Allowable uses and management actions with potential to degrade water quality in the Bighorn and Clarks Fork of the Yellowstone Rivers and their tributaries could directly affect special status fish species in the Planning Area and indirectly impact federally listed fish in the Yellowstone River. The types of impacts projected to affect water quality and quantity in these watersheds are anticipated to be common to all alternatives and, therefore, are discussed in the following section. A detailed discussion of the anticipated impacts to fish from changes in water quality and quantity is included in Section 4.4.5 Fish and Wildlife Resources - Fish. This section focuses on the direct impacts to special status fish species habitat from proactive management, which varies by alternative.
The potential for management to result in adverse impacts to special status fish species is primarily a function of impacts to surface water quality and quantity. Reduced water flow in the Yellowstone River can lead to adverse impacts to the ecosystems that support special status fish species. Increased sediment in the Bighorn and Clarks Fork of the Yellowstone Rivers may contribute to sedimentation in the Yellowstone River.
Water quality is affected by surface-disturbing activities and associated soil erosion, particularly on soils highly susceptible to water erosion that contribute to sedimentation. Sedimentation reduces the quality of in stream habitat for most fish by filling in pools, reducing thermal recovery areas, and covering stream bottoms with a more uniform layer of sediment, which smothers eggs and alevin, thereby reducing fish reproduction rates. Appendix T provides data regarding surface-disturbance acreage and reasonable foreseeable actions related to development by alternative. Principle impacts from surface-disturbing activities would result from removing vegetation and disturbing soil, thereby increasing the potential for offsite erosion and sediment delivery into the Bighorn and Clarks Fork of the Yellowstone Rivers and their tributaries. Other actions, including concentration of livestock, fire and fuels management, OHV use, and reclamation of disturbed areas are anticipated to remove or reduce vegetation and disturb soil, but are expected to have less potential to degrade water quality in the Bighorn and Clarks Fork of the Yellowstone watersheds and therefore less potential to impact fish downstream. See Section 4.1.4 Water for more information regarding potential impacts to surface water quality.
Spanish Point Karst (designated under all alternatives) is the only ACEC that benefits water quality by restricting surface-disturbing activities and pesticide application in this area. WSAs contain 0.7 miles of occupied Yellowstone cutthroat trout habitat, and the restrictions on resource uses and activities to maintain their wilderness characteristics may result in indirect beneficial impacts to special status fish species under all of the alternatives.
Water used for well construction and completion may reduce the amount of water available for use in the Bighorn and Clarks Fork of the Yellowstone Rivers, and therefore in the Yellowstone River downstream of the Planning Area as well. Produced water from oil and gas wells may alter flow regimes and water quantity in streams containing special status fish species. See Section 4.4.5 Fish and Wildlife Resources - Fish for a description of the impacts from produced water. Produced water from CBNG drilling is assumed to have a negligible influence on surface water quantity and quality in the Bighorn River and the Clarks Fork of the Yellowstone River watersheds. See Section 4.1.4 Water for more information regarding potential impacts to surface water quantity.
The BLM projects 15,710 acres of long-term surface disturbance from BLM-authorized actions under Alternative A (Table 4-1) resulting in an estimated erosion rate of 25,167 tons per year (Appendix V). Surface-disturbing activities remove vegetation and disturb soil, thereby increasing the potential for offsite erosion and sediment delivery to the Bighorn, Shoshone, and Clarks Fork of the Yellowstone rivers, among the waterways in the Planning Area that drain into the Yellowstone River. Sedimentation fills in pools and covers stream bottoms with a more uniform layer of sediment that adversely affects special status fish species. Surface-disturbing activities would reduce water quality and degrade Yellowstone cutthroat trout and other special status fish species habitat in the Planning Area. The greater the surface disturbance, the greater potential for adverse impacts to special status fish species.
Under Alternative A, 4,033,195 acres are available for locatable mineral entry, 863,564 acres are open with standard constraints for oil and gas leasing, and 3,975,695 acres are open to mineral materials disposal. This alternative would develop an estimated 1,130 new federal wells. Alternative A closes 59,192 acres to motorized vehicle use and limits motorized vehicle use to designated roads and trails in areas with fragile soils, limiting vehicle-caused soil disturbance and resulting contributions to sediment loads. Adverse impacts to special status fish species from sedimentation due to surface disturbance and erosion, depleted water quantity due to mineral development, and altered flow regimes due to soil compaction and produced water discharge would occur but would be mitigated under Alternative A.
Alternative A designates three ACECs, containing 9.8 miles of occupied Yellowstone cutthroat trout habitat, that would benefit special status fish species by restricting surface-disturbing activities in these areas and reducing the likelihood of sedimentation in the associated watersheds. Managing all 20 WSR eligible waterways, containing 3.1 miles of Yellowstone cutthroat trout habitat, would result in beneficial impacts to special status fish species habitat relative to the other alternatives by restricting resource uses and activities to maintain the free-flowing nature of these waterways. However, WSR eligible waterway segment management may prevent construction of fish barriers to protect special status fish species habitat, if the natural free-flowing nature of the stream would be impaired by these actions.
Under Alternative A, the BLM requires the stabilization of existing watershed improvement projects where they have failed to promote/enhance/improve watershed stability, and routinely seeds, or requires permittees and operators to seed, disturbed areas with native plant species to reestablish vegetation cover over disturbed soils within 5 years. These actions would beneficially impact special status species fishbearing streams by reducing sedimentation. Alternative A implements watershed improvement practices from Wyoming’s Bighorn Basin water quality plans and encourages natural flow regimes in streams supporting fisheries in compliance with the state’s water laws, providing potential indirect beneficial impacts to special status fish species. Surface discharge under Alternative A may have adverse impacts if produced water degrades water quality in special status fish species inhabited streams and rivers. Alternative A places restrictions on surface-disturbing activities around riparian/wetland areas. Forest management under Alternative A allows for 30,000 acres of treatment that could contribute to soil disturbance and sedimentation in the short term, but may have beneficial impacts by preventing stand-replacing wildfires, which may cause much more sedimentation, in the long term. Overall, resource management actions under Alternative A would result in beneficial impacts to special status fish species.
Proactive management actions that have direct beneficial impacts to special status fish under Alternative A include restoring stream segments for fisheries habitat, constructing barriers to prevent nonnative fish from colonizing habitat occupied by native fish species, and introducing special status fish species to waters outside of their historic range on a case-by-case basis. Additional long-term beneficial impacts may result from considering restoring Yellowstone cutthroat trout to its native waters in the Planning Area. Prohibiting surface-disturbing activities within 500 feet of surface water and/or riparian habitat except when impacts can be mitigated would limit direct adverse impacts to special status fish species habitat.
Impacts to special status fish species would be similar to those described under Alternative A, although to a lesser extent. Surface disturbance under Alternative B would be the least of the alternatives (Table 4-1) resulting in a 31 percent decrease in long-term erosion (Appendix V) and, therefore, the least adverse impact to special status fish species.
Compared to the other alternatives, Alternative B allows fewer opportunities for resource use that result in surface disturbance and more restrictions are placed on mineral and ROW development, motorized vehicle use, and livestock grazing. Overall, Alternative B has the least potential to result in adverse impacts to special status fish species due to resource uses that can affect water quality or quantity.
The special designations under Alternative B have the greatest beneficial impact to special status fish species. Alternative B expands three ACECs (Carter Mountain, Five Springs Falls, and Upper Owl Creek) and designates four new ACECs (Chapman Bench, Clarks Fork Canyon, Rattlesnake Mountain, and Sheep Mountain) that restrict surface-disturbing activities. The Clarks Fork Canyon ACEC protects a large portion of Clarks Fork of the Yellowstone watershed from the adverse impacts of surface-disturbing activities and mineral development, resulting in the greatest direct beneficial impacts to special status fish species in the Yellowstone River. ACECs encompass 42.7 miles of Yellowstone cutthroat trout habitat. Managing all 20 WSR suitable waterways would result in similar impacts to those under Alternative A. Additionally, designating all LWCs as Wild Lands and restricting resource uses and activities in these areas to protect wilderness characteristics may beneficially impact 8.8 miles of Yellowstone cutthroat trout habitat under this alternative.
Similarly to Alternative A, Alternative B stabilizes watershed improvement projects if they are no longer meeting resource objectives to prevent the release of stored sediment. Alternative B provides greater short-term beneficial impacts to special status fish species habitat than Alternative A by requiring more immediate and precisely defined vegetation reestablishment goals in disturbed areas, thereby preventing potential sedimentation. Alternative B also creates greater beneficial impacts than the other alternatives by developing watershed improvement practices, which all activity plans and permitted activities include, in cooperation with local governments. The BLM manages forests and woodlands through natural processes under Alternative B, as opposed to mechanical treatments emphasized under other alternatives, likely resulting in less surface disturbance and impacts to water quality in the short term. However, if maintained stand density results in high intensity wildfires, long-term adverse impacts to water quality and flow regimes may result. Alternative B manages all riparian/wetland areas to achieve DPC, providing the greatest long-term potential beneficial impacts to special status fish species habitat, relative to the other alternatives.
Proactive management actions under Alternative B would result in greater direct beneficial impacts to special status fish compared to the other alternatives. This alternative restores important fisheries habitat on 3 miles of streams, constructs nonnative fish barriers except in WSR suitable waterway segments, removes barriers or constructs fish passageways to enable native fish to occupy all suitable habitats, pursues restoring Yellowstone cutthroat trout to all its original waters, and introduces special status fish species outside their historic range, if environmentally feasible, in coordination with WGFD and other stakeholders.
Adverse impacts to special status fish species from surface disturbance would be greatest under Alternative C. Surface disturbance under Alternative C would be the highest of the alternatives (Table 4-1), resulting in a 164 percent increase in long-term erosion (Appendix V) compared to Alternative A and, therefore, the greatest adverse impact to special status fish species.
Alternative C provides the least restriction on resource use, especially surface-disturbing activities such as minerals development, having the greatest potential adverse impact on special status fish species by altering water quantity and quality. The BLM manages livestock grazing to optimize commodity production while meeting rangeland health standards, not to enhance other resource values, resulting in the greatest potential adverse impacts to special status fish species from riparian/wetland area degradation and vegetation removal that can impact water quality and quantity.
Other than the Spanish Point Karst ACEC, the Brown/Howe Dinosaur Area ACEC is the only ACEC designated under Alternative C; this ACEC may have a beneficial impact by preventing sedimentation in waterways as surface-disturbing activities must be mitigated, but management of the ACEC generally allows mineral development and other types of surface-disturbing activities that may affect water quality. ACECs under this alternative contain only 0.2 miles of Yellowstone cutthroat trout habitat. In addition, Alternative C does not recommend any WSR eligible waterway segments as suitable for inclusion in the NWSRS. Under Alternative C, special designations do not provide any substantial beneficial impact to surface water quality or fisheries habitat, and therefore this alternative has the least potential to beneficially impact special status fish species.
Alternative C only stabilizes watershed improvement projects if they are not meeting resource objectives, on a case-by-case basis. Alternative C applies less stringent restoration requirements than Alternative B to limit soil erosion in disturbed areas. The BLM does not implement watershed improvement plans (BMPs are relied on to mitigate adverse impacts) under Alternative C, providing the least potential beneficial impacts to special status fish species compared to the other alternatives. Forest management treatments emphasize commercial and economic objectives, resulting in the greatest potential impacts to water quality, compared to the other alternatives.
The proactive management actions that result in direct beneficial impacts to special status fish under Alternative C are similar to those under Alternative A, except that the BLM only restores stream segments with special status fish species on a case-by-case basis and does not construct nonnative fish barriers. Alternative C provides the fewest beneficial impacts to special status fish species from proactive management compared to the other alternatives.
Impacts to special status fish species from surface disturbance would be similar to those described under Alternative A. The projected surface disturbance is slightly more under Alternative D—estimated to result in a 17 percent increase in long-term erosion compared to Alternative A (Appendix V)—but reclamation and restoration practices are likely to limit erosion and sedimentation more than under Alternative A.
Alternative D allows fewer opportunities for resource use that can result in surface disturbance than Alternative C. The BLM places more restrictions on minerals, ROWs, and motorized vehicle use under Alternative D than under alternatives A and C. Livestock grazing management under Alternative D would result in impacts similar to those under Alternative A. Overall, Alternative D has more potential to result in adverse impacts to special status fish species than Alternative B, but less than alternatives A and C.
Special designations under Alternative D would have a greater beneficial impact to special status fish species than under alternatives A and C, but less than under Alternative B. Alternative D designates the Clarks Fork, PETM, and Sheep Mountain ACECs in addition to the ACECs designated under Alternative A, containing 10.7 miles of Yellowstone cutthroat trout habitat, and applies additional resource use restrictions in the Chapman Bench Management Area to minimize impacts to special status species. Additionally, designating 52,485 acres of LWCs as Wild Lands and restricting resource uses and activities in these areas to protect wilderness characteristics may beneficially impact 7 miles of Yellowstone cutthroat trout habitat. Alternative D does not recommend any WSR eligible waterway segments as suitable for inclusion in the NWSRS. Special status fish species habitat would not be protected to the same degree in these areas as under alternatives A and B. However, the BLM could construct fish barriers on these waterways to prevent the spread of nonnative fish species that may adversely impact special status fish species.
Management actions to stabilize watershed improvement projects and reestablish vegetation in disturbed areas under Alternative D would result in similar beneficial impacts to those under Alternative A, but to a greater extent. Watershed improvement practices would result in similar beneficial impacts to those under Alternative B. Forest management would result in impacts similar to those under Alternative A, but there would be more potential adverse impacts from allowing clear cutting, similar to Alternative C. Management of riparian/wetland resources under Alternative D would be similar to Alternative C. However, managing streams with unique fishery values to meet DFC would result in greater beneficial impacts to special status fish species in these areas. Under Alternative D, the BLM would place more restrictions on surface-disturbing activities near riparian/wetland areas, which would limit impacts to a greater extent. Overall, resource management under Alternative D would result in more beneficial impacts to special status fish species than alternatives A and C, but fewer than Alternative B.
Proactive management actions under Alternative D would result in similar beneficial impacts to special status fish species as under Alternative B, but to a lesser extent because the BLM would perform similar management actions, but on a priority basis. Surface-disturbance restrictions would limit direct adverse impacts to special status fish species habitat similarly to Alternative A. Pursuing the restoration of Yellowstone cutthroat trout to historically occupied watersheds would result in similar beneficial impacts to those under Alternative B.