This section characterizes surface water and groundwater resources and describes water use and current water management practices in the Planning Area.

The Bighorn Basin is a semi-arid desert that receives little moisture. Lower elevations of the Basin are some of the driest parts of Wyoming. Mean annual precipitation ranges from less than 5 inches to more than 40 inches at higher elevations of mountain ranges. Most precipitation at lower elevations of the basin comes in the form of periodic rainfall from April through June. During these months, most smaller stock reservoirs in the Planning Area depend on these rainfall events to capture and store surface runoff. Snow is very light, with annual averages of 15 to 20 inches at lower elevations and 36 to 48 inches at 5,000 to 6,000 feet amsl. Large snowfall events at lower elevations in the basin are infrequent, with fewer than 3 days annually receiving 5 or more inches.

Surface Water

Surface water resources in the Planning Area fall within U.S. Geological Survey (USGS) Water Resources Region 10 and are all tributaries of the Missouri River. The Bighorn River, Wind River, Clarks Fork of the Yellowstone River, and their associated tributaries, including the Nowood, Greybull and Shoshone river systems, comprise the main source of surface water in the Bighorn Basin. The Bighorn River begins at the Wedding of the Waters and flows through the center of the Bighorn Basin into Bighorn Lake (also known as Yellowtail Reservoir) on the Wyoming-Montana border. The river upstream of Wedding of the Waters is referred to as Wind River. Wind River and its tributaries flow into Boysen Reservoir, which the U.S. Bureau of Reclamation (BOR) manages. The Clarks Fork of the Yellowstone River, flowing out of the Absaroka Mountains, comprises an important source of surface water along the northwest corner of the Planning Area. The North and South Forks of the Shoshone River meet at Buffalo Bill Reservoir (an important water source for the City of Cody and surrounding communities) and then outflow into the Bighorn River, which flows into Bighorn Lake several miles south of the Wyoming-Montana border. Map 3 shows the locations of major surface water features and watersheds at hydrologic unit level 4 in the Planning Area.

Additional watersheds in the Planning Area include Kirby Creek, Nowater River, East Fork of the Nowater River, Fifteenmile Creek, Shell Creek and its tributary (Trapper Creek), Tenmile Creek, Coal Draw Creek, Sand Draw Creek, Elk Creek, Red Canyon Creek, Whistle Creek, Coon Creek, Dry Creek, and Little Dry Creek. Many of the streams in these watersheds, such as those located at lower elevations, are intermittent to ephemeral and flow only in response to snow melt and storm events.

The effective life (and associated costs) of water development projects, such as stock reservoirs and spring developments, depends on watershed conditions. The development and use of resources requiring surface disturbance, resource uses, motorized-vehicle use, and recreation can impact surface water quality, primarily by increasing sediment loads. Stream bank degradation and erosion, and gully erosion (see Section 3.1.3 Soil) due to poor vegetative cover and surface disturbances (e.g., roads and construction activities), are the predominant sources of excessive sediment in streams. Proper management of vegetation and surface-disturbing activities such as road construction, forestry, oil and gas discharges, and mining in the Planning Area can mitigate sediment delivery due to these activities.

Public comments during the scoping process indicated that, in particular, the movement of sediment into Bighorn Lake is an issue of concern. Bighorn Lake was formed in 1965 with completion of the Yellowtail Dam (managed by the BOR) across the Bighorn River. The contributing drainage area to this reservoir is 19,650 square miles and consists of the Planning Area and portions of the Bighorn Basin in Wyoming (USACE and BOR 2009). A 2009 study by the BOR and U.S. Army Corps of Engineers summarized the major causes of sediment production in the drainage basin as the high gradients of the Bighorn Lake tributaries (ranging from about 50 feet per mile in the foothill zone to about 20 feet per mile in the central portion of the Bighorn Basin), low precipitation, the ease with which the underlying rocks in the Planning Area erode, and the lack of vegetative cover to prevent soil erosion (USACE and BOR 2009). The study noted that these factors lead to greater rates of sediment production relative to other nearby drainages, such as the Wind River Basin to the south.

The Wyoming DEQ, in compliance with the federal Clean Water Act, requires that water quality be maintained or improved for all waters of the state (Wyoming DEQ 2002). The Wyoming DEQ has an ongoing monitoring program (Wyoming DEQ 2004) designed to (1) determine the overall quality of the waters of the state, (2) determine the extent of water quality changes over time, (3) identify problem areas and areas in need of protection, and (4) determine the effectiveness of existing clean water programs. Monitoring performed by the BLM is commonly more intensive and site-specific (tied to specific actions) than that which is carried out by the Wyoming DEQ; however, the two programs are complementary.

The Wyoming DEQ regulates all surface discharge of water, including water produced from oil and gas development and storm water discharges, through the Wyoming Pollutant Discharge Elimination System permit process. Wyoming Pollutant Discharge Elimination System permits require compliance with specific water quality standards that vary by stream class, and are periodically reviewed and revised for existing uses. The stream classes and water quality standards are defined in Wyoming Surface Water Quality Standards Water Quality Rules and Regulations Chapter 1 (Wyoming DEQ 2007). Water discharged on the surface must be suitable for existing or planned uses, such as agriculture and livestock, and cannot result in a violation of water quality standards in the receiving stream.

The Wyoming DEQ identifies waterbodies with impaired water quality. The state updates this list of streams, rivers, ponds, and lakes every 2 years and uses the list to develop a total maximum daily load (TMDL) allocation of pollutants. Wyoming’s Integrated Water Quality Assessment Report (305[b] Report) summarizes water quality conditions in the state. Streams, rivers, ponds, and lakes that do not meet designated uses are considered “impaired.” This report includes Wyoming’s 2008 303(d) List of Waters Requiring TMDLs (303[d] List), which identifies “impaired” waters that require development of TMDLs. Other “impaired” waters might not require TMDLs. Table 3-6 lists the streams in the Planning Area the Wyoming DEQ considers impaired, due to watershed degradation or because waters in the stream exceed water quality limits. When surface water flows occur, these creeks carry large amounts of sediment downstream. The conditions of these watersheds are partially linked to upland conditions. Proper functioning condition (PFC) assessments (refer to Section 3.4.3 Vegetation - Riparian/Wetlands Resources) provide indirect indicators of water quality and watershed health.

BLM-administered lands in the Planning Area contain Wyoming DEQ Class 1, Outstanding Waters. These are the most important waters of the state and meet criteria for water quality, and aesthetic, scenic, recreational, ecological, agricultural, botanical, zoological, municipal, industrial, historical, geological, cultural, archeological, and fish and wildlife resources, and have the presence of substantial quantities of developable water and other values of present and future benefit to the people (Wyoming DEQ Rules and Regulations Chapter 1 Section 4. A). Class 1 waters in the Planning Area include the main stem of the Middle Fork of the Powder River through its entire length above the mouth of Buffalo Creek; the segment of the Middle Fork of the Powder River along with its tributaries of Rock Creek; and Bar C Creek. These streams are in higher-elevation watershed recharge areas and provide perennial streamflow for fisheries, along with associated riparian habitat and downstream water to the public.

Class 2 waters are waters other than those designated as Class 1 that are known to support fish habitat or drinking-water supplies (or where these uses are obtainable). Class 2 waters include the Clarks Fork of the Yellowstone River and the primary tributaries in the Bighorn River Drainage, including Bighorn River, Shoshone River, Greybull River, Nowood River, Shell Creek, Bear Creek, and Five Springs Creek. These creeks are ecologically important and the state of Wyoming has identified them as important for meeting their designated uses. The BLM manages some smaller tracts on these waters that provide for habitat and fisheries.

Other important surface waters include perennial creeks on the west slope of the Big Horn Mountains and the Absaroka Front, Trapper Creek, Deer Creek, Medicine Lodge Creek, Dry Medicine Lodge Creek, Alkali Creek, Johnny Creek, White Creek, North Beaver Creek, South Beaver Creek, Grass Creek, Cottonwood Creek, Owl Creek, Gooseberry Creek, and others. All provide good-quality water and riparian habitat for wildlife, fisheries, and recreational pursuits.

Groundwater

There are 12 major aquifers in the Planning Area  Quaternary, Fort Union/Lance, Willwood, Mesaverde, Frontier, Muddy, Cloverly, Sundance, Phosphoria, Ten Sleep, Madison, and Flathead. The Madison is the primary aquifer that supplies water for several municipalities in the Planning Area (Wyoming Water Development Commission 2003).

Groundwater recharge occurs from direct infiltration of precipitation into the shallower aquifers, from infiltration into the rock outcrop areas of the deeper aquifers, and from leakage between aquifers. Groundwater quality depends primarily on the source geologic formation or aquifer. Groundwater is used to meet the demand of current uses on public land, such as livestock, wildlife, mineral development, and industrial.

Geologic formations aging from Precambrian to the shallow Quaternary deposits produce groundwater throughout the basin. The most reliable and accessible shallow groundwater supplies are from aquifers in unconsolidated deposits along the larger waterbodies such as the Bighorn, Greybull, Nowood, and Shoshone Rivers (Plafcan et al. 1993). The Clarks Fork of the Yellowstone River also provides reliable and accessible supplies of groundwater. Larger producing wells also originate in deep limestone and dolomite aquifers of the Madison Limestone and Bighorn Dolomite formations. These formations crop out along the flanks of the basin and are found at extensive depths that produce large amounts of water for municipalities and agricultural purposes.

The Madison Aquifer is an important regional water source for the northern plains states (including western South Dakota, Wyoming, and potentially western Montana in the near future) due to increasing populations and development in this area and the limited number of other undeveloped water sources (USGS 2009). Issues related to water levels and the aquifer’s recharge rate are some of the primary areas of concern related to this water resource. An important area within the Madison aquifer is the Spanish Point Karst Area of Critical Environmental Concern (ACEC), a specially designated area that protects surface and groundwater recharge areas and sensitive karst watercourses; refer to Section 3.7.1 Areas of Critical Environmental Concern for additional information on the Spanish Point Karst ACEC.

Surface Water and Groundwater Quantity and Use

Both surface water and groundwater are sources of water in the Planning Area. Surface water sources typically meet existing uses on public lands, but natural climatic fluctuations, such as drought, can make marginally adequate sources unreliable. Groundwater sources are adequate to meet the demand of all current uses on public land (primarily for agricultural, municipal, industrial, livestock, and wildlife).

Active water wells in the Planning Area are permitted through the Wyoming State Engineer’s Office within the four counties of the Planning Area (Wyoming State Engineers Office 2006). A permittee can apply for water rights on BLM-administered land; if the permittee demonstrates beneficial use, then the Wyoming State Engineer’s Office can permit the water right. The issuance of the water right in no way authorizes a permittee to develop water on BLM-administered lands, or any lands that they do not own. This requires independent negotiations between the permittee and the BLM to acquire the appropriate special use permit or ROW. The Wyoming State Engineer’s Office does not require that landowner authorization be obtained before it issues the water right. Table 3-7 summarizes water uses in each of the four counties. Approximately 82 percent of the total surface water and groundwater use in the Planning Area is for agricultural purposes (Table 3-8).

According to the Wyoming Water Development Commission’s 2003 Wind/Bighorn River Basin Plan (Wyoming Water Development Commission 2003), there remains approximately 1.7 million acre-feet of unallocated flow for the state of Wyoming to develop. Despite this apparent surplus, many areas in these basins chronically experience water shortages. Groundwater sources are adequate to meet the demand of all current uses on public land (primarily livestock, wildlife, and recreation); however, there has been substantial local water development in recent years, which may result in excessive depletion that could affect current or future demand.

There is an anticipated increase in future demand for surface water for irrigation and other consumptive uses in the Planning Area. Table 3-9 lists projected future demand for water in the Bighorn Basin, as outlined in the Wind/Bighorn River Basin Plan. Due to unappropriated surface water, future reservoirs in the area are possible. Projected future water development projects have been analyzed and prioritized through the Wind/Bighorn Basin Advisory Group.

Regional water development projects are being considered as part of watershed planning in the Kirby Creek, Owl Creek, Nowood River, Cottonwood Creek, and Grass Creek watersheds. This is in addition to potential water demands that could result from the Westside Irrigation Project. Municipal water projects will continue to include replacement of surface water sources with deep groundwater supplies (Wyoming Water Development Commission 2003).

Oil and gas development can result in large volumes of produced water that can have beneficial and adverse effects on surface water and can reduce groundwater availability; however, water users in the Planning Area overwhelmingly view produced water as beneficial. The release of produced water can increase or extend the period of flow in drainages; such releases can provide valuable sources of water and are highly coveted by users in the Planning Area. However, discharges of produced water also can increase the total dissolved solids concentration of surface waters, result in increased survival and spread of invasive species adapted to the conditions created, and substantially increase erosion in ephemeral drainages (BLM, State of Montana DEQ, and MBOGC 2003; BLM 2009i).

Management Challenges

There are a number of management challenges for water resources in the Planning Area. Surface water quality must be maintained or improved in compliance with federal standards, while development and other resource use can impact surface water quality by increasing sediment load. Sediment loading into Bighorn Lake is an issue of public concern. Currently, groundwater sources are adequate to meet the demand of all current uses on public land, yet the anticipated increase in future demand for irrigation and other consumptive uses could affect the level and recharge rate of important aquifers. Produced water is also a management challenge. Many residents indicate produced water is beneficial to the users, yet these discharges can also adversely affect surface water quality and increase invasive species prevalence and erosion.