Appendix A Hydrology Reportdeq.state.wy.us/wqd/watershed/Program Documents...Appendix A – Hydrology Report A-2 1939-1940, 1950-1957, and 1977-1998. Since 1998, flow has been collected

Appendix A Hydrology Report Prepared by: The RETEC Group, Inc. 2409 Research Blvd., Suite 106 Fort Collins, Colorado 80526 RETEC Project Number: APC02-18086-410 Prepared for: Anadarko Petroleum Corporation P.O. Box 10 Midwest, Wyoming 82643 Prepared by: DRAFT ____________________________________________________

Margaret C. Zebley, P.E., Project Engineer Reviewed by: DRAFT ____________________________________________________

Robert Friesen, P.E., Supervising Engineer

October 25, 2004

Table of Contents

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1 Introduction................................................................................................... A-1 2 Hydrologic Data............................................................................................ A-1

2.1 USGS Data........................................................................................ A-1 2.2 2003 – 2004 Field Data..................................................................... A-2

3 Hydrologic Conditions.................................................................................. A-2 3.1 Salt Creek Conditions ....................................................................... A-3

3.1.1 Salt Creek Watershed............................................................ A-3 3.1.2 Salt Creek Hydrologic Conditions ........................................ A-3

3.2 Powder River Conditions.................................................................. A-4 3.2.1 Powder River Watershed ...................................................... A-4 3.2.2 Powder River Hydraulic Conditions..................................... A-5

3.3 Salt Creek Comparison to Powder River .......................................... A-5 3.4 Groundwater Uses............................................................................. A-6

4 Produced Water Discharges.......................................................................... A-6 4.1 NPDES Permits and Discharge Locations........................................ A-6 4.2 Effects of Produced Water Discharges ............................................. A-6

5 Effects of Discontinuing Produced Water Discharges.................................. A-7 5.1 Predicted Salt Creek Flow Characteristics........................................ A-8 5.2 Predicted Powder River Flow Characteristics .................................. A-8 5.3 Agricultural Uses .............................................................................. A-8 5.4 Future Allocations............................................................................. A-8

6 Conclusions................................................................................................... A-9 7 References................................................................................................... A-10 List of Tables Table A-1 Produced Water Discharges to Salt Creek Table A-2 Salt Creek Annual Flows and Estimated Available Flows List of Figures Figure A-1 USGS Gage Locations Figure A-2 October 2003 and April 2004 Flow Measurements Figure A-3 Salt Creek Mean Monthly Flows Figure A-4 Mean Monthly Flow Rate Comparison Between Salt Creek and

Powder River Figure A-5 Annual Flow Comparison Between Salt Creek and Powder River Figure A-6 Comparison of Minimum Mean Monthly Flows Salt Creek, Powder

River, and Produced Water Discharges Figure A-7 Salt Creek Contribution to Powder River Figure A-8 NPDES Permitted Discharges

Table of Contents

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List of Acronyms ac-ft acre-feet AMSL above mean sea level cfs cubic feet per second HUC Hydrologic Unit Code NPDES National Pollutant Discharge Elimination System PRCD Powder River Conservation District RETEC The RETEC Group, Inc. UAA Use Attainability Analysis USEPA United States Environmental Protection Agency USGS United States Geological Survey

Appendix A – Hydrology Report

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1 Introduction This report evaluates available data for the hydrology of Salt Creek and the Powder River downstream of its confluence with Salt Creek and is presented in support the Salt Creek Use Attainability Analysis (UAA). The goal of this evaluation is to analyze the hydrology of the Salt Creek basin, the contributions of the basin to the Powder River, and to evaluate possible effects of eliminating currently permitted produced water discharges to Salt Creek.

This report includes the following sections:

• Section 2 discusses the hydrologic data used in this evaluation

• Section 3 discusses permitted produced water discharges to Salt Creek

• Section 4 includes an evaluation of hydrologic conditions in the Salt Creek and the Powder River

• Section 5 discusses predicted changes to the Salt Creek water budget if permitted discharges were discontinued

• Section 6 presents the conclusions of this report

• Section 7 provides references cited in this report.

2 Hydrologic Data Data used for evaluation of hydrologic conditions in Salt Creek and the Powder River were obtained from the United States Geological Survey (USGS) and from recent field sampling events performed by the Powder River Conservation District (PRCD) and The RETEC Group, Inc. (RETEC). Following is a discussion of data that were used in this evaluation.

2.1 USGS Data Hydrologic data for the Salt Creek drainage (Hydrologic Unit Code [HUC] 10090204) consist of flow discharge data collected from a USGS stream gage (Station 06313400) located on Salt Creek near Sussex, Wyoming, as shown in Figure A-1. The gage was operated from 1976 to 1993, barring occasional periods of equipment malfunction.

Powder River (HUC 10090202) flow data were also collected from a stream gage operated by the USGS (Station 06313500). This gage is located on the Powder River immediately downstream of the confluence with Salt Creek at Sussex, Wyoming (Figure A-1). The gage was operated during the years of


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1939-1940, 1950-1957, and 1977-1998. Since 1998, flow has been collected on a continuous basis, barring occasional periods of equipment malfunction.

Due to the different monitoring periods for each gaging station: (Salt Creek: 1977-1993; Powder River: 1939-1940, 1950-1957, and 1977-1998), and incompleteness of data prior to 1970, the comparison between the Salt Creek and Powder River gages is limited to the years from 1977 to 1993. Also, the nearest gage upstream of the confluence between Salt Creek and the Powder River is over 11 miles upstream of Sussex, rendering upstream flow data comparison questionable. Therefore, this evaluation relies primarily on USGS data from the stations near Sussex, Wyoming.

2.2 2003 – 2004 Field Data Recent hydrologic data for Salt Creek and the Powder River were developed from 2003 and 2004 water quality monitoring performed by the PRCD sampling program (October 2003) and the RETEC synoptic sampling program in April 2004. The main objective of the PRCD monitoring and RETEC sampling was the monitoring and evaluation of water quality parameters on Salt Creek. However, flow data taken during the water quality sampling events were included in this evaluation.

The PRCD has been monitoring water quality in the Salt Creek watershed under a Section 319 grant from the United States Environmental Protection Agency (USEPA). The District conducted monthly water quality monitoring from April 2003 through the end of the water year in October 2003. Recently, the District reinitiated monthly monitoring starting in April 2004 and will conclude in October 2004.

The RETEC synoptic surveys were undertaken, in order to characterize high-flow conditions and baseflow conditions. Samples and flow measurements were collected in 11 locations as shown in Figure A-2. Details of the sampling event are provided in the Water Quality Report (Appendix B). Multiple data points in the same month were averaged to represent one flow value.

3 Hydrologic Conditions Data were reviewed to provide an evaluation of the hydrologic conditions of Salt Creek. This evaluation was performed to generate a baseline scenario of conditions within the Salt Creek basin that currently include produced water discharges to the creek. The evaluation also includes a discussion of conditions within the Powder River and the contribution of Salt Creek flows to the Powder River.


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3.1 Salt Creek Conditions Following is a discussion of the characteristics of the Salt Creek watershed and hydrologic conditions of the creek.

3.1.1 Salt Creek Watershed The Salt Creek drainage covers an area of approximately 806 square miles encompassing parts of Natrona County, Johnson County, and Converse County, Wyoming (PRCD, 2004) as shown in Figure A-1. Elevation within the basin range varies 6,020 feet (ft) above mean sea level (AMSL) near the headwaters at the southern extent of the basin, to approximately 4,390 ft AMSL at the confluence with the Powder River in the north (PRCD, 2004). The drainage area of Salt Creek upstream of the USGS stream gage 06313400 covers approximately 769 square miles and includes every significant tributary and water source in the basin. The USGS gage sits at an elevation of 4,480 AMSL. Several tributaries feed into Salt Creek, including Teapot Creek, Cottonwood Creek, Castle Creek, Dugout Creek, and Meadow Creek.

The watershed is semi-arid, receiving approximately 13 to 15 inches of total precipitation per year as reported in the Powder / Tongue River Basin Plan (Basin Plan) (WWDC, 2002a). The topography within the basin is characterized as rolling plains (Montana DEQ, 2003). Vegetation within the basin consists primarily of shrub- and grass-lands with minor areas of deciduous and evergreen forests (Montana DEQ, 2003). The habitats directly associated with or adjacent to Salt Creek include mixed grass prairie, Wyoming big sagebrush, desert shrub, forest-dominated riparian, and dry land crops.

3.1.2 Salt Creek Hydrologic Conditions According to the Wyoming State Water Quality Assessment Report (WDEQ 2002),

“Most reaches in this semi-arid watershed are non-perennial. Salt Creek now has perennial flow due to discharge water from oil treaters, but reportedly is naturally non-perennial.”

Prior to the start of produced water discharges, Salt Creek was likely an intermittent stream, generally flowing during periods of snowmelt and precipitation events. Currently, the upper reaches of Salt Creek continue to exhibit intermittent flow. However, flows are continuous downgradient of the vicinity of the communities of Midwest and Edgerton, Wyoming (Figure A-1). The continuous flows are the result of produced water discharges to Salt Creek that began in approximately 1970. There are no flow data in Salt Creek prior to the start of produced water discharges.


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Flow fluctuations within the creek are seasonal and vary considerably, largely in response to spring snowmelt and early summer precipitation as shown in Figure A-3. Salt Creek USGS data show that the mean monthly creek flows vary from 5 cubic feet per second (cfs) to over 400 cfs. Salt Creek flow typically peaks in May and exhibits its lowest flow in December and January. The upper reaches of Salt Creek and associated tributaries generally exhibit very low to no flow during dry periods. Along the lower reach of Salt Creek, minimum flows for the creek are maintained by water discharges and are fairly stable, varying between 5 to 19 cfs as shown in Figure A-3.

Recent hydrologic data for Salt Creek are depicted in Figure A-2. This figure illustrates the change in flow along the creek during the October 2003 and April 2004 sampling events performed by RETEC. Flow in the creek is generally intermittent above the produced water discharge area. In addition, the October 2003 sampling event performed by RETEC verified that all sample stations upstream of the produced water discharge area were dry at the time of sampling. Therefore, flows measured at the USGS Salt Creek gauging station are largely the result of produced water discharges during dry periods.

3.2 Powder River Conditions Following is a discussion of the characteristics of the Powder River watershed and hydrologic conditions of the river.

3.2.1 Powder River Watershed The State of Wyoming Water Quality Assessment Report (WDEQ, 2002) describes the Powder River as follows:

“The Upper Powder Watershed encompasses most of the drainages into the Powder River main stem from the confluence of the North and Middle Forks downstream to the confluence of the Powder River and Clear Creek. Except for the main stem, most reaches in this semi-arid watershed are non-perennial. “

The Powder River HUC, 10090204, covers a drainage area of 3,090 square miles, which is measured at the USGS gauging station at Sussex, Wyoming (Figure A-1). The gage elevation is 4,362.16 ft AMSL. The headwaters of the Powder River are located in north central Wyoming and the River flows east of out the Bighorn Mountains and north into Montana to join the Yellowstone River. Elevation within this portion of upstream of Sussex, Wyoming ranges from 4,500 to 8,800 ft AMSL in the southern Bighorn Mountains.

The portion of the Powder River watershed in the vicinity of Salt Creek is semi-arid, receiving approximately 13 to 15 inches of total precipitation per year WWDC, 2002a). The topography within the basin varies from mountainous to rolling plains. Vegetation in the Powder River area consists primarily of shrub- and grass-lands.


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3.2.2 Powder River Hydraulic Conditions The Powder River is perennial along the reach containing Salt Creek. Some reaches and tributaries, such as the South Fork of the Powder River, exhibit intermittent flow characteristics (PRCD, 2004). The USGS data collected from the Powder River near Sussex, Wyoming illustrates that the flow is highly variable, both on a seasonal and an annual basis with ranges between 18 cfs to more than 2,500 cfs (Figure A-4). Like Salt Creek, flow fluctuations are generally due to seasonal variations such as snowmelt and summer rainstorms. Powder River flow at Sussex exhibits a small peak in February and March in response to snow melt at lower elevations (Montana DEQ, 2003). Typically the peak flow occurs in May in response to snow melt at higher elevations and rainfall events. Low-flow conditions occur in August and from November through January as shown in Figure A-4. Additionally, no flow (isolated pools likely connected by subsurface flow) has been observed upstream of Salt Creek during dry summer months.

3.3 Salt Creek Comparison to Powder River Although the magnitude of flow in the Powder River is generally much higher, both drainages exhibit similar annual flow fluctuations. Figures A-4 and A-5 illustrate the annual flow and mean monthly flows for the Powder River, as well as provide a comparison to Salt Creek flow. The mean monthly flow trends are similar (Figure A-4) and the annualized flow rates generally show similar fluctuations (Figure A-5). A comparison of the minimum mean monthly flows, shown in Figure A-6, indicates that the minimum flow rates in each drainage are almost equal during the dry summer months (July through September).

The contribution of flow from Salt Creek to the Powder River varies throughout the year as shown in Figure A-7. During the period of comparable flow data, the average Salt Creek contribution (i.e., that portion of flow in the Powder River that can be attributed to Salt Creek discharge) varied from a low of approximately 13 percent during May (peak runoff flowing through the Powder River) to a high of approximately 49 percent during the dry summer months. However, data indicate that there are periods when Salt Creek contributes almost 100 percent of the flow measured in the Powder River. This condition generally occurs only during dry summer months when little to no flow is measured in the Powder River, while produced water discharges maintain baseflow conditions in Salt Creek. Note that significant irrigation withdrawals occur from the Powder River upstream of Salt Creek via the Sierra Ditch (at Kaycee). Return flows (if any) from this ditch rejoin the Powder River several miles downstream of Salt Creek.

Recent sampling events on the Powder River illustrate that the addition of Salt Creek flows, and thus produced water discharges, have a direct impact on the flow in the Powder River. Figure A-2 illustrates the increase in flow in the Powder River across the confluence of Salt Creek during each sampling event.


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During spring snowmelt conditions (April 2004), Salt Creek flow increased the Powder River flow by approximately 9 percent. Similar measurements during drier conditions (October 2003) show an increase in Powder River flow of approximately 80 percent. It is apparent that during the lowest flows in the Powder River (July through October), Salt Creek provides a substantial portion, and occasionally all, of the Powder River flow measured at Sussex, Wyoming.

3.4 Groundwater Uses The consumptive use of groundwater in the Salt Creek basin is limited and has little effect of on Salt Creek flows. There are a number of permitted wells and springs in the vicinity of Salt Creek (WWDC, 2002b, 2002c); however, the volume of water produced from these wells and springs (approximately 0.44 cfs) would have a minimal impact upon surface water flow in Salt Creek. The Casper Regional Water System (WWDC, 2002a) provides the drinking water supplies for the communities of Midwest and Edgerton, Wyoming. Therefore, groundwater within the basin is not a source of drinking water for these communities.

4 Produced Water Discharges Permits were reviewed to determine the volume of produced water currently discharged to Salt Creek. Following is a discussion of the evaluation of permitted discharges in the Salt Creek basin.

4.1 NPDES Permits and Discharge Locations There are currently 21 National Pollutant Discharge Elimination System (NPDES) permitted outfalls that discharge to Salt Creek. Oil and gas producers hold all of these permits. Five of the permits are currently inactive. Additionally, two of the remaining permits discharge little to no flow to Salt Creek. These outfalls are illustrated in Figure A-8 and are also summarized in Table A-1. Each of the permits is discussed in greater detail in the Water Quality Report (Appendix B).

4.2 Effects of Produced Water Discharges Permitted produced water discharges in the Salt Creek basin total approximately 13.6 cubic feet per second (cfs), as summarized in Table A-1. It is assumed that these flows occur in generally a continuous manner throughout the year.

The discharges have transformed the lower reaches of Salt Creek into a perennial stream. Figure A-3 illustrates the relationship of these discharges to the minimum mean monthly flow in Salt Creek. It is apparent that the produced water sustains baseflow conditions within the creek. Additionally, it


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is likely that a portion of the produced water infiltrates the bed of the creek and thereby recharges the near-surface groundwater in the area. Although data are insufficient for a detailed analysis, a comparison of flows measured during sampling events in October 2003 and April 2004 indicate a potential loosing reach (surface water discharging to groundwater) between stations WQ-1 and S-10. Alternatively, groundwater may also discharge into the streambed as indicated by increased flows between stations S-10 and S-11. These conditions likely vary throughout the year in response to seasonal flow fluctuations within Salt Creek.

Produced water discharges have also increased baseflow conditions in the Powder River. As shown in Figure A-6, the produced water discharges are almost equal to the minimum monthly mean flows measured in the Powder River. Similarly, Salt Creek’s contribution to Powder River flow is almost 100 percent during dry summer months. Therefore, it is probable that during extended dry periods produced water discharged into Salt Creek prevents intermittent flow characteristics in the Powder River.

Salt Creek is currently used for livestock watering. According to the Livestock Report (Appendix G), a number of ranches use the Creek for watering of cattle and sheep. Frontage of Salt Creek used for livestock watering varies from 2 to 25.8 miles. According to the Livestock Report’s survey of local ranches:

“Several of the respondents recall the time prior to the start of water flooding at the Salt Creek and Teapot Dome fields. At that time Salt Creek would dry up or be reduced to boggy pools in summer. Adequate (i.e. not too alkaline) water was limited to more or less brief periods during spring months.”

Therefore, produced water discharges to Salt Creek provide a vital source of water for cattle operations along the creek. Additional detail regarding livestock is provided in the Livestock Report (Appendix G).

5 Effects of Discontinuing Produced Water Discharges An evaluation was performed to predict the effects of discontinuing produced water discharges to Salt Creek. The following areas were evaluated: effects upon Salt Creek flows, effects upon Powder River flows, potential impacts to agricultural stakeholders, and potential impacts upon future water allocations for the Powder River basin. Each area is discussed below.


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5.1 Predicted Salt Creek Flow Characteristics Discontinuing produced water discharges in the Salt Creek basin would likely result in decreased flow within the creek. This may result in Salt Creek exhibiting intermittent flow characteristics, especially during dry summer months. Figure A-3 illustrates that baseflow conditions within the creek closely match produced water discharges in the basin. The degree of potential intermittent flow conditions would be dependent on both future precipitation events and future water use practices. Negative water quality impacts are also expected and are discussed in detail in the Water Quality Report.

5.2 Predicted Powder River Flow Characteristics Discontinuing produced water discharges in the Salt Creek basin would likely result in a decreased flow within the Powder River. Although the reach of the Powder River in the vicinity of Salt Creek is perennial, visual observations upstream of the confluence with Salt Creek have indicated that, on rare occasions, flow in the riverbed has been reduced to isolated pools connected via subsurface flow. Discontinuing discharges to Salt Creek may increase the extent and frequency of such observations downstream of Salt Creek, leading to negative impacts on both water quality and aquatic life in the Powder River. The degree of potential intermittent flow would be dependent on numerous future climate variables and future water used practices within the basin.

5.3 Agricultural Uses Agricultural uses of Salt Creek may decrease with the absence of the produced water discharges. Historically, Salt Creek has become dry during the summer months without the additional water from the produced water discharges. Also, the water remaining in the creek may exhibit poorer quality leading to reduced benefit for livestock. Therefore, agricultural use of Salt Creek, in the form of livestock production, would likely decrease due to reduced water resources.

There is currently no crop production in the Salt Creek valley. No surface water rights are currently allocated from Salt Creek, and no removals for irrigation occur. Therefore, it is anticipated that there would be no change to irrigation practices in the basin as a result eliminated produced water discharges.

5.4 Future Allocations Estimates of future potential water allocations were developed for Salt Creek and the Powder River. One of the objectives of the Basin Plan (WWDC, 2002a) was to quantify available surface water supplies. USGS streamflow data, collected from 1970 through 1999, was incorporated into a numerical model to estimate future available surface water resources within the Powder


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River basin. Salt Creek was included as a tributary to the Powder River. Details of the analysis are provided in the Basin Plan (WWDC, 2002). A summary of the analysis is provided in Table A-2.

The estimated available flow in Salt Creek varies from approximately 22,000 acre-feet (ac-ft) during dry years to approximately 49,400 ac-ft during wet years. The normal-year available flow is estimated to be approximately 33,700 ac-ft., as documented in the Basin Plan.

Produced water discharges to Salt Creek currently are permitted at 13.63 cfs, which equates to approximately 9,850 ac-ft per year. These discharges comprise between 20 and 45 percent (wet and dry years, respectively) of the available flows attributed to Salt Creek. During dry years especially, produced water discharges constitute a large portion of flows that may be allocated at some point in the future.

The State of Wyoming’s allocation of available flow in the Powder River is estimated to range from 74,300 to 211,500 ac-ft for dry and wet years, respectively, as detailed in the Basin Plan (WWDC, 2002). The contribution to this allocation provided by produced water discharges in Salt Creek varies from 4.6 to 13.3 percent. Therefore, Salt Creek flows can provide a sizeable portion of allotted flows in the Powder River.

6 Conclusions It can be seen from an evaluation of USGS data, recent hydrologic data, current agricultural practices, and potential future water allotments that produced water discharges provide significant benefits within the basin and on a regional basis as well. These discharges have transformed Salt Creek into a perennial stream downstream of the discharge area, resulting in:

• Improved water quality within Salt Creek enabling increased livestock production in the basin

• Increased flows to the Powder River ensuring continuous flows in the river downstream of the confluence with Salt Creek benefiting aquatic life

• Increased flows to the Powder River that can contribute a sizeable portion of future allotted flow that may be required by the State of Wyoming

Eliminating future produced water discharges may have the following effects:

• Reduced flow in Salt Creek resulting in an intermittent stream with poorer water quality


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• Reduced flow in the Powder River resulting in potentially future intermittent flow conditions

• Reduced livestock production in the basin as a result of less water available for livestock watering and poorer quality water for the cattle

• Negative impacts on future Wyoming Powder River allotments requirements

7 References Montana DEQ (Department of Environmental Quality), 2003. Total

Maximum Daily Load (TMDL) Status Report, Powder River TMDL Planning Area. March 14.

PRCD (Powder River Conservation District), 2004. Final Salt Creek / South Fork 319 Watershed Assessment. March 1.

WWDC (Wyoming Water Development Commission), 2002a. Powder / Tongue River Basin Plan. Final Report. February.

WWDC (Wyoming Water Development Commission), 2000b. Powder / Tongue River Basin Plan. United States Geological Survey National Water Inventory System Spring Sites, in Decimal Degrees. NAD 1927.

WWDC (Wyoming Water Development Commission), 2002c. Powder Tongue River Basin Plan. United States Geological Survey National Water Inventory System Well Sites, in Decimal Degrees. NAD 1927.

WDEQ (Wyoming Department of Environmental Quality), 2002. Wyoming’s 2002 305(b) State Water Quality Assessment Report 2002 303(d) List of Waters Requiring TMDLs.

Tables

Table A-1Produced Water Discharges to Salt Creek

Permit No. Discharge ProducerPermitStatus Receiving Water Discharge Name

DischargeFlowRatecfs(1) % of total Notes

WY-002828 APC(2) (Howell and Westport) Active Bothwell Dr. to Salt LACT-4 0.27 2.0 Average 2001-2003WY-002836 APC (Howell and Westport) Active Salt Cr. LACT-5 0.59 4.3 Average 2001-2003WY-002879 APC (Howell and Westport) Active Salt Cr. LACT-10 0.22 1.6 Average 2001-2003WY-002887A APC (Howell and Westport) Active Salt Cr. LACT-11A 0.39 2.9 Average 2001-2003WY-002887B APC (Howell and Westport) Active Salt Cr. LACT-11B 0.06 0.4 Average 2001-2003WY-030384 APC (Howell and Westport) Active Salt Cr. LACT-20 6.73 49.4 Average 2001-2003WY-002445 APC (Howell and Westport) Active Castle Cr. to Salt BATT A 1.95 14.3 Average 2001-2003WY-002453 APC (Howell and Westport) Active Teapot Cr. to Salt BATT B 0.47 3.4 Average 2001-2003WY-002470 APC (Howell and Westport) Inactive Castle Cr. to Salt STALEY A&D 0.00 0.0 No flow since Oct 2001WY-000868 APC (Howell and Westport) Active Pavey Dr to Meadow MC/Tensleep A 0.12 0.9 Average 2001-2003WY-000990 APC (Howell and Westport) Active Meadow Creek SUSSEX B2/C 0.00 0.0 Average, 2003 dataWY-001040 APC (Howell and Westport) Active Meadow Creek SUSSEX A 0.08 0.6 Average, 2003 dataWY-024236 APC (Howell and Westport) Active West Spring Draw W SUSSEX A2 0.01 0.1 Average, 2003 dataWY-028894 USDOE Inactive Little Teapot Cr to Salt #3 Tank 0.00 0.0 Value provided by NPOSR(3)

WY-032115 USDOE Inactive Little Teapot Cr to Salt Peripheral Water Inj. 0.00 0.0 Value provided by NPOSRWY-028274 USDOE Active Little Teapot Cr to Salt B-TP Tank Battery 2.60 19.1 Value provided by NPOSRWY-025518 Manx Inactive Bothwell Dr. to Salt W. Salt Creek 0.00 0.0 DMR Report at WDEQWY-002941 Chapman Active Salt Cr. Lease 46 0.03 0.2 DMR Report at WDEQWY-001121 Sage Active Little Teapot Cr to Salt East Teapot Unit 0.01 0.1 Estimate from description by operatorWY-000744 Natural Gas Processing Active Coal Draw to Salt E. Salt Creek Flood 0.10 0.7 DMR Report at WDEQWY-000736 WyOIl and Mining Inactive E. Teapot to Teapot Burke Ranch Unit 0.00 0.0 DMR Report at WDEQ

TOTAL 13.63Notes:1. cfs = cubic feet per second2. APC = Anadarko Petroleum Corporation3. NPOSR = Naval Petroleum and Oil Shale Reserve

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Table A-2Salt Creek Annual Flows and Estimated Available Flows (1)

Units Dry Years(3) Normal Years(5) Wet Years(6)

Average Annual Flows(2) Acre Feet 26,941 32,423 44,913Estimated Available Flows Acre Feet 22,035 33,722 49,377Produced Water Discharges to Salt Creek Acre Feet 9,846 9,846 9,846

Produced Water Contribution to Estimated Available Flows % 45% 29% 20%

Notes:1. Data and analysis taken from Powder/Tongue River Basin Plan (WWDC, 2002a).2. Average annual flow data from USGS Station - Salt Creek Near Sussex, Wyoming (06313400)3. Dry years are 1980, 1981, 1985, 1988, 1989, 1994.4. Normal years are 1970-74, 1976, 1977, 1979, 1982, 1983, 1986, 1987, 1990-93, 1996, 1998.5. Wet years are 1975, 1978, 1984, 1995, 1997, 1999.

W:\Anadarko - Salt Creek Hydro/[Charts and Table.xls]Table 2-formatted Page 1 of 1

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East Teapot Creek

TEAP

OT CR

Coal Draw

S-9

S-8

S-6

S-5

S-4

S-1

P-2P-1

M-2

M-3

WQ-9WQ-8WQ-7

WQ-6

WQ-4

WQ-3

WQ-2

WQ-1

S-11

S-10

WQ-11

WQ-10S-3

S-2

WQ-5S-7

M-1

387!(

#

!(259

5400

4800

5200

4 600

5 000

5600

58 0 0

6000

4400

6200

5 200

6000

5 000

5000

6000

520 0

5 600

5400

5800

5400

6000

5600

4600

540 0

5200

4800

5 800

5 40 0

5400

5200

56 0 0

5600

5 4 00

62 005 600

5400

5600

5000

4800

56

00

5 000

50 00

6000

5600

5600

520

05200

5000

5 600

6200

ANADARKOSALT CREEK INVESTIGATION OCTOBER 2003 AND APRIL 2004

FLOW MEASUREMENTSAPC02-16608-410T:/ANADARKO_SALTCREEK/PROJECTS/Oct03SamplingEvent_fig2.MXD

LEGEND

STREAM CLASSIFICATIONStream Order 6-7Stream Order 4-5Stream Order 2-3Stream Order 1Stream Order 0

FILE:

Sampling Station(Flow Units = cfm)#

DWN. BY: KBL/ftcDATE: 7/8/04 FIGURE: A-2

p

0 2 41 Miles

NOTE: Sampling events performed by PRCD on October 9-10, 2003 and by RETEC on April 30, 2004

£

S-8Apr-04 22.1

WQ-9Apr-04 4.7

M-2Apr-04 1.1

M-1Apr-04 0.7

S-11Apr-04 19.8Oct-03 18.0

S-10Apr-04 16.0Oct-03 13.0

S-2Apr-04 0.07Oct-03 0.0

S-1Apr-04 0.011Oct-03 DRY

P-2Apr-04 152Oct-03 18P-1

Apr-04 140Oct-03 10

S-3Apr-04 0.022Oct-03 DRY

S-9Oct-03 DRY

S-4Oct-03 DRY

S-5Oct-03 DRY

S-6Oct-03 DRY

W:\Anardarko - Salt Creek Hydro\Report\[Charts and Table.xls]Fig 3 - Salt Creek Flows Page 1 of 1

Figure A-3Salt Creek Mean Monthly Flows

(Data from 1977 - 1993)

0

50

100

150

200

250

300

350

400

450

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Month

Mea

n M

onth

ly F

low

(cfs

)

Min. Mean Flow Max. Mean Flow Produced Water Discharges

Produced Water Discharges (13.6 cfs)(Mean of data 2001-2003)

W:\Anardarko - Salt Creek Hydro\Report\[Charts and Table.xls]Fig 4 - Monthly Mean Comp Page 1 of 1

Figure A-4 Mean Monthly Flow Rate Comparison Between Salt Creek and Powder River

(Data from 1977 - 1993)

0

500

1000

1500

2000

2500

3000


Month

Mea

n M

onth

ly F

low

Rat

e (c

fs)

Salt Creek Min. Salt Creek Max. Powder River Min. Powder River Max.

W:\Anardarko - Salt Creek Hydro\Report\[Charts and Table.xls]Fig 5 - Annual Flow Comp. Page 1 of 1

Figure A-5Annual Flow Rate Comparison Between Salt Creek and Powder River

0

100

200

300

400

500

1978 1979 1980 1983 1986 1987 1988 1989 1990 1991 1992

Year

Ann

ual F

low

Rat

e (c

fs)

Salt Creek Powder River

W:\Anardarko - Salt Creek Hydro\Report\[Charts and Table.xls]Fig 6- Salt Creek Min. Flows Page 1 of 1

Figure A-6Comparison of Minimum Mean Monthly Flows

Salt Creek, Powder River, and Produced Water Discharges(Data from 1977 - 1993)

0

40

80

120

160

200


Month

Min

imum

Mea

n M

onth

ly F

low

(cfs

)

Salt Creek Min. Mean Flow Powder River Min. Mean Flow Produced Water Discharges

Produced Water Discharges (13.6 cfs - Mean of Data from 2002-2003)

W:\Anardarko - Salt Creek Hydro\Report\[Charts and Table.xls]Fig 7 - Percentage of Flow Page 1 of 1

Figure A-7Salt Creek Contribution to Powder River

(Data from 1977 - 1993)

0%

20%

40%

60%

80%

100%


Month

Perc

enta

ge o

f Pow

der R

iver

Flo

wfr

om S

alt C

reek

Range of Salt Creek Contributions to the Powder River -Expressed as a Percentage of Total Powder River Flow

Average Contribution of Salt Creek Flows to Powder River