Limiting Factors



Blue Mountain Province

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.