Limiting Factors



Blue Mountain Province

Asotin Subbasin 391, 393

BULL TROUT
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Habitat Quantity and Quality Access and Availability Freshwater-Instream Agricultural Practices; Forest Management Migration Impediments Juveniles, adults Seasonal water temperatures and poor habitat conditions exclude bull trout use of the mainstem Asotin Creek below the confluence of Charley Creek
Habitat Quantity and Quality Morphological Changes Freshwater - Floodplain Agricultural Practices; Urbanization Diking; Impervious Surfaces (Road Density); Riparian Degradation Juveniles, adults Confinement by roads and dikes, and resulting loss of riparian function affect most life stages.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater - Riparian Agricultural Practices; Urbanization; Forest Management Diking; Filling; Impervious Surfaces (Road Density); Riparian Degradation All Channel instability impacts egg incubation throughout the subbasin. Confinement by roads and dikes, and resulting loss of riparian function affect most life stages.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practices; Forest Management Diking; Wood/Structure Removal Juveniles, adults Lack of habitat diversity and quantity throughout the subbasin are primary factors limiting bull trout.
Water Quality Temperature -- Agricultural Practices; Forest Management; Riparian Degradation All Water temperature may be the most limiting factor for bull trout in the subbasin.
SPRING CHINOOK
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Habitat Quantity and Quality Access and Availability; Morphological Changes Estuary Agricultural Practices; Urbanization Diking; Filling; Riparian Degradation; Wetland Loss Smolts Historical complex habitats have been modified through channelization, diking, development and other practices.
Habitat Quantity and Quality Morphological Changes Freshwater - Floodplain Agricultural Practices; Urbanization Diking; Impervious Surfaces (Road Density); Riparian Degradation Juveniles, adults Confinement by roads and dikes, and resulting loss of riparian function affect most life stages.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater - Riparian Agricultural Practices; Urbanization; Forest Management Diking; Filling; Impervious Surfaces (Road Density); Riparian Degradation All Channel instability impacts egg incubation throughout the subbasin. Confinement by roads and dikes, and resulting loss of riparian function affect most life stages.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practices; Forest Management Diking; Wood/Structure Removal Juveniles, adults Lack of habitat diversity and quantity throughout the subbasin are the primary factors limiting spring Chinook.
Instantaneous Mortality Anthropogenic Mortality -- Fishery Management Harvest Adults Spring Chinook are primarily subject to freshwater harvest.
Instantaneous Mortality Anthropogenic Mortality -- Dam or Hydropower Facility Management Migration Impediments Juveniles Juveniles and adults must pass eight mainstem dams
Water Quality Turbidity; Temperature -- Agricultural Practices; Urbanization; Forest Management Diking; Filling; Impervious Surfaces (Road Density); Riparian Degradation; Bank Destabilization All Sediment load impacts egg incubation, and high temperatures limit production.
SUMMER STEELHEAD
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Habitat Quantity and Quality Access and Availability; Morphological Changes Estuary Agricultural Practices; Urbanization Diking; Filling; Riparian Degradation; Wetland Loss Smolts Historical complex habitats have been modified through channelization, diking, development and other practices.
Habitat Quantity and Quality Morphological Changes Freshwater - Floodplain Agricultural Practices; Urbanization Diking; Impervious Surfaces (Road Density); Riparian Degradation Juveniles Confinement by roads and dikes, and resulting loss of riparian function affect most life stages.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater - Riparian Agricultural Practices; Urbanization; Forest Management Diking; Filling; Impervious Surfaces (Road Density); Riparian Degradation Eggs, juveniles Channel instability impacts egg incubation throughout the subbasin. Confinement by roads and dikes, and resulting loss of riparian function affect most life stages.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practices; Forest Management Diking; Wood/Structure Removal Juveniles Lack of habitat quantity (pools) and diversity impact steelhead rearing in Hefflefinger and Coombs creeks, as well as most reaches of the South Fork of the North Fork. Habitat diversity and quantity are also the primary limiting factors for the Charley Creek watershed.
Instantaneous Mortality Anthropogenic Mortality -- Dam or Hydropower Facility Management Migration Impediments Juveniles Juveniles and adults must pass eight mainstem dams during migration.
Water Quality Turbidity; Temperature -- Agricultural Practices; Urbanization; Forest Management Diking; Filling; Impervious Surfaces (Road Density); Riparian Degradation; Bank Destabilization Eggs, fry, winter parr Sediment load impacts steelhead egg incubation in the mainstem, George Creek, lower South Fork, Ten Mile Creek, and Lick Creek. High temperatures limit steelhead production in Ten Mile Creek.

Grande Ronde Subbasin 422, 423

BULL TROUT
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Habitat Quantity and Quality Access and Availability Freshwater-Instream Dam or Hydropower Facility Management Migration Impediments Juveniles, adults Wallowa Lake Dam and Beaver Creek Dam are barriers to passage.
Habitat Quantity and Quality Morphological Changes Freshwater-Floodplain Agricultural Practices; Urbanization Wetland Loss; Impervious Surfaces (Road Density); Riparian Degradation Juveniles, adults Extensive wetlands have been eliminated by agriculture, road building, livestock, and removal of beavers.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Forest Management Impervious Surfaces (Road Density); Riparian Degradation Juveniles, adults Past and present forest management practices have decreased riparian function. Bull trout have been affected by loss of shade and instream structure.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practices Riparian Degradation; Bank Destabilization Juveniles, adults Agricultural practices and livestock grazing have widened the stream channel in the Upper Grande Ronde.
Sediment Conditions Increased Sediment Quantity Freshwater-Instream Agricultural Practices; Forest Management Sediment: Bank Destabilization; Pre-Spawn Adults Increased sedimentation has resulted in the siltation of spawning gravel.
Water Quality Temperature -- Agricultural Practices; Forest Management Riparian Degradation All Increased water temperatures in the Upper Grande Ronde have resulted in thermal barriers.
SPRING CHINOOK
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Habitat Quantity and Quality Access and Availability Freshwater-Instream Dam or Hydropower Facility Management Migration Impediments Adults Wallowa Lake Dam and Upper Alder Slope Diversion are significant barriers to adult fish passage.
Habitat Quantity and Quality Access and Availability; Morphological Changes Estuary Agricultural Practices; Urbanization Diking; Filling; Riparian Degradation; Wetland Loss Smolts Historical complex habitats have been modified through channelization, diking, development and other practices.
Habitat Quantity and Quality Morphological Changes Freshwater-Floodplain Agricultural Practices; Urbanization Diking; Impervious Surfaces (Road Density); Riparian Degradation; Wetland Loss Juveniles Extensive wetlands have been eliminated by agriculture, road building, livestock, and removal of beavers.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Agricultural Practices; Urbanization; Forest Management Diking; Filling; Impervious Surfaces (Road Density); Riparian Degradation Juveniles Agricultural activities have drained and cleared many riparian areas in the Wallowa River watershed. Agriculture has reduced shade and confined the channel in Catherine Creek.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practices; Forest Management Diking; Filling; Wood/Structure Removal; Wetland Loss Juveniles Historic splash damming on the Minam River cleared woody debris and simplified the channel. Extensive channelization in the upper Grande Ronde has resulted in loss of both riverine and wetland habitats.
Instantaneous Mortality Anthropogenic Mortality -- Fishery Management Harvest Adults Spring Chinook are primarily subject to freshwater harvest.
Instantaneous Mortality Anthropogenic Mortality -- Dam or Hydropower Facility Management Migration Impediments Juveniles Juveniles and adults must pass eight mainstem dams during migration.
Sediment Conditions Increased Sediment Quantity Freshwater-Instream Agricultural Practices; Forest Management Sediment: Bank Destabilization; Eggs; Pre-spawn Adults Sediment impacts are widespread throughout the Upper Grande Ronde watershed.
Water Quality Turbidity; Temperature -- Agricultural Practices; Urbanization; Forest Management Diking; Filling; Impervious Surfaces (Road Density); Riparian Degradation; Bank Destabilization Eggs Reduced peak flows from operation of Wallowa Lake Dam has increased sediment accumulation below the dam. Temperature and impacts are widespread throughout the Upper Grande Ronde watershed.
Water Quantity Decreased Water Quantity -- Dam or Hydropower Facility Management Water: Storage or Withdrawal Juveniles Water diversions exacerbate summer low flows in the Wallowa River watershed. Water withdrawls significantly reduce the flow of Catherine Creek from June through September, with one diversion transfering water to the Powder River Subbasin. Diversions also reduce flow in the Upper Grande Ronde.
SUMMER STEELHEAD
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Habitat Quantity and Quality Access and Availability Freshwater-Instream Dam or Hydropower Facility Management Migration Impediments Adults Wallowa Lake Dam and Upper Alder Slope Diversion are significant barriers to adult fish passage.
Habitat Quantity and Quality Access and Availability; Morphological Changes Estuary Agricultural Practices; Urbanization Diking; Filling; Riparian Degradation; Wetland Loss Smolts Historical complex habitats have been modified through channelization, diking, development and other practices.
Habitat Quantity and Quality Morphological Changes Freshwater-Floodplain Agricultural Practices; Urbanization Diking; Impervious Surfaces (Road Density); Riparian Degradation; Wetland Loss Juveniles Extensive wetlands have been eliminated by agriculture, road building, livestock, and removal of beavers.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Agricultural Practices; Urbanization; Forest Management Diking; Filling; Impervious Surfaces (Road Density); Riparian Degradation Juveniles Impacts to riparian function from grazing and roads limit steelhead rearing habitat in the Wildcat Creek watershed. Extensive grazing has reduced riparian function in some parts of the Joseph Creek watershed. Agricultural activities have drained and cleared many riparian areas in the Wallowa River watershed. Agriculture has reduced shade and confined the channel in Catherine Creek.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practices; Forest Management Diking; Filling; Wood/Structure Removal; Wetland Loss Juveniles Historic splash damming on the Minam River cleared woody debris and simplified the channel. Extensive channelization in the upper Grande Ronde has resulted in loss of both riverine and wetland habitats.
Instantaneous Mortality Anthropogenic Mortality -- Dam or Hydropower Facility Management Migration Impediments Juveniles Juveniles and adults must pass eight mainstem dams during migration.
Sediment Conditions Increased Sediment Quantity Freshwater-Instream Agricultural Practices; Forest Management Sediment: Bank Destabilization; Eggs; Pre-spawn Adults Sedimentation limits steelhead spawning and egg incubation in tributaries of the Lower Grande Ronde. Sedimentation is also significant in the Joseph Creek watershed. Sediment impacts are widespread throughout the Upper Grande Ronde watershed.
Water Quality Turbidity; Temperature -- Agricultural Practices; Urbanization; Forest Management Diking; Filling; Impervious Surfaces (Road Density); Riparian Degradation; Bank Destabilization Eggs Reduced peak flows from operation of Wallowa Lake Dam has increased sediment accumulation below the dam. Temperature impacts are widespread throughout the Upper Grande Ronde watershed.
Water Quantity Decreased Water Quantity -- Dam or Hydropower Facility Management Water: Storage or Withdrawal Summer parr Water diversions exacerbate summer low flows in the Wallowa River watershed. Water withdrawals significantly reduce the flow of Catherine Creek from June through September, with one diversion transfering water to the Powder River Subbasin. Diversions also reduce flow in the Upper Grande Ronde.

Imnaha Subbasin 424, 425

BULL TROUT
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Habitat Quantity and Quality Access and Availability Freshwater-Instream Dam or Hydropower Facility Management Migration Impediments Juveniles, adults Seasonal barriers such as irrigation diversions in the Big Sheep Creek watershed impede migrations of bull trout. Diversions associated with the Wallowa Valley Improvement Canal have created barriers to migrating bull trout in Big Sheep, Little Sheep, and McCully creeks.
Habitat Quantity and Quality Morphological Changes Freshwater-Floodplain Agricultural Practices; Urbanization Wetland Loss; Impervious Surfaces (Road Density); Riparian Degradation Juveniles, adults Modification through riprapped banks, dredging, and elimination of off-channel refugia has reduced or eliminated rearing habitat.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Agricultural Practices Riparian Degradation Juveniles, adults Cultivation, farming, and pasturing have reduced riparian habitat in many tributaries, especially in the Big Sheep Creek watershed.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practices Riparian Degradation; Bank Destabilization Juveniles, adults Channels have attained unsuitable width:depth ratios, which create a shallow and wide system.
Sediment Conditions Increased Sediment Quantity Freshwater-Instream Agricultural Practices; Forest Management Sediment: Bank Destabilization; All Increased sediment is a key attribute limiting bull trout production
Water Quality Temperature -- Agricultural Practices; Forest Management Riparian Degradation All High water temperature is a key attribute limiting bull trout production
Water Quantity Decreased Water Quantity -- Dam or Hydropower Facility Management Water: Storage or Withdrawal Eggs, adults Reduction of flows by irrigation deiversions limits spawning and incubation in Big Sheep Creek.
FALL CHINOOK
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Habitat Quantity and Quality Access and Availability; Morphological Changes Estuary Agricultural Practices; Urbanization Diking; Filling; Riparian Degradation; Wetland Loss Smolts Historical complex habitats have been modified through channelization, diking, development and other practices.
Habitat Quantity and Quality Morphological Changes Freshwater-Floodplain Erosion Control; Agricultural Practices; Urbanization Diking; Impervious Surfaces (Road Density); Riparian Degradation Juveniles In areas modified through riprapped banks, dredging, and elimination of off-channel refugia the diversity of overwintering habitat has been reduced or eliminated.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Agricultural Practices Diking; Filling; Riparian Degradation Juveniles Cultivation, farming, and pasturing have reduced riparian habitat in many tributaries. Poor riparian condition throughout the subbasin limits Chinook productivity.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practices; Forest Management Diking; Filling; Wood/Structure Removal; Wetland Loss Juveniles, Pre-spawn adults Pre-spawning Chinook are impacted by losses of habitat diversity and streambed instability in the lower reaches of the Imnaha.
Instantaneous Mortality Anthropogenic Mortality -- Fishery Management Harvest Adults Fall Chinook are subject to both ocean and freshwater harvest.
Instantaneous Mortality Anthropogenic Mortality -- Dam or Hydropower Facility Management Migration Impediments Juveniles Juveniles and adults must pass eight mainstem dams during migration.
Water Quality Temperature -- Agricultural Practices Riparian Degradation Eggs, juveniles High temperatures affect the productivity of Chinook in the Lower Imnaha.
SPRING CHINOOK
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Habitat Quantity and Quality Access and Availability; Morphological Changes Estuary Agricultural Practices; Urbanization Diking; Filling; Riparian Degradation; Wetland Loss Smolts Historical complex habitats have been modified through channelization, diking, development and other practices.
Habitat Quantity and Quality Morphological Changes Freshwater-Floodplain Agricultural Practices; Urbanization Diking; Impervious Surfaces (Road Density); Riparian Degradation; Wetland Loss Juveniles In areas modified through riprapped banks, dredging, and elimination of off-channel refugia the diversity of overwintering habitat has been reduced or eliminated.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Agricultural Practices Diking; Filling; Riparian Degradation Juveniles Cultivation, farming, and pasturing have reduced riparian habitat in many tributaries. Poor riparian condition throughout the subbasin limits Chinook productivity.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practices; Forest Management Diking; Filling; Wood/Structure Removal All Pre-spawning Chinook are impacted by losses of habitat diversity and streambed instability in the middle and lower reaches of the Imnaha. Insufficient substrate size in the Middle and Upper Imnaha limits Chinook spawning and incubation success.
Instantaneous Mortality Anthropogenic Mortality -- Fishery Management Harvest Adults Spring Chinook are primarily subject to freshwater harvest.
Instantaneous Mortality Anthropogenic Mortality -- Dam or Hydropower Facility Management Migration Impediments Juveniles Juveniles and adults must pass eight mainstem dams during migration.
Water Quality Turbidity; Temperature -- Agricultural Practices; Forest Management Diking; Filling; Riparian Degradation; Bank Destabilization Eggs, juveniles High temperatures affect the productivity of spring/summer Chinook in the Lower Imnaha. Summer temperatures and sediment loads in Big Sheep Creek impede migration of spring/summer Chinook.
Water Quantity Decreased Water Quantity -- Dam or Hydropower Facility Management Water: Storage or Withdrawal Adults Low summer flows, exacerbated by irrigation diversions, impede migration of spring/summer Chinook into Big Sheep Creek.
SUMMER STEELHEAD
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Habitat Quantity and Quality Access and Availability; Morphological Changes Estuary Agricultural Practices; Urbanization Diking; Filling; Riparian Degradation; Wetland Loss Smolts Historical complex habitats have been modified through channelization, diking, development and other practices.
Habitat Quantity and Quality Morphological Changes Freshwater-Floodplain Agricultural Practices; Urbanization Diking; Impervious Surfaces (Road Density); Riparian Degradation; Wetland Loss Juveniles In areas modified through riprapped banks, dredging, and elimination of off-channel refugia the diversity of overwintering habitat has been reduced or eliminated.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Agricultural Practices Diking; Filling; Riparian Degradation Juveniles Cultivation, farming, and pasturing have reduced riparian habitat in many tributaries. Poor riparian condition throughout the subbasin limits steelhead productivity.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practices; Forest Management Diking; Filling; Wood/Structure Removal; Wetland Loss Juveniles Lack of diverse, deep, and cool habitat types in the Big Sheep Creek and Little Sheep Creek watersheds limit steelhead fry colonization and summer rearing.
Instantaneous Mortality Anthropogenic Mortality -- Dam or Hydropower Facility Management Migration Impediments Juveniles Juveniles and adults must pass eight mainstem dams during migration.
Water Quality Turbidity; Temperature -- Agricultural Practices; Forest Management Diking; Filling;+E64 Riparian Degradation; Bank Destabilization Eggs, juveniles Summer temperatures and sediment loads in Big Sheep Creek limit steelhead.
Water Quantity Increased Water Quantity -- Forest Management Water: Runoff Coefficient Alteration All Frequent high flow events in the Big Sheep Creek and Little Sheep Creek watersheds resulting from modification of upland vegetation through timber harvest and fires have changed spawning substrate availability and disrupt steelhead incubation.

Snake Hells Canyon Subbasin 426

BULL TROUT
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Habitat Quantity and Quality Morphological Changes Freshwater-Instream Dam or Hydropower Facility Management Water: Storage or Withdrawal Juveniles, adults Spawning and rearing habitats in the Snake River have been inundated.
Habitat Quantity and Quality Access and Availability Freshwater-Instream Dam or Hydropower Facility Management Migration Impediments Adults Hells Canyon Dam completely blocks fish passage out of the subbasin to the Upper Snake River.
Habitat Quantity and Quality Morphological Changes Freshwater-Floodplain Agricultural Practices; Forest Management; Urbanization Wetland Loss; Impervious Surfaces (Road Density); Riparian Degradation Juveniles, adults Road construction has altered the quality, quantity, and connectivity of habitat in tributary watersheds.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Agricultural Practices Riparian Degradation Juveniles, adults Livestock grazing degrades riparian habitats in tributary watersheds. Introduction of exotic plants has reduced riparian function.
Water Quality Temperature -- Agricultural Practices; Forest Management Riparian Degradation All Temperatures exceed state standards in the entire reach of the Snake River.
FALL CHINOOK
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Habitat Quantity and Quality Morphological Changes Freshwater-Instream Dam or Hydropower Facility Management Water: Storage or Withdrawal Juveniles, adults Spawning and rearing habitats in the Snake River have been inundated.
Habitat Quantity and Quality Access and Availability Freshwater-Instream Dam or Hydropower Facility Management Migration Impediments Adults Hells Canyon Dam completely blocks fish passage out of the subbasin to the Upper Snake River.
Habitat Quantity and Quality Access and Availability; Morphological Changes Estuary Agricultural Practices; Urbanization Diking; Filling; Riparian Degradation; Wetland Loss Smolts Historical complex habitats have been modified through channelization, diking, development and other practices.
Habitat Quantity and Quality Morphological Changes Freshwater-Floodplain Agricultural Practices; Forest Management; Urbanization Wetland Loss; Impervious Surfaces (Road Density); Riparian Degradation Juveniles, adults Road construction has altered the quality, quantity, and connectivity of habitat in tributary watersheds.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Agricultural Practices Riparian Degradation Juveniles, adults Riparian growth along the Snake River is hindered by lack of sediment and therefore lack of substrate. Livestock grazing degrades riparian habitats in tributary watersheds. Introduction of exotic plants has reduced riparian function.
Instantaneous Mortality Anthropogenic Mortality -- Fishery Management Harvest Adults Fall Chinook are subject to both ocean and freshwater harvest.
Instantaneous Mortality Anthropogenic Mortality -- Dam or Hydropower Facility Management Migration Impediments Juveniles Juveniles and adults must pass eight mainstem dams during migration.
Instantaneous Mortality Predation -- Fishery Management Species Introduction Juveniles Smallmouth bass prey on juvenile salmonids in the Snake River.
Water Quality Temperature -- Dam or Hydropower Facility Management Water: Temperature and Gas Alteration All Temperatures exceed state standards in the entire reach of the Snake River. Sediment is deficient below Hells Canyon Dam due to trapping of suspended sediment and bedload. Dissolved gas levels below Hells Canyon Dam may impair fish populations
Water Quantity Altered Flow Timing -- Dam or Hydropower Facility Management Water: Storage or Withdrawal Juveniles, adults Hydropower operations at Hells Canyon and Lower Granite dams have altered flow regimes. Fall Chinook are susceptible because changes in flow affect spawning timing, spawning location, egg incubation, and out-migration of juveniles.
PACIFIC LAMPREY
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Habitat Quantity and Quality Morphological Changes Freshwater-Instream Dam or Hydropower Facility Management Water: Storage or Withdrawal Juveniles, adults Spawning and rearing habitats in the Snake River have been inundated.
Habitat Quantity and Quality Access and Availability Freshwater-Instream Dam or Hydropower Facility Management Migration Impediments Adults Hells Canyon Dam completely blocks fish passage out of the subbasin to the Upper Snake River.
Habitat Quantity and Quality Access and Availability; Morphological Changes Estuary Agricultural Practices; Urbanization Diking; Filling; Riparian Degradation; Wetland Loss Juveniles Historical complex habitats have been modified through channelization, diking, development and other practices.
Habitat Quantity and Quality Morphological Changes Freshwater-Floodplain Agricultural Practices; Forest Management; Urbanization Wetland Loss; Impervious Surfaces (Road Density); Riparian Degradation Juveniles, adults Road construction has altered the quality, quantity, and connectivity of habitat in tributary watersheds.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Agricultural Practices Riparian Degradation Juveniles, adults Livestock grazing degrades riparian habitats in tributary watersheds. Introduction of exotic plants has reduced riparian function.
Instantaneous Mortality Anthropogenic Mortality -- Dam or Hydropower Facility Management Migration Impediments Juveniles, adults Juveniles and adults must pass eight mainstem dams during
Water Quality Temperature -- Dam or Hydropower Facility Management Water: Temperature and Gas Alteration All Temperatures exceed state standards in the entire reach of the Snake River. Sediment is deficient below Hells Canyon Dam due to trapping of suspended sediment and bedload. Dissolved gas levels below Hells Canyon Dam may impair fish populations
REDBAND TROUT
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Habitat Quantity and Quality Morphological Changes Freshwater-Instream Dam or Hydropower Facility Management Water: Storage or Withdrawal Juveniles, adults Spawning and rearing habitats in the Snake River have been inundated.
Habitat Quantity and Quality Morphological Changes Freshwater-Floodplain Agricultural Practices; Forest Management; Urbanization Wetland Loss; Impervious Surfaces (Road Density); Riparian Degradation Juveniles, adults Road construction has altered the quality, quantity, and connectivity of habitat in tributary watersheds.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Agricultural Practices Riparian Degradation Juveniles, adults Livestock grazing degrades riparian habitats in tributary watersheds. Introduction of exotic plants has reduced riparian function.
Water Quality Temperature -- Dam or Hydropower Facility Management Water: Temperature and Gas Alteration All Temperatures exceed state standards in the entire reach of the Snake River.
SOCKEYE
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Habitat Quantity and Quality Access and Availability Freshwater-Instream Dam or Hydropower Facility Management Migration Impediments Adults Hells Canyon Dam completely blocks fish passage out of the subbasin to the Upper Snake River.
Habitat Quantity and Quality Access and Availability; Morphological Changes Estuary Agricultural Practices; Urbanization Diking; Filling; Riparian Degradation; Wetland Loss Smolts Historical complex habitats have been modified through channelization, diking, development and other practices.
Instantaneous Mortality Anthropogenic Mortality -- Dam or Hydropower Facility Management Migration Impediments Juveniles Juveniles and adults must pass eight mainstem dams during migration.
Instantaneous Mortality Predation -- Fishery Management Species Introduction Juveniles Smallmouth bass prey on juvenile salmonids in the Snake River.
Water Quality Temperature -- Dam or Hydropower Facility Management Water: Temperature and Gas Alteration All Temperatures exceed state standards in the entire reach of the Snake River. Sediment is deficient below Hells Canyon Dam due to trapping of suspended sediment and bedload. Dissolved gas levels below Hells Canyon Dam may impair fish populations
SPRING/SUMMER CHINOOK
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Habitat Quantity and Quality Morphological Changes Freshwater-Instream Dam or Hydropower Facility Management Water: Storage or Withdrawal Juveniles, adults Spawning and rearing habitats in the Snake River have been inundated.
Habitat Quantity and Quality Access and Availability Freshwater-Instream Dam or Hydropower Facility Management Migration Impediments Adults Hells Canyon Dam completely blocks fish passage out of the subbasin to the Upper Snake River.
Habitat Quantity and Quality Access and Availability; Morphological Changes Estuary Agricultural Practices; Urbanization Diking; Filling; Riparian Degradation; Wetland Loss Smolts Historical complex habitats have been modified through channelization, diking, development and other practices.
Habitat Quantity and Quality Morphological Changes Freshwater-Floodplain Agricultural Practices; Forest Management; Urbanization Wetland Loss; Impervious Surfaces (Road Density); Riparian Degradation Juveniles, adults Road construction has altered the quality, quantity, and connectivity of habitat in tributary watersheds.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Agricultural Practices Riparian Degradation Juveniles, adults Riparian growth along the Snake River is hindered by lack of sediment and therefore lack of substrate. Livestock grazing degrades riparian habitats in tributary watersheds. Introduction of exotic plants has reduced riparian function.
Instantaneous Mortality Anthropogenic Mortality -- Fishery Management Harvest Adults Spring/Summer Chinook are primarily subject to freshwater harvest.
Instantaneous Mortality Anthropogenic Mortality -- Dam or Hydropower Facility Management Migration Impediments Juveniles Juveniles and adults must pass eight mainstem dams during migration.
Instantaneous Mortality Predation -- Fishery Management Species Introduction Juveniles Smallmouth bass prey on juvenile salmonids in the Snake River.
Water Quality Temperature -- Dam or Hydropower Facility Management Water: Temperature and Gas Alteration All Temperatures exceed state standards in the entire reach of the Snake River. Sediment is deficient below Hells Canyon Dam due to trapping of suspended sediment and bedload. Dissolved gas levels below Hells Canyon Dam may impair fish populations
SUMMER STEELHEAD
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Habitat Quantity and Quality Morphological Changes Freshwater-Instream Dam or Hydropower Facility Management Water: Storage or Withdrawal Juveniles, adults Spawning and rearing habitats in the Snake River have been inundated.
Habitat Quantity and Quality Access and Availability Freshwater-Instream Dam or Hydropower Facility Management Migration Impediments Adults Hells Canyon Dam completely blocks fish passage out of the subbasin to the Upper Snake River.
Habitat Quantity and Quality Access and Availability; Morphological Changes Estuary Agricultural Practices; Urbanization Diking; Filling; Riparian Degradation; Wetland Loss Smolts Historical complex habitats have been modified through channelization, diking, development and other practices.
Habitat Quantity and Quality Morphological Changes Freshwater-Floodplain Agricultural Practices; Forest Management; Urbanization Wetland Loss; Impervious Surfaces (Road Density); Riparian Degradation Juveniles, adults Road construction has altered the quality, quantity, and connectivity of habitat in tributary watersheds.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Agricultural Practices Riparian Degradation Juveniles, adults Riparian growth along the Snake River is hindered by lack of sediment and therefore lack of substrate. Livestock grazing degrades riparian habitats in tributary watersheds. Introduction of exotic plants has reduced riparian function.
Instantaneous Mortality Anthropogenic Mortality -- Dam or Hydropower Facility Management Migration Impediments Juveniles Juveniles and adults must pass eight mainstem dams during migration.
Instantaneous Mortality Predation -- Fishery Management Species Introduction Juveniles Smallmouth bass prey on juvenile salmonids in the Snake River.
Water Quality Temperature -- Dam or Hydropower Facility Management Water: Temperature and Gas Alteration All Temperatures exceed state standards in the entire reach of the Snake River. Sediment is deficient below Hells Canyon Dam due to trapping of suspended sediment and bedload. Dissolved gas levels below Hells Canyon Dam may impair fish populations
WHITE STURGEON
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Habitat Quantity and Quality Morphological Changes Freshwater-Instream Dam or Hydropower Facility Management Water: Storage or Withdrawal Juveniles, adults Spawning habitats in the Snake River have been inundated.
Habitat Quantity and Quality Access and Availability Freshwater-Instream Dam or Hydropower Facility Management Migration Impediments Adults Hells Canyon Dam completely blocks fish passage out of the subbasin to the Upper Snake River. White sturgeon have been effectively isolated.