B1- BEAR CREEK DAM-1 APPENDIX B1-BEAR CREEK DAM

capacity of about 410 cfs at the multi-purpose pool level. The service gates can be operated from the adit structure located at the exit portal of the outlet works or from the domed gate control structure. The adit structure also houses the Data Collection Platform (DCP) as well as a standby generator to provide emergency power to operate the outlet works service and emergency gates. A gated outlet structure is located on the Harriman Canal in the south embankment. The invert elevation of the canal as it enters the south embankment is 5548.0 ft. In order to keep flood water stored in the reservoir from flowing into the Harriman Canal below the project, a gated control structure is located in this south embankment. This structure contains an 84 X 84 inch sluice gate. The conduit entering and leaving this structure is an 84-inch diameter reinforced concrete pipe.

In response to the contracts for temporary water storage, a revised Memorandum of Understanding (MOU) between the Corps of Engineers and the State of Colorado was signed on June 20, 1988. This memorandum supersedes the previous MOU dated May 11, 1977. Under normal conditions the Bear Creek Dam outlet works are set to automatically pass stream flow up to 500 cfs when pool elevations are above the drop inlet-outlet weir crest of 5558.0 ft. When conditions warrant, higher releases are made by opening two slide service gates in the dome-type gated control structure buried under the embankment. Under the revised MOU, the State Engineer or his representative will determine the storage and releases necessary to satisfy downstream water right requirements when the pool level is below elevation 5559.0 ft. Elevation 5559.0 ft is one foot into the flood storage zone and was selected to allow flexibility in targeting authorized pool levels. The State of Colorado, Department of Natural Resources, Division of Game, Fish and Parks, in a letter dated October 1, 1970, agreed to provide water for the initial filling and replenishment of evaporation losses from the recreation pool, by purchase or other means, consistent with federal and state laws to assure effective operation of the project for recreation.

Operation of Bear Creek requires both individual and system reservoir regulation. System regulation requires coordination of Bear Creek with Cherry Creek and Chatfield reservoirs. The three reservoirs will be regulated independent from each other during flood inflow periods (when releases are reduced to assure control of each flood event) and/or when they are the only reservoir with flood storage to be evacuated. System regulation of the three parallel reservoirs is necessary after flood inflows cease and during the evacuation of flood storage from more than one of the projects. Due to the close guarding of water rights in the State of Colorado, the State Engineer's Office is consulted on release rates to assure releases satisfy downstream water right requirements. During flood or apparent flood situations, Bear Creek Dam releases are reduced to as low as zero in an effort to reduce downstream flooding or essential downstream water right requirements as determined by the State. Table 2 shows the reservoir release rate based on pool elevation.

APPENDIX B1-BEAR CREEK DAM-2 APPENDIX B1-BEAR CREEK DAM

Table 2 Reservoir Release Schedule Elevation (ft) Release Rate (cfs) From To 5558 5611.5 streamflow up to 500 5611.5 5625 1,000 5625 5635.5 1,500 5635.5 5667 2,000

Rainfall runoff from major storm events occurs so rapidly in this area that there is minimal time available for evaluating downstream flood conditions. The reservoir design of Bear Creek and Chatfield includes zero releases during flood events to provide the best downstream flood control. Bear Creek design storage is based on releasing no water for two days, then progressively increasing releases to a maximum of 1,500 cfs as the flood pool fills. System or coordinated regulation of the three projects in parallel will be necessary only after the cessation of flood flows and during flood storage evacuation.

Deviations from the release schedule are made if conditions at the time result in improved reservoir regulation. For example (1) releases according to the schedule should not exceed downstream channel capacity unless the safety of the dam is in question and (2) temporary delays of a few days duration in the evacuation of flood storage will be considered to mitigate damages and/or for special circumstances downstream.

When portions of the flood control storage zone of Cherry Creek, Chatfield, and Bear Creek reservoirs are occupied, an equal protective balance of remaining flood control storage should be maintained during the evacuation of these projects. This balance is based on establishing an equal risk in each project of filling the remaining flood control space from a similar subsequent flood. The storage remaining should provide equal protection at each project against runoff from rainfall of standard project flood magnitude. Please review the Water Control Plan and Manual for further details.

2. Operation for Report Period. From September through most of April the inflow was controlled by the weir. The snowpack was near normal in the Bear Creek basin until mid-April when continued snowfall accumulation occurred into late-May. It was apparent by the end of April that the flood control storage space would be utilized due to late snowfall accumulation and continued rainfall. The Echo Lake SNOTEL site, the only site in the Bear Creek basin, peaked at just over 13 inches in late-May when the 30-year average peak is just over 9 inches in late April. The rainfall in the basin in May and June was considerably above normal.

On April 24, the gates were set to release a maximum of 300 cfs due to the heavy rainfall forecast below the dam. On May 5, following improved downstream conditions, the release was increased to 400 cfs with 3% of the flood control storage occupied. This resulted in a combined Tri-Lakes release of

APPENDIX B1- BEAR CREEK DAM-3 APPENDIX B1-BEAR CREEK DAM

1,450 cfs (1,000 cfs from Chatfield and 50 cfs from Cherry Creek). Beginning May 6 and as needed, the NWS provided inflow forecasts for Bear Creek Dam, but continued heavy rainfall forced the inflow higher than forecast. The Corps CWMS model was used for comparison but was lacking the snowmelt capability and did not have enough rain in the forecast period. On May 9 the release was reduced to 200 cfs to allow for downstream channel capacity due to forecast heavy rainfall. This resulted in a combined Tri-Lakes release of 450 cfs (200 cfs from Chatfield and 50 cfs from Cherry Creek). At this point over 11% of the flood storage was occupied. A new record peak daily inflow of 1,183 cfs was set on May 11 beating the previous record of 1,172 cfs set in 2013. As downstream conditions improved, the release was increased to 400 cfs on May 10 and then to 500 cfs on May 12. This resulted in a combined Tri-Lakes release of 2000 cfs (1,500 cfs from Chatfield and 0 cfs from Cherry Creek). These release changes were coordinated with the Platte Canyon Water and Sanitation District due to concerns with their aerial pipeline that crosses Bear Creek near Sheridan, Colorado that collects debris during high flow. A break in rainfall runoff occurred from May 11-17 at which time the inflow dropped below the 500 cfs release resulting in the first peak pool elevation of 5597.9 feet (nearly 30% of flood control storage) on May 16.

More heavy rainfall on May 18-19 forced the inflow back above the 500 cfs release and the reservoir rose above the previous peak. At this time, about 15,000 ac-ft of snow water equivalent was estimated in the mountains of Bear Creek basin. On May 22, the reservoir had risen to elevation 5600 feet and was forecast to rise to 5613 feet if the entire basin experienced an additional 0.5 inch of rainfall. The NWS provided two inflow forecasts on May 22, the first with minimal snowmelt showing the reservoir peaking at 5601.6 feet and the second showing the reservoir continuing to climb into the following week. At the time, about 21,000 ac-ft of snow water equivalent was estimated in the mountains. The snowpack was near the peak on May 24 with 21,100 ac-ft of snow water equivalent estimated in the mountains.

A secondary peak pool elevation of 5602.7 feet (just over 36% full) was experienced on May 26. There was concern that the above normal snowpack (estimated 20,700 ac-ft of snow water equivalent) could melt quickly and with continued heavy rainfall force the inflow back up. This could cause the reservoir to rise to pool elevation 5611.5 feet which would require a release of 1,000 cfs according to the reservoir release schedule provided in the water control plan. Flood inundation maps were used to determine downstream potential impact areas. The mapping showed that the Bear Creek Shopping Center was impacted at 1,000 cfs. On May 28, the Corps generated three forecasts based on different snowmelt rates as follows:

1. Peak pool elevation of 5606 feet (assuming a steady mountain snowmelt) 2. Peak pool elevation of 5610 feet (assuming a faster mountain snowmelt) 3. Peak pool elevation of 5615 feet (assuming a rapid mountain snowmelt)

APPENDIX B1-BEAR CREEK DAM-4 APPENDIX B1-BEAR CREEK DAM

The inflow continued to slowly drop due to a slow mountain snowmelt and did not exceed the second peak pool of 5602.7 feet reached on May 26 (the second highest pool of record), thus the maximum release was 500 cfs during the report period.

During the month of May the Bear Creek basin above Bear Creek Dam received 6 to 10 inches of rainfall, which was over 4 inches above normal. The city of Denver also received a similar amount of heavy rainfall during this period. Figure 1 shows the precipitation that fell in May.

Bear Creek Dam

Figure 1: May 2015 Accumulated Precipitation

The 500 cfs release was held until May 29 when the release was reduced to 230 cfs for 4 hours to enable debris removal from the Platte Canyon Water and Sanitation District pipeline crossing Bear Creek near Sheridan, Colorado. On June 11 after the reservoir had dropped to about 23% full, the release was reduced to 200 cfs for 2 days to allow for downstream channel capacity due to forecast heavy rainfall. This resulted in a combined Tri-Lakes release of 1,250 cfs (1,000 cfs from Chatfield and 50 cfs from Cherry Creek). Debris removal on the aerial pipeline was also made possible during this time period. The release was increased back to 500 cfs on June 13 after the downstream conditions had improved to continue evacuation of the flood control storage as the reservoir had risen to 28% full. This resulted in a combined Tri-Lakes release of 1,550 cfs (1,000 cfs from Chatfield and 50 cfs from Cherry Creek).

On June 22, the reservoir release ramp down process began in order to keep the daily reservoir pool elevation drop less than 2 feet. To meet the requirement, the

APPENDIX B1- BEAR CREEK DAM-5 APPENDIX B1-BEAR CREEK DAM

release was decreased from 500 cfs to 350 cfs on June 22 when the reservoir was less than 20% full. The release from Cherry Creek Dam was increased resulting in no change to the combined Tri-Lakes 3,600 cfs release. On July 2, the release was decreased to 225 cfs when the reservoir was less than 10% full. This resulted in a combined Tri-Lakes release of 2,075 cfs (1,800 cfs from Chatfield and 50 cfs from Cherry Creek). On July 24, the release was decreased again to 175 cfs when the reservoir was less than 5% full. This resulted in a combined Tri-Lakes release of 890 cfs (700 cfs from Chatfield and 15 cfs from Cherry Creek). The flood storage was essentially evacuated on July 30 and the gates were set to allow the weir to control the inflow up to 500 cfs.

During the month of June the heaviest rain was experienced downstream of Bear Creek Dam. This area saw 6 to 10 inches of rainfall, which was over 5 inches above normal. Figure 2 shows the precipitation that fell in June.

Bear Creek Dam

Figure 2: June 2015 Accumulated Precipitation

Not only was the record peak daily inflow from 2013 broken in 2015, but the 2015 flood inflow volume (73,700 ac-ft) exceeded the 2013 flood inflow volume (28,400 ac-ft). Figure 3 shows a comparison between 2015 and 2013.

APPENDIX B1-BEAR CREEK DAM-6 APPENDIX B1-BEAR CREEK DAM

2500

2000 ft)

- 2015 2013 1500

1000 Inflow Volume (ac Volume Inflow 500

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 Number of Days

Figure 3: 2015 and 2013 Inflow Volume Comparison

Historical as well as reporting period details are contained in parts a through c of the following table and in Figures 4 and 5.

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 1183 cfs 10-May-15 Lowest 5549.2 ft 18-Oct-99 2nd 1172 cfs 16-Sep-13 2nd 5555.4 ft 15-Sep-02 3rd 910 cfs 30-Apr-80 3rd 5555.5 ft 10-Sep-12 Daily Outflow - Date Highest 800 cfs 11-Jun-79 c. Report Period 2nd 800 cfs 04-May-80 Total Inflow Total Outflow 3rd 612 cfs 23-Jun-95 84,135 ac-ft 241% of norm 83,738 ac-ft 242% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 5607.8 ft 21-Sep-13 1183 cfs 10-May-15 509 cfs 15-Jun-15 2nd 5602.7 ft 26-May-15 Peak Pool Elev Min Pool Elev 3rd 5587.1 ft 17-Jun-95 5602.7 ft 26-May-15 5558.3 ft 29-Sep-15

APPENDIX B1- BEAR CREEK DAM-7 APPENDIX B1 - BEAR CREEK DAM Prepared By:____JB By:____JB ___ Prepared By:___ KS ___ Reviewed Release Inflow Top of Flood Control Top Zone (5635.5)

FIGURE 4 - BEAR CREEK DAM POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX B1 - BEAR CREEK DAM - 8 APPENDIX B1 - BEAR CREEK DAM Prepared By:____JB By:____JB ___ Prepared By:___ KS ___ Reviewed Top of ConservationTop Zone (5558) Top of Flood Control Top Zone (5635.5)

FIGURE 5 - BEAR CREEK DAM HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX B1 - BEAR CREEK DAM - 9 APPENDIX B1-BEAR CREEK DAM

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APPENDIX B1-BEAR CREEK DAM-10 APPENDIX B2-BOWMAN-HALEY DAM

BOWMAN-HALEY DAM AND LAKE GRAND RIVER BASIN, NORTH DAKOTA 2014- 2015 REGULATION

1. Project Description and Water Control Plan. Bowman-Haley Dam is located in southwestern North Dakota on the North Fork of the Grand River. The reservoir has an uncontrolled morning glory spillway at the top of the multipurpose pool (2754.8 ft) and allows for gated regulation from the outlet works. Since the mid-1990s, an effort has been made to maintain the pool level at Bowman Haley below the top of multipurpose pool at all times. Maintaining the pool at a lower level, generally by releasing through the low-level gate, is an attempt to reduce shoreline erosion, help establish riparian vegetation, and improve water quality by reducing turbidity from wave wash. This change in regulation was coordinated with the Natural Resources Conservation Service, the North Dakota Game and Fish Department, and the Bowman County Water Management District. Since 2006 the desired pool level has been 3 to 4 feet below 2754.8 ft. Because of some recent high water years, the shoreline erosion has become worse, with little vegetation becoming established; however, by keeping the reservoir at a lower elevation, a reduction in erosion has been observed. In addition, by releasing from the lower strata of the reservoir, it is hoped the overall quality of the water in the reservoir will be improved. Generally the low-level gate is left open all winter, and the main gate is set at about 3 inches open. These gate openings result in a low release through the winter and keep the gates from freezing shut. In wet years a higher winter release is set to keep the pool from rising over the winter. In January or February, the main gate is opened completely, allowing the full 20 cfs to release through the low-level gate for the water quality benefit. Table 1 shows the storage zones for Bowman- Haley Reservoir.

Table 1 Bowman-Haley Reservoir Storage Allocations, 2010 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) PD (ac-ft) (ac-ft) Inactive 2715.0-2740.0 2,436 2,436 Multipurpose 2740.0-2754.8 15,196 17,632 Flood Control 2754.8-2777.0 72,696 90,329 Surcharge 2777.0-2789.0 77,296 -

2. Operation for Report Period. Wet conditions going into the winter resulted in higher than average reservoir inflow. Releases were set to match inflows at 40 cfs on October 14, 2014. The pool level slowly dropped from 2752.5 ft down to 2751.5 ft over the winter. In mid-January the air temperature was above normal for a couple weeks, increasing the inflow by the end of the month. By mid- February cooler temperatures dropped the inflow back to match the releases. The reservoir rose about one foot during this period. Spring thaw and minor rainfall runoff facilitated a slow pool rise from April to June. One inch of rain fell in the basin on June 16, causing the peak for the year on June 27 of 2753.7 ft. Releases were increased on June 23 to 80 cfs to lower the reservoir to its target level of 2751.8 ft by August 5. At that time releases were reduced to match

APPENDIX B2- BOWMAN-HALEY DAM-1 APPENDIX B2-BOWMAN-HALEY DAM

inflows at 40 cfs. Dry weather resulted in a continued decline of inflows, and releases were reduced to 0 cfs on August 17. Due to evaporation, the pool level continued to drop slowly, and the elevation at the end of the water year was 2751.0 ft.

Historical as well as reporting period details are contained in parts a through c of the following table and in Figures 1 and 2.

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 5310 cfs 27-Mar-78 Lowest 2746.3 ft 06-May-13 2nd 3378 cfs 17-Mar-09 2nd 2747.2 ft 30-Sep-12 3rd 2527 cfs 22-May-11 3rd 2747.6 ft 11-Jun-92 Daily Outflow - Date Highest 2390 cfs 28-Mar-78 c. Report Period 2nd 1785 cfs 14-Apr-09 Total Inflow Total Outflow 3rd 1256 cfs 14-May-95 32,811 ac-ft 134% of norm 30,099 ac-ft 156% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 2762.7 ft 28-Mar-78 211 cfs 26-Jul-15 119 cfs 01-Oct-14 2nd 2759.8 ft 13-Apr-09 Peak Pool Elev Min Pool Elev 3rd 2758.5 ft 13-Mar-72 2753.7 ft 26-Jun-15 2751.0 ft 29-Sep-15

APPENDIX B2- BOWMAN-HALEY DAM-2 APPENDIX B2 - BOWMAN-HALEY DAM Release Prepared By:____JM By:____JM _ Prepared By:___ Reviewed JB __ Inflow Top of ConservationTop Zone (2754.8) Top of Flood Control Top Zone (2777)

FIGURE 1 - BOWMAN-HALEY DAM POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPPENDIX B2 - BOWMAN-HALEY DAM - 3 APPENDIX B2 - BOWMAN-HALEY DAM Prepared By:____JM By:____JM __ Prepared By:___ Reviewed JB ___ Top of ConservationTop Zone (2754.8) Top of Flood Control Top Zone (2777)

FIGURE 2 - BOWMAN-HALEY DAM POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX B2 - BOWMAN-HALEY DAM - 4 APPENDIX B3-BULL HOOK-SCOTT COULEE-CEDAR CANYON DAMS

BULL HOOK-SCOTT COULEE DAMS MILK RIVER BASIN, MONTANA 2014-2015 REGULATION

1. Project Description and Water Control Plan. Bull Hook and Scott Coulee Dams are both part of the Bull Hook Unit providing flood control for the city of Havre, Montana. Bull Hook and Scott Coulee Dams are both located south of Havre on Bull Hook and Scott Coulee Creeks, respectively. After construction, dam ownership was turned over to the City of Havre, MT.

Under normal circumstances, the conduit valves of both dams will be kept partially open to evacuate accumulated storage as expeditiously as possible to allow the dams to function as flood protection facilities if excess runoff occurs upstream. Valve openings are to be maintained that will allow only the minimal damages to occur in the City of Havre.

At times of high flows on the Milk River, it may be necessary to shut off releases in both dams to prevent flooding behind the Milk River levees. No reports of heavy inflow into Bull Hook and Scott Coulee Dams were made during the report period.

CEDAR CANYON DAM (RED DALE GULCH) RAPID CREEK BASIN, SOUTH DAKOTA 2014-2015 REGULATION

1. Project Description and Water Control Plan. Cedar Canyon Dam is located on the western outskirts of Rapid City, South Dakota. After construction, dam ownership was turned over to the City of Rapid City, SD. The dam is designed as a detention structure with no permanent storage. However, a small pool may sometimes exist in the dead storage below the invert of the outlet pipe. The dam collects runoff from approximately 261 acres. The outlet and spillway are uncontrolled.

Spring and summer were extremely wet in the Rapid City area. May and July saw 150-300% of normal precipitation while June saw 200-400% of normal precipitation. Flood water was stored behind the dam during this time, but its elevation was not measured. This is only the second time in reported history that flood water was stored with the first being in 2011. This year’s water level exceeded that seen in 2011. Appendix A gives pertinent data for this reservoir.

APPENDIX B3- BULL HOOK-SCOTT COULEE-CEDAR CANYON DAMS-1 APPENDIX B3-BULL HOOK-SCOTT COULEE-CEDAR CANYON DAMS

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APPENDIX B3-BULL HOOK-SCOTT COULEE-CEDAR CANYON DAMS-2 APPENDIX B4-CHATFIELD DAM

CHATFIELD DAM AND LAKE SOUTH PLATTE RIVER BASIN, COLORADO 2014-2015 REGULATION

1. Project Description and Water Control Plan. Chatfield Dam is located in Denver, Colorado on the South Platte River. The dam was completed in 1975 for the authorized purpose of flood control, and later was authorized for general recreation and fish and wildlife recreation. The outlet works is located near the left abutment and consists primarily of a gated intake tower, service bridge, twin oblong conduit, and stilling basin. The intake structure has two (6ft X 13.5ft) hydraulically operated slide service gates as well as one (6.0ft X 14.6ft) wheel wire rope hoist operated emergency gate and one (8ft X 22.5ft) bulkhead gate. The inside width and height of the twin oblong conduit is 11.0 feet wide, 16.0 feet high, and 1,280 feet long. An auxiliary pipe, suspended inside one of the barrels of the main conduit, is provided for the purpose of satisfying downstream water rights by supplying water to three irrigation ditches and the fish hatchery. This auxiliary pipe is gated at the upstream end. Gates at the downstream end of the auxiliary pipe and at the outlets are used to control releases to the various users. The discharge channel has been re-aligned to flow into the spillway pilot channel. The auxiliary pipe system has a total release capacity of 140 cfs. The system individual outlet capacities are 35 cfs to the City Ditch, 35 cfs to the Last Chance Ditch, 40 cfs to the Nevada Ditch, and 30 cfs to the fish hatchery. The upstream auxiliary pipe is 72 inches in diameter and the gate is a butterfly valve. There are two downstream pipes, one 54 inches and one 48 inches in diameter, both with a butterfly valve gate. Table 1 shows the storage zones for Chatfield Reservoir.

Table 1 Chatfield Reservoir Storage Allocations, 2010 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) PD (ac-ft) (ac-ft) Inactive 5377-5385 16 16 Multipurpose 5385-5432 27,060 27,076 Flood Control 5432-5500 205,985 233,061 Surcharge 5500-5521.6 116,392 -

Flood control releases are controlled and regulated by the two 6 X 13.5 foot service gates. The outlet works has a discharge capacity of 8,400 cfs at full flood control pool of 5500.0 ft. A 2ft X 2ft gate-within-a-gate is provided on each of the two service gates for fine regulation of low flow releases. Emergency and bulkhead gates are located upstream from the two 6 X 13.5 foot service gates.

Before Chatfield Dam became operational, the Corps Water Control and Water Quality Section requested the Colorado State Engineers Office, acting through the District 8 Water Commissioner, to assume responsibility for determining releases from the multipurpose pool in an effort to free the Corps from water rights conflicts. This relationship was included in a formal document dated March 30, 1973, that increased the multipurpose pool from elevation 5430.0 ft to 5432.0 ft and specified water storage commitments by the State. By contract, the State

APPENDIX B4-CHATFIELD DAM-1 APPENDIX B4- CHATFIELD DAM

is committed to maintain the pool above elevation 5423.0 ft for recreation and fish and wildlife purposes. Since 1979, the City of Denver, through the State of Colorado, has been permitted to regulate storage in the conservation pool in return for the city's commitment to provide sufficient water recreation storage. The city is committed to keeping 20,000 ac-ft (elevation 5426.94 ft) of water in the pool from May 1 through August 31, and permitted to use 10,000 ac-ft of storage space in the reservoir between elevations 5423.8 and 5432.0 ft. The original top of multipurpose pool level was at elevation 5426.0 ft. Whenever the pool exceeds the base of the flood control zone, elevation 5432.0 ft, the District Engineer determines Chatfield releases.

Rainfall runoff from major storm events occurs so rapidly in this area that there is minimal time available for evaluating downstream flood conditions. System or coordinated regulation of the three projects in parallel will be necessary only after the cessation of flood flows and during flood storage evacuation. During flood inflow events and when flood control storage is occupied, releases will generally be kept as large as possible targeting a flow past the South Platte River at Denver, Colorado streamgage of 5,000 cfs; though there are areas that only have an estimated capacity of 2,000 to 3,000 cfs downstream from the dam. Consideration will be given to reducing releases to zero as was contemplated in the reservoir design if heavy rainfall and runoff are known to exist below Chatfield.

Irrigation diversions on the South Platte River below the City of Denver are quite extensive. A flow of about 4,500 cfs at Henderson, Colorado is necessary to supply full water rights demands. When not inconsistent with flood control regulation at Cherry Creek and Chatfield reservoirs, it is desirable that releases be controlled so as to maintain flows from the reservoirs which in conjunction with incremental flows do not exceed the irrigation requirement at Henderson.

When portions of the flood control storage zone of Cherry Creek, Chatfield, and Bear Creek reservoirs are occupied, an equal protective balance of remaining flood control storage should be maintained during the evacuation of these projects. This balance is based on establishing an equal risk in each project of filling the remaining flood control space from a similar subsequent flood. The storage remaining should provide equal protection at each project against runoff from rainfall of standard project flood magnitude. Please review the Water Control Plan and Manual for further details.

A reallocation study was completed at Chatfield in FY14 resulting in a new joint use pool for flood control and water supply with 20,600 ac-ft of available storage to be implemented in a phased approach basin on mitigation. In May 2013 the Chatfield, Cherry Creek, and Bear Creek proposed Water Control Plans (WCPs) were approved by the Northwest Division Missouri River Basin Water Management (MRBWM) office, contingent on reallocation implementation. The water control manual updates were partially drafted in FY14 and FY15 with no

APPENDIX B4- CHATFIELD DAM-2 APPENDIX B4-CHATFIELD DAM

further significant changes to the water control plan. The Chatfield Reallocation implementation phase began in FY15.

2. Operation for Report Period. From September through April the reservoir was operated for downstream water rights. The snowpack was near normal in the upper South Platte River basin until early-May when continued snowfall accumulation occurred into late-May. It was apparent in early May that the flood control storage space would be utilized due to late snowfall accumulation and continued rainfall. The upper South Platte basin SNOTEL average peaked at about 16 inches in late May and the 30 year average peak is 11.5 inches in late April. The rainfall in the basin in May and June was considerably above normal.

On May 6, the release was reduced to 500 cfs and reduced again on May 9 to 200 cfs to allow for downstream channel capacity due to forecast heavy rainfall and the use flood control storage space was initialized. This resulted in a combined Tri-Lakes release of 450 cfs (200 cfs from Bear Creek and 50 cfs from Cherry Creek). Beginning May 8 and as needed, the NWS provided inflow forecasts for Chatfield Dam. The May 11 NWS inflow forecast resulted in a peak pool elevation of 5440.3 feet. From May 10-14 following improved downstream conditions, the Chatfield release was increased from 200 cfs to 1,900 cfs at a rate less than 500 cfs per day. This resulted in a combined Tri-Lakes release of 2,650 cfs (500 cfs from Bear Creek and 250 cfs from Cherry Creek). At this point over 6% of the flood control storage was occupied. A break in rainfall runoff occurred from May 11-17 at which time the inflow dropped below the 1900 cfs release resulting in the first peak pool elevation of 5440.1 feet (over 6% full) on May 15.

More heavy rainfall on May 18-19 forced the inflow back above the 1900 cfs release and the reservoir rose above the previous peak. On May 20, the release was increased to 2,050 cfs and the release from Cherry Creek was reduced by 150 cfs resulting in no change to the combined release from the Tri-Lakes. Continued heavy rainfall and mountain snowmelt runoff forced the daily average inflow above 2,800 cfs surpassing the NWS inflow forecasts at the end of May. The release was increased from 2,050 cfs to 2,600 cfs from May 25-27 as downstream conditions had improved. This resulted in a combined Tri-Lakes release of 3,250 cfs (500 cfs from Bear Creek and 150 cfs from Cherry Creek). On June 1, the release was increased to 2,700 cfs and the release from Cherry Creek was reduced by 125 cfs. A break in rainfall runoff occurred from May 26 - June 3 at which time the inflow dropped below the 2,700 cfs release resulting in the second peak pool elevation of 5441.5 feet (nearly 8% full) on May 27. The reservoir was allowed to continue to evacuate the flood control storage with the 2,700 cfs release to make room for the peak mountain snowmelt runoff and by June 10 had dropped to about 3% full.

During the month of May the upper South Platte River basin above Chatfield Dam received 4 to 10 inches of rainfall, which was 2 to 8 inches above normal.

APPENDIX B4-CHATFIELD DAM-3 APPENDIX B4- CHATFIELD DAM

The city of Denver received 8 inches of heavy rainfall during this period. Figure 1 shows the precipitation that fell in May.

Chatfield Dam

Figure 1: May 2015 Accumulated Precipitation

The NWS inflow forecasts in early June predicted that the inflow would continue to drop, which would have resulted in additional flood storage evacuation but continued rainfall forced the inflow up. The Corps inflow forecast on June 10 followed the actual inflow until the heavy rainfall on June 10-12. On June 10, the release was reduced from 2,700 cfs to 2,200 cfs to allow for downstream channel capacity due to forecast heavy rainfall. On June 11, it was reduced from 2200 cfs to 1,600 cfs in the morning and again to 1000 cfs in the afternoon to allow for additional downstream channel capacity due to forecast heavy rainfall. This resulted in a combined Tri-Lakes release of 1,250 cfs (200 cfs from Bear Creek and 50 cfs from Cherry Creek). The flow at the South Platte River at Denver streamgage dropped by about 1,200 cfs before the heavy rainfall runoff was experienced in Denver from June 11-12. Late on June 12 following the heavy rainfall, the Corps considered increasing the release to 1,500 cfs due to a new record peak daily inflow of 3,896 cfs set on June 13 surpassing the previous record of 3,394 cfs set in 1995. Instead, the State of Colorado requested that the Corps shut the gates at Chatfield following the rain from June 10-12 to provide relief to water supply infrastructure downstream of Denver. With the help of National Weather Service river forecast scenarios, it was determined that shutting off releases would not impact the peak stage at Kersey due to the travel time. Using the NWS inflow forecast, it was also determined that the peak pool elevation would be impacted by reducing the release as follows:

1. Peak pool elevation of 5448.1 feet (14.7% full) holding the 1,000 cfs release through June 16

APPENDIX B4- CHATFIELD DAM-4 APPENDIX B4-CHATFIELD DAM

2. Peak pool elevation of 5450.2 feet (16.9% full) reducing the release to 500 cfs on June 12 and holding through June 16 3. Peak pool elevation of 5451.7 feet (17.5% full) reducing the release to 500 cfs on June 12 and to 0 cfs on June 13 and holding through June 16

The Corps held the release from Chatfield at 1,000 cfs from June 11-15 instead of going up to 1,500 cfs thereby reducing the stage at the streamgage on the South Platte River at Kersey by 0.5 feet on June 14. On June 15, the streamgage at Kersey fell below flood stage and the Chatfield release was increased from 1,000 cfs to 1,500 cfs. This resulted in a combined Tri-Lakes release of 2,100 cfs (500 cfs from Bear Creek and 100 cfs from Cherry Creek). Leading up to the third peak pool elevation, the actual and forecast inflows were watched closely. The forecast peak pool elevation fluctuated about one foot but stayed close to a peak pool elevation 5448 feet. The release was increased twice on June 16 once in the morning from 1,500 cfs to 2,000 cfs and again to 2500 cfs in the afternoon as the streamgages at Weldona and Balzac had exited flood stage. This resulted in a combined Tri-Lakes release of 3,100 cfs (500 cfs from Bear Creek and 100 cfs from Cherry Creek). Following coordination with the State of Colorado, it was determined that a more aggressive release plan to get the flood storage evacuated was preferred so that repair work could begin on the downstream water supply infrastructure. The flood storage evacuation was expected to coincide with decreasing downstream coincident flow. For the above reasons and since the inflow continued to stay above 3,000 cfs, the release was increased again from 2,500 cfs to 3,000 cfs on June 17 following behind the downstream peaks resulting from snowmelt and rainfall runoff from contributing tributaries. This resulted in a combined Tri-Lakes release of 3600 cfs (500 cfs from Bear Creek and 100 cfs from Cherry Creek).

The upstream gages began to recede around June 15 while the Chatfield inflow began to recede on June 20 both as a result of a break in rainfall and a nearly melted mountain snowpack. The break in rainfall runoff continued through the rest of June causing a steady drop in the inflow below the 3,000 cfs release. This resulted in a third peak pool elevation of 5448.5 feet (over 14% full) on June 19. This set a new record peak daily pool elevation surpassing the record of 5447.6 feet set in 1980. At the request of local authorities to search for a missing tuber and in coordination with the State of Colorado, the release from Chatfield Dam was reduced temporarily from 3,000 cfs to 1,000 cfs for 7 hours on June 23. The release reduction was projected to drop the South Platte River by about one foot from the dam through Denver, Colorado. The reservoir rose by about half of a foot during this time but did not result in another peak pool elevation.

On June 30, the reservoir release ramp down process began. The release was decreased from 3,000 cfs to 2,500 cfs on June 30 when the flood control storage was about 9% full. This resulted in a combined Tri-Lakes release of 3100 cfs (350 cfs from Bear Creek and 250 cfs from Cherry Creek). On July 2, the release was decreased to 1,800 cfs when the reservoir was about 7% full. This

APPENDIX B4-CHATFIELD DAM-5 APPENDIX B4- CHATFIELD DAM

resulted in a combined Tri-Lakes release of 2,075 cfs (225 cfs from Bear Creek and 50 cfs from Cherry Creek). On July 14, the release was decreased to 1300 cfs and again to 800 cfs when the reservoir was about 5% full to accommodate repair work on the water supply infrastructure in the Brighton, CO area. This resulted in a combined Tri-Lakes release of 1,035 cfs (225 cfs from Bear Creek and 10 cfs from Cherry Creek). On July 16 following the repair work, the release was increased from 800 cfs to 1,450 cfs and again to 2,100 cfs to evacuate the remaining flood control storage. This resulted in a combined Tri-Lakes release of 2,325 cfs (225 cfs from Bear Creek and 0 cfs from Cherry Creek). The release was ramped down from 2,100 cfs to 550 cfs in 4 steps from July 23-25. This resulted in a combined Tri-Lakes release of 740 cfs (175 cfs from Bear Creek and 15 cfs from Cherry Creek). The flood storage was essentially evacuated on July 25 and the reservoir was operated for water supply for the remainder of the water year.

During the month of June the heaviest rain was experienced downstream of Chatfield Dam. This area saw 6 to 10 inches of rainfall, which was over 5 inches above normal. Figure 2 shows the precipitation that fell in June.

Chatfield Dam

Figure 2: June 2015 Accumulated Precipitation

Not only was the record peak daily inflow from 1995 broken in 2015, but the 2015 flood inflow volume (346,600 ac-ft) exceeded the 1995 flood inflow volume (281,100 ac-ft). Figure 3 shows a comparison between 2015 and 1995.

APPENDIX B4- CHATFIELD DAM-6 APPENDIX B4-CHATFIELD DAM

8000 2015 7000 1995 6000 feet) - 5000 4000 3000 2000 Inflow Volume (ac Volume Inflow 1000 0 0 10 20 30 40 50 60 70 80 90 100 Number of Days Figure 3: 2015 and 1995 Inflow Volume Comparison

Historical as well as reporting period details are contained in parts a through c of the following table and in Figures 4 and 5.

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 3896 cfs 12-Jun-15 Lowest 5422.9 ft 31-Oct-06 2nd 3394 cfs 01-Jul-95 2nd 5423.0 ft 29-Aug-03 3rd 3370 cfs 29-May-83 3rd 5423.1 ft 03-Aug-04 Daily Outflow - Date Highest 3350 cfs 06-Jul-95 c. Report Period 2nd 3067 cfs 19-Jun-15 Total Inflow Total Outflow 3rd 3034 cfs 14-May-84 398,692 ac-ft 265% of norm 400,621 ac-ft 275% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 5448.5 ft 19-Jun-15 3896 cfs 12-Jun-15 3067 cfs 19-Jun-15 2nd 5447.6 ft 25-May-80 Peak Pool Elev Min Pool Elev 3rd 5447.1 ft 29-Jun-83 5448.5 ft 19-Jun-15 5426.9 ft 30-Aug-15

APPENDIX B4-CHATFIELD DAM-7 APPENDIX B4 - CHATFIELD DAM Prepared By:____JB By:____JB _ Prepared By:___ KS ___ Reviewed Release Inflow Elevation Top of Flood Control Top Zone (5500)

FIGURE 4 - CHATFIELD DAM POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX B4 - CHATFIELD DAM - 8 APPENDIX B4 - CHATFIELD DAM Prepared By:___ By:___ JB_Prepared __ By:___ KS ___ Reviewed Top of ConservationTop Zone (5432) Elevation Release Top of Flood Control Top Zone (5500)

FIGURE 5 - CHATFIELD DAM HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX B4 - CHATFIELD DAM - 9 APPENDIX B4- CHATFIELD DAM

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APPENDIX B4- CHATFIELD DAM-10 APPENDIX B5-CHERRY CREEK DAM

CHERRY CREEK DAM AND LAKE SOUTH PLATTE RIVER BASIN, COLORADO 2014-2015 REGULATION

1. Project Description and Water Control Plan. Cherry Creek Dam is located in Denver, Colorado on Cherry Creek, a tributary to the South Platte River. The dam was completed in June of 1950 for the authorized purpose of flood control, and later was authorized for general recreation and fish and wildlife recreation. The outlet works are located on the right abutment and consist of an approach channel, intake structure, triple barrel concrete conduit, stilling basin, and escape channel. The structures were designed to serve as a permanent outlet for the release, regulation, and control of flood flows and conservation storage. The intake structure at the upstream end of the conduit includes the trash rack structure, gate chamber, and control tower. A service bridge provides access from the dam crest to the intake structure. The control tower houses the gate hydraulic operating equipment, DCP, heating and ventilating systems, standby generator, and overhead crane. Control of the discharge is provided by five hydraulically operated slide gates (6 X 9 foot) located in the gate chamber. The flow through the five control gates is carried through a suitable transition to the triple barrel conduit section. The two 8 X 12 foot outside conduits are 679.5 feet long with an inlet invert elevation of 5504.0 ft. Inverts and crowns are semi- circular in shape. The principle elements of Cherry Creek’s stilling basin include the sloping apron, the concrete stilling pool, training walls, baffle piers, basin transition, and outlet sill. The stilling basin is 165 feet long. The spillway, located in the east abutment ridge 2,500 feet upstream from the dam, is an ungated side- channel canal discharging into the adjacent Tollgate Creek, thus bypassing the Cherry Creek Channel through the city of Denver. Table 1 shows the storage zones for Cherry Creek Reservoir.

Table 1 Cherry Creek Reservoir Storage Allocations, 2006-07 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) PD (ac-ft) (ac-ft) Multipurpose 5504-5550 12,558 12,558 Flood Control 5550-5598* 79,294 91,852 Surcharge 5598-5645** 181,942** - * Top of Original Design Flood Control Pool is 5598.0 ft PD, which was the original spillway crest elevation. Due to sloughing of spillway side slopes, spillway crest elevation is 5610.6 ft PD. ** The 2006-07 survey did not include the top 5 feet of storage in the surcharge zone. The curve was linearly interpolated to obtain the entire zone’s storage capacity.

Flood control releases are controlled and regulated by the five 6 X 9 foot service gates. The outlet works has a discharge capacity of 8,200 cfs at a pool elevation of 5600.0 ft. Two 18 inch diameter low-level gates are used for fine regulation of low flow releases.

Rainfall runoff from major storm events occurs so rapidly in this area that there is minimal time available for evaluating downstream flood conditions. The revised PMF and design storm routings indicate inadequate flood control storage at

APPENDIX B5-CHERRY CREEK DAM-1 APPENDIX B5- CHERRY CREEK DAM

Cherry Creek Reservoir. This requires close monitoring of Cherry Creek Reservoir and basin conditions as defined in the flood warning standard operating procedure. System or coordinated regulation of the three projects in parallel will be necessary only after the cessation of flood flows and during flood storage evacuation.

When portions of the flood control storage zone of Cherry Creek, Chatfield, and Bear Creek reservoirs are occupied, an equal protective balance of remaining flood control storage should be maintained during the evacuation of these projects. This balance is based on establishing an equal risk in each project of filling the remaining flood control space from a similar subsequent flood. The storage remaining should provide equal protection at each project against runoff from rainfall of standard project flood magnitude. Please review the Water Control Plan and Manual for further details.

On April 1, 1988, the State of Colorado, through the State Engineer, implemented strict administration of water rights within the Cherry Creek basin. When a senior water right is in effect, the Cherry Creek Reservoir is required to pass inflow through the project. The Water Control and Water Quality Section coordinates releases from the project to comply with downstream water rights as determined by the Colorado State Engineer’s office. Cherry Creek Dam and Reservoir is typically regulated within a transition zone of 5550.0 to 5551.0 ft. The transition zone was established to provide operational flexibility to keep the reservoir at or near the full conservation pool level of 5550.0 ft. Many occasions arise when small Cherry Creek inflows or rainfall on the immediate reservoir area cause small increases in the pool level, many of which will cause the pool to exceed elevation 5550.0 ft. The release of these small volumes will cause frequent and difficult gate operation. The quantity of water so released would also be insufficient in most instances to be practical or beneficial to State water users. If the State Engineer has no call for releases, these small inflows will be accumulated in the reservoir to a maximum elevation of 5551.0 ft.

When no water rights call is on Cherry Creek during non-flood regulation, it is the responsibility of the Water Control and Water Quality Section to determine the release rate to keep the Cherry Creek pool at or near 5550.0 ft by releasing inflows and accounting for evaporation.

To reduce the probability of unacceptable risk, an Interim Risk Reduction Measure (IRRM) Plan was completed for Cherry Creek Dam in October 2008. The plan was reviewed and updated with current information in 2013. After technical review, the document was better organized and went through another review in FY14 gaining approval. Risks associated with modifying the Cherry Creek Water Control Plan (WCP) and increasing or removing South Platte River at Denver streamgage flow target will be studied in FY16. The study includes two phases, a coincident flow study to be complete mid-January and a reservoir regulation study to be complete summer of 2016. The goal is to ensure 5,000 cfs can be released from Cherry Creek Dam during an extreme flood event at Cherry

APPENDIX B5- CHERRY CREEK DAM-2 APPENDIX B5-CHERRY CREEK DAM

Creek Dam no matter the condition at the Denver streamgage. The study will achieve this by further refining a new reservoir release pool elevation trigger at Cherry Creek Dam that was first developed during the concurrent Cherry Creek Dam Safety Modification Study (DSMS). The Bear Creek and Chatfield system evacuation plans will also be adjusted to prevent negatively impacting them.

The Cherry Creek DSMS began in FY 2013 to address the Probable Maximum Flood overtopping concern. The study is scheduled to be complete at the end of 2017 with scheduled completion of the design and construction phase at the end of 2020.

2. Operation for Report Period. The reservoir operated above the base of the flood control pool during the report period with the exception of the month of September. The reservoir operated in the transition zone (5550 to 5551 feet) from October 1 until mid-April. Above normal rainfall runoff was experienced in the Cherry Creek basin in May and June, which forced the daily inflow the highest it has been since 1983.

On April 20, heavy rainfall runoff forced the reservoir above elevation 5551 feet. The release was increased to 50 cfs to begin evacuation of the flood control storage. Continued heavy rainfall pushed the reservoir to nearly elevation 5553 feet on May 11 and the release was increased to 100 cfs to slow the rate of rise as the downstream conditions had improved. This resulted in a combined Tri- Lakes release of 1,500 cfs (1,000 cfs from Chatfield and 400 cfs from Bear Creek). The gates were shut on May 12 to allow storage accumulation in the reservoir to calibrate the redundant pool elevation radar sensor. The sensor was installed as an Interim Risk Reduction Measure to provide back-up elevation instrumentation in the event of an extreme storm. On May 13, the release was increased to 250 cfs to begin evacuating the flood control storage (about 4%). This resulted in a combined Tri-Lakes release of 2,250 cfs (1,500 cfs from Chatfield and 500 cfs from Bear Creek). A formal small sedimentation flush was planned for mid-May, but instead was done during the flood control regulation. On May 16, the release was cut back to 50 cfs to accommodate a large marathon taking place along the Cherry Creek bike path, which lowered the stage level along Cherry Creek from the dam to the with the South Platte River by 0.5 to 1 ft. On May 17 following the marathon, the release was increased back to 250 cfs. By May 20, the daily inflow had dropped from about 500 cfs to about 100 cfs and less than 2% of the flood control storage was occupied. The Cherry Creek Dam release was reduced by 150 cfs down to 100 cfs while the Chatfield release was increased by 150 cfs resulting in no change to the combined release from the Tri-Lakes. No flood storage evacuation progress was made with a release of 100 cfs so on May 27 the release was increased to 150 cfs. This resulted in a combined Tri-Lakes release of 3,250 cfs (2,600 cfs from Chatfield and 500 cfs from Bear Creek). The Cherry Creek flood control storage was evacuated on June 1 thus the Cherry Creek release was reduced by 125 cfs while the Chatfield release was increased by 100 cfs.

APPENDIX B5-CHERRY CREEK DAM-3 APPENDIX B5- CHERRY CREEK DAM

More rainfall runoff in early-June produced a spike in inflow. On June 10, the release was increased to 50 cfs to begin flood storage evacuation as the downstream conditions had improved. This resulted in a combined Tri-Lakes release of 2,750 cfs (2,200 cfs from Chatfield and 500 cfs from Bear Creek). Continued heavy rainfall runoff forced the daily average inflow on June 12 to 1,231 cfs, the largest inflow since 1983. On June 14, the release was increased to 100 cfs to slow the rate of fill as the downstream conditions had improved. This resulted in a combined Tri-Lakes release of 1,600 cfs (1,000 cfs from Chatfield and 500 cfs from Bear Creek). The peak pool elevation of 5555.3 feet (just over 6% full) was experienced on June 18, the highest since 1983. On June 22, the release from Cherry Creek Dam was increased by 150 cfs while the release from Bear Creek Dam was decreased by 150 cfs resulting in no change to the combined release from the Tri-Lakes Dams. The flood storage was essentially evacuated on July 1 and the release was set to 50 cfs to evacuate the remaining flood control storage (about 1%). This resulted in a combined Tri- Lakes release of 2,900 cfs (2,500 cfs from Chatfield and 350 cfs from Bear Creek).

On August 11, additional rainfall runoff caused the reservoir to rise above the transition zone to elevation 5551.2 feet on August 13. The release was increased to 65 cfs on August 19 to evacuate the flood control storage. The remainder of the year was spent operating for downstream water rights.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2.

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 6150 cfs 16-Jun-65 Lowest 5543.5 ft 29-Jan-65 2nd 3195 cfs 06-May-73 2nd 5545.0 ft 31-Jul-64 3rd 1440 cfs 24-Jul-83 3rd 5545.9 ft 23-Nov-78 Daily Outflow - Date Highest 560 cfs 07-Aug-65 c. Report Period 2nd 450 cfs 27-Mar-60 Total Inflow Total Outflow 3rd 402 cfs 28-Apr-07 27,689 ac-ft 233% of norm 25,070 ac-ft 279% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 5565.8 ft 03-Jun-73 1231 cfs 12-Jun-15 262 cfs 14-May-15 2nd 5562.5 ft 01-Aug-65 Peak Pool Elev Min Pool Elev 3rd 5557.8 ft 26-Jul-83 5555.3 ft 17-Jun-15 5549.7 ft 02-Sep-15

APPENDIX B5- CHERRY CREEK DAM-4 APPENDIX B5 - CHERRY CREEK DAM Prepared By:____JB By:____JB ___ Prepared By:___ KS ___ Reviewed Release Inflow Top of Flood Control Top Zone (5598)

FIGURE 1 - CHERRY CREEK DAM POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPPENDIX B5 - CHERRY CREEK DAM - 5 APPENDIX B5 - CHERRY CREEK DAM Prepared By:____JB By:____JB ___ Prepared By:___ KS ___ Reviewed Top of ConservationTop Zone (5550) Top of Flood Control Top Zone (5598)

FIGURE 2 - CHERRY CREEK DAM HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX B5 - CHERRY CREEK DAM - 6 APPENDIX B6-COLD BROOK DAM

COLD BROOK DAM AND LAKE FALL RIVER BASIN, SOUTH DAKOTA 2014 - 2015 REGULATION

1. Project Description and Water Control Plan. Cold Brook Dam is located north of Hot Springs, South Dakota on Cold Brook, a tributary of the Fall River. Releases from Cold Brook Reservoir are regulated to comply with state water law. Larive Lake Resort, located below the dam, holds a senior water right entitling it to the Cold Brook Reservoir inflow up to 1.1 cfs. Appendix A gives pertinent data for this reservoir.

An outlet works with port openings at elevation 3585.0 ft and a crest at elevation 3600.0 ft regulates the pool level and outflows from Cold Brook Reservoir. The outlet works is uncontrolled, which means that there are no gates on the port openings or main crest to regulate flows once the pool level rises above the crest of the port openings. Following the grouting of the port openings in 2013, the average crest of the uncontrolled port openings rose to 3585.3 feet, as surveyed by the Omaha District Water Control and Water Quality Section staff in November 2013. There are three low-level gates in the outlet works, each having a capacity of 20 cubic feet per second (cfs). These gates are normally closed, but can be opened to lower the pool below elevation 3585.0 ft. In spring of 2001 the gage house downstream of the dam near the stilling basin was moved to the upstream side of the dam, and two 8-inch valves were installed on the 8-inch supply line to Larive Lake. One valve is used for controlling flows to Larive Lake and the other valve is used to divert flows into the stilling basin below the outlet works. The new gage house location caused data issues with silt deposition and ice each year, and in spring of 2014, the gage house was moved again to a new location on the top of the dam. A new radar gage was also purchased and installed at Cold Brook Reservoir off the outlet works tower during FY14; the Omaha District began using it for comparison during FY15.

Releases from Cold Brook Dam flow into Cold Brook. Cold Brook flows into the Fall River approximately one half mile downstream of Cold Brook Dam.

Table 1 shows the storage zones for Cold Brook Reservoir.

Table 1 Cold Brook Reservoir Storage Allocations, 1966 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) PD (ac-ft) (ac-ft) Multipurpose 3548.0-3585.0 520 520 Flood Control 3585.0-3651.4 6,711 7,231 Surcharge 3651.4-3667.2 3,723 -

2. Operation for Report Period. The reservoir operated in fill and spill mode throughout much of the report period. The reservoir held steady over the winter at around 3585.5 ft, with above-average groundwater inflows keeping the pool slightly above the top of the port openings. To accommodate a larger swim

APPENDIX B6-COLD BROOK DAM-1 APPENDIX B6- COLD BROOK DAM

beach as the recreation season approached, the project office requested that the pool level be lowered to the base of flood control, 3585.0 ft. The 8-inch valve was opened on March 31, 2015 to release 1 cfs in addition to the water exiting the reservoir over the weir crest. The drawdown was completed and the valve closed at the end of April. With no reservoir release, the pool quickly rose again to reach its equilibrium pool around 3585.5 ft. On May 26, the 8-inch valve was opened again to draw the pool down to 3585.0 ft, but rainfall increased inflows enough that the pool was not dropping as expected. On the afternoon of June 18 one of the 12-inch gates was opened slightly to facilitate a faster drawdown. Rainfall quickly pushed the pool back up into the flood pool. The Cold Brook at Argyle Road flood warning system went off with this storm that dropped between 0.50 and 1 inch of rain, notifying the Fall River County Emergency Management office, the campground located just upstream of the reservoir, and the project office ranger. The sirens that went off in the campground area with this warning were not heard by the campground host, and it was determined that the intense rain in the area obstructed the sound. The gate was opened again a few days later on June 22. Again when the gate was closed a storm dropped up to 0.75 inches of rainfall in the area, putting the pool on a sharp rising trend. This storm also set off the Argyle Road flood warning system, and the sirens were still not heard by the campground host, so the Omaha District field technician went out to re-position the sirens to point directly at the campsites. Testing of the sirens confirmed it was much easier to hear for future warnings.

It was decided that both for recreational benefits and to ensure no outflow during an inspection the next week, a drawdown to one foot below the base of flood pool, 3584.0 ft, would be initiated on June 25. The drawdown was completed by July 5 and the gates were shut, at which time another storm dropped up to 0.75 inches of rain in the basin. It was determined that holding the pool near 3585.0 ft with the constant rainfall and high inflows to the reservoir was unrealistic. So on July 9 the 8-inch valve was opened again and left open to help the pool reach equilibrium at a lower elevation. The pool peaked at elevation 3585.65 ft for the water year on July 27 after a storm dropped up to 1.5 inches of rain in the basin. The pool steadied out at around 3585.5 ft by the end of July, and held steady through the rest of the water year. The Omaha District Water Control and Water Quality Section informed the Big Bend Project Office in charge of Cold Brook Reservoir that it would be beneficial to consider some construction to extend the beach to a higher elevation since the new “normal” pool is 3585.3 ft rather than 3585.0 ft.

Rainfall amounts from May through July totaled between 14 and 20 inches for the three months, between 200-300% of normal rainfall for that time period. The campground had continual flooding issues with the rain, but it was found that the primary reason for the problems was not a high pool elevation but a culvert that transfers upstream inflows to the pool. A study was initiated with the Hydraulics Section to determine the correct culvert size needed to accommodate higher inflows. It is expected the study should be completed in FY16.

APPENDIX B6- COLD BROOK DAM-2 APPENDIX B6-COLD BROOK DAM

Historical as well as reporting period details are contained in paragraphs 2a through 2c of the following table and in Figures 1 and 2.

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 74 cfs 14-Jul-62 Lowest 3576.6 ft 23-Oct-77 2nd 65 cfs 08-Jul-61 2nd 3576.8 ft 14-Sep-81 3rd 40 cfs 19-May-82 3rd 3576.9 ft 01-Oct-80 Daily Outflow - Date Highest 19 cfs 04-Jul-99 c. Report Period 2nd 19 cfs 04-Jul-99 Total Inflow Total Outflow 3rd 19 cfs 04-Jul-99 1,954 ac-ft 257% of norm 1,856 ac-ft 283% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 3585.8 ft 10-Aug-14 7 cfs 07-Jul-15 7 cfs 19-Jun-15 2nd 3585.7 ft 28-Jun-10 Peak Pool Elev Min Pool Elev 3rd 3585.7 ft 30-Jun-10 3585.7 ft 27-Jul-15 3584.1 ft 04-Jul-15

APPENDIX B6-COLD BROOK DAM-3 APPENDIX B6 - COLDBROOK DAM Release Prepared By:____JM By:____JM __ Prepared By:___ Reviewed JB ___ Inflow Top of Flood Control Top Zone (3651.4)

FIGURE 1 - COLDBROOK DAM POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX B6 - COLDBROOK DAM - 4 APPENDIX B6 - COLDBROOK DAM Prepared By:____JM By:____JM __ Prepared By:___ Reviewed JB ___ Top of Flood Control Top Zone (3651.4)

FIGURE 2 - COLDBROOK DAM HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX B6 - COLDBROOK DAM - 5 APPENDIX B6- COLD BROOK DAM

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APPENDIX B6- COLD BROOK DAM-6 APPENDIX B7-COTTONWOOD SPRINGS DAM

COTTONWOOD SPRINGS DAM AND LAKE FALL RIVER BASIN, SOUTH DAKOTA 2014 - 2015 REGULATION

1. Project Description and Water Control Plan. Cottonwood Springs Dam is located on Cottonwood Springs approximately 1/2 mile above its confluence with Hot Brook, a tributary of the Fall River. The site is located 4.5 miles west of Hot Springs, Fall River County, South Dakota. The purpose for the project is to provide flood protection for Hot Springs, South Dakota and along the Fall River. Appendix A gives pertinent data for this reservoir. Table 1 shows the storage zones for Cottonwood Springs Reservoir.

Table 1 Cottonwood Springs Reservoir Storage Allocations, 1971 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) PD (ac-ft) (ac-ft) Inactive 3832-3868 406 406 Multipurpose 3868-3875 257 663 Flood Control 3875-3936 7,752 8,415 Surcharge 3936-3950 3,221 -

2. Operation for Report Period. The reservoir pool began the year at elevation 3858.0 ft and slowly dropped through the winter and spring. Above average precipitation occurred throughout the summer, causing the reservoir pool to begin rising in early May. The pool continued its rise with increased groundwater inflows and finished the year at a peak pool elevation of 3859.3 ft.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2.

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 52 cfs 20-Aug-93 Lowest 3832.4 ft 30-Sep-89 2nd 10 cfs 21-Jun-95 2nd 3832.6 ft 03-Aug-90 3rd 8 cfs 01-Feb-97 3rd 3832.9 ft 15-Aug-93 Daily Outflow - Date c. Report Period No release since dam construction. Total Inflow Total Outflow 81 ac-ft 208% of norm 0 ac-ft Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 3872.7 ft 23-Mar-00 2 cfs 25-May-15 0 cfs 03-Oct-14 2nd 3871.6 ft 31-Jul-99 Peak Pool Elev Min Pool Elev 3rd 3869.7 ft 04-Jan-01 3859.3 ft 30-Sep-15 3856.9 ft 04-May-15

APPENDIX B7-COTTONWOOD SPRINGS DAM-1 APPENDIX B7 - COTTONWOOD DAM Prepared By:____JM By:____JM __ Prepared By:___ Reviewed JB ___ Inflow Release Top of Flood Control Top Zone (3936) of ConservationTop Zone (3875)

FIGURE 1 - COTTONWOOD DAM POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX B7 - COTTONWOOD DAM - 2 APPENDIX B7 - COTTONWOOD DAM Prepared By:____JM By:____JM __ Prepared By:___ Reviewed JB ___ Top of Flood Control Top Zone (3936) Release

FIGURE 2 - COTTONWOOD DAM HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX B7 - COTTONWOOD DAM - 3 APPENDIX B7- COTTONWOOD SPRINGS DAM

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APPENDIX B7- COTTONWOOD SPRINGS DAM-4 APPENDIX B8-KELLY ROAD DAM

KELLY ROAD DAM SAND CREEK BASIN, COLORADO 2014-2015 REGULATION

1. Project Description and Water Control Plan. Kelly Road Detention Dam is located on Westerly Creek, a tributary of Sand Creek and the South Platte River and provides flood control for the City of Aurora, Colorado. It is located entirely within the boundaries of the former Lowry Air Force Base. The project's sole purpose is flood control and was not designed to permanently store water. Water is automatically impounded by the project and released through a ground level 24-inch corrugated metal pipe (CMP) conduit or high overflow inlet. A gate on the 24-inch conduit is kept in the open position. The intended closure of the gate is to contain oil or other spills within the air base. After construction, dam ownership was turned over to the City of Aurora, CO. The City of Aurora is responsible for obtaining pool gage readings during flood periods and general observation of project operation.

The dry detention dam stores flood water that is slowly released over a weir structure located at elevation 5358.4 feet (240 ac-ft). The top of the chute spillway crest is located at elevation 5362 feet (360 ac-ft). The associated max release at this elevation is 570 cfs. Appendix A gives pertinent data for this reservoir.

2. Operation for Report Period. The above normal rainfall runoff experienced in Denver in May and June, summarized in detail in the Bear Creek, Chatfield and Cherry Creek operations, forced the reservoir to rise over 20 feet with a maximum inflow of approximately 3300 cfs and a maximum release of approximately 1800 cfs.

APPENDIX B8-KELLY ROAD DAM-1 APPENDIX B8- KELLY ROAD DAM

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APPENDIX B8-KELLY ROAD DAM-2 APPENDIX B9-WESTERLY CREEK DAM

WESTERLY CREEK DAM SAND CREEK BASIN, COLORADO 2014-2015 REGULATION

1. Project Description and Water Control Plan. Westerly Creek Dam is located approximately 0.8 miles upstream from the Kelly Road Dam on the southern edge of the former Lowry Air Force Base. Construction of Westerly Creek Dam was completed in July of 1991. Both the dam and the detention area are located within the confines of the former Lowry Air Force Base and were constructed for the purpose of flood control. The reservoir is generally dry and no permanent storage is provided. The reservoir is discharged by an orifice- controlled outlet structure and overflow spillway. The capacity of the outlet works is 98 cfs at a pool capacity elevation of 5431.4 ft. Discharge from the outlet works is governed by the capacity of the existing 48-inch RCP storm sewer running into the Kelly Road pool. The sluice gate is intended to remain open unless overtopping of the Kelly Road Dam is imminent or the downstream storm sewer capacity is exceeded due to inflows from the downstream drainage area. At this time the gate would be closed until downstream conditions permit releases from the Westerly Creek pool.

The dry detention dam stores flood water that is slowly released over a weir structure located at elevation 5389 feet (0 ac-ft). The top of the spillway crest is located at elevation 5419 feet (4,150 ac-ft). The associated max release at this elevation is 82 cfs. Appendix A gives pertinent data for this reservoir.

2. Land Transfer. As part of the closure of Lowry Air Force Base, lands on the base that are necessary for the continued function of the Westerly Creek Dam Project are being transferred to both public and private interests. The land transfer is being coordinated by the Lowry Redevelopment Authority (LRA). Westerly Creek Dam was constructed by the Corps of Engineers, as per a Local Cooperation Agreement (LCA) with the Urban Drainage and Flood Control District. The Westerly Creek Dam embankment and spillway footprint were transferred fee title to the Urban Drainage and Flood Control District and dam ownership has been turned over to them. Other areas necessary for the operation of the project such as areas along the downstream toe of the embankment and the pool area above elevation 5429 ft are being sold to private developers with a flowage easement and restrictions on the types of development that can occur.

3. Operation for Report Period. The above normal rainfall runoff experienced in Denver in May and June, summarized in detail in the Bear Creek, Chatfield and Cherry Creek operations, forced the reservoir to rise over 6 feet. No inflow and release records are available for this time period.

APPENDIX B9- WESTERLY CREEK DAM-1 APPENDIX B9- WESTERLY CREEK DAM

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APPENDIX B9- WESTERLY CREEK DAM-2 APPENDIX B10-PAPILLION CREEK DAM NO. 11

GLENN CUNNINGHAM DAM AND LAKE PAPILLION CREEK BASIN - NO. 11, NEBRASKA 2014-2015 REGULATION

1. Project Description and Water Control Plan. Papillion Creek Reservoir No. 11 dam construction began in 1973. The initial fill of the operating pool was on September 2, 1977. It is operated as a fill and spill reservoir with the authorized purposes of flood risk management, recreation, fish and wildlife enhancement, and water quality. Recreation is administered through the City of Omaha. The reservoir is located on Knight Creek in the Little Papillion Creek watershed. A lake rehabilitation project known as the Pawnee Wetland project was begun in October 2005 and completed in early 2009. The rehabilitation project, sponsored by the City of Omaha, removed sediment and constructed underwater features. This Pawnee Wetland project resulted in a labyrinth weir at the upper end of the pool to prevent sediment from entering the multi-purpose pool during routine storms. In addition to the uncontrolled service spillway, there is a gated outlet which is 30 inches by 30 inches square used as a low flow gate and an adjustable slide gate which can be used to draw the pool elevation down between 1117 and 1121 ft. The adjustable slide gate was installed during the lake rehabilitation project. Appendix A gives pertinent data for this reservoir. Table 1 shows the storage zones for Papio Creek Reservoir 11.

Table 1 Papio Creek Dam 11 Reservoir Storage Allocations, 2009 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) PD (ac-ft) (ac-ft) Multipurpose 1085-1121 3,015 3,015 Flood Control 1121-1142 13,573 16,588 Surcharge 1142-1147 5,397 -

2. Operation for Report Period. The reservoir operated in fill and spill mode during the report period. A series of intense storms in the area caused the reservoir to peak above its flood pool several times. A storm in early May dropped 3.5 inches of rain in the basin, resulting in the report period peak pool elevation of 1122.4 ft on May 8. The pool had evacuated to an elevation of 1121.6 when two more rainfall events in on June 11 and 15 dropped a total of 4.0 inches of rainfall, causing the pool to rise 0.5 feet to elevation 1122.1. The heaviest precipitation event occurred in early September, dropping over 5 inches in the basin causing the pool to rise 0.6 feet. However, due to the low pool elevation at the time, the pool peaked just above the base of the flood pool.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2.

APPENDIX B10- PAPILLION CREEK DAM NO. 11-1 APPENDIX B10-PAPILLION CREEK DAM NO. 11

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 931 cfs 07-Aug-99 Lowest 1100.9 ft 09-Jun-06 * 2nd 391 cfs 05-Jul-98 2nd 1100.9 ft 01-Jan-07 * 3rd 362 cfs 22-Jun-94 3rd 1100.9 ft 01-Jan-08 * Daily Outflow - Date Highest 157 cfs 8-Aug-99 c. Report Period 2nd 152 cfs 18-Jun-84 Total Inflow Total Outflow 3rd 116 cfs 16-Jun-80 8,628 ac-ft 130% of norm 7,710 ac-ft 142% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 1125.3 ft 07-Aug-99 159 cfs 08-May-15 48 cfs 09-May-15 2nd 1124.4 ft 17-Jun-84 Peak Pool Elev Min Pool Elev 3rd 1123.9 ft 15-Jun-98 1122.4 ft 08-May-15 1120.5 ft 15-Sep-15 *Due to pool drawdown for lake restoration work.

APPENDIX B10- PAPILLION CREEK DAM NO. 11-2 APPENDIX B10 - PAPILLION CREEK DAM NO. 11 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ ow fl n Ifl I Release Top of Flood Control Top Zone (1142)

FIGURE 1 - PAPILLION CREEK DAM NO. 11 POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX B10 - PAPILLION CREEK DAM NO. 11 - 3 APPENDIX B10 - PAPILLION CREEK DAM NO. 11 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ Top of Conservation Zone (1121) Top of Flood Control Top Zone (1142)

FIGURE 2 - PAPILLION CREEK DAM NO. 11 POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX B10 - PAPILLION CREEK DAM NO. 11 - 4 APPENDIX B11-PAPILLION CREEK DAM NO. 16

STANDING BEAR DAM AND LAKE PAPILLION CREEK BASIN - NO. 16, NEBRASKA 2014-2015 REGULATION

1. Project Description and Water Control Plan. Papillion Creek Reservoir No. 16 dam construction began in 1972. The initial fill of the operating pool was on October 24, 1977. It is operated as a fill and spill reservoir with the authorized purposes of flood risk management, recreation, fish and wildlife enhancement, and water quality. Recreation is administered through the City of Omaha. The reservoir is located on a tributary of the Big Papillion Creek. In addition to the uncontrolled service spillway, there is one gated outlet which is 30 inches by 30 inches square. Table 1 shows the storage zones for Papio Creek Reservoir 16. Appendix A gives pertinent data for this reservoir.

Table 1 Papio Creek Dam 16 Reservoir Storage Allocations, 2009 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) PD (ac-ft) (ac-ft) Multipurpose 1060-1104 1,141 1,141 Flood Control 1104-1121 3,532 4,673 Surcharge 1121-1127 2,051 -

2. Operation for Report Period. The reservoir operated in fill and spill mode throughout the report period. A series of intense storms in the area caused the reservoir to peak above its flood pool several times. A storm in early May dropped 3.5 inches of rain in the basin, resulting in the report period peak pool elevation of 1108.2 ft on May 7, 4.2 feet into the flood pool and the second highest historical daily peak elevation in the period of record. The highest historical average daily inflow in the period of record was also reached during this event, with an average flow of 277 cfs reached on May 7. Another precipitation event occurred on August 18, dropping over 2.5 inches in the basin, however, the dryer summer conditions limited the pool rise to 2 ft peaking, at elevation 1106.3 ft. One final late season rainfall event occurred on September 23-24 dropping a total of 2.5 inches in the basin causing the pool to rise 3 ft and peak at elevation 1106.7 ft.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2.

APPENDIX B11- PAPILLION CREEK DAM NO. 16-1 APPENDIX B11-PAPILLION CREEK DAM NO. 16

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 277 cfs 07-May-15 Lowest 1096.0 ft 28-Feb-91 2nd 266 cfs 14-Jun-84 2nd 1097.6 ft 06-Jun-90 3rd 235 cfs 08-Aug-87 3rd 1098.3 ft 09-Feb-82 Daily Outflow - Date Highest 65 cfs 16-Jun-84 c. Report Period 2nd 60 cfs 4-Sep-10 Total Inflow Total Outflow 3rd 57 cfs 12-Jun-08 4,213 ac-ft 250% of norm 3,627 ac-ft 301% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 1108.6 ft 12-Jun-08 277 cfs 07-May-15 53 cfs 08-May-15 2nd 1108.2 ft 07-May-15 Peak Pool Elev Min Pool Elev 3rd 1107.8 ft 16-Jun-84 1108.2 ft 07-May-15 1103.7 ft 11-Dec-14

APPENDIX B11- PAPILLION CREEK DAM NO. 16-2 APPENDIX B11 - PAPILLION CREEK DAM NO. 16 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ Inflow Release Top of ConservationTop Zone (1104) Top of Flood Control Top Zone (1121)

FIGURE 1 - PAPILLION CREEK DAM NO. 16 POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX B11 - PAPILLION CREEK DAM NO. 16 - 3 APPENDIX B11 - PAPILLION CREEK DAM NO. 16 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ Top of ConservationTop Zone (1104) Top of Flood Control Top Zone (1121)

FIGURE 2 - PAPILLION CREEK DAM NO. 16 HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX B11 - PAPILLION CREEK DAM NO. 16 - 4 APPENDIX B12-PAPILLION CREEK DAM NO. 18

ZORINSKY DAM AND LAKE PAPILLION CREEK BASIN - NO. 18, NEBRASKA 2014-2015 REGULATION

1. Project Description and Water Control Plan. Papillion Creek Reservoir No. 18 dam construction began on April 21, 1983. The initial fill of the operating pool was on April 22, 1992. It is operated as a fill and spill reservoir with the authorized purposes of flood risk management, recreation, fish and wildlife enhancement, and water quality. Recreation is administered through the City of Omaha. The reservoir is located on the Boxelder Creek in the West Branch Papillion Creek watershed. In addition to the uncontrolled service spillway, there is a low flow gated outlet which is 36 inches by 36 inches square. A 6-inch diameter opening at elevation 1104.25 ft on the intake structure provides a low flow augmentation release for downstream water quality. This opening can be regulated by a separate slide gate. Table 1 shows the storage zones for Papio Creek Reservoir 18. Appendix A gives pertinent data for this reservoir.

Table 1 Papio Creek Dam 18 Reservoirs Storage Allocations, 2007 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) PD (ac-ft) (ac-ft) Multipurpose 1060.5-1110.0 2,781 2,781 Flood Control 1110.0-1128.2 7,476 10,257 Surcharge 1128.2-1138.2 7,273 -

2. Operation for Report Period. The reservoir operated in fill and spill mode throughout the report period. A series of intense storms in the area caused the reservoir to peak above its flood pool several times. A storm in early May dropped 3.5 inches of rain in the basin, resulting in the report period peak pool elevation of 1115.0 ft on May 7, 5.0 feet into the flood pool and the second- highest historical daily peak elevation in the period of record. The peak daily average inflow for the report period of 684 cfs exceeded the last historical peak by over 100 cfs. The reservoir also reached the third highest daily average outflow during this event, releasing 117 cfs on May 8. The heaviest precipitation event occurred on August 18, dropping over 5 inches in the basin, however, the dryer summer conditions limited the pool rise to 3.5 ft peaking, at elevation 1113.7 ft. One final late season rainfall event occurred on September 23-24 dropping a total of 2.5 inches in the basin causing the pool to rise 2.5 ft and peak at elevation 1112.4 ft.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2.

APPENDIX B12- PAPILLION CREEK DAM NO. 18-1 APPENDIX B12-PAPILLION CREEK DAM NO. 18

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 684 cfs 07-May-15 Lowest 1091.7 ft 07-Apr-11 * 2nd 561 cfs 15-Jun-91 2nd 1102.7 ft 21-Sep-11 3rd 530 cfs 25-Jul-93 3rd 1105.2 ft 13-Dec-10 Daily Outflow - Date Highest 142 cfs 26-Jul-93 c. Report Period 2nd 119 cfs 13-Jun-08 Total Inflow Total Outflow 3rd 117 cfs 08-May-15 8,836 ac-ft 170% of norm 7,762 ac-ft Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 1116.8 ft 25-Jul-93 684 cfs 07-May-15 117 cfs 09-May-15 2nd 1115.0 ft 06-May-15 Peak Pool Elev Min Pool Elev 3rd 1114.6 ft 13-Jun-08 1115.0 ft 07-May-15 1109.9 ft 11-Dec-14 *Due to pool drawdown for zebra mussel control.

APPENDIX B12- PAPILLION CREEK DAM NO. 18-2 APPENDIX B12 - PAPILLION CREEK DAM NO. 18 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ Inflow Release Top of Flood Control Top Zone (1128.2)

FIGURE 1 - PAPILLION CREEK DAM NO. 18 POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX B12 - PAPILLION CREEK DAM NO. 18 - 3 APPENDIX B12 - PAPILLION CREEK DAM NO. 18 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ Top of ConservationTop Zone (1110) Top of Flood Control Top Zone (1128.2)

FIGURE 2 - PAPILLION CREEK DAM NO. 18 HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX B12 - PAPILLION CREEK DAM NO. 18 - 4 APPENDIX B13-PAPILLION CREEK DAM NO. 20

WEHRSPANN DAM AND LAKE PAPILLION CREEK BASIN - NO. 20, NEBRASKA 2014-2015 REGULATION

1. Project Description and Water Control Plan. Papillion Creek Reservoir No. 20 dam construction began on July 24, 1981. The initial fill of the operating pool was on May 26, 1987. It is operated as a fill and spill reservoir with the authorized purposes of flood risk management, recreation, fish and wildlife enhancement, and water quality. Recreation is administered through the Papio Natural Resources District. The reservoir is located on a tributary of the South Branch Papillion Creek in the West Branch Papillion Creek watershed. In addition to the uncontrolled service spillway, there is a low flow gated outlet which is 30 inches by 30 inches square. A 6-inch diameter opening at elevation 1090.0 feet on the intake structure provides a low flow augmentation release for downstream water quality. This opening can be regulated by a separate slide gate. Table 1 shows the storage zones for Papio Creek Reservoir 20. Appendix A gives pertinent data for this reservoir.

Table 1 Papio Creek Dam 20 Reservoir Storage Allocations, 2009 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) PD (ac-ft) (ac-ft) Multipurpose 1069-1095.83 2,309 2,309 Flood Control 1095.83-1113.1 6,203 8,512 Surcharge 1113.1-1125.8 7,980 -

2. Operation for Report Period. The reservoir operated in fill and spill mode throughout the report period. A series of intense storms in the area caused the reservoir to peak above its flood pool several times. The pool reached the report period peak elevation of 1098.0 ft on May 7 after a storm dropped almost 3.5 inches of rain in the basin. Another precipitation event occurred on August 18, dropping over 3 inches in the basin, however, the dryer summer conditions limited the pool rise to 2 ft peaking, at elevation 1096.8 ft. One final late season rainfall event occurred on September 23-24 dropping a total of 3 inches in the basin causing the pool to rise 3 ft and peak at elevation 1096.7 ft.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2.

APPENDIX B13- PAPILLION CREEK DAM NO. 20-1 APPENDIX B13-PAPILLION CREEK DAM NO. 20

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 678 cfs 28-Jun-93 Lowest 1085.4 ft 02-May-90 2nd 515 cfs 25-Aug-87 2nd 1085.9 ft 28-Jan-91 3rd 341 cfs 14-Jun-91 3rd 1086.9 ft 02-Jun-89 Daily Outflow - Date Highest 124 cfs 25-Jul-93 c. Report Period 2nd 82 cfs 12-Jun-08 Total Inflow Total Outflow 3rd 77 cfs 26-Aug-87 3,650 ac-ft 150% of norm 2,288 ac-ft Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 1103.2 ft 24-Jul-93 249 cfs 08-May-15 56 cfs 09-May-15 2nd 1099.5 ft 25-Aug-87 Peak Pool Elev Min Pool Elev 3rd 1098.9 ft 24-Jun-10 1098.0 ft 07-May-15 1095.5 ft 12-Dec-14

APPENDIX B13- PAPILLION CREEK DAM NO. 20-2 APPENDIX B13 - PAPILLION CREEK DAM NO. 20 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ Inflow Release Top of Conservation Zone (1095.8) Top of Flood Control Top Zone (1113.1)

FIGURE 1 - PAPILLION CREEK DAM NO. 20 POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX B13 - PAPILLION CREEK DAM NO. 20 - 3 APPENDIX B13 - PAPILLION CREEK DAM NO. 20 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ Top of ConservationTop Zone (1095.8) Top of Flood Control Top Zone (1113.1)

FIGURE 2 - PAPILLION CREEK DAM NO. 20 HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX B13 - PAPILLION CREEK DAM NO. 20 - 4 APPENDIX B14-PIPESTEM DAM

PIPESTEM DAM AND LAKE PIPESTEM CREEK, JAMES RIVER BASIN, NORTH DAKOTA 2014-2015 REGULATION

1. Project Description and Water Control Plan. Pipestem Dam is located on Pipestem Creek, a tributary of the James River in Jamestown, North Dakota. Appendix A gives pertinent data for this reservoir. Table 1 shows the storage zones for Pipestem Reservoir. Pipestem Reservoir is regulated as a system with Jamestown Reservoir, which is owned by the Bureau of Reclamation. The current water control plan was finalized at the end of 2002 and approved in October 2008. This plan was the product of a study initiated in 1996. Details of this plan are contained in the report “Jamestown and Pipestem Reservoirs Water Control Plan Review and Update, July 2000” and are summarized in Table 2.

Pipestem has two main gates which release water from a wet well. The wet well is fed from flow over a weir at elevation 1442.5 ft or through a low-level gate. Generally, when large releases are made the low-level gate is opened to release water from the bottom of the lake with low dissolved oxygen to improve water quality. The water flowing over the weir and from the low-level gate will mix in a wet well prior to going through the main gates. The low-level gate has historically been closed in the winter and fall, and the inflows were passed over the weir with the reservoir operating as a fill and spill project. Starting in 2014, a small winter release was made to improve water quality in the lake. When the pool level comes up and the flow over the weir increases the main gates are used to control the releases from the project.

Table 1 Pipestem Reservoir Storage Allocations, 2002 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) PD (ac-ft) (ac-ft) Inactive 1400.0-1415.0 0 0 Multipurpose 1415.0-1442.5 8,354 8,354 Flood Control 1442.5-1496.3 135,040 143,394 Surcharge 1496.3-1502.8 34,305 -

Table 2 Summary of the Range of Releases Estimated in Simulating Flood Control Regulation for the Period 1954 to 1998.* Typical Peak Annual Reservoir Normal Type of Forecasted Levels Normal Maximum Release Maximum Flow Calendar Year Jamestown Pipestem Pool Jamestown Combined Year Inflow Volume Pool Level Level Reservoir Pipestem Reservoir Release (ac-ft) (ft) (ft) (cfs) (cfs) (cfs) 1. High >160,000 Above 1445.4 Above 1489.0 1200-1800 1200-1800 1800 2. High >160,000 1440.0-1445.4 1478.2-1489.0 750-1200 750-1200 750-1800 3. High >160,000 Below 1440.0 1478.2-1489.0 450-750 750-1200 750-1200 4. Medium 160,000 – 90,000 Below 1440.0 Below 1478.2 450 450 450-750 5. Low 90, 000 – 0 Below 1433.0 Below 1460.0 200 120 200 * This table is not to be used as the final guide in determining releases under real time conditions.

APPENDIX B14- PIPESTEM DAM-1 APPENDIX B14-PIPESTEM DAM

2. Operation for Report Period. The water year began with average soil moisture conditions but dried out through the winter as below normal precipitation was received. A low level winter release of 10 cfs was continued throughout the winter to evacuate water with low dissolved oxygen from the bottom of the lake and improve water quality. Inflows remained steady around 10 cfs until January, when it dropped slightly. The pool elevation dropped below the top of the conservation pool in early January and continued to drop until spring snowmelt began.

Over the winter an average snowpack developed, with the peak occurring on March 5. The National Operational Hydrologic Remote Sensing Center (NOHRSC) modeled the peak to be about 1.0 inches of snow water equivalent (SWE) in the Jamestown basin and 1.5 inches of SWE in the Pipestem basin. Based on the peak snowpack on March 5 and assuming average summer rainfall, a spring forecast of near 100,000 acre-feet of flow volume past the James River at Jamestown gage was calculated, forecasting a medium flow year for the basin. Shortly after the initial forecast was created, warm weather permeated the basin and melted all the snow on the ground. While other snows left trace amounts of SWE in the upper basins, the snow never accumulated significantly again. In early April the forecast was modified to reflect the below- average precipitation received for the end of the winter and early spring. The new forecast fell within the criteria for a low flow year with an annual estimated flow volume past the Jamestown gage of 77,500 acre-feet resulting in a planned maximum combined release of less than 200 cfs. This forecast and the combined releases of less than 200 cfs were shared at the James River Annual Operations meeting on April 7 at Jamestown, ND. At the meeting, there were no concerns with the plan.

The peak inflow due to snowmelt was low. It was near 100 cfs at Pipestem and near 40 cfs at Jamestown. No releases were initiated from Jamestown until May when the reservoir entered the flood control pool. Releases from Pipestem reached a peak of 35 cfs in mid-March but were quickly reduced to 0 cfs to allow the pool to fill as the inflow began to drop. Above average rainfall was seen during the month of May both above and below the reservoirs, ranging from 150% of normal to 300% of normal. Several storms caused the pools to quickly rise to their peak pools for the year. Total May rainfall ranged from 4 to 6 inches above the reservoirs. Releases were initiated from Jamestown when it reached the base of the flood control pool in mid-May. The release was gradually increased to a maximum release of 300 cfs, which caused the pool to peak less than one foot into the flood pool at elevation 1431.8 ft. The pool was drawn down to the base of flood pool by the June 1 target, and at that time releases were reduced to match inflow. Pipestem pool elevation peaked on May 31 at 1452.4 ft. Releases were initiated from Pipestem Reservoir at 160 cfs and held until June 16. To slow the rate of evacuation of the flood pool, the release from Pipestem was gradually reduced to 120 cfs by June 18. The maximum

APPENDIX B14- PIPESTEM DAM-2 APPENDIX B14-PIPESTEM DAM

combined release during the report period was 300 cfs from Jamestown in late May.

In June and July, the upper basin dried out with below average precipitation, while normal to slightly above normal precipitation was seen in the lower part of the basin. Long travel times and runoff from below the reservoirs kept some downstream gaging stations in flood stage through some of the drier season as well. The James River at Columbia and Stratford gages were above flood stage from late May through part of July.

Rainfall on June 14, 17, and 23 resulted in Jamestown Reservoir rising back into the flood pool. Releases were increased from the reservoir to 130 cfs with the second storm. The flood pool was evacuated by the end of the month by holding the 130 cfs release. Pipestem Reservoir also rose with these storms, and releases were increased from 120 cfs to 135 cfs. On August 3 inflows had decreased enough that a ramp down of releases was initiated. The flood pool at Jamestown Reservoir was evacuated on August 28. Releases were reduced to 0 cfs by the end of the reporting period as dry conditions persisted and inflows dropped. A Pipestem winter release for water quality is planned but was delayed until further into winter to prevent the pool from dropping too much.

Figure 1 shows the flow volume past the James River at Jamestown gage for the period of record including the 2015 calendar year through September 2015. The 2015 calendar year flow volume was calculated to be 49,500 acre-feet. The months of October, November, and December were calculated using provisional data. While the annual flow volume matches a low flow year according to Table 2, the extremely above average rainfall through the month of May caused the maximum combined releases to exceed 200 cfs in order to meet the June 1 evacuation target at Jamestown Reservoir. There were no concerns through the City of Jamestown with the higher combined releases to meet this target.

The low level gate at Pipestem Reservoir was opened to release 10 cfs through the reporting period until the low level gate mechanism was replaced in August. The gate mechanism was replaced at that time and is now fully functioning. The low level gate was closed for the rest of the reporting period.

APPENDIX B14- PIPESTEM DAM-3 APPENDIX B14-PIPESTEM DAM

Figure 1. Flow Volume past the James River at Jamestown Gage for the Period of Record.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 2 and 3.

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 9232 cfs 15-Apr-09 Lowest 1439.7 ft 17-Feb-93 2nd 4374 cfs 16-Jul-93 2nd 1440.0 ft 01-Jan-77 3rd 4205 cfs 11-Apr-11 3rd 1440.1 ft 31-Jul-92 Daily Outflow - Date Highest 1422 cfs 10-May-09 c. Report Period 2nd 1081 cfs 7-Jul-2011 Total Inflow Total Outflow 3rd 1008 cfs 11-Oct-11 27,132 ac-ft 48% of norm 24,756 ac-ft Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 1492.2 ft 24-Apr-09 557 cfs 19-May-15 161 cfs 11-Jun-15 2nd 1488.7 ft 21-Aug-11 Peak Pool Elev Min Pool Elev 3rd 1487.0 ft 10-May-97 1452.4 ft 31-May-15 1442.0 ft 30-Sep-15

APPENDIX B14- PIPESTEM DAM-4 APPENDIX B14 - PIPESTEM DAM Release Prepared By:____JM By:____JM __ Prepared By:___ Reviewed JB ___ Inflow Top of Flood Control Top Zone (1496.3)

FIGURE 2 - PIPESTEM DAM POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX B14 - PIPESTEM DAM - 5 APPENDIX B14 - PIPESTEM DAM Prepared By:___ By:___ JM ___ Prepared By:___ Reviewed JB ___ Top of ConservationTop Zone (1442.5)

FIGURE 3 - PIPESTEM DAM HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX B14 - PIPESTEM DAM - 6 APPENDIX B15-SALT CREEK DAM NO. 2

OLIVE CREEK DAM AND LAKE SALT CREEK BASIN - NO. 2, NEBRASKA 2014-2015 REGULATION

1. Project Description and Water Control Plan. Salt Creek Dam No. 2 is located in Lancaster County, Nebraska on a tributary of the Olive Branch of Salt Creek approximately 6 road miles from Hallam, Nebraska and was closed on September 20, 1963. Table 1 shows the storage zones for the reservoir. It was designed to hold 9.1 inches of runoff in the flood control pool with a 510 cfs bank full channel capacity below the dam. It is operated as a fill and spill reservoir with the primary purpose of flood risk management. Recreation is administered through the Nebraska Game and Parks Commission. In addition to the uncontrolled service spillway, there is a low flow gated outlet which is 36 inches by 36 inches square. The reservoir also has a stop log structure to allow a pool level drawdown; the stop log dimensions are shown in Table 2. Each stop log is 58 inches in length. Appendix A gives pertinent data for this reservoir.

Table 1 Salt Creek Dam 2 Reservoir Storage Allocations, 1993 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) PD (ac-ft) (ac-ft) Sediment 1314.0-1335.0 1,100 1,100 Multipurpose - - 1,100 Flood Control 1335.0-1350.0 3,857 4,957 Surcharge 1350.0-1357.1 2,907 -

Table 2 Salt Creek Reservoir 2 Stop Log Configuration Stop Log Stop Log Height Inches Below Conservation Pool with Number (in) Board Removed 8 7 7 7 5 12 6 7 19 5 5 24 4 7 31 3 5 36 2 7 43 1 5 48

2. Operation for Report Period. The reservoir operated in fill and spill mode throughout the report period. On May 6-7, a significant rainfall event occurred over the Salt Creek Basin. An average of 4 inches of rain fell over the entire basin, with some areas receiving up to 8 inches. Due to an active weather pattern in the early spring, antecedent conditions for the basin were fairly saturated, leading to most of the rainfall running off rather than being absorbed by the soil. As a result of the rainfall, there was extensive flooding throughout the City of Lincoln and its suburbs. By 0600 on May 7, Salt Creek Dam 2 had reached an elevation of 1345.5, just 4.5 feet below the top of the flood control pool and the crest of the emergency spillway. Figure 1 shows the precipitation that fell over the Salt Creek Basin during the event.

APPENDIX B15- SALT CREEK DAM NO. 2-1 APPENDIX B15-SALT CREEK DAM NO. 2

Figure 1. Precipitation totals May 6-7 in the Salt Creek basin.

In response to the storm event, teams were dispatched throughout the City of Lincoln and the outlying dams to monitor the reservoirs, levees, and embankment structures. With many of the reservoirs nearing or exceeding record pools, quick forecasts were necessary to determine where the fastest response was needed. Since no forecasting tools were in place for the reservoirs, spreadsheets were used to determine forecasted peak pools based on estimated inflows. HMS models were ultimately developed for each of the Salt Creek reservoirs to be used in future forecasts which can predict peak pool elevations in response to rainfall events. Initial forecasts at Salt Creek Dam 2 showed the possibility of peaking near the spillway crest, so the reservoir was a high priority for monitoring.

The pool elevation for Olive Creek reached an hourly peak of 1345.6 ft on the morning of May 7 in response to the rainfall across the basin, with almost 63% of its flood pool occupied. The official daily data record reports the daily peak pool for the report period at 1345.3 ft at 2400 on May 7, a new historical record

APPENDIX B15- SALT CREEK DAM NO. 2-2 APPENDIX B15-SALT CREEK DAM NO. 2

elevation by almost 3 feet. The average daily inflow for May 7 to the reservoir was 813 cfs, the second highest daily inflow of record, with an hourly peak of 9,272 cfs. The average daily outflow was 133 cfs.

The active weather pattern persisted into June, continuing the flooding conditions throughout the Salt Creek Basin. Three rainfall events occurred on June 4, June 11, and June 15, keeping all of the reservoirs in the flood control pool. A second peak pool during the reporting period occurred in response to the June 4 event, at Olive Creek reaching an elevation of 1341.6 ft. These storms provided a good opportunity to test the recently created HMS forecast tools generated during the May event. The models were used to forecast the peak pool elevations and helped determine that no Salt Creek reservoirs were in danger of releasing through the emergency spillways.

Flood damages prevented for FY15 for the ten Salt Creek Dams totaled $75,816,200, almost equal to the cumulative flood damages prevented for the life of the projects through FY14. This brought the total cumulative flood damages prevented from the ten dams through FY15 to $153,903,900. In addition to the considerable flood damage prevention of the dams, the Antelope Creek Local Protection Project in Lincoln, NE also provided significant flood damage protection for FY15, again near the cumulative damages prevented for the life of the project through FY14. FY15 flood damages prevented for the Antelope Creek project totaled $31,220,900, bringing cumulative flood damages prevented through FY15 to $69,279,500. See Chapter 4 for other information on flood damages prevented for Omaha District projects.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 2 and 3. a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 920 cfs 24-May-04 Lowest 1324.3 ft 01-Dec-99 * 2nd 813 cfs 07-May-15 2nd 1324.3 ft 01-Jun-00 * 3rd 764 cfs 13-Jun-84 3rd 1326.3 ft 04-Jul-92 Daily Outflow - Date Highest 188 cfs 25-May-04 c. Report Period 2nd 179 cfs 26-Jul-93 Total Inflow Total Outflow 3rd 176 cfs 13-Oct-73 5,272 ac-ft 240% of norm 4,228 ac-ft 261% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 1345.3 ft 07-May-15 813 cfs 08-May-15 133 cfs 09-May-15 2nd 1342.6 ft 24-Jul-93 Peak Pool Elev Min Pool Elev 3rd 1342.6 ft 12-Jun-84 1345.3 ft 07-May-15 1332.3 ft 03-May-15 *Due to lake renovation and habitat enhancement.

APPENDIX B15- SALT CREEK DAM NO. 2-3 APPPENDIX B15 - SALT CREEK DAM NO. 2 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ Inflow Release Top of Flood Control Top Zone (1350)

FIGURE 1 - SALT CREEK DAM NO. 2 POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX B15 - SALT CREEK DAM NO. 2 - 4 APPENDIX B15 - SALT CREEK DAM NO. 2 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ Top of ConservationTop Zone (1335) Top of Flood Control Top Zone (1350)

FIGURE 2 - SALT CREEK DAM NO. 2 HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX B15 - SALT CREEK DAM NO. 2 - 5 APPENDIX B15-SALT CREEK DAM NO. 2

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APPENDIX B15- SALT CREEK DAM NO. 2-6 APPENDIX B16-SALT CREEK DAM NO. 4

BLUESTEM DAM AND LAKE SALT CREEK BASIN - NO. 4, NEBRASKA 2014-2015 REGULATION

1. Project Description and Water Control Plan. Salt Creek Dam No. 4 is located in Lancaster County, Nebraska on a tributary of the Olive Branch of Salt Creek approximately 2 miles west of Sprague, Nebraska and was closed on September 12, 1962. The reservoir was designed to hold 8.8 inches of runoff in the flood control pool with a 1,000 cfs bank full channel capacity below the dam. It is operated as a fill and spill reservoir with the primary purpose of flood risk management. Recreation is administered through the Nebraska Game and Parks Commission. In addition to the uncontrolled service spillway, there is a low flow gated outlet which is 36 inches by 36 inches square. Table 1 shows the storage zones for Salt Creek Reservoir 4. Appendix A gives pertinent data for this reservoir.

Table 1 Salt Creek Dam 4 Reservoir Storage Allocations, 1993 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) PD (ac-ft) (ac-ft) Sediment 1277.0-1306.1 2,146 2,146 Multipurpose 1306.1-1307.4 386 2,532 Flood Control 1307.4-1322.5 7,134 9,666 Surcharge 1322.5-1331.7 7,227 -

2. Operation for Report Period. The reservoir operated in fill and spill mode throughout the report period. On May 6-7, a significant rainfall event occurred over the Salt Creek Basin. An average of 4 inches of rain fell over the entire basin, with some areas receiving up to 8 inches. A full description of the event is contained in the Salt Creek Dam No. 2 – Olive Creek Lake Operation Summary in Appendix B15.

By 0600 on May 7, the pool elevation had reached 1316.0 ft, 6.5 feet below the crest of the emergency spillway. Initial forecasts showed the possibility of peaking near the spillway crest, so the reservoir was a high priority for monitoring. The pool elevation for Bluestem Lake reached an hourly peak of 1316.7 ft on the afternoon of May 7 in response to the rainfall across the basin, with over 53% of its flood pool occupied. The official daily data record reports the daily peak pool for the report period at 1316.3 ft at 2400 on May 7, the second highest pool elevation in the period of record. The average daily inflow for May 7 to the reservoir was 1,501 cfs, a new record daily inflow, with an hourly peak of 8,930 cfs. The average daily outflow was 277 cfs, the second highest daily outflow in the period of record, with a peak hourly release of 301 cfs.

The active weather pattern continued into June, continuing the flooding conditions throughout the Salt Creek Basin. A second peak pool during the reporting period occurred as a response to the rain event on June 15, reaching an elevation of 1314.1 ft.

APPENDIX B16- SALT CREEK DAM NO. 4-1 APPENDIX B16-SALT CREEK DAM NO. 4

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2.

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 1501 cfs 07-May-15 Lowest 1299.1 ft 28-Oct-91 2nd 1447 cfs 11-Oct-73 2nd 1299.5 ft 31-May-92 3rd 996 cfs 09-May-96 3rd 1299.9 ft 01-Sep-77 Daily Outflow - Date Highest 342 cfs 13-Oct-73 c. Report Period 2nd 277 cfs 08-May-15 Total Inflow Total Outflow 3rd 198 cfs 14-Jun-84 9,927 ac-ft 224% of norm 7,928 ac-ft 243% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 1316.5 ft 11-Oct-73 1501 cfs 08-May-15 277 cfs 09-May-15 2nd 1316.3 ft 07-May-15 Peak Pool Elev Min Pool Elev 3rd 1314.5 ft 13-Jun-84 1316.3 ft 07-May-15 1304.9 ft 01-Oct-14

APPENDIX B16- SALT CREEK DAM NO. 4-2 APPPENDIX B16 - SALT CREEK DAM NO. 4 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ Release Inflow Top of ConservationTop Zone (1307.4) Top of Flood Control Top Zone (1322.5)

FIGURE 1 - SALT CREEK DAM NO. 4 POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX B16 - SALT CREEK DAM NO. 4 - 3 APPPENDIX B16 - SALT CREEK DAM NO. 4 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ Top of ConservationTop Zone (1307.4) Top of Flood Control Top Zone (1322.5)

FIGURE 2 - SALT CREEK DAM NO. 4 HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX B16 - SALT CREEK DAM NO. 4 - 4 APPENDIX B17-SALT CREEK DAM NO. 8

WAGON TRAIN DAM AND LAKE SALT CREEK BASIN - NO. 8, NEBRASKA 2014-2015 REGULATION

1. Project Description and Water Control Plan. Salt Creek Dam No. 8 is located in Lancaster County, Nebraska on a tributary of the Hickman Branch of Salt Creek approximately 2 miles east of Hickman, Nebraska and was closed on September 24, 1962. Table 1 shows the storage zones for the reservoir. It was designed to hold 10.4 inches of runoff in the flood control pool with a 600 cfs bank full channel capacity below the dam. It is operated as a fill and spill reservoir with the primary purpose of flood risk management. Recreation is administered through the Nebraska Game and Parks Commission. In addition to the uncontrolled service spillway, there is a low flow gated outlet which is 36 inches by 36 inches square. The reservoir also has a stop log structure to allow a pool level drawdown; the stop log dimensions are shown in Table 2. Each stop log is 58 inches in length. Appendix A gives pertinent data for this reservoir.

Table 1 Salt Creek Dam 8 Reservoir Storage Allocations, 1993 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) PD (ac-ft) (ac-ft) Sediment 1260.0-1284.6 1,070 1,070 Multipurpose 1284.6-1287.8 710 1,780 Flood Control 1287.8-1302.0 6,595 8,375 Surcharge 1302.0-1309.8 5,947 -

Table 2 Salt Creek Reservoir 8 Stop Log Configuration Stop Log Height Inches Below Conservation Pool with Stop Log Number (in) Board Removed 11 7 7 10 5 12 9 5 17 8 5 22 7 7 29 6 5 34 5 7 41 4 7 48 3 7 55 2 7 62 1 7 69

2. Operation for Report Period. The reservoir operated in fill and spill mode throughout the report period. On May 6-7, a significant rainfall event occurred over the Salt Creek Basin. An average of 4 inches of rain fell over the entire basin, with some areas receiving up to 8 inches. A full description of the event is contained in the Salt Creek Dam No. 2 – Olive Creek Lake Operation Summary in Appendix B15.

The pool elevation for Wagon Train Lake reached an hourly peak of 1294.9 ft on the evening of May 7 in response to the rainfall across the basin, with almost 40% of its flood control pool occupied. This matches the official daily data record, and was the third highest elevation in the period of record. The average

APPENDIX B17- SALT CREEK DAM NO. 8-1 APPENDIX B17-SALT CREEK DAM NO. 8

daily inflow for May 7 to the reservoir was 1,237 cfs, a new historical record, with an hourly peak of 5,734 cfs. The average daily outflow was 249 cfs with a peak hourly release of 287 cfs.

The active weather pattern continued into June, continuing the flooding conditions throughout the Salt Creek Basin. A second peak pool during the reporting period occurred as a response to the rain event on June 15, reaching an elevation of 1292.6 ft.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2.

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 1237 cfs 07-May-15 Lowest 1273.1 ft 05-Apr-00 * 2nd 1199 cfs 11-Oct-73 2nd 1275.0 ft 19-Feb-01 * 3rd 1037 cfs 24-Jul-93 3rd 1275.5 ft 04-Apr-99 * Daily Outflow - Date Highest 334 cfs 25-Jul-93 c. Report Period 2nd 329 cfs 12-Oct-73 Total Inflow Total Outflow 3rd 280 cfs 06-Jun-08 9,249 ac-ft 177% of norm 7,199 ac-ft 170% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 1295.5 ft 05-Jun-08 1237 cfs 08-May-15 249 cfs 09-May-15 2nd 1295.4 ft 12-Oct-73 Peak Pool Elev Min Pool Elev 3rd 1294.9 ft 07-May-15 1294.9 ft 07-May-15 1287.0 ft 01-Oct-14 *Due to lake renovation and habitat enhancement.

APPENDIX B17- SALT CREEK DAM NO. 8-2 APPPENDIX B17 - SALT CREEK DAM NO. 8 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ Release Inflow Top of ConservationTop Zone (1287.8) Top of Flood Control Top Zone (1302)

FIGURE 1 - SALT CREEK DAM NO. 8 POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX B17 - SALT CREEK DAM NO. 8 - 3 APPPENDIX B17 - SALT CREEK DAM NO. 8 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ Top of Conservation Zone (1287.8) Top of Flood Control Top Zone (1302)

FIGURE 2 - SALT CREEK DAM NO. 8 HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX B17 - SALT CREEK DAM NO. 8 - 4 APPENDIX B18-SALT CREEK DAM NO. 9

STAGECOACH DAM AND LAKE SALT CREEK BASIN - NO. 9, NEBRASKA 2014-2015 REGULATION

1. Project Description and Water Control Plan. Salt Creek Dam No. 9 is located in Lancaster County, Nebraska on a tributary of the Hickman Branch of Salt Creek approximately 1 mile south of Hickman, Nebraska and was closed on August 27, 1963. The reservoir was designed to hold 9.1 inches of runoff in the flood control pool with a 1,200 cfs bank full channel capacity below the dam. It is operated as a fill and spill reservoir with the primary purpose of flood risk management. Recreation is administered through the Nebraska Game and Parks Commission. In addition to the uncontrolled service spillway, there is a low flow gated outlet which is 36 inches by 36 inches square. Table 1 shows the storage zones for Salt Creek Reservoir 9. Appendix A gives pertinent data for this reservoir.

Table 1 Salt Creek Dam 9 Reservoir Storage Allocations, 1990 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) PD (ac-ft) (ac-ft) Sediment 1246.0-1271.1 1,451 1,451 Multipurpose - - 1,451 Flood Control 1271.1-1285.0 4,413 5,864 Surcharge 1285.0-1291.6 3,578 -

Operation for Report Period. The reservoir operated in fill and spill mode throughout the report period. On May 6-7, a significant rainfall event occurred over the Salt Creek Basin. An average of 4 inches of rain fell over the entire basin, with some areas receiving up to 8 inches. A full description of the event is contained in the Salt Creek Dam No. 2 – Olive Creek Lake Operation Summary in Appendix B15.

The pool elevation for Stagecoach Lake reached an hourly peak of 1279.1 ft on the afternoon of May 7 in response to the rainfall across the basin, with over 46% of its flood pool occupied. The official daily data record reports the daily peak pool for the report period at 1278.9 ft at 2400 on May 7, the third highest daily pool in the period of record. The average daily inflow for May 7 to the reservoir was 897 cfs, the third highest daily inflow on record, with an hourly peak of 7,640 cfs. The average daily outflow was 133 cfs.

The active weather pattern continued into June, continuing the flooding conditions throughout the Salt Creek Basin. A second peak pool during the reporting period occurred as a response to a rain event on June 4, reaching an elevation of 1277.6 ft.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2.

APPENDIX B18- SALT CREEK DAM NO. 9-1 APPENDIX B18-SALT CREEK DAM NO. 9

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 1030 cfs 22-May-04 Lowest 1259.6 ft 31-Oct-91 2nd 958 cfs 10-Oct-73 2nd 1260.5 ft 09-Aug-76 3rd 897 cfs 06-May-15 3rd 1260.7 ft 07-Jan-92 Daily Outflow - Date Highest 193 cfs 06-Jun-08 c. Report Period 2nd 190 cfs 12-Oct-73 Total Inflow Total Outflow 3rd 180 cfs 24-May-04 6,002 ac-ft 186% of norm 4,846 ac-ft 190% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 1279.7 ft 05-Jun-08 897 cfs 07-May-15 133 cfs 08-May-15 2nd 1279.0 ft 11-Oct-73 Peak Pool Elev Min Pool Elev 3rd 1278.9 ft 07-May-15 1278.9 ft 07-May-15 1270.7 ft 12-Nov-14

APPENDIX B18- SALT CREEK DAM NO. 9-2 APPPENDIX B18 - SALT CREEK DAM NO. 9 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ Release Inflow Top of Flood Control Top Zone (1285)

FIGURE 1 - SALT CREEK DAM NO. 9 POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX B18 - SALT CREEK DAM NO. 9 - 3 APPPENDIX B18 - SALT CREEK DAM NO. 9 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ Top of ConservationTop Zone (1271.1) Top of Flood Control Top Zone (1285)

FIGURE 2 - SALT CREEK DAM NO. 9 HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX B18 - SALT CREEK DAM NO. 9 - 4 APPENDIX B19-SALT CREEK DAM NO. 10

YANKEE HILL DAM AND LAKE SALT CREEK BASIN - NO. 10, NEBRASKA 2014-2015 REGULATION

1. Project Description and Water Control Plan. Salt Creek Dam No. 10 is located in Lancaster County, Nebraska on Cardwell Branch, a tributary of Salt Creek approximately 4 road miles from Denton, Nebraska and was closed on October 5, 1965. Table 1 shows the storage zones for the reservoir. It was designed to hold 12.4 inches of runoff in the flood control pool with a 540 cfs bank full channel capacity below the dam. It is operated as a fill and spill reservoir with the primary purpose of flood risk management. Recreation is administered through the Nebraska Game and Parks Commission. In addition to the uncontrolled service spillway, there is a low flow gated outlet which is 30 inches by 42 inches. The reservoir also has a stop log structure to allow a pool level drawdown; the stop log dimensions are shown in Table 2. Each stop log is 58 inches in length. Appendix A gives pertinent data for this reservoir.

Table 1 Salt Creek Dam 10 Reservoir Storage Allocations, 1994 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) PD (ac-ft) (ac-ft) Sediment 1218.0-1241.9 1,058 1,058 Multipurpose 1241.9-1244.9 571 1,629 Flood Control 1244.9-1262.0 5,839 7,468 Surcharge 1262.0-1267.8 3,225 -

Table 2 Salt Creek Reservoir 10 Stop Log Configuration Stop Log Height Inches Below Conservation Pool with Stop Log Number (in) Board Removed 6 6.5 6.5 5 6.5 13 4 6.5 19.5 3 6.5 26 2 6.5 32.5 1 6.5 39

Operation for Report Period. The reservoir operated in fill and spill mode throughout the report period. On May 6-7, a significant rainfall event occurred over the Salt Creek Basin. An average of 4 inches of rain fell over the entire basin, with some areas receiving up to 8 inches. A full description of the event is contained in the Salt Creek Dam No. 2 – Olive Creek Lake Operation Summary in Appendix B15.

The pool elevation for Yankee Hill Lake reached an hourly peak of 1253.6 ft on the afternoon of May 7 in response to the rainfall across the basin, with almost 41% of its flood pool occupied. The official daily data record reports the daily peak pool for the report period at 1253.5 ft, a new historical record elevation by over a foot. The average daily inflow for May 7 to the reservoir was 896 cfs, a new historical record, with an hourly peak of 4,911 cfs. The average daily outflow was 138 cfs, the second highest daily outflow in the period of record.

APPENDIX B19- SALT CREEK DAM NO. 10-1 APPENDIX B19-SALT CREEK DAM NO. 10

The active weather pattern continued into June, continuing the flooding conditions throughout the Salt Creek Basin. A second peak pool during the reporting period occurred as a response to the rain event on June 15, reaching an elevation of 1252.2 ft, the third highest pool in the period of record.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2.

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 896 cfs 06-May-15 Lowest 1232.0 ft 26-Oct-03 * 2nd 690 cfs 10-Oct-73 2nd 1233.8 ft 09-Mar-03 * 3rd 609 cfs 23-Jul-93 3rd 1236.5 ft 21-Aug-02 * Daily Outflow - Date Highest 145 cfs 12-Oct-73 c. Report Period 2nd 138 cfs 07-May-15 Total Inflow Total Outflow 3rd 133 cfs 24-Jul-93 8,287 ac-ft 176% of norm 7,373 ac-ft 184% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 1253.5 ft 06-May-15 896 cfs 07-May-15 138 cfs 08-May-15 2nd 1252.3 ft 11-Oct-73 Peak Pool Elev Min Pool Elev 3rd 1252.1 ft 14-Jun-15 1253.5 ft 07-May-15 1244.0 ft 30-Sep-15 *Due to lake renovation and habitat enhancement.

APPENDIX B19- SALT CREEK DAM NO. 10-2 APPENDIX B19 - SALT CREEK DAM NO. 10 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ Release Inflow Top of Flood Control Top Zone (1262)

FIGURE 1 - SALT CREEK DAM NO. 10 POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX B19 - SALT CREEK DAM NO. 10 - 3 APPENDIX B19 - SALT CREEK DAM NO. 10 Prepared By:___ By:___ JBPrepared _ By:___ Reviewed MN ___ Top of ConservationTop Zone (1244.9) Top of Flood Control Top Zone (1262)

FIGURE 2 - SALT CREEK DAM NO. 10 HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX B19 - SALT CREEK DAM NO. 10 - 4 APPENDIX B20-SALT CREEK DAM NO. 12

CONESTOGA DAM AND LAKE SALT CREEK BASIN - NO. 12, NEBRASKA 2014-2015 REGULATION

1. Project Description and Water Control Plan. Salt Creek Dam No. 12 is located in Lancaster County, Nebraska on Holmes Creek, which flows into Haines Branch, a tributary of Salt Creek approximately 2 miles north of Denton, Nebraska and was closed on September 24, 1963. The reservoir was designed to hold 10.0 inches of runoff in the flood control pool with a 1,400 cfs bank full channel capacity below the dam. It is operated as a fill and spill reservoir with the primary purpose of flood risk management. Recreation is administered through the Nebraska Game and Parks Commission. In addition to the uncontrolled service spillway, there is a low flow gated outlet which is 36 inches by 36 inches. Table 1 shows the storage zones for the reservoir. Appendix A gives pertinent data for this reservoir.

A deviation request was submitted and approved in FY13 to draw down the reservoir to the low level gate invert elevation of 1228.0 ft for an outlet works modification and eventual lake rehabilitation. After the completion of a favorable Environmental Assessment, a second deviation would be necessary for pumping out the rest of the lake. The low level gate was opened on October 1, 2013, and has remained open all of FY14 and FY15 as the Nebraska Game and Parks Commission went through the Corps approval process for the modification. The second deviation for a full drawdown was approved at the end of FY15, and the outlet works modification is scheduled for completion by December 2015. The lake rehabilitation is still in the design and contracting process.

Table 1 Salt Creek Dam 12 Reservoir Storage Allocations, 1996 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) PD (ac-ft) (ac-ft) Sediment 1197.0-1232.9 1,808 1,808 Multipurpose - - 1,808 Flood Control 1232.9-1252.0 7,607 9,415 Surcharge 1252.0-1258.2 3,927 -

Operation for Report Period. The reservoir operated in fill and spill mode near the low level gate invert elevation throughout the report period. On May 6-7, a significant rainfall event occurred over the Salt Creek Basin. An average of 4 inches of rain fell over the entire basin, with some areas receiving up to 8 inches. A full description of the event is contained in the Salt Creek Dam No. 2 – Olive Creek Lake Operation Summary in Appendix B15.

The pool elevation for Conestoga Lake reached an hourly peak of 1238.6 ft for this event on the morning of May 8, with almost 20% of its flood pool occupied. The average daily inflow for May 7 to the reservoir was 1,053 cfs, the highest daily inflow of record, with an hourly peak of 4,571 cfs.

APPENDIX B20- SALT CREEK DAM NO. 12-1 APPENDIX B20-SALT CREEK DAM NO. 12

The active weather pattern continued into June, continuing the flooding conditions throughout the Salt Creek Basin. The peak hourly elevation for the reporting period occurred in response to a rain event on June 15. The pool reached an hourly peak elevation of 1240.2 ft, with almost 28% of its flood pool occupied. The official daily data record reports the daily peak pool for the report period at 1239.9 ft from a June 11 storm, the third highest pool elevation in the period of record for Conestoga Lake. The average daily outflow reached the third highest in the period of record at 162 cfs.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2. a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 1053 cfs 07-May-15 Lowest 1224.9 ft 22-Apr-07 2nd 899 cfs 23-Jul-93 2nd 1225.0 ft 28-Dec-06 3rd 693 cfs 17-May-74 3rd 1227.6 ft 24-Aug-14 Daily Outflow - Date Highest 185 cfs 25-Mar-87 c. Report Period 2nd 180 cfs 24-Jul-93 Total Inflow Total Outflow 3rd 162 cfs 15-Jun-15 13,220 ac-ft 286% of norm 12,593 ac-ft 323% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 1241.1 ft 24-Mar-87 1053 cfs 07-May-15 162 cfs 15-Jun-15 2nd 1240.6 ft 23-Jul-93 Peak Pool Elev Min Pool Elev 3rd 1239.9 ft 11-Jun-15 1239.9 ft 11-Jun-15 1228.4 ft 07-Mar-15

APPENDIX B20- SALT CREEK DAM NO. 12-2 APPENDIX B20 - SALT CREEK DAM NO. 12 Prepared By:___ By:___ JBPrepared _ By:___ Reviewed MN ___ Release Inflow Top of Flood Control Top Zone (1252)

FIGURE 1 - SALT CREEK DAM NO. 12 POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX B20 - SALT CREEK DAM NO. 12 - 3 APPENDIX B20 - SALT CREEK DAM NO. 12 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ Top of ConservationTop Zone (1232.9) Top of Flood Control Top Zone (1252)

FIGURE 2 - SALT CREEK DAM NO. 12 HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX B20 - SALT CREEK DAM NO. 12 - 4 APPENDIX B21-SALT CREEK DAM NO. 13

TWIN LAKES DAM AND LAKE SALT CREEK BASIN - NO. 13, NEBRASKA 2014-2015 REGULATION

1. Project Description and Water Control Plan. Salt Creek Dam No. 13 is located in Seward County, Nebraska on a tributary of the South Branch of Middle Creek, which is a tributary of Salt Creek. The dam is comprised of two embankments that are joined by a cut channel; the outlet works for the east embankment serve both dams. Dam closure was on August 1, 1965 for the east embankment and September 26, 1965 for the west embankment. The embankments are located on separate tributaries of Middle Creek, a tributary of Salt Creek. The reservoir was designed to hold 8.9 inches of runoff in the flood control pool with a 3,200 cfs bank full channel capacity below the dam. It is operated as a fill and spill reservoir with the primary purpose of flood risk management. Recreation is administered through the Nebraska Game and Parks Commission. In addition to the uncontrolled service spillway, there is a low flow gated outlet which is 42 inches by 54 inches. Table 1 shows the storage zones for Salt Creek Reservoir 13. Appendix A gives pertinent data for this reservoir.

Table 1 Salt Creek Dam 13 Reservoir Storage Allocations, 1994 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) PD (ac-ft) (ac-ft) Sediment 1306.0-1337.4 1,414 1,414 Multipurpose 1337.4-1341.0 747 2,161 Flood Control 1341.0-1355.0 5,028 7,189 Surcharge 1355.0-1361.6 3,721 -

2. Operation for Report Period. The reservoir operated in fill and spill mode throughout the report period. On May 6-7, a significant rainfall event occurred over the Salt Creek Basin. An average of 4 inches of rain fell over the entire basin, with some areas receiving up to 8 inches. A full description of the event is contained in the Salt Creek Dam No. 2 – Olive Creek Lake Operation Summary in Appendix B15.

The pool elevation for Twin Lakes reached an hourly peak of 1344.8 ft late morning on May 7 in response to the rainfall across the basin, with almost 20% of its flood pool occupied. The average daily inflow for May 7 to the reservoir was 515 cfs with an hourly peak of 2,136 cfs. The average daily outflow was 134 cfs.

The active weather pattern continued into June, continuing the flooding conditions throughout the Salt Creek Basin. The peak hourly elevation for the reporting period occurred in response to a rain event on June 15. The pool reached an hourly peak elevation of 1345.3 ft, with almost 23% of its flood pool occupied. The official daily data record reports the daily peak pool for the report period at 1345.1 ft.

APPENDIX B21- SALT CREEK DAM NO. 13-1 APPENDIX B21-SALT CREEK DAM NO. 13

Historical as well as reporting period details are contained paragraphs 2a through 2c and Figures 1 and 2.

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 632 cfs 13-Jul-93 Lowest 1332.1 ft 31-Oct-91 2nd 551 cfs 06-May-07 2nd 1332.2 ft 18-Aug-89 3rd 539 cfs 23-Mar-87 3rd 1332.3 ft 15-May-92 Daily Outflow - Date Highest 168 cfs 30-Jun-83 c. Report Period 2nd 166 cfs 25-Mar-87 Total Inflow Total Outflow 3rd 165 cfs 27-Jul-93 5,016 ac-ft 144% of norm 4,082 ac-ft 154% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 1346.9 ft 29-Jun-83 515 cfs 07-May-15 134 cfs 15-Jun-15 2nd 1346.0 ft 23-Mar-87 Peak Pool Elev Min Pool Elev 3rd 1345.6 ft 26-Jul-93 1345.1 ft 15-Jun-15 1340.8 ft 13-Nov-14

APPENDIX B21- SALT CREEK DAM NO. 13-2 APPENDIX B21 - SALT CREEK DAM NO. 13 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ Release Inflow Top of ConservationTop Zone (1341) Top of Flood Control Top Zone (1355)

FIGURE 1 - SALT CREEK DAM NO. 13 POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX B21 - SALT CREEK DAM NO. 13 - 3 APPENDIX B21 - SALT CREEK DAM NO. 13 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ Top of ConservationTop Zone (1341) Top of Flood Control Top Zone (1355)

FIGURE 2 - SALT CREEK DAM NO. 13 HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX B21 - SALT CREEK DAM NO. 13 - 4 APPENDIX B22-SALT CREEK DAM NO. 14

PAWNEE DAM AND LAKE SALT CREEK BASIN - NO. 14, NEBRASKA 2014-2015 REGULATION

1. Project Description and Water Control Plan. Salt Creek Dam No. 14 is located in Lancaster County, Nebraska on a tributary of Middle Creek a tributary of Salt Creek and was closed on July 16, 1964. The reservoir was designed to hold 10.9 inches of runoff in the flood control pool with a 3,000 cfs bank full channel capacity below the dam. It is operated as a fill and spill reservoir with the primary purpose of flood risk management. Recreation is administered through the Nebraska Game and Parks Commission. In addition to the uncontrolled service spillway, there is a low flow gated outlet which is 42 inches by 60 inches. Table 1 shows the storage zones for Salt Creek Reservoir 14. Appendix A gives pertinent data for this reservoir.

Table 1 Salt Creek Dam 14 Reservoir Storage Allocations, 1991 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) PD (ac-ft) (ac-ft) Sediment 1206.0-1244.3 7,500 7,500 Multipurpose - - 7,500 Flood Control 1244.3-1263.5 20,097 27,597 Surcharge 1263.5-1269.1 8,549 -

2. Operation for Report Period. The reservoir operated in fill and spill mode throughout the report period. On May 6-7, a significant rainfall event occurred over the Salt Creek Basin. An average of 4 inches of rain fell over the entire basin, with some areas receiving up to 8 inches. A full description of the event is contained in the Salt Creek Dam No. 2 – Olive Creek Lake Operation Summary in Appendix B15.

Pawnee Lake was on the northern edge of the storms during the May event, receiving 3 to 4 inches of rain rather than those basins that saw rainfall totals between 5 and 8 inches. The pool elevation for Pawnee Lake reached an hourly peak elevation for the reporting period at 1246.3 ft on the afternoon of May 7 in response to the rainfall across the basin, with just over 7% of the flood pool occupied. The average daily inflow for May 7 to the reservoir was 577 cfs with an hourly peak of 2,220 cfs.

The active weather pattern continued into June, continuing the flooding conditions throughout the Salt Creek Basin. The peak hourly elevation for the reporting period occurred in response to a rain event on June 15. The pool reached an hourly peak elevation of 1246.3 ft, matching its hourly peak from the May event. The official daily data record reports the daily peak pool for the report period at 1246.2 ft.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2.

APPENDIX B22- SALT CREEK DAM NO. 14-1 APPENDIX B22-SALT CREEK DAM NO. 14

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 1381 cfs 24-Mar-87 Lowest 1240.2 ft 14-Oct-79 2nd 1347 cfs 13-Jul-93 2nd 1241.1 ft 13-Dec-12 3rd 1113 cfs 05-May-07 3rd 1241.1 ft 07-Dec-06 Daily Outflow - Date Highest 420 cfs 25-Jul-93 c. Report Period 2nd 419 cfs 25-Mar-87 Total Inflow Total Outflow 3rd 311 cfs 13-Jun-84 5,853 ac-ft 87% of norm 3,009 ac-ft 71% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 1249.1 ft 25-Jul-93 577 cfs 07-May-15 139 cfs 15-Jun-15 2nd 1248.4 ft 24-Mar-87 Peak Pool Elev Min Pool Elev 3rd 1247.1 ft 12-Jun-84 1246.2 ft 15-Jun-15 1244.2 ft 03-Dec-14

APPENDIX B22- SALT CREEK DAM NO. 14-2 APPENDIX B22 - SALT CREEK DAM NO. 14 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ Release Top of ConservationTop Zone (1244.3) Inflow Top of Flood Control Top Zone (1263.5)

FIGURE 1 - SALT CREEK DAM NO. 14 POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX B22 - SALT CREEK DAM NO. 14 - 3 APPENDIX B22 - SALT CREEK DAM NO. 14 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ Top of ConservationTop Zone (1244.3) Top of Flood Control Top Zone (1263.5)

FIGURE 2 - SALT CREEK DAM NO. 14 HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX B22 - SALT CREEK DAM NO. 14 - 4 APPENDIX B23-SALT CREEK DAM NO. 17

ANTELOPE CREEK DAM AND HOLMES PARK LAKE SALT CREEK BASIN - NO. 17, NEBRASKA 2014-2015 REGULATION

1. Project Description and Water Control Plan. Salt Creek Dam No. 17 is located on Antelope Creek a tributary to Salt Creek in the southeast portion of the city of Lincoln, Nebraska and was closed on August 1, 1962 for the south embankment and September 17, 1962 for the north embankment. Table 1 shows the storage zones for the reservoir. It was designed to hold 20.1 inches of runoff in the flood control pool. It is operated as a fill and spill reservoir with the primary purpose of flood risk management. Recreation is administered through the City of Lincoln. In addition to the uncontrolled service spillway, there is a low flow gated outlet which is 36 inches by 36 inches. The reservoir also has a stop log structure to allow a pool level drawdown; the stop log dimensions are shown in Table 2. Each stop log is 36 inches in length. Appendix A gives pertinent data for this reservoir.

Table 1 Salt Creek Dam 17 Reservoir Storage Allocations, 1993 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) PD (ac-ft) (ac-ft) Sediment 1218.0-1240.0 538 538 Multipurpose 1240.0-1242.4 220 758 Flood Control 1242.4-1266.0 5,870 6,628 Surcharge 1266.0-1269.7 1,490 -

Table 2 Salt Creek Reservoir 17 Stop Log Configuration Stop Log Height Inches Below Conservation Pool with Stop Log Number (in) Board Removed 7 6 6 6 6 12 5 6 18 4 6 24 3 6 30 2 6 36 1 6 42

2. Operation for Report Period. The reservoir operated in fill and spill mode throughout the report period. On May 6-7, a significant rainfall event occurred over the Salt Creek Basin. An average of 4 inches of rain fell over the entire basin, with some areas receiving up to 8 inches. A full description of the event is contained in the Salt Creek Dam No. 2 – Olive Creek Lake Operation Summary in Appendix B15.

Holmes Lake was on the northern edge of the storms during the May event, receiving 3 to 4 inches of rain rather than those basins that saw rainfall totals between 5 and 8 inches. Though the basin received less rainfall, the urban location of the watershed caused faster and higher runoff amounts, leading to more volume stored in the flood pool than reservoirs receiving the same amounts of rain. The pool elevation for Holmes Lake reached an hourly peak of 1250.2 ft

APPENDIX B23- SALT CREEK DAM NO. 17-1 APPENDIX B23-SALT CREEK DAM NO. 17

on the morning of May 7 in response to the rainfall across the basin, with over 21% of its flood pool occupied. The official daily data record reports the daily peak pool for the report period at 1249.2 ft on May 7, the second highest daily elevation in the period of record. The average daily inflow for May 7 to the reservoir was 282 cfs with an hourly peak of 3,033 cfs. The average daily outflow was 115 cfs with a peak hourly release of 158 cfs.

The active weather pattern continued into June, continuing the flooding conditions throughout the Salt Creek Basin. A second peak pool during the reporting period occurred in response to a rain event on June 11, at Holmes Lake reaching an elevation of 1247.3 ft.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2. a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 604 cfs 24-Jul-93 Lowest 1231.0 ft 01-Oct-03 2nd 567 cfs 08-Sep-89 2nd 1231.0 ft 01-Oct-04 3rd 451 cfs 20-Jul-96 3rd 1231.0 ft 01-Oct-05 Daily Outflow - Date Highest 187 cfs 29-Jun-83 c. Report Period 2nd 174 cfs 25-Jul-93 Total Inflow Total Outflow 3rd 140 cfs 09-Sep-89 6,226 ac-ft 190% of norm 5,567 ac-ft 199% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 1250.0 ft 24-Jul-93 300 cfs 12-Jun-15 115 cfs 08-May-15 2nd 1249.2 ft 07-May-15 Peak Pool Elev Min Pool Elev 3rd 1249.1 ft 08-Sep-89 1249.2 ft 07-May-15 1240.1 ft 03-Aug-15

APPENDIX B23- SALT CREEK DAM NO. 17-2 APPENDIX B23 - SALT CREEK DAM NO. 17 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ Release Inflow Top of Flood Control Top Zone (1266)

FIGURE 1 - SALT CREEK DAM NO. 17 POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX B23 - SALT CREEK DAM NO. 17 - 3 APPENDIX B23 - SALT CREEK DAM NO. 17 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ Top of ConservationTop Zone (1242.4) Top of Flood Control Top Zone (1266)

FIGURE 2 - SALT CREEK DAM NO. 17 HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX B23 - SALT CREEK DAM NO. 17 - 4 APPENDIX B24-SALT CREEK DAM NO. 18

BRANCHED OAK DAM AND LAKE SALT CREEK BASIN - NO. 18, NEBRASKA 2014-2015 REGULATION

1. Project Description and Water Control Plan. Salt Creek Dam No. 18 is located in Lancaster County, Nebraska at the confluence of the Middle Oak Creek and Oak Creek, tributaries of North Oak Creek which flows into Salt Creek and was closed on December 31, 1967. The reservoir was designed to hold 15.1 inches of runoff in the flood control pool with a 4,100 cfs bank full channel capacity below the dam. It is operated as a fill and spill reservoir with the primary purpose of flood risk management. Recreation is administered through the Nebraska Game and Parks Commission. In addition to the uncontrolled service spillway, there is a low flow gated outlet which is 48 inches by 72 inches. A downstream water-rights holder can request a release through the Nebraska Department of Water Resources. This water-right is released through a 10 inch gate located on the intake structure at elevation 1276.3 ft. Table 1 shows the storage zones for Salt Creek Reservoir 18. Appendix A gives pertinent data for this reservoir.

Table 1 Salt Creek Dam 18 Reservoir Storage Allocations, 1991 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) PD (ac-ft) (ac-ft) Sediment 1250.0-1275.7 12,364 12,364 Multipurpose 1275.7-1284.0 12,724 25,088 Flood Control 1284.0-1311.0 71,671 96,759 Surcharge 1311-1317.3 24,714 -

2. Operation for Report Period. The reservoir operated in fill and spill mode throughout the report period. On May 6-7, a significant rainfall event occurred over the Salt Creek Basin. An average of 4 inches of rain fell over the entire basin, with some areas receiving up to 8 inches. A full description of the event is contained in the Salt Creek Dam No. 2 – Olive Creek Lake Operation Summary in Appendix B15.

Branched Oak Lake was on the northern edge of the storms during the May event, receiving 3 to 4 inches of rain rather than those basins that saw rainfall totals between 5 and 8 inches. The pool elevation for Branched Oak Lake reached an hourly peak of 1286.1 ft on the afternoon of May 8 in response to the rainfall across the basin, with over 5% of its flood pool occupied. This matches the official daily data record. The average daily inflow for May 7 to the reservoir was 1,568 cfs with an hourly peak of 2,768 cfs. The average daily outflow was 228 cfs with a peak hourly release of 234 cfs.

The active weather pattern continued into June, continuing the flooding conditions throughout the Salt Creek Basin. A second peak pool during the reporting period occurred in response to a rain event on June 11, at Branched Oak Lake reaching an elevation of 1285.2 ft.

APPENDIX B24- SALT CREEK DAM NO. 18-1 APPENDIX B24-SALT CREEK DAM NO. 18

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2.

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 3700 cfs 25-Aug-87 Lowest 1278.2 ft 24-Oct-04 2nd 1945 cfs 22-May-98 2nd 1278.3 ft 24-Dec-03 3rd 1820 cfs 23-Jul-93 3rd 1278.4 ft 12-Jan-02 Daily Outflow - Date Highest 774 cfs 25-Jul-93 c. Report Period 2nd 730 cfs 26-Aug-87 Total Inflow Total Outflow 3rd 670 cfs 19-Jun-83 23,443 ac-ft 95% of norm 17,408 ac-ft 94% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 1287.9 ft 26-Aug-87 1568 cfs 08-May-15 228 cfs 10-May-15 2nd 1287.8 ft 24-Jul-93 Peak Pool Elev Min Pool Elev 3rd 1287.7 ft 18-Jun-83 1286.1 ft 08-May-15 1283.6 ft 14-Jul-15

APPENDIX B24- SALT CREEK DAM NO. 18-2 APPENDIX B24 - SALT CREEK DAM NO. 18 Prepared By:____JB By:____JB __ Prepared By:___ Reviewed MN ___ Release Inflow Top of Flood Control Top Zone (1311)

FIGURE 1 - SALT CREEK DAM NO. 18 POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX B24 - SALT CREEK DAM NO. 18 - 3 APPENDIX B24 - SALT CREEK DAM NO. 18 Prepared By:___JB By:___JB ___ Prepared By:__MN Reviewed ___ Top of ConservationTop Zone (1284) Top of Flood Control Top Zone (1311)

FIGURE 2 - SALT CREEK DAM NO. 18 HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX B24 - SALT CREEK DAM NO. 18 - 4 APPENDIX B25-SNAKE CREEK DAM (LAKE AUDUBON)

SNAKE CREEK DAM AND LAKE AUDUBON LAKE SAKAKAWEA SUBIMPOUNDMENT MISSOURI RIVER BASIN, NORTH DAKOTA 2014-2015 REGULATION

1. Project Description and Water Control Plan. Lake Audubon, a subimpoundment of Garrison Reservoir (Lake Sakakawea), is located 8 miles northeast of Riverdale, North Dakota. Impounded by the "Snake Creek Embankment," the lake was constructed in 1954 with the primary purpose of relocating U.S. Highway 83 and a railroad across the Snake Creek arm of Garrison Reservoir. Lake Audubon also provides for the dual purpose of fish and wildlife enhancement, and diversion of water into McClusky Canal for irrigation purposes. The lake is operated in cooperation with the Bureau of Reclamation (Reclamation), U.S. Fish and Wildlife Service (FWS), and the North Dakota Game and Fish Department, in accordance with the 1996 Letter of Understanding.

The embankment has a crest elevation of 1865.0 feet. Garrison Reservoir pool levels are limited to less than 15 feet above the Lake Audubon pool for dam safety consideration. Most of the time, however, the Lake Audubon level is higher than the Garrison pool. If the latter condition exists, the Snake Creek pumping plant, operated by Reclamation, is used to transfer water from Garrison Reservoir to Lake Audubon. Gravity flow discharge to or from Lake Audubon is conveyed by a gated conduit, which is 7 feet wide by 10 feet high with invert elevation at 1810.0 feet. This gated conduit is normally closed. The storage available in Lake Audubon is part of the Garrison Reservoir flood control storage, so if Garrison Reservoir pool levels exceed 1845.0 feet, water may be transferred from Garrison Reservoir into Lake Audubon, either by pumping, or by gravity flow through the conduit. Following is a list of pertinent elevations for both Lake Audubon and Garrison Reservoir.

Lake Audubon Normal Target Elevations Ice out to June 1 - 1847.2 feet June 1 to Labor Day - 1846.8 to 1847.0 feet Labor Day to November 15 - gradual ramp down to 1845.0 feet November 15 to Ice out - 1844.5 to 1845.0 feet

Garrison Reservoir Storage Allocation Exclusive Flood Control: 1850 to 1854 feet Flood Control Storage and Multiple Use: 1837.5 to 1850 feet

2. Operation for Report Period. Lake Audubon was operated in accordance with the plan described throughout the report period. In late September a drawdown of the Lake was initiated to ramp down to 1845.0 ft more quickly than normal due to a maintenance issue on Highway 83. Since this was within the target elevation plans no deviation was necessary.

APPENDIX B25- SNAKE CREEK DAM (LAKE AUDUBON)-1 APPENDIX B25-SNAKE CREEK DAM (LAKE AUDUBON)

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2. a. Maximums of Record: Pool - Date Highest 1849.5 ft 4-Jun-11 2nd 1848.6 ft 26-Apr-76 3rd 1848.6 ft 22-May-79 b. Minimums of Record (since initial fill) Pool - Date Lowest 1843.0 ft 5-Dec-06 2nd 1843.3 ft 21-Mar-85 3rd 1843.5 ft 28-Jan-92 c. Report Period Peak Pool Elev Min Pool Elev 1847.2 ft 07-Jul-15 1844.6 ft 21-Oct-14

APPENDIX B25- SNAKE CREEK DAM (LAKE AUDUBON)-2 APPENDIX B25 - SNAKE CREEK DAM & LAKE AUDUBON Prepared By:____JM By:____JM _ Prepared By:___ Reviewed JB ___

FIGURE 1 - SNAKE CREEK DAM & LAKE AUDUBON POOL ELEVATIONS FOR REPORT PERIOD.

APPENDIX B25 - SNAKE CREEK DAM & LAKE AUDUBON - 3 APPENDIX B25 - SNAKE CREEK DAM & LAKE AUDUBON Prepared By:____JM By:____JM __ Prepared By:___ Reviewed JB ___ Approximate Summer Target (1847) Summer Approximate

FIGURE 2 - SNAKE CREEK DAM & LAKE AUDUBON HISTORICAL POOL ELEVATIONS.

APPENDIX B25 - SNAKE CREEK DAM & LAKE AUDUBON - 4 APPENDIX B26-SPRING CREEK DAM (LAKE POCASSE)

SPRING CREEK DAM AND LAKE POCASSE (LAKE OAHE SUBIMPOUNDMENT) MISSOURI RIVER BASIN, SOUTH DAKOTA 2014-2015 REGULATION

1. Project Description and Water Control Plan. Lake Pocasse is operated and administered as the Pocasse National Wildlife Refuge by the Department of the Interior's Fish and Wildlife Service under an agreement with the Corps of Engineers. The pool levels of Oahe Reservoir and Lake Pocasse are contiguous at or above elevation 1617.0 ft, the top of the annual flood control and multiple use zones in Lake Oahe. The long-term plan of regulation is to maintain the Lake Pocasse level as high as possible. Every 4 to 5 years, an early summer drawdown to elevation 1614.0 ft will assist in the re-establishment of shoreline vegetation and improved water quality. In addition, upon evaluation of hydrologic conditions prior to the spring runoff each year above Pocasse, decisions may be made to lower the pool to accommodate the appropriate runoff volumes. Appendix A gives pertinent data for this sub impoundment.

2. Operation for Report Period. SWE values were below average in the Lake Pocasse basin, peaking at between trace and one inch. The peak pool occurred in November at an elevation of 1618.0 ft before a decline occurred through the rest of the winter. The pool rose slightly from the snowmelt in early March to near 1617.5 ft. In late April and early May rainfall drove the pool to 1617.7 ft, where it dropped through the rest of the year. There were no concerns with flood operations during the reporting period.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2. a. Maximums of Record: Pool - Date Highest 1625.0 ft 23-Mar-87 2nd 1624.6 ft 31-Mar-97 3rd 1622.0 ft 29-Jul-93 b. Minimums of Record (since initial fill) Pool - Date Lowest 1602.7 ft 23-Sep-90 2nd 1605.0 ft 24-Oct-92 3rd 1605.1 ft 20-Jan-91 c. Report Period Peak Pool Elev Min Pool Elev 1618.0 ft 13-Nov-14 1616.4 ft 29-Sep-15

APPENDIX B26- SPRING CREEK DAM (LAKE POCASSE)-1 APPENDIX B26 - LAKE POCASSE Prepared By:____JM By:____JM __ Prepared By:___ Reviewed JB ___ Top of Flood Control Top Zone (1625)

FIGURE 1 - LAKE POCASSE POOL ELEVATIONS FOR REPORT PERIOD.

APPENDIX B26 - LAKE POCASSE - 2 APPENDIX B26 - LAKE POCASSE Prepared By:____JM By:____JM __ Prepared By:___ Reviewed JB ___ Top of Conservation Zone (1617)

FIGURE 2 - LAKE POCASSE HISTORICAL POOL ELEVATIONS.

APPENDIX B26 - LAKE POCASSE - 3 APPENDIX B26-SPRING CREEK DAM (LAKE POCASSE)

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APPENDIX B26- SPRING CREEK DAM (LAKE POCASSE)-4 APPENDIX B27-SPRING GULCH CREEK DAM

SPRING GULCH CREEK DAM SOUTH PLATTE RIVER BASIN, COLORADO 2014-2015 REGULATION

1. Project Description and Water Control Plan. Spring Gulch Creek Dam is located on the eastern side of Chatfield Reservoir in Denver, Colorado. The dam is still owned and maintained by the Corps of Engineers, though some surrounding land has been leased to the Highlands Ranch Metro District. The dam is designed as a detention structure with no permanent storage. However, a small pool may sometimes exist in the dead storage below the invert of the outlet pipe. The outlet and spillway are uncontrolled. Appendix A gives pertinent data for this reservoir.

2. Operation for Report Period. During the months of May and June, heavy rainfall runoff was also experienced at Spring Gulch being in such close proximity to Chatfield Reservoir. The access road and trail found within the operating pool upstream of the dam was washed out during high inflows. Highlands Ranch Metro District repaired the road shortly after it was damaged. No estimations on peak inflow, pool elevation or release were made.

APPENDIX B27- SPRING GULCH CREEK-1 APPENDIX B27-SPRING GULCH CREEK DAM

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APPENDIX B27- SPRING GULCH CREEK- 2

APPENDIX C – USBR PROJECT PERTINENT DATA SHEETS

Boysen Dam and Reservoir ...... C-1 Canyon Ferry Dam and Reservoir ...... C-1 Clark Canyon Dam and Reservoir ...... C-1 Glendo Dam and Reservoir ...... C-1 Heart Butte Dam and Reservoir (Lake Tschida) ...... C-2 Jamestown Dam and Reservoir ...... C-2 Keyhole Dam and Reservoir ...... C-2 Pactola Dam and Reservoir ...... C-2 Shadehill Dam and Reservoir ...... C-3 Tiber Dam and Reservoir (Lake Elwell) ...... C-3 Yellowtail Dam and Reservoir (Bighorn Lake) ...... C-3

APPENDIX C - BUREAU PROJECTS PERTINENT DATA

SUMMARY OF ENGINEERING DATA ITEM SUBJECT BOYSEN CANYON FERRY CLARK CANYON GLENDO NO GENERAL 1 Location of dam 20 mi S of Thermopolis,Wy 17 mi NE of Helena, MT 18 mi SW of Dillon, MT 4.5 mi SE of Glendo, WY 2 River and river mile Wind RM 295 Missouri RM 2253 Beaverhead North Platte RM 280 3 Drainage area (sq. mi.) 7710 15900 2320 14330 4 Reservoir length (mi.) 17.5 at el. 4725 25 at el. 3800 5 at el. 5560.4 15 at el. 4635 5 Location of Damtender On site On site Dillon, MT On site 6 Travel time to Missouri River 6 days 4.5 days to Ft. Peck 2.5 days to Three Forks About 3 weeks 7 Max. discharge of record 29,800 cfs Jul 1923 47,000 cfs Jun 1908 3720 cfs Jun 1908 30,000 cfs Jun 1908 8 Project cost (1) $33,468,000 $42,546,000 $12,108,000 $44,371,000 DAM AND EMBANKMENT 9 Top of dam – ft 4758 3808.5 5578 4675 10 Length of dam - ft. 1143 1000 2950 2096 11 Height of dam - ft. 150 225 147.5 167 12 Stream bed – ft 4608 3635.5 5446.5 4508 13 Abutment formation Sandstone-shale-limestone Shale - slate Sand - bentonitic tuff Sandstone - shale 14 Type of fill Rolled earth Concrete gravity Rolled earth Rolled earth 15 Fill quantity in cu. yds. 1,527,000 407,100 1,884,000 2,676,000 16 Date of closure October 1951 March 1953 August 1964 June 1956 17 Date of initial fill (top of cons. pool) June 1952 July 1955 June 1965 May 1959 SPILLWAY 18 Discharge capacity - cfs (Max. pool) 20,000 at el. 4725 150,000 9530 10,300 19 Crest elevation – ft 4700 3766 5560.4 4653 20 Width - ft. 60 (net) 68 (total) 204 (net) 222 (gross) 100 45 21 Gates, number, size, type 2 (30 x 25 ft) radial 4 (51 x 34.5 ft) radial Ungated chute Ungated ogee weir RESERVOIR ELEV AND AREA (ac) (2001 data) (1997 data) (2000 data) (2003 data) 22 Maximum pool 4752.0 30,856 3800.0 34,048 5571.9 6,606 4669.0 23,320 23 Top of flood control pool 4732.2 22,190 3800.0 34,048 5560.4 5,904 4653.0 17,986 24 Top of replacement storage pool none 3797.0 33,345 5556.5 5,699 none 25 Top of joint use pool 4725.0 19,502 3783.0 29,777 5546.1 5,151 none 26 Top of conservation pool 4717.0 16,303 3770.0 23,964 5535.7 4,407 4635.0 12,005 27 Top of inactive pool 4685.0 8,709 3728.0 10,978 5470.6 184 4570.0 2,771 STORAGE ZONES, ELEV AND CAP (af) (2001 data) (1997 data) (2000 data) (2003 data) 28 Surcharge zone 4732.2-4752.0 520,679 none 5560.4-5571.9 71,882 4653.0-4669.0 329,251 29 Exclusive flood control zone 4725.0-4732.2 150,632 3797.0-3800.0 101,089 5556.5-5560.4 22,621 4635.0-4653.0 271,017 30 Replacement storage zone none 3783.0-3797.0 445,564 5546.1-5556.5 56,455 none 31 Joint use zone 4717.0-4725.0 144,229 3770.0-3783.0 348,725 5535.7-5546.1 50,207 none 32 Conservation zone 4685.0-4717.0 378,184 3728.0-3770.0 701,568 5470.6-5535.7 123,099 4570.0-4635.0 440,449 33 Inactive zone 4608.0-4685.0 219,181 3636.5-3728.0 395,956 5446.5-5470.6 1,061 4508.0-4570.0 51,573 34 Gross Storage (Excl. of surcharge) 892226 af 1,992,977 af 253,443 af 763,039 af OUTLET WORKS 35 Number and size - conduits 1 - 66 in. I.D., 1 - 57 in. I.D. 4 - 84 in. ID, 1-13 ft. ID pump intake 1 - 9 ft. I.D. 1 - 21 ft. I.D. 36 Conduit length - ft. 300 84 in. - 115 741 2300 37 Number - size - type gates 2 - 48 in. Jet valves 4 - 77 in. Slide 9500 cfs 2 - 3 x 6.5 ft. Slide 3 - 7.25 x 7.75 ft. Slide 38 Disch cap - cfs (At base of EFC zone) 66 in. - 640 cfs 1 - 13 ft. dia. 600 cfs 2200 cfs 11,300 cfs 57 in. – 670 cfs 3 - 13.5 ft. dia. 5970 cfs POWER INSTALLATION 39 No. and size of turbines 2 - 10,500 HP 3 - 23,500 HP 2 - 16,750 HP 40 No. and rating of generators 2 - 7500 KW 3 - 16,667 KW none 2 - 12,000 KW 41 Plant capacity 15,000 KW 50,000 KW 24,000 KW

C-1 42 Power plant disch cap (at base of EFC) 5200 cfs 5200 cfs 3300 cfs (1) These costs to complete the dam and reservoir, the associated recreation and fish and wildlife facilities and the power plant are applicable. Costs do not include irrigation facilities except those located at the dam. Costs are as of June 30, 1976. C-2 APPENDIX C - BUREAU PROJECTS PERTINENT DATA

SUMMARY OF ENGINEERING DATA ITEM SUBJECT HEART BUTTE JAMESTOWN KEYHOLE PACTOLA NO GENERAL 1 Location of dam 15 mi S of Glen Ullin, ND 1 mi N of Jamestown, ND 12 mi NE of Moorcroft, WY 15 mi W of Rapid City, SD 2 River and river mile Heart RM 103.5 James RM 580 Belle Fourche RM 289 Rapid Cr. RM 110 3 Drainage area (sq. mi.) 1710 1300 1950 319 4 Reservoir length (mi.) 12 at el. 2094.5 40 at el. 1454 10 at el. 4111.4 4.5 at el. 4621.5 5 Location of Damtender On site none Pactola Dam On site 6 Travel time to Missouri River 2 days About 7 weeks 5 days 3 days 7 Max. discharge of record 30,500 cfs May 1970 + 8000 cfs Apr 1969 12,000 cfs Apr 1924 2200 cfs May 1952 8 Project cost (1) $3,576,000 $3,717,000 $4,722,000 $7,861,000 DAM AND EMBANKMENT 9 Top of dam – ft 2124.0 1471.0 4134.0 4655.0 (2) 10 Length of dam - ft. 1850 1418 3420 5290 11 Height of dam - ft. 124 85 118 245 12 Stream bed – ft 2000 1386 4016 4422 13 Abutment formation Sandstone Pierre shale Sandstone and shale Slate and schist 14 Type of fill Rolled earth Rolled earth Rolled earth and rock Rolled earth and rock 15 Fill quantity in cu. yds. 1,140,000 963,000 1,329,000 4,532,000 16 Date of closure Aug 1949 May 1953 Mar 1952 Aug 1956 17 Date of initial fill (top of cons. pool) Apr 1950 Apr 1965 May 1978 Jun 1963 SPILLWAY 18 Discharge capacity - cfs (Max. pool) 5,650 2,930 11,000 255,000 19 Crest elevation – ft 2064.5 1454 4099.3 4621.5 20 Width - ft. 27 9.5 19.25 425 21 Gates, number, size, type Ungated glory hole Ungated glory hole Ungated ogee weir Ungated ogee weir RESERVOIR ELEV AND AREA (ac) (1992 data) (2009 data) (2003 data) (1988 data) 22 Maximum pool 2119.5 11,244 1464.4 17,435 4128.7 20,721 4651.7 1,557 23 Top of flood control pool 2094.5 6,738 1454.0 13,213 4111.5 13,730 4621.5 1,232 24 Top of replacement storage pool none none none none 25 Top of joint use pool none 1431.0 2,276 none none 26 Top of conservation pool 2064.5 3,299 1428.0 1,856 4099.3 9,411 4580.2 861 27 Top of inactive pool 2030.0 634 1400.0 164 4051.0 815 4456.1 99 STORAGE ZONES, ELEV AND CAP (af) (1992 data) (2009 data) (2003 data) (1988 data) 28 Surcharge zone 2094.5-2119.5 221,801 1454.0-1464.4 158,917 4111.5-4128.7 294,187 4621.5-4651.7 41,891 29 Exclusive flood control zone 2064.5-2094.5 147,027 1431.0-1454.0 190,502 4099.3-4111.5 140,463 4580.2-4621.5 43,063 30 Replacement storage zone none none none none 31 Joint use zone none 1428.0-1431.0 6,262 none none 32 Conservation zone 2030.0-2064.5 61,915 1400.0-1428.0 23,934 4051.0-4099.3 182,079 4456.1-4580.2 54,958 33 Inactive zone 2000.0-2030.0 5,227 1390.0-1400.0 292 4016.0-4051.0 6,592 4422.0-4456.1 1,017 34 Gross Storage (Excl. of surcharge) 214,169 af 220,990 af 329,134 af 99,038 af OUTLET WORKS 35 Number and size - conduits 1 - 63 in. I.D. 1 - 9.5 ft. - 13.5 ft. 1 - 9.5 x 8.25 1 - 6 ft.

36 Conduit length - ft. 597 443.75 653.4 740 37 Number - size - type gates 1 - 4 x 5 ft. Slide 2 - 5 x 6 ft. Slide 2 - 3.5 x 3.5 ft. Slide 2 - 2.75 x 2.75 ft. Slide 38 Disch cap - cfs (at base of EFC zone) 690 2175 at el. 1429.8 1250 1020 POWER INSTALLATION 39 No. and size of turbines 40 No. and rating of generators none none none none 41 Plant capacity 42 Power plant disch cap (at base of EFC)

(1) These costs to complete the dam and reservoir, the associated recreation and fish and wildlife facilities and the power plant are applicable. Costs do not include irrigation facilities except those located at the dam. Costs are as of June 30, 1976. (2) Pactola Dam was raised 15 feet in 1987 APPENDIX C - BUREAU PROJECTS PERTINENT DATA

SUMMARY OF ENGINEERING DATA ITEM SUBJECT SHADEHILL TIBER YELLOWTAIL NO GENERAL 1 Location of dam 1 mi W of Shadehill, SD 15 mi SW of Chester, MT 45 mi SW of Hardin, MT 2 River and river mile Grand RM 90 Marias RM 71 Bighorn 3 Drainage area (sq. mi.) 3120 4850 19626 4 Reservoir length (mi.) 10 at el. 2302 25 at el. 3012.5 71 at el. 3657 5 Location of Damtender none On site On site 6 Travel time to Missouri River 2 days 1.25 days 4 days 7 Max. discharge of record 58,000 cfs Apr 1950 40,000 cfs Jun 1948 37,400 cfs Jun 1935 8 Project cost (1) $7,269,000 $44,909,000 (1983) $95,900,000 DAM AND EMBANKMENT 9 Top of dam – ft 2318 3026 3660 10 Length of dam - ft. 12,840 4300 1450 11 Height of dam - ft. 122 201 524 12 Stream bed – ft 2196 2823.5 3166 13 Abutment formation Sand, silt and clay Shale and sandstone Limestone 14 Type of fill Rolled earth Rolled earth Concrete thin-arch 15 Fill quantity in cu. yds. 3,391,000 12,049,000 1,546,000 16 Date of closure July 1950 October 1950 December 1966 17 Date of initial fill (top of conser. pool) April 1952 August 1956 June 1967 SPILLWAY (Service) 18 Discharge capacity - cfs (Max. pool) 5700 127,000 cfs 68,470 92,000 19 Crest elevation – ft 2272.0 2302.0 2975 3593 20 Width - ft. - 1500 66 50 (net) 21 Gates, number, size, type Ungated glory hole/earth channel 3 - 22 x 38 ft. radial 2 - 25 x 64.4 ft. radial RESERVOIR ELEV AND AREA (ac) (1993 data) (2002 data) (2007 data) 22 Maximum pool 2312.0 13,166 3020.2 25,407 3660.0 17,940 23 Top of flood control pool 2302.0 10,746 3012.5 23,165 3657.0 17,279 24 Top of replacement storage pool none 3008.1 22,000 none 25 Top of joint use pool none 2993.0 18,275 3640.0 12,595 26 Top of conservation pool 2272.0 5,019 2976.0 12,710 3614.0 6,335 27 Top of inactive pool 2250.8 2,450 2966.4 10,819 3547.0 3,996 STORAGE ZONES, ELEV AND CAP (af) (1993 data) (2002 data) (2007 data) 28 Surcharge zone 2302.0-2312.0 119,560 3012.5-3020.2 181,722 3657.0-3660.0 52,829 29 Exclusive flood control zone 2272.0-2302.0 230,004 2993.0-3012.5 403,075 3640.0-3657.0 258,323 30 Replacement storage zone none 2993.0-3008.1 303,725 none 31 Joint use zone none 2976.0-2993.0 258,436 3614.0-3640.0 232,365 32 Conservation zone 2250.8-2272.0 76,303 2966.4-2976.0 112,882 3547.0-3614.0 318,298 33 Inactive zone 2198.0-2250.8 43,869 2823.5-2966.4 554,330 3166.0-3547.0 469,910 34 Gross Storage (Excl. of surcharge) 350,176 af 1,328,723 af 1,278,896 af OUTLET WORKS 35 Number and size - conduits 1 - 7 ft. I.D. 1 conduit containing 2 - 84 in. 1 - 72", 1 - 22" pipes 1 - 9.5 ft. 36 Conduit length - ft. 355 72" - 1110 22"-1090 289 - 216 - 305 37 Number - size - type gates 1 - 6 x 6 ft. radial 1-5x5' Slide, 1-18" butterfly (2) 3 - bulkhead gates 38 Disch. capac. - cfs (At base of EFC zone) 600 at el. 2260 1425 at el. 2993 84 in. - 2500 each/9.5 ft. - 862 POWER INSTALLATION 39 No. and size of turbines 4 - 87,500 HP 40 No. and rating of generators none none 4 - 62,500 KW 41 Plant capacity 250,000 KW 42 Power Plant disch. capac.(At base of EFC) 7800 cfs (1) These costs to complete the dam and reservoir, the associated recreation and fish and wildlife facilities and the power plant are applicable. Costs do not include irrigation facilities except those located at the dam. Costs are as of June 30, 1976. (2) Tiber Auxiliary Outlet - No. and size of conduits 1 - 10.75 ft. I.D. Conduit length - ft. 1535 C-3 No. - Size - Type gates 1 - 7.25 x 9.25 ft. slide 2 - 7.0 x 12.0 ft. slide Discharge capacity – cfs 4250 at el. 3020.2 APPENDIX C – BUREAU PROJECTS PERTINENT DATA

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C-4 APPENDIX D – USBR PROJECT OPERATION SUMMARIES

D1-Boysen Dam and Reservoir ...... D1-1 D2-Canyon Ferry Dam and Reservoir ...... D2-1 D3-Clark Canyon Dam and Reservoir ...... D3-1 D4-Glendo Dam and Reservoir ...... D4-1 D5-Heart Butte Dam and Reservoir (Lake Tschida) ...... D5-1 D6-Jamestown Dam and Reservoir ...... D6-1 D7-Keyhole Dam and Reservoir ...... D7-1 D8-Pactola Dam and Reservoir ...... D8-1 D9-Shadehill Dam and Reservoir ...... D9-1 D10-Tiber Dam and Reservoir (Lake Elwell) ...... D10-1 D11-Yellowtail Dam and Reservoir (Bighorn Lake) ...... D11-1

APPENDIX D1-BOYSEN DAM

BOYSEN DAM AND RESERVOIR WIND RIVER BASIN, WYOMING 2014-2015 REGULATION

1. Project Description and Water Control Plan. The Bureau of Reclamation constructed Boysen Dam and power plant during the period 1945-1952. Boysen Dam provides flood control, irrigation, power, silt control, recreation, and fish and wildlife. Boysen Dam impounds water from the Wind River north of Thermopolis, WY. Under the provisions of Section 7 of the 1944 Flood Control Act, regulations for the operation of flood control storage in the reservoir will be prepared by the Omaha District.

The primary flood control purpose of Boysen Reservoir is for the local reduction of flow in the reaches between Boysen Dam and Yellowtail Dam. Effective flood control will require close coordination of operations at Boysen and Yellowtail Reservoirs. The operation of Boysen is subject to the restrictions of Sections 7 and 9 of the Flood Control Act of 1944. The procedures for flood control operations at Boysen are described in an agreement between the Bureau of Reclamation and the Corps of Engineers published in the Federal Register dated April 12, 1967. The Corps issues instructions on release rates when the pool is in the exclusive flood control pool or in that portion of the joint-use pool required for seasonal flood control. Storage space in the joint use pool (4717 – 4725 ft) shall be kept available for flood control purposes, February 1 – July 31, inclusive, in accordance with the Flood Control Storage Reservation Diagram dated March 14, 1967. Normally, conservation functions will result in evacuation of the joint- use space by February 1 each year. In the event that complete evacuation of the joint-use space has not been accomplished by February 1, inflow forecasts will indicate the necessity of non-damaging evacuation of this space prior to the May 1, the onset of flood season. Filling to elevation 4725 ft prior to the end of the flood season is a prime requisite for regulation of the reservoir. The exclusive flood control zone (4725 – 4732 ft) all lies above the top of the spillway gates, thus control of this zone is afforded only by raising the spillway gates and allowing for increased releases downstream.

Table 1 presents the Boysen Reservoir storage allocations.

Table 1 Boysen Reservoir Storage Allocations, 2001 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) NGVD 29 (ac-ft) (ac-ft) Inactive 4608.0-4685.0 219,181 219,181 Conservation 4685.0-4717.0 378,184 597,365 Joint Use 4717.0-4725.0 144,229 741,594 Flood Control 4725.0-4732.2 150,632 892,226 Surcharge 4732.2-4752.0 520,679 -

APPENDIX D1-BOYSEN DAM-1 APPENDIX D1-BOYSEN DAM

2. Operation for Report Period. Three federal agencies, the Corps of Engineers, Bureau of Reclamation, and the Natural Resources Conservation Service (NRCS) are responsible for providing independent monthly April-July inflow forecasts for Boysen. Table 2 displays the agencies’ forecasts for Boysen Reservoir. The actual 2015 April-July Boysen Reservoir inflow was 749.7 kaf (131% of the USBR April-July 30 year average of 572 kaf). Note the percentage of normal for the Corps of Engineers and NRCS forecasts are based on different averages than the USBR.

Table 2 Forecasted % of Normal Apr-Jul 2015 Boysen Reservoir Inflow Agency Jan 1 Feb 1 Mar 1 Apr 1 May 1 Jun 1 85% 68% 86% 43% 17%* 57%** Corps of Engineers (516 kaf) (413 kaf) (521 kaf) (264 kaf) (93 kaf) (241 kaf) Bureau of Reclamation 94% 84% 84% 56% 56% 112% Operating Forecast*** (500 kaf) (450 kaf) (450 kaf) (300 kaf) (300 kaf) (600 kaf) 87% 80% 84% 48% 46%* 320%** NRCS (530 kaf) (485 kaf) (515 kaf) (290 kaf) (255 kaf) (75 kaf) * May-July % of normal inflow forecast ** June-July % of normal inflow forecast *** This forecast may reflect an average of agency forecasts for inclusion in the Bureau of Reclamation Monthly Operating Plan.

The snowpack above Boysen Reservoir was below the average during the report period. The snowpack peaked in the middle of March at about 8.5 inches of snow water equivalent (SWE) while the average snowpack peaks in early April at about 12 inches of SWE. The rainfall experienced in April was 1-3 inches above normal, in May was 5-8 inches above normal, and in June was 1-3 inches above normal. Due to the heavy rainfall during this time period and that the reservoir was held higher in the joint use zone due to the below normal inflow forecast the flood control zone was utilized with consideration of the flood control operation at Yellowtail Dam.

Coordination between the Corps and Reclamation related to the use of flood control storage began in May and continued until the reservoir exited the flood control pool in early July. The reservoir inflow forecasts varied due to the difficulty in predicting spring and early summer rainfall. This resulted in varying peak pool elevation forecasts. In early June about 28% of the flood control pool was forecast to be filled due to heavy rainfall runoff and by the middle of June 45% was forecast to be filled.

The above normal rainfall in the Wind River basin forced the average daily inflow to Boysen Dam to nearly 11,000 cfs resulting in a peak pool elevation of 4728.3 feet (45% occupied). The maximum daily outflow from Boysen Dam was 7,500 cfs in June.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2

APPENDIX D1-BOYSEN DAM-2 APPENDIX D1-BOYSEN DAM

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 19253 cfs 23-Jun-67 Lowest 4684.2 ft 18-Mar-56 2nd 17976 cfs 17-Jun-63 2nd 4686.4 ft 22-Sep-60 3rd 16641 cfs 2-Jul-11 3rd 4686.9 ft 24-Sep-02 Daily Outflow - Date Highest 14204 cfs 7-Jul-67 c. Report Period 2nd 10688 cfs 16-Jun-91 Total Inflow Total Outflow 3rd 9512 cfs 16-Jul-95 1,200,379 ac-ft 120% of norm 1,179,632 ac-ft 120% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 4730.8 ft 6-Jul-67 11,006 cfs 12-Jun-15 7,539 cfs 15-Jun-15 2nd 4729.9 ft 5-Jul-57 Peak Pool Elev Min Pool Elev 3rd 4729.2 ft 16-Jun-91 4728.3 ft 18-Jun-15 4718.9 ft 30-Sep-15

APPENDIX D1-BOYSEN DAM-3 APPENDIX D1 - BOYSEN DAM Release Prepared By:____JB ___ KS ___ By:___ Reviewed Inflow Top ofTop Conservation Zone (4717) Top of Flood Control Zone (4732)

FIGURE 1 - BOYSEN DAM POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX D1 - BOYSEN DAM - 4 APPENDIX D1 - BOYSEN DAM Prepared By:____JB ___ KS ___ By:___ Reviewed Top ofTop Conservation Zone (4717) Top ofTop Joint Use Zone (4725)

FIGURE 2 - BOYSEN DAM HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX D1 - BOYSEN DAM - 5 APPENDIX D1-BOYSEN DAM

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APPENDIX D1-BOYSEN DAM-6 APPENDIX D2-CANYON FERRY DAM

CANYON FERRY DAM AND RESERVOIR MISSOURI RIVER BASIN, MONTANA 2014-2015 REGULATION

1. Project Description and Water Control Plan. The Bureau of Reclamation constructed Canyon Ferry Dam and power plant during the period 1949-1954. Canyon Ferry Dam provides flood control, irrigation, power, recreation, fish and wildlife, municipal and industrial water supply. Canyon Ferry Dam impounds water from the Missouri River near Helena, MT and upstream of Great Falls, MT. Under the provisions of Section 7 of the 1944 Flood Control Act, regulations for the operation of flood control storage in the reservoir will be prepared by the Omaha District.

Canyon Ferry Reservoir is regulated by the Bureau of Reclamation, except when the pool level rises into the exclusive flood control zone, or that portion of the joint use zone (3770-3783 ft) required for flood control, as per the Field Working Agreement dated May 23, 1977. When this occurs, release determination is the responsibility of the Corps of Engineers for local flood control.

Beginning near the first of January, releases will be set based on the most probable spring inflow forecast to allow the reservoir to fill to elevation 3797.0 ft prior to July 31. Prior to May 1, any evacuation necessary to achieve the May 1 requirement will be made in a gradual and orderly manner by the Reclamation. Under the provisions of Section 7 of the 1944 Flood Control Act, regulations for the operation of flood control storage (3797-3800 ft) in the reservoir will be prepared by the Omaha District.

Table 1 shows the storage zones for Canyon Ferry Reservoir.

Table 1 Canyon Ferry Reservoir Storage Allocations, 1997 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) NGVD29 (ac-ft) (ac-ft) Inactive 3636.5-3728.0 395,956 395,956 Conservation 3728.0-3770.0 701,568 1,097,524 Joint Use– Local 3770.0-3783.0 348,725 1,446,249 Joint Use- Replacement Zone 3783.0-3797.0 445,564 1,891,813 Flood Control 3797.0-3800.0 101,089 1,992,902

2. Operation for Report Period. Three federal agencies, the Corps of Engineers, Bureau of Reclamation, and the Natural Resources Conservation Service (NRCS) are responsible for providing monthly independent April-July inflow forecasts for Canyon Ferry. Table 2 displays the agencies’ forecasts for Canyon Ferry Reservoir. The actual 2015 April-July Canyon Ferry Reservoir inflow was 1150.9 kaf (67% of the USBR April-July 30 year average of 1718 kaf). Note the percentage of normal for the Corps of Engineers and NRCS forecasts are based on different averages than the USBR.

APPENDIX D2- CANYON FERRY DAM-1 APPENDIX D2-CANYON FERRY DAM

Table 2 Forecasted % of Normal Apr-Jul 2015 Canyon Ferry Reservoir Inflow Agency Jan 1 Feb 1 Mar 1 Apr 1 May 1* Jun 1** 104% 94% 87% 65% 61% 55% Corps of Engineers (actual) (1956 kaf) (1773 kaf) (1648 kaf) (1222 kaf) (954 kaf) (568 kaf) Bureau of Reclamation 110% 98% 90% 65% 55% 65% Operating Forecast**** (1867.8 kaf) (1661.7 kaf) (1530.2 kaf) (1107.5 kaf) (750 kaf) (597 kaf) 97% 86% 83% 56% 42% 41% NRCS*** (1730 kaf) (1540 kaf) (1480 kaf) (1010 kaf) (615 kaf) (390 kaf) * May-July % of normal inflow forecast ** June-July % of normal inflow forecast *** Missouri River at Toston forecast **** This forecast may reflect an average of agency forecasts for inclusion in the Bureau of Reclamation Monthly Operating Plan.

The snowpack above Canyon Ferry Reservoir was below the average during the report period. The snowpack peaked in mid-April at about 12 inches of SWE while the average snowpack peaks in mid-April at almost 16 inches of SWE. The rainfall experienced in May was 1-3 inches above normal.

The reservoir was held higher in the joint use zone due to the below normal inflow forecast. Despite forecasts in mid-June that showed the possible need for up to 10% of flood control storage, the reservoir operated within the conservation zone during the report period, peaking just below the base of the flood control pool, elevation 3797 feet.

The above normal rainfall in the upper Missouri River basin forced the average daily inflow to Canyon Ferry Dam to over 13,000 cfs. The maximum daily outflow was increased from 3,550 to 5,780 cfs over a 4 day period in early June to fill the remaining joint-use storage zone without using the flood control storage zone.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2.

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 35330 cfs 12-Jun-97 Lowest 3764.7 ft 11-Apr-67 2nd 32724 cfs 15-Jun-11 2nd 3769.2 ft 17-Apr-97 3rd 29055 cfs 24-May-81 3rd 3772.8 ft 25-Mar-62 Daily Outflow - Date Highest 25720 cfs 13-Jun-81 c. Report Period 2nd 25429 cfs 22-Jun-97 Total Inflow Total Outflow 3rd 24370 cfs 19-Jun-64 2,891,929 ac-ft 78% of norm 3,036,124 ac-ft 82% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 3800.0 ft 15-Jul-55 13,486 cfs 04-Jun-15 5,681 cfs 6-Jun-15 2nd 3800.0 ft 23-Jun-64 Peak Pool Elev Min Pool Elev 3rd 3800.0 ft 2-Jul-62 3796.8 ft 19-Jun-15 3784.3 ft 30-Sep-15

APPENDIX D2- CANYON FERRY DAM-2 APPENDIX D2 - CANYON FERRY DAM Release Prepared By:____JB ___ KS ___ By:___ Reviewed Inflow Top ofTop Conservation Zone (3770) Top of Flood Control Zone (3800)

FIGURE 1 - CANYON FERRY DAM POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

AAPPENDIX D2 - CANYON FERRY DAM - 3 APPENDIX D2 - CANYON FERRY DAM Prepared By:____JB ___ KS ___ By:___ Reviewed Top ofTop Joint Use - Local Zone (3783) Top ofTop Joint Use - Replacement Zone (3797)

FIGURE 2 - CANYON FERRY DAM HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX D2 - CANYON FERRY DAM - 4 APPENDIX D3-CLARK CANYON DAM

CLARK CANYON DAM AND RESERVOIR BEAVERHEAD RIVER BASIN, MONTANA 2014-2015 REGULATION

1. Project Description and Water Control Plan. The Bureau of Reclamation constructed Clark Canyon Dam (Hap Hawkins Lake) during the period 1961- 1964. Clark Canyon Dam provides flood control, irrigation, recreation, fish and wildlife, municipal and industrial water supply. Clark Canyon Dam impounds water from the Beaverhead River upstream of Dillon, MT. Under the provisions of Section 7 of the 1944 Flood Control Act, regulations for the operation of flood control storage in the reservoir will be prepared by the Omaha District.

The water control plan requires that the joint-use zone be drawn down to elevation 5542.1 ft before the winter freeze-up and then held at or below that elevation until March 1. From March 1 through July 15 releases are based on forecasted inflows with the objective of filling Clark Canyon for conservation to elevation 5546.1 ft, the base of the flood control pool. However, if necessary, the Corps and the Reclamation may decide to utilize the joint-use zone (5535.7- 5546.1 ft) and/or the replacement storage zone (5546.1-5556.5 ft) for local flood control and/or replacement flood control. Replacement flood control storage would be used by the Corps to assist in the operation of the Missouri River mainstem reservoir system.

Table 1 shows the storage zones for Clark Canyon Reservoir.

Table 1 Clark Canyon Reservoir Storage Allocations, 2000 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) NGVD29 (ac-ft) (ac-ft) Inactive 5446.5-5470.6 1,061 1,061 Conservation 5470.6-5535.7 123,099 124,160 Joint Use 5535.7-5546.1 50,207 174,367 Replacement Storage 5546.1-5556.5 56,455 230,822 Flood Control 5556.5-5560.4 22,621 253,443 Surcharge 5560.4-5571.9 71,882 -

2. Operation for Report Period. Three federal agencies, the Corps of Engineers, Bureau of Reclamation, and the Natural Resources Conservation Service (NRCS) are responsible for providing monthly independent April-July inflow forecasts for Clark Canyon. Table 2 displays the agencies’ forecasts for Clark Canyon Reservoir. The actual 2015 April-July Clark Canyon Reservoir inflow was 44.0 kaf (57% of the USBR 30-year April-July average of 77.2 kaf). Note the percentage of normal for the Corps of Engineers and NRCS forecasts are based on different averages than the USBR and that the Corps of Engineers’ forecast is an April through June inflow volume for the forecasts in January, February, March, and April. The May forecast includes May through June and the June forecast includes June only.

APPENDIX D3- CLARK CANYON DAM-1 APPENDIX D3-CLARK CANYON DAM

Table 2 Forecasted % of Normal Apr-Jun 2015 Clark Canyon Reservoir Inflow Agency Jan 1 Feb 1 Mar 1 Apr 1 May 1** Jun 1*** 65%* 56%* 49%* 20%* 9% 28%* Corps of Engineers1 (53 kaf) (45 kaf) (40 kaf) (16 kaf) (9 kaf) (10 kaf) Bureau of Reclamation 86% 77% 64% 39% 40% 56% Operating Forecast2 (67 kaf) (60 kaf) (49 kaf) (30 kaf) (25 kaf) (27 kaf) 78% 56% 53% 17% -31% 23% NRCS (79 kaf) (57 kaf) (54 kaf) (18 kaf) (-20 kaf) (8 kaf) * April-June % of normal inflow forecast ** May-July % of normal inflow forecast *** June-July % of normal inflow forecast 1The Corps of Engineers’ May 1 forecast includes May-June % of normal inflow, and the June 1 forecast only includes June % of normal inflow. 2This forecast may reflect an average of agency forecasts for inclusion in the Bureau of Reclamation Monthly Operating Plan.

The snowpack above Clark Canyon Reservoir peaked in mid-April slightly above 10 inches of SWE, below the average snowpack peak of around 14 inches of SWE. The below normal SWE in the basin resulted in below normal inflow through the spring into the summer. The reservoir operated well within the conservation zone for the entire report period.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2.

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 3474 cfs 22-Jun-84 Lowest 5490.0 ft 18-Aug-03 2nd 2800 cfs 20-Jun-75 2nd 5491.3 ft 29-Aug-02 3rd 2563 cfs 6-Jun-95 3rd 5498.6 ft 20-Aug-04 Daily Outflow - Date Highest 2586 cfs 25-Jun-84 c. Report Period 2nd 1538 cfs 26-Jul-95 Total Inflow Total Outflow 3rd 1289 cfs 30-Jul-75 142,901 ac-ft 57% of norm 136,047 ac-ft 55% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 5564.7 ft 25-Jun-84 723 cfs 01-Jul-15 812 cfs 9-Jul-15 2nd 5556.9 ft 22-Jul-75 Peak Pool Elev Min Pool Elev 3rd 5556.0 ft 18-Jul-11 5534.9 ft 30-Apr-15 5515.4 ft 20-Sep-15

APPENDIX D3- CLARK CANYON DAM-2 APPENDIX D3 - CLARK CANYON DAM Release Prepared By:____JM ___ Reviewed By:___ JB ___ Top ofTop Joint Use Zone (5546.1) Top ofTop Joint Use - Replacement Zone (5556.5) Inflow Top of Flood Control Zone (5560.4) ofTop Conservation Zone (5535.7)

FIGURE 1 - CLARK CANYON DAM POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX D3 - CLARK CANYON DAM - 3 APPENDIX D3 - CLARK CANYON DAM Prepared By:____JM ___ Reviewed By:___ JB ___ Top ofTop Joint Use Zone (5546.1) Top ofTop Conservation Zone (5535.7)

FIGURE 2 - CLARK CANYON DAM HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX D3 - CLARK CANYON DAM - 4 APPENDIX D4-GLENDO DAM

GLENDO DAM AND RESERVOIR NORTH PLATTE RIVER BASIN, WYOMING 2014-2015 REGULATION

1. Project Description and Water Control Plan. The Bureau of Reclamation constructed Glendo Dam and Powerplant in October 1957 as part of the Missouri River Basin Project, Glendo Unit. The Glendo Unit provides irrigation, power generation, flood control, fish and wildlife enhancement, recreation, sediment retention, pollution abatement, and improvement of the quality of municipal and industrial water supply in the North Platte River valley between Gray Reef Dam and Glendo Reservoir. Glendo Dam impounds water from the North Platte River downstream of Casper, WY. Under the provisions of Section 7 of the 1944 Flood Control Act, regulations for the operation of flood control storage in the reservoir will be prepared by the Omaha District.

Several considerations are given in determining releases from Glendo Dam: 1) upstream system inflows, 2) incremental inflows downstream of Glendo Dam and upstream of Guernsey Dam, which has a total storage capacity of only 45,000 acre-feet, 3) downstream irrigation canal diversions from the North Platte River, 4) releases from Grayrocks Dam on the Laramie River, and 5) incremental inflows between Guernsey Dam and the Nebraska communities along the North Platte River including Mitchell, Scottsbluff, Bridgeport, Lisco and Lewellen.

The general objectives of the water control plan calls for the Corps District Engineer to make discharges from Glendo Dam which are considered necessary based on known hydrologic conditions at the time, with the objective of prevention or reduction of flood damages along the North Platte River in Wyoming and Nebraska from Glendo Dam to Lake McConaughy (Kingsley Dam).

Table 1 shows Glendo Reservoir storage allocations.

Table 1 Glendo Reservoir Storage Allocations, 2003 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) NGVD29 (ac-ft) (ac-ft) Inactive 4508.0-4570.0 51,573 51,573 Conservation 4570.0-4635.0 440,449 492,022 Flood Control 4635.0-4653.0 271,017 763,039 Surcharge 4653.0-4669.0 329,251 -

Figure 1 clarifies the positioning of the reservoirs, diversion canals, and rivers of the North Platte River Basin.

APPENDIX D4- GLENDO DAM-1 APPENDIX D4-GLENDO DAM

Figure 1. North Platte River System Diagram, not to scale.

2. Operation for Report Period. Three federal agencies, the Corps of Engineers, Bureau of Reclamation, and the Natural Resources Conservation Service (NRCS) are responsible for providing independent monthly April-July inflow forecasts for Glendo. Table 2 displays the agencies’ forecasts for Glendo Reservoir. The Corps of Engineers forecast was the natural flow forecast for the North Platte River. The 2015 April-July North Platte River inflow was 478 kaf (55% of the USBR 30-year April-July average of 871 kaf). Note the percentage of normal for the Corps of Engineers and NRCS forecasts are based on different averages than the USBR.

Table 2 Forecasted % of Normal Apr-Jul 2015 Glendo Reservoir Inflow Agency Jan 1 Feb 1 Mar 1 Apr 1 May 1 Jun 1 73% 51% 52% 23% 14%* 43%** Corps of Engineers (natural) (630 kaf) (441 kaf) (449 kaf) (195 kaf) (100 kaf) (165 kaf) Bureau of Reclamation 108% 65% 59% 36% 37% 83% Operating Forecast*** (939 kaf) (565 kaf) (515 kaf) (310 kaf) (320 kaf) (720 kaf) 88% 54% 60% 37% 23%* 72%** NRCS (720 kaf) (445 kaf) (495 kaf) (300 kaf) (153 kaf) (270 kaf) The Bureau of Reclamation forecast represents a summation of the Seminoe, Sweetwater and Alcova to Glendo forecasts * May-July % of normal inflow forecast ** June-July % of normal inflow forecast *** This forecast may reflect an average of agency forecasts for inclusion in the Bureau of Reclamation Monthly Operating Plan.

The snowpack above Seminoe Reservoir and above Glendo Reservoir both peaked below the average peaks of 22 inches and 12 inches of SWE, respectively. Due to above normal temperatures, the Seminoe snowpack

APPENDIX D4- GLENDO DAM-2 APPENDIX D4-GLENDO DAM peaked in early March at about 15 inches of SWE while the average snowpack peaks near mid-April. The Glendo snowpack also peaked in early March at close to 8 inches of SWE while the average snowpack peaks in mid-April. Early forecasts indicated a below average inflow volume for Glendo Reservoir due to the low snowpack in the basin.

Above average temperatures in March caused the basin snowpack to peak much earlier than normal. As a result, inflows into Seminoe and Pathfinder (upper reservoirs) rose significantly in March, and the initial snowmelt volume was captured in those reservoirs. Glendo began to see increased inflows in April as the upper reservoirs evacuated their water downstream to Glendo in preparation for irrigation season. A series of storms from April 16-19 and on April 26 and 27 dropped up to a total of 3 inches of precipitation over Glendo Reservoir, with 1.5 to 4 inches falling in the upper North Platte River basin and 3 to 6 inches in the Laramie River basin, which discharges into the North Platte below Guernsey Reservoir. Total precipitation for the month of April was between 150% and 300% of normal, and inflows into Glendo Reservoir were near 3,000 cfs by the end of the month.

The pattern of intermittent storms falling over the North Platte River and Laramie River basins in Wyoming continued into May. In addition to the rainfall, the snowmelt continued to contribute to the flow in the Laramie River and the North Platte River upstream of Glendo. By May 14, the Alcova to Glendo Reservoir reach had received 37 kaf of water, already nearing the 50 kaf May forecast. Seminoe and Pathfinder Reservoirs were storing as much volume as possible to decrease inflows to Glendo downstream. Irrigation demand was low and was anticipated to drop off completely as the wet weather continued. On May 22, Glendo Reservoir entered its flood pool. Pool forecasts at this time anticipated a small encroachment (less than 10%) in the flood pool which would be evacuated near the end of June.

On May 25, releases out of Glendo were decreased from 570 to 400 cfs to provide some relief downstream. The North Platte River near Henry, NE briefly exceeded flood stage in late May, dropping out by early June as flows began to recede. However, the downstream stages at Mitchell, NE, and Lewellen, NE stayed above flood stage well into June. Releases lower than 400 cfs were discussed, but inflows continued to be high, reaching a peak daily average inflow of 3,983 cfs on May 25. Laramie River flows were also high, causing downstream North Platte River flows to rise. The Laramie River near Fort Laramie gage entered flood stage on May 21. Gray Rocks Reservoir was in its surcharge zone from all the rain and melting snow, and was releasing 4,000 cfs by May 25. All the water supply storage on the Laramie River was full and flows were not expected to recede for up to a month depending on snowmelt. Minor flooding issues were being seen in Henry, Mitchell, and Scottsbluff, NE, and the North Platte River at Bridgeport was bankfull. Soil conditions were saturated throughout the North Platte River in Wyoming and western Nebraska and the

APPENDIX D4- GLENDO DAM-3 APPENDIX D4-GLENDO DAM

Laramie River in Wyoming. Total precipitation for the month of May was between 200% and 400% of normal.

By June 1, the Laramie River had begun to recede and as a result flows were declining on the North Platte downstream of the Laramie River confluence. Glendo releases were increased to 1,000 cfs; the flood pool was almost 20% full at an elevation of 4639.2 ft. Irrigation demands had still not come on due to saturated basin conditions, and one irrigation district estimated it would be at least mid-June before they would divert any water out of the river. Glendo releases were stepped up incrementally over the next few days as downstream conditions improved. On June 4, Gray Rocks Reservoir cut releases, so Glendo releases were increased by 500 cfs to 1,800 cfs. Inflows into Glendo continued to decline, dropping below the 1,800 cfs release on June 5. The reservoir pool peaked on June 5 at an elevation of 4639.9, slightly above 23% into the flood pool. By June 15, the drier weather pattern resulted in an irrigation demand downstream of Glendo and the irrigation districts began diverting water. Releases were increased from Glendo to 2,400 cfs as more water was diverted downstream. Gains downstream of Glendo were closely monitored and as they receded the Glendo release was increased. On June 17, a thunderstorm dropped up to 1.5 inches of rain downstream on the North Platte River between Glendo and Bridgeport, NE. Releases were reduced to 2,200 cfs for a day in consideration of downstream flows. On June 22, releases were increased to 2,700 cfs as irrigation districts began to increase their diversions from the river. Two release scenarios were analyzed on June 26, one increasing the release by 300 cfs and one by 500 cfs. Because the downstream river flows were still high the releases were increased by 300 cfs to 3,000 cfs, resulting in the peak release for the year. This release allowed Glendo Reservoir to continue to evacuation of flood storage. Glendo Reservoir evacuated its flood pool on July 2.

Historical as well as reporting period details for Glendo Reservoir are contained in paragraphs 2a through 2c and Figures 2 and 3.

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 18840 cfs 15-May-65 Lowest 4548.1 ft 28-Sep-66 2nd 17560 cfs 13-Jun-70 2nd 4560.4 ft 26-Sep-72 3rd 14661 cfs 21-May-73 3rd 4560.7 ft 29-Sep-69 Daily Outflow - Date Highest 10214 cfs 30-Jun-84 c. Report Period 2nd 10060 cfs 26-Aug-83 Total Inflow Total Outflow 3rd 9644 cfs 2-Jun-73 900,056 ac-ft 77% of norm 830,598 ac-ft 73% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 4650.9 ft 28-May-73 3,983 cfs 25-May-15 7,998 cfs 5-Aug-15 2nd 4650.3 ft 14-Jun-83 Peak Pool Elev Min Pool Elev 3rd 4649.1 ft 24-May-71 4639.9 ft 04-Jun-15 4581.0 ft 1-Oct-14

APPENDIX D4- GLENDO DAM-4 APPENDIX D4 - GLENDO DAM Release Prepared By:____JM ___ Reviewed By:___ JB ___ Inflow Top of Flood Control Zone (4653)

FIGURE 2 - GLENDO DAM POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX D4 - GLENDO DAM - 5 APPENDIX D4 - GLENDO DAM Prepared By:____JM ___ Reviewed By:___ JB ___ Top ofTop Conservation Zone (4635)

FIGURE 3 - GLENDO DAM HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX D4 - GLENDO DAM - 6 APPENDIX D5-HEART BUTTE DAM

HEART BUTTE DAM AND RESERVOIR (LAKE TSCHIDA) HEART RIVER BASIN, NORTH DAKOTA 2014 - 2015 REGULATION

1. Project Description and Water Control Plan. Heart Butte Reservoir, located on the Heart River in southwestern North Dakota, is regulated by the Bureau of Reclamation except when the pool level rises into the exclusive flood control zone. When this occurs, release determination is the responsibility of the Corps of Engineers as per the Field Working Agreement dated March 15, 1951 and the provisions of Section 7 of the 1944 Flood Control Act.

The plan for flood control regulation is to restrict discharges to the capacity of the ungated glory-hole spillway except as necessary for irrigation requirements, unless otherwise directed by the Corps of Engineer’s District Engineer. The ungated spillway with a crest elevation at the base of the flood control pool, elevation 2064.5 ft has a capacity of 4450 cfs at a water surface elevation of 2094.5 ft (top of the flood control pool). This discharge is well within the downstream channel capacity. Whenever the reservoir is above elevation 2064.5 ft and below elevation 2067 ft, the Reclamation’s Regional Director will, at the request of the District Engineer, make supplemental releases up to the full capacity of the irrigation outlet for the purpose of expediting evacuation of the flood control storage. The main purpose for this is to benefit downstream landowners who have low water crossings that cannot be used during high releases. Once the lake level drops below the crest of the spillway, an attempt is made to control downstream releases at less than 100 to 150 cfs so farmers can cross the river for farming operations.

Table 1 shows the storage zones for Heart Butte Reservoir.

Table 1 Heart Butte Reservoir Storage Allocations, 1992 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) NGVD29 (ac-ft) (ac-ft) Inactive 2000.0-2030.0 5,227 5,227 Conservation 2030.0-2064.5 61,915 67,142 Flood Control 2064.5-2094.5 147,027 214,169 Surcharge 2094.5-2119.5 221,801 -

2. Operation for Report Period. Normal to below normal precipitation in October- December 2014 resulted in an elevation decline from approximately 2 feet below the base of flood control to approximately 2.5 feet below the base of flood control. A winter release of 40 cfs was held through the winter until late January. The reservoir began to rise on January 24 when a few days of warm weather caused the plains snowpack in the basin to melt, and entered the flood pool on January 30. Gated releases were increased to 100 cfs on January 28 as inflows continued to rise and were maintained as the reservoir entered the flood pool. The peak release reached during January was a total of 200 cfs. As inflows steadied slightly over 200 cfs, it was thought the pool would peak shortly so no further gate changes were made. However, continued snow accumulation and melt through the next few weeks caused the pool to sharply rise again in February. On February 12, the pool elevation peaked at 2066.5, two feet into the flood pool due to snowmelt. This resulted in the report period peak pool elevation. APPENDIX D5- HEART BUTTE DAM-1 APPENDIX D5-HEART BUTTE DAM

Gated releases were increased incrementally to 350 cfs in addition to spillway flow to facilitate a faster drawdown, and the reservoir exited the flood pool on February 27.

The remainder of the snowpack began melting in early March, increasing flows at the upstream gages and into the reservoir. A gated release of 200 cfs was maintained in anticipation of a quick snowmelt peak. A second reservoir peak of 2064.7 ft was experienced on March 21. On March 26 the gated release was increased to 300 cfs to accommodate a scheduled gate inspection. The flood pool was evacuated on March 28.

In late April and early May above average precipitation was seen over the basin. Inflows and the reservoir pool began to slowly rise. Heart Butte entered its flood pool on May 17, 2015 for the third time during the reporting period. Releases were increased to 100 cfs and held there due to downstream flooding conditions. The wet May pattern continued and inflows remained near 150 cfs. After a month in the flood pool, downstream conditions had abated and releases were increased to 200 cfs on June 15 to allow the pool to peak and begin to decline. A third reservoir peak of 2064.8 ft was experienced on June 16. Releases were increased again on June 18, and the flood pool was evacuated on June 20.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2.

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 22092 cfs 9-May-70 Lowest 2049.0 ft 25-Oct-91 2nd 21662 cfs 17-Apr-50 2nd 2049.2 ft 16-Oct-92 3rd 15670 cfs 23-Mar-09 3rd 2051.4 ft 7-Nov-90 Daily Outflow - Date Highest 4100 cfs 9-Apr-52 c. Report Period 2nd 3932 cfs 1-Apr-78 Total Inflow Total Outflow 3rd 3875 cfs 18-Apr-09 96,762 ac-ft 107% of norm 86,363 ac-ft 97% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 2086.2 ft 9-Apr-52 1,281 cfs 12-Feb-15 819 cfs 13-Feb-15 2nd 2083.8 ft 31-Mar-78 Peak Pool Elev Min Pool Elev 3rd 2082.7 ft 12-May-70 2066.5 ft 12-Feb-15 2061.8 ft 18-Jan-15

APPENDIX D5- HEART BUTTE DAM-2 APPENDIX D5 - HEART BUTTE DAM Prepared By:____JM ___ Reviewed By:___ JB ___ Release Inflow Top of Flood Control Zone (2094.5)

FIGURE 1 - HEART BUTTE DAM POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX D5 - HEART BUTTE DAM - 3 APPENDIX D5 - HEART BUTTE DAM Prepared By:____JM ___ Reviewed By:___ JB ___ Top ofTop Conservation Zone (2064.5) Top of Flood Control Zone (2094.5)

FIGURE 2 - HEART BUTTE DAM HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX D5 - HEART BUTTE DAM - 4 APPENDIX D6-JAMESTOWN DAM

JAMESTOWN DAM AND RESERVOIR JAMES RIVER BASIN, NORTH DAKOTA 2014-2015 REGULATION

1. Project Description and Water Control Plan. Jamestown Reservoir is on the James River on the north side of Jamestown, ND. Jamestown Reservoir is regulated by the Bureau of Reclamation except when the pool level rises into the exclusive flood control zone or that portion of joint use conservation-flood control zone required for flood control. When this occurs, release determination is the responsibility of the Corps of Engineers under the provisions of Section 7 of the 1944 Flood Control Act. Pipestem Reservoir is operated jointly with Jamestown Reservoir for flood control. A water control plan was finalized at the end of 2002. This plan was the product of a study initiated in 1996. This new plan was officially adopted in 2008. Details of this plan are contained in the study write-up “Jamestown and Pipestem Reservoirs Water Control Plan Review and Update, July, 2000”. For a description of the joint operation of Jamestown and Pipestem Reservoirs, refer to the Pipestem Reservoir narrative located in Appendix B14 of this report.

Table 1 shows the storage zones for Jamestown Reservoir.

Table 1 Jamestown Reservoir Storage Allocations, 2009 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) PD (ac-ft) (ac-ft) Inactive 1390.0-1400.0 292 292 Conservation 1400.0-1428.0 23,934 24,226 Joint Use 1428.0-1431.0 6,262 30,488 Flood Control 1431.0-1454.0 190,502 220,990 Surcharge 1454.0-1464.4 158,917 -

2. Operation for Report Period. Jamestown Reservoir held steady over the winter until early March when the spring snowmelt began. For conservation purposes, the releases from the reservoir were held at 0 cfs until May 20, when rainfall resulted in a reservoir rise into the flood pool. The report period peak pool elevation of 1431.8 ft occurred on May 25. The release was steadily increased to a maximum release of 300 cfs by May 30 to evacuate the flood pool by the June 1 target. A detailed description of Jamestown Reservoir operations is contained in the Pipestem Reservoir operation summary in Appendix B14.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2.

APPENDIX D6- JAMESTOWN DAM-1 APPENDIX D6-JAMESTOWN DAM

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 14305 cfs 16-Apr-11 Lowest 1420.9 ft 3-Mar-93 2nd 11646 cfs 15-Apr-09 2nd 1421.3 ft 24-Sep-92 3rd 7689 cfs 17-Apr-69 3rd 1422.7 ft 30-Sep-91 Daily Outflow - Date Highest 1807 cfs 23-May-09 c. Report Period 2nd 1702 cfs 2-May-97 Total Inflow Total Outflow 3rd 1601 cfs 5-May-11 26,719 ac-ft 45% of norm 16,246 ac-ft 28% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 1454.1 ft 27-Apr-09 1,183 cfs 17-May-15 304 cfs 30-May-15 2nd 1451.2 ft 2-May-11 Peak Pool Elev Min Pool Elev 3rd 1445.8 ft 16-Apr-10 1431.8 ft 25-May-15 1429.3 ft 1-Oct-14

APPENDIX D6- JAMESTOWN DAM-2 APPENDIX D6 - JAMESTOWN DAM Release Prepared By:____JM ___ Reviewed By:___ JB ___ Inflow Top of Flood Control Zone (1454)

FIGURE 1 - JAMESTOWN DAM POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX D6 - JAMESTOWN DAM - 3 APPENDIX D6 - JAMESTOWN DAM Prepared By:____JM ___ Reviewed By:___ JB ___ Top ofTop Conservation Zone (1429.8) Top ofTop Joint Use Zone (Changed from 1432.71431 in(Changed from to June 2000)

FIGURE 2 - JAMESTOWN DAM HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX D6 - JAMESTOWN DAM - 4 APPENDIX D7-KEYHOLE DAM

KEYHOLE DAM AND RESERVOIR BELLE FOURCHE RIVER BASIN, WYOMING 2014 - 2015 REGULATION

1. Project Description and Water Control Plan. Keyhole Reservoir, located on the Belle Fourche River in northeastern Wyoming, is regulated by the Bureau of Reclamation except when the pool level rises into the exclusive flood control zone as per the Field Working Agreement dated February 11, 1970. When this occurs, release determination is the responsibility of the Corps of Engineers under the provisions of Section 7 of the 1944 Flood Control Act.

The water control plan for flood operations calls for a combination of gated and uncontrolled releases through the reservoir outlet works to result in a maximum release of 3,000 cfs. Included in the plan is a table specifying gate changes with every 0.1 foot of elevation change. The water control plan was written when an on-site dam tender was employed. In subsequent years the gate changes are handled out of the USBR Rapid City field office making it difficult to follow the specified releases to that level of detail. The water control office will look into updating the water control plan in the near future to aid the functionality of flood control operations.

Table 1 shows the storage zones for Keyhole Reservoir.

Table 1 Keyhole Reservoir Storage Allocations, 2003 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) PD (ac-ft) (ac-ft) Inactive 4016.0-4051.0 6,592 6,592 Conservation 4051.0-4099.3 182,079 188,671 Flood Control 4099.3-4111.5 140,463 329,134 Surcharge 4111.5-4128.7 294,187 -

2. Operation for Report Period. Keyhole Reservoir started the report period two feet below the top of the conservation zone and remained near that elevation over the winter. The average basin snowpack was below normal, peaking with less than one inch of snow water equivalent. In early March, warm temperatures melted the snow. Inflows stayed under 500 cfs through the month of May. Toward the end of May and through the month of June, a series of moderately- sized rainfall events occurred over the area. This caused the pool to steadily rise throughout early summer. A deviation was approved on June 5 in anticipation of entering the flood control pool to increase releases at 0.5 foot increments instead of 0.1 foot increments as specified in the water control plan. The deviation specified holding a release near 100 cfs until the pool reached an elevation of 4100 feet. The USBR began increasing releases out of the reservoir early on June 7. When the pool entered the flood control zone on June 7, gated releases were already at 100 cfs. The flood pool was evacuated on June 9, but inflows stayed high, so gated releases continued at 100 cfs. In mid-June the pool rose into the flood pool for a second time. The peak pool for the reporting period

APPENDIX D7- KEYHOLE DAM-1 APPENDIX D7-KEYHOLE DAM

occurred on June 27 at an elevation of 4099.6 feet, 0.3 feet into the flood pool and the second highest pool level in the period of record. Gated releases throughout the event were held at 100 cfs. The flood pool was evacuated on July 9 and release operations were handed back to the USBR. Dryer weather and irrigation demands through the rest of the summer drew the reservoir down, ending the report period 2.5 feet below the top of conservation pool at 4096.8 feet.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2.

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 10665 cfs 19-May-78 Lowest 4060.3 ft 1-Nov-92 2nd 5182 cfs 13-Mar-96 2nd 4066.4 ft 2-Nov-91 3rd 4779 cfs 29-Feb-72 3rd 4066.9 ft 12-Dec-90 Daily Outflow - Date Highest 1347 cfs 24-May-78 c. Report Period 2nd 825 cfs 23-May-62 Total Inflow Total Outflow 3rd 800 cfs 11-Mar-72 44,820 ac-ft 243% of norm 19,890 ac-ft 145% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 4100.4 ft 21-May-78 4,077 cfs 01-Jun-15 117 cfs 29-Jun-15 2nd 4099.6 ft 27-Jun-15 Peak Pool Elev Min Pool Elev 3rd 4099.4 ft 14-Mar-12 4099.6 ft 27-Jun-15 4096.9 ft 16-Nov-14

APPENDIX D7- KEYHOLE DAM-2 APPENDIX D7 - KEYHOLE DAM Release Prepared By:____JB ___ Reviewed By:___ MN ___ Inflow Top of Flood Control Zone (4111.5)

FIGURE 1 - KEYHOLE DAM POOL ELEVATIONS, INFLOWS, AAND RELEASES FOR REPORT PERIOD.

APPENDIX D7 - KEYHOLE DAM - 3 APPENDIX D7 - KEYHOLE DAM Prepared By:____JB ___ Reviewed By:___ MN ___ Top of Flood Control Zone (4111.5)

FIGURE 2 - KEYHOLE DAM HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX D7 - KEYHOLE DAM - 4 APPENDIX D8-PACTOLA DAM

PACTOLA DAM AND RESERVOIR RAPID CREEK BASIN, SOUTH DAKOTA 2014 - 2015 REGULATION

1. Project Description and Water Control Plan. Pactola Reservoir is located on Rapid Creek upstream of Rapid City, SD. Pactola Reservoir is regulated by the Bureau of Reclamation except when the pool level rises into the exclusive flood control zone as per the Field Working Agreement dated August 27, 1969. When this occurs, release determination is the responsibility of the Corps of Engineers under the provisions of Section 7 of the 1944 Flood Control Act. Table 1 shows the storage zones for Pactola Reservoir. The Water Control Plan specifies releases for a given pool elevation as detailed in Table 2. When flows get over 500 cfs in Rapid City, bicycle paths and other recreational areas begin to flood. At 500 cfs, there are also impacts to yards and outbuildings of residential areas outside the city limits along Highway 44.

Table 1 Pactola Reservoir Storage Allocations, 1988 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) NGVD29 (ac-ft) (ac-ft) Inactive 4422.0-4456.1 1,017 1,017 Conservation 4456.1-4580.2 54,958 55,975 Flood Control 4580.2-4621.5 43,063 99,038 Surcharge 4621.5-4651.7 41,891 -

Table 2 Pactola Reservoir Release Schedule Reservoir Elevation in ft Required Release in CFS From To Below 4580.2 Conservation Requirement 4580.20 4582.00 Inflows up to 250 4582.01 4583.00 300 4583.01 4585.00 400 4585.01 4590.00 500 4590.01 4595.00 700 4595.01 4600.00 900 4600.01 4621.50 1000

2. Operation for Report Period. Pactola Reservoir started the report period drawndown from the top of the conservation pool to elevation 4567.7 ft (82% of the multipurpose pool) in preparation for downstream spillway construction on Canyon Lake Dam spillway in Rapid City. This was done to minimize downstream damages at the construction site due to Pactola Reservoir releases. It was forecasted that about a 20 cfs release would meet the release requirement from Pactola Reservoir and allow it to slowly fill over the fall and winter months while the downstream construction was completed. However, Pactola Reservoir rose faster than predicted during the fall of 2014 with above average inflow volume. To counteract this record inflow, the Canyon Lake Dam spillway contractor modified the downstream bypass channel to allow for a release of at least 50 cfs from Pactola Reservoir without impacts to the downstream spillway construction at the end of November 2014. At that time Pactola Reservoir had

APPENDIX D8- PACTOLA DAM-1 APPENDIX D8-PACTOLA DAM

risen to 4575.7 feet (93% of the multipurpose pool). The larger release kept Pactola Reservoir from rising more quickly during the winter of 2015. However, continued above normal inflow kept the reservoir pool higher than anticipated.

By late February, Pactola Reservoir had risen to 4576.6 feet (95% of the multipurpose pool), the snowpack accumulation was below normal at 86%, and the downstream spillway construction at Canyon Lake Dam was projected to be completed by April 1, 2015 prior to the typical snowmelt runoff season. A deviation from the water control plan to store up to 5% in the flood control pool to allow Pactola Reservoir to control the reservoir release to accommodate downstream construction was approved on March 4th with the following caveats: 1. If drastic rises in mountain snowpack were to occur during the last two months of snowpack accumulation in 2015, more aggressive releases may have been determined necessary to avoid large flood control releases at Pactola Reservoir 2. Releases will be increased to evacuate the flood control storage space as soon as the downstream construction is complete and downstream conditions permit so as to not induce flooding. The deviation was coordinated with the Reclamation Dakotas Area Office.

The below average snowpack in the basin peaked in early March and by the end of March the snow had melted and was en route to Pactola Reservoir. The inflow to the reservoir did not appear to be significantly impacted by the snowmelt runoff.

The construction at Canyon Lake Dam spillway was delayed by rainfall and not completed until April 30. Normal operation at Pactola Reservoir was not achieved until May 4 following the removal of the Canyon Lake Dam spillway bypass canal.

During the month of May the Rapid Creek basin above Rapid City received 6 to 10 inches of rainfall, which was 3 to 5 inches above normal. Figure 1 shows the precipitation that fell in May.

APPENDIX D8- PACTOLA DAM-2 APPENDIX D8-PACTOLA DAM

Pactola Dam

Figure 1. May 2015 Accumulated Precipitation.

Due to the above normal rainfall that followed the spring snowmelt, the inflow began to rise and on May 11 Pactola Reservoir rose above the base of the flood control pool, elevation 4580.2 feet. As a result the release was slowly increased from 50 cfs to 250 cfs following the rise in inflow as prescribed in the release schedule found in the above Table 2. Prior to exceeding the 200 cfs release, a press release was put out because bike paths below the dam are impacted at this level. The forecast showed a peak pool elevation of 4581.3 feet in mid-May, but continued heavy rainfall forced the inflow higher than the forecast. On May 18, the reservoir rose above elevation 4582.0 feet and the release was increased from 250 cfs to 300 cfs following the release schedule and favorable downstream conditions.

From May 18 to 23 the reservoir inflow began to drop but another round of rainfall in the river basin beginning on May 24 pushed the inflow up over 700 cfs. The additional inflow forced the reservoir pool elevation over 4583.0 feet requiring an increase in the release to 400 cfs. After checking the downstream condition, the release was increased from 300 cfs to 350 cfs on May 24 and then from 350 to 400 cfs on May 25.

Continued rainfall kept the inflow above 700 cfs and on May 27 the reservoir pool elevation exceeded 4585.0 feet requiring an increase in the release to 500 cfs. It was determined after coordination with the Pennington County emergency management office that since the downstream condition had improved and streamgages were dropping that the release would be increased to 500 cfs in two steps, matching the record release set in 1965. The Corps, Reclamation, and local emergency manager agreed that a cut in the release would be considered if

APPENDIX D8- PACTOLA DAM-3 APPENDIX D8-PACTOLA DAM

there was a forecast for heavy rainfall in Rapid City with the understanding that there is a travel time of 6 to 8 hours to make an impact. The maximum daily average release for the report period was 514 cfs on June 26, a new historical record release.

On May 29 the reservoir exceeded the previous maximum record pool elevation of 4585.9 feet (12% of the flood storage occupied) set in 1965 and 24 hour monitoring of dam was initiated.

During the month of June the Rapid Creek basin above Rapid City received an additional 5 to 10 inches of rainfall, which was 3 to 8 inches above normal. Figure 2 shows the precipitation that fell in June.

Pactola Dam

Figure 2. June 2015 Accumulated Precipitation.

As the rainfall subsided, the inflow slowly dropped from 700 cfs beginning May 30 and was below 500 cfs by June 9. The reservoir peaked initially at pool elevation 4787.7 feet (16% of the flood storage occupied) on June 9.

Additional above normal rainfall in mid-June to late June forced the inflow back up to 700 cfs by June 24. On June 25 the pool was forecast to peak at 4588.5 feet but the inflow stayed higher than anticipated and the reservoir peaked at 4589.4 feet (19% of the flood storage occupied) on June 29.

The 500 cfs release was held until July 24 when about 1% of the flood control pool was occupied. The release was dropped over a 5 day period to 150 cfs to

APPENDIX D8- PACTOLA DAM-4 APPENDIX D8-PACTOLA DAM match the inflow at which time the reservoir was operated for conservation purposes.

The daily peak inflow did not surpass the top three records listed in the below table, but the total inflow volume for the report period was 111,586 acre-feet (295% of normal), which is highest on record. The previous record was 104,207 acre-feet set in water year 1999.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 3 and 4.

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 1132 cfs 16-May-65 Lowest 4531.5 ft 24-Jan-91 2nd 1009 cfs 19-Jun-98 2nd 4531.9 ft 21-Dec-90 3rd 741 cfs 31-May-96 3rd 4532.1 ft 16-Sep-90 Daily Outflow - Date Highest 514 cfs 26-Jun-15 c. Report Period 2nd 500 cfs 20-May-65 Total Inflow Total Outflow 3rd 438 cfs 02-Jun-96 111,586 ac-ft 295% of norm 105,270 ac-ft 287% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 4589.4 ft 29-Jun-15 720 cfs 29-May-2015 514 cfs 26-Jun-2015 2nd 4585.9 ft 19-May-65 Peak Pool Elev Min Pool Elev 3rd 4585.4 ft 21-May-78 4589.4 ft 29-Jun-2015 4568.6 ft 1-Oct-2014

APPENDIX D8- PACTOLA DAM-5 APPENDIX D8 - PACTOLA DAM Release Prepared By:____JB ___ KS ___ By:___ Reviewed Inflow Top of Flood Control Zone (4621.5)

FIGURE 3 - PACTOLA DAM POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX D8 - PACTOLA DAM - 6 APPENDIX D8 - PACTOLA DAM Prepared By:____JB ___ KS ___ By:___ Reviewed Top ofTop Conservation Zone (4580.2) Top of Flood Control Zone (4621.5)

FIGURE 4 - PACTOLA DAM HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX D8 - PACTOLA DAM - 7 APPENDIX D8-PACTOLA DAM

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APPENDIX D8- PACTOLA DAM-8 APPENDIX D9-SHADEHILL DAM

SHADEHILL DAM AND RESERVOIR GRAND RIVER BASIN, SOUTH DAKOTA 2014 - 2015 REGULATION

1. Project Description and Water Control Plan. Shadehill Reservoir is located on the Grand River near Lemmon, South Dakota and is regulated by the Bureau of Reclamation except when the pool level rises into the exclusive flood control zone as per the Field Working Agreement dated May 15, 1972. When this occurs, release determination is the responsibility of the Corps of Engineers under the provisions of Section 7 of the 1944 Flood Control Act. At pool elevation 2272 ft, releases begin through the uncontrolled outlet in fill and spill operations. At the top of the flood control pool the uncontrolled outlet structure has a capacity of approximately 5,200 cfs. In 1952, the Corps established a safe downstream channel capacity of 5,000 cfs. There is a gated structure that can release up to 600 cfs.

Table 1 shows the storage zones for Shadehill Reservoir.

Table 1 Shadehill Reservoir Storage Allocations, 1993 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) PD (ac-ft) (ac-ft) Inactive 2198-2250.8 43,869 43,869 Conservation 2250.8-2272.0 76,303 120,172 Flood Control 2272.0-2302.0 230,004 350,176 Surcharge 2302.0-2312.0 119,560 -

2. Operation for Report Period. Shadehill Reservoir did not enter the flood control pool during the reporting period. A small rainfall event in October caused the reservoir to rise to its peak pool elevation for the reporting period of 2271.9 ft. Shadehill Reservoir was drawn down steadily through the fall and winter and maintained 3 to 4 feet below the base of the flood pool through the rest of winter and spring. The pool began to fill in early May as releases were decreased. The pool filled to an elevation of 2271.4 ft and was maintained through the rest of the summer.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2.

APPENDIX D9- SHADEHILL DAM-1 APPENDIX D9-SHADEHILL DAM

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 32152 cfs 8-Apr-52 Lowest 2257.3 ft 5-Mar-08 2nd 21204 cfs 14-Apr-09 2nd 2258.6 ft 17-Nov-81 3rd 11333 cfs 22-Mar-97 3rd 2258.9 ft 17-Mar-62 Daily Outflow - Date Highest 5078 cfs 10-Apr-52 c. Report Period 2nd 4706 cfs 18-Apr-09 Total Inflow Total Outflow 3rd 4120 cfs 3-Apr-78 73,832 ac-ft 94% of norm 65,270 ac-ft 86% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 2297.9 ft 10-Apr-52 871 cfs 08-Jul-15 251 cfs 7-Nov-14 2nd 2290.8 ft 18-Apr-09 Peak Pool Elev Min Pool Elev 3rd 2282.4 ft 2-Apr-78 2271.9 ft 05-Oct-14 2268.1 ft 23-Jan-15

APPENDIX D9- SHADEHILL DAM-2 APPENDIX D9 - SHADEHILL DAM Prepared By:____JB ___ Reviewed By:___ MN ___ Top ofTop Conservation Zone (2272) Inflow Release Top of Flood Control Zone (2302)

FIGURE 1 - SHADEHILL DAM POOL ELEVATIONS, INFLOWS,, AND RELEASES FOR REPORT PERIOD.

APPENDIX D9 - SHADEHILL DAM - 3 APPENDIX D9 - SHADEHILL DAM Prepared By:____JB ___ Reviewed By:___ MN ___ Top ofTop Conservation Zone (2272) Top of Flood Control Zone (2302)

FIGURE 2 - SHADEHILL DAM HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX D9 - SHADEHILL DAM - 4 APPENDIX D10-TIBER DAM

TIBER DAM AND RESERVOIR (LAKE ELWELL) MARIAS RIVER BASIN, MONTANA 2014-2015 REGULATION

1. Project Description and Water Control Plan. The Bureau of Reclamation constructed Tiber Dam (Lake Elwell) and power plant during the period 1951- 1956. Tiber Dam provides flood control, irrigation, power, recreation, fish and wildlife, and municipal water supply. Tiber Dam impounds water from the Marias River near Shelby, MT. Under the provisions of Section 7 of the 1944 Flood Control Act, regulations for the operation of flood control storage in the reservoir will be prepared by the Omaha District.

In accordance with the Water Control Agreement, the replacement zone (2993- 3008.1 ft) and part of the joint use zone (2976-2993 ft) will be evacuated to elevation 2982.0 ft by December 1 while the remainder of the joint-use zone should be vacated to elevation 2976.0 ft by March 1 dependent upon inflow forecasts. March-June releases are based on forecasted inflows with the objective of filling Lake Elwell to elevation 2993.0 ft by the end of June.

Table 1 shows the storage zones for Tiber Reservoir.

Table 1 Tiber Reservoir Storage Allocations, 2002 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) NGVD29 (ac-ft) (ac-ft) Inactive 2823.5-2966.4 554,330 554,330 Conservation 2966.4-2976.0 112,882 667,212 Joint Use 2976.0-2993.0 258,436 925,648 Replacement Storage 2993.0-3008.1 303,725 1,229,373 Flood Control 2993.0-3012.5 403,075 1,328,723 Surcharge 3012.5-3020.2 181,722 -

2. Operation for Report Period. Three federal agencies, the Corps of Engineers, Bureau of Reclamation and the NRCS are responsible for providing independent monthly April-July inflow forecasts for Tiber. Table 2 displays the agencies’ forecasts for Tiber Dam. The actual 2015 April-July Tiber Dam inflow was 193 kaf (52% of the USBR April-July 30 year average of 371 kaf). Note the percentage of normal for the Corps of Engineers and NRCS forecasts are based on different averages than the USBR.

APPENDIX D10- TIBER DAM-1 APPENDIX D10-TIBER DAM

Table 2 Forecasted % of Normal Apr-Jul 2015 Tiber Dam Inflow Agency Jan 1 Feb 1 Mar 1 Apr 1 May 1* Jun 1** 89% 77% 62% 45% 28% 8% Corps of Engineers^ (378 kaf) (325 kaf) (262 kaf) (192 kaf) (104 kaf) (17 kaf) Bureau of Reclamation 105% 93% 86% 60% 44% 37% Operating Forecast**** (392 kaf) (346 kaf) (319 kaf) (223 kaf) (139 kaf) (70.3 kaf) 110% 94% 90% 46% 44% 17% NRCS*** (380 kaf) (325 kaf) (310 kaf) (157 kaf) (124 kaf) (24 kaf) * May-July % of normal inflow forecast ** June-July % of normal inflow forecast *** Marias River near Shelby forecast **** This forecast may reflect an average of agency forecasts for inclusion in the Bureau of Reclamation Monthly Operating Plan. ^Pike Creek SnoTEL was removed April 2012 from the Corps of Engineers’ forecast

The snowpack above Tiber Dam peaked at 11.3 inches of SWE in early March while the average snowpack peaks in early-April at 18.3 inches of SWE. The mountain snowmelt inflows peaked at about 2400 cfs in early-June and helped to fill the reservoir. During the runoff period, releases were being kept low (around 600 cfs) to fill the reservoir. Unexpected rainfall increased the inflow by about 500 cfs in early June and the release was increased to about 900 cfs to prevent the unnecessary use of the flood control pool. The pool elevation peaked on July 15 at 2993.0 feet, the base of the flood control pool.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2.

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 102888 cfs 10-Jun-64 Lowest 2953.8 ft 31-Mar-68 2nd 52981 cfs 21-Jun-75 2nd 2955.3 ft 28-Apr-67 3rd 26391 cfs 26-Feb-86 3rd 2956.3 ft 14-Mar-69 Daily Outflow - Date Highest 10300 cfs 13-Jun-64 c. Report Period 2nd 5777 cfs 25-Jun-75 Total Inflow Total Outflow 3rd 5308 cfs 22-Jun-67 476,380 ac-ft 80% of norm 447,436 ac-ft 78% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 3011.4 ft 19-Jul-11 2,445 cfs 04-Jun-15 913 cfs 5-Jun-15 2nd 3005.6 ft 12-Jul-65 Peak Pool Elev Min Pool Elev 3rd 3001.9 ft 13-Jun-64 2993.0 ft 15-Jun-15 2985.0 ft 24-Jan-15

APPENDIX D10- TIBER DAM-2 APPENDIX D10 - TIBER DAM Prepared By:____JB ___ KS ___ By:___ Reviewed Release Inflow Top of Flood Control Zone (3012.5) Top ofTop Conservation Zone (2976)

FIGURE 1 - TIBER DAM POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX D10 - TIBER DAM - 3 APPENDIX D10 - TIBER DAM Prepared By:____JB ___ KS ___ By:___ Reviewed Top ofTop Conservation Zone (2976)

FIGURE 2 - TIBER DAM HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX D10 - TIBER DAM - 4 APPENDIX D11-YELLOWTAIL DAM

YELLOWTAIL DAM AND RESERVOIR (BIGHORN LAKE) BIGHORN RIVER BASIN, MONTANA 2014-2015 REGULATION

1. Project Description and Water Control Plan. The Bureau of Reclamation constructed Yellowtail Dam (Bighorn Lake) and power plant during the period 1963-1966. Yellowtail Dam provides flood control, irrigation, power, recreation, fish and wildlife, industrial and municipal water supply. Yellowtail Dam impounds water from the Bighorn River near Billings, MT. Under the provisions of Section 7 of the 1944 Flood Control Act, regulations for the operation of flood control storage in the reservoir will be prepared by the Omaha District.

Bighorn Reservoir is regulated for flood control primarily for the reduction and prevention of flooding downstream from the project, on both the Bighorn and Yellowstone Rivers. Flood control regulation criteria is published in the Federal Register, at page 17996, Volume 36, issue of September 9, 1971 and is also contained in the September 21, 1971 Field Working Agreement. The criteria for flood control regulation of the exclusive flood control storage space is as follows.

“…shall be regulated for flood control on the Bighorn and Yellowstone Rivers. Any water temporarily stored in this space shall be released as rapidly as practicable. The objectives of the flood control operation are to limit, insofar as practicable, the flow in the Bighorn River to 20,000 cfs. and/or a stage of 14.2 feet at St. Xavier, Mont., and the flow in the Yellowstone River to 65,000 c.f.s. and/or a stage of 13 feet at Miles City, Mont.”

Desired target flows provided in “Chapter IX - Flood Control Regulation” of the “December 1971 Report on Reservoir Regulation for Flood Control (Revised January 1974)” are as follows.

20,000 cfs 14.2 feet at St. Xavier 25,000 cfs 10.5 feet at Bighorn 65,000 cfs 13.0 feet at Miles City 100,000 cfs 19.0 feet at Sidney

Yellowtail Reservoir will be regulated to be no higher than elevation 3630.0 ft by December 1 to reduce chances of headwater ice problems. During the remainder of the winter and early spring releases above those required for irrigation and fisheries will be scheduled on the basis of anticipated inflows to have the pool at or below the base of the joint use zone (3614 ft) by May 1. A greater drawdown to below elevation 3595 ft may be scheduled if May-July inflows are anticipated to be sufficient to allow filling of the joint use zone. March through July releases will be based on forecasted inflows with the objective of filling Yellowtail Reservoir to elevation 3640.0 ft by the end of July.

APPENDIX D11- YELLOWTAIL DAM-1 APPENDIX D11-YELLOWTAIL DAM

Table 1 presents the 1982 survey of Bighorn Lake storage allocations.

Table 1 Yellowtail Reservoir Storage Allocations, 2007 Survey Pool Elevation Zone Capacity Cum Capacity Storage Zones (ft) NGVD29 (ac-ft) (ac-ft) Inactive 3166-3547 469,910 469,910 Conservation 3547-3614 318,298 788,208 Joint Use 3614-3640 232,365 1,020,573 Flood Control 3640-3657 258,323 1,278,896 Surcharge 3657-3660 52,829 -

2. Operation for Report Period. Three federal agencies, the Corps of Engineers, Bureau of Reclamation, and the NRCS are responsible for providing independent monthly April-July inflow forecasts for Yellowtail. Table 2 displays the agencies’ forecasts for Yellowtail Dam. The actual 2015 April-July Yellowtail Dam inflow was 1542.8 kaf (142% of the USBR April-July 30 year average of 1086 kaf). Note the percentage of normal for the Corps of Engineers and NRCS forecasts are based on different averages than the USBR.

Table 2 Forecasted % of Normal Apr-Jul 2015 Yellowtail Dam Inflow Agency Jan 1 Feb 1 Mar 1 Apr 1 May 1* Jun 1** 91% 79% 97% 60% 52% 84% Corps of Engineers (actual) (1060 kaf) (921 kaf) (1129 kaf) (700 kaf) (522 kaf) (612 kaf) Bureau of Reclamation 101% 94% 99% 62% 58% 155% Operating Forecast**** (1095.7 kaf) (1015.8 kaf) (1065.6 kaf) (675.5 kaf) (541.8 kaf) (1027 kaf) 101% 94% 100% 64% 49% 79% NRCS*** (1400 kaf) (1300 kaf) (1380 kaf) (890 kaf) (620 kaf) (730 kaf) * May-July % of normal inflow forecast ** June-July % of normal inflow forecast *** Bighorn River near St. Xavier forecast **** This forecast may reflect an average of agency forecasts for inclusion in the Bureau of Reclamation Monthly Operating Plan.

The snowpack above Yellowtail Dam was below the average during the report period. The snowpack peaked in late March at almost 11 inches of SWE while the average snowpack peaks in mid-April and is just above 14 inches of SWE. The rainfall experienced in May was 5-8 inches above normal and in June was 1- 3 inches above normal. The reservoir was held higher in the joint use zone due to the below normal inflow forecast. As a result, the heavy rainfall caused the flood control zone to be utilized with consideration of the flood control operation at Boysen Dam.

Coordination between the Corps and Reclamation related to the use of flood control storage began in May and continued until the reservoir exited the flood control pool in late July. The reservoir inflow forecasts varied due to the difficulty in predicting spring and early summer rainfall as well as the changing flood control operation at Boysen and Buffalo Bill Dams located upstream of Yellowtail Dam. This resulted in varying peak pool elevation forecasts. In early June about 10% of the flood control pool was forecast to be filled due to heavy rainfall runoff and by the middle of June 44% was forecast to be filled.

APPENDIX D11- YELLOWTAIL DAM-2 APPENDIX D11-YELLOWTAIL DAM

The above normal rainfall in the Bighorn River basin forced the average daily inflow to Yellowtail Dam to over 19,000 cfs resulting in a peak pool elevation of 3647.9 feet (43% occupied). The maximum daily outflow from Yellowtail Dam was 14,325 cfs in June.

Historical as well as reporting period details are contained in paragraphs 2a through 2c and Figures 1 and 2.

a. Maximums of Record: b. Minimums of Record (since initial fill) Daily Inflow - Date Pool - Date Highest 29776 cfs 1-Jul-67 Lowest 3572.8 ft 11-Mar-03 2nd 23215 cfs 19-May-78 2nd 3581.8 ft 8-May-04 3rd 21006 cfs 11-Jun-97 3rd 3582.3 ft 21-May-02 Daily Outflow - Date Highest 24721 cfs 8-Jul-67 c. Report Period 2nd 15394 cfs 17-Jun-11 Total Inflow Total Outflow 3rd 14947 cfs 3-Jul-70 2,771,984 ac-ft 117% of norm 2,794,479 ac-ft 119% of norm Pool - Date Peak Daily Inflow Peak Daily Outflow Highest 3656.4 ft 6-Jul-67 19,225 cfs 11-Jun-15 14,287 cfs 10-Jun-15 2nd 3655.0 ft 24-Jul-11 Peak Pool Elev Min Pool Elev 3rd 3651.7 ft 14-Jul-97 3647.9 ft 20-Jun-15 3621.2 ft 6-May-15

APPENDIX D11- YELLOWTAIL DAM-3 APPENDIX D11 - YELLOWTAIL DAM Prepared By:____JB ___ KS ___ By:___ Reviewed Release Inflow Top ofTop Conservation Zone (3614) Top of Flood Control Zone (3657)

FIGURE 1 - YELLOWTAIL DAM POOL ELEVATIONS, INFLOWS, AND RELEASES FOR REPORT PERIOD.

APPENDIX D11 - YELLOWTAIL DAM - 4 APPENDIX D11 - YELLOWTAIL DAM Prepared By:____JB ___ KS ___ By:___ Reviewed Top ofTop Joint Use Zone (3640) Top ofTop Conservation Zone (3614)

FIGURE 2 - YELLOWTAIL DAM HISTORICAL POOL ELEVATIONS AND RELEASES.

APPENDIX D11 - YELLOWTAIL DAM - 5 APPENDIX D11-YELLOWTAIL DAM

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APPENDIX D11- YELLOWTAIL DAM-6