Limiting Factors



Lower Columbia Province

Willamette Subbasin 367, 371, 373, 374

BULL TROUT
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Food Competition -- Fishery Management Species Introduction Juveniles, adults Competition and hybridization with brook trout is a concern.
Habitat Quantity and Quality Access and Availability Freshwater-Instream Dam or Hydropower Facility Management; Forest Management; Urbanization Migration Impediments Juveniles, adults Major barriers to upstream migration include Cougar Dam, Trail Bridge Dam, and Smith Dam in the McKenzie River Watershed. Some culverts have been identified as barriers. Hydro facilities may pose risks to downstream-migrating bull trout.
Habitat Quantity and Quality Morphological Changes Freshwater-Floodplain Agricultural Practices; Urbanization Diking; Filling; Riparian Degradation; Wetland Loss Juveniles, adults Land use practices have led to losses of wetlands and floodplain function.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Forest Management; Agricultural Practices; Urbanization Impervious Surfaces (Road Density); Riparian Degradation Juveniles, adults Removal of streamside vegetation and road building in the Clackamas River Watershed have reduced habitat. Invasive plants limit the growth of native vegetation needed for habitat and channel formation processes.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Forest Management; Agricultural Practices; Urbanization Riparian Degradation; Wood/Structure Removal Juveniles, adults Limited wood in many watersheds has reduced the frequency and depth of pools, limiting rearing. Channels have been simplified.
Water Quality Temperature -- Agricultural Practicies; Forest Management; Dam or Hydropower Facility Management Water: Temperature and Gas Alteration; Riparian Degradation All Stream temperatures in many watersheds exceed criteria for summer maximum for juvenile salmonid rearing.
Water Quantity Decreased Water Quantity -- Agricultural Practicies; Dam or Hydropower Facility Management Water: Runoff Coefficient Alteration; Water: Storage or Withdrawal, Channelization, Management Juveniles, adults Frequency and magnitude of high flows are not sufficient to create and maintain channel complexity and provide nutrients from floodplain areas. Additional flow reductions are associated with irrigation diversions in many watersheds.
CHUM
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; Filling; Riparian Degradation; Wetland Loss Fry Land use practices have led to losses of wetlands and floodplain function.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practicies; Forest Management; Dam or Hydropower Facility Management Diking; Filling; Wood/Structure Removal Fry Reduction of off-channel habitat and limited wood in the Clackamas River Watershed have reduced the frequency and depth of pools, limiting rearing. Hydro operations on the Clacakamas River result impaired gravel recruitment, and channel incision.
Water Quality Temperature -- Agricultural Practicies; Forest Management; Dam or Hydropower Facility Management Water: Temperature and Gas Alteration; Riparian Degradation Fry Stream temperatures in many watersheds exceed criteria for summer maximum for juvenile salmonid rearing. Hydro operations on the Clacakamas River result in elevated water temperatures
Water Quantity Decreased Water Quantity -- Agricultural Practicies; Dam or Hydropower Facility Management Water: Runoff Coefficient Alteration; Water: Storage or Withdrawal, Channelization, Management Fry Frequency and magnitude of high flows are not sufficient to create and maintain channel complexity and provide nutrients from floodplain areas. Additional flow reductions are associated with irrigation diversions in many watersheds.
COASTAL CUTTHROAT
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Habitat Quantity and Quality Access and Availability Freshwater-Instream Forest Management; Urbanization Migration Impediments Juveniles, adults Some culverts may be barriers to migration.
Habitat Quantity and Quality Morphological Changes Freshwater-Floodplain Agricultural Practices; Urbanization Diking; Filling; Riparian Degradation; Wetland Loss Juveniles, adults Land use practices have led to losses of wetlands and floodplain function.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Forest Management; Agricultural Practices; Urbanization Impervious Surfaces (Road Density); Riparian Degradation Juveniles, adults Removal of streamside vegetation and road building in the Clackamas River Watershed have reduced habitat. Invasive plants limit the growth of native vegetation needed for habitat and channel formation processes.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Forest Management; Agricultural Practices; Urbanization Riparian Degradation; Wood/Structure Removal Juveniles, adults Limited wood in many watersheds has reduced the frequency and depth of pools, limiting rearing. Channels have been simplified.
Water Quality Temperature -- Agricultural Practicies; Forest Management; Dam or Hydropower Facility Management Water: Temperature and Gas Alteration; Riparian Degradation All Stream temperatures in many watersheds exceed criteria for summer maximum for juvenile salmonid rearing.
Water Quantity Decreased Water Quantity -- Agricultural Practicies; Dam or Hydropower Facility Management Water: Runoff Coefficient Alteration; Water: Storage or Withdrawal, Channelization, Management Juveniles, adults Frequency and magnitude of high flows are not sufficient to create and maintain channel complexity and provide nutrients from floodplain areas. Additional flow reductions are associated with irrigation diversions in many watersheds.
COHO
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Biological Viability Criteria Diversity -- Artificial Propogation Straying Adult spawners Large numbers of stray coho spawning with indigenous populations pose serious genetic risks.
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; Filling; Riparian Degradation; Wetland Loss Juveniles Land use practices have led to losses of wetlands and floodplain function.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Forest Management; Agricultural Practices; Urbanization Impervious Surfaces (Road Density); Riparian Degradation Juveniles Removal of streamside vegetation and road building in the Clackamas River Watershed have reduced habitat.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practicies; Forest Management; Dam or Hydropower Facility Management Diking; Filling; Wood/Structure Removal Juveniles Reduction of off-channel habitat and limited wood in the Clackamas River Watershed have reduced the frequency and depth of pools, limiting rearing. Hydro operations on the Clacakamas River result impaired gravel recruitment, and channel incision.
Instantaneous Mortality Anthropogenic Mortality -- Fishery Management Harvest Adults Coho are subject to both ocean and freshwater harvest.
Water Quality Temperature -- Agricultural Practicies; Forest Management; Dam or Hydropower Facility Management Water: Temperature and Gas Alteration; Riparian Degradation Juveniles Stream temperatures in many watersheds exceed criteria for summer maximum for juvenile salmonid rearing. Hydro operations on the Clacakamas River result in elevated water temperatures
Water Quantity Decreased Water Quantity -- Agricultural Practicies; Dam or Hydropower Facility Management Water: Runoff Coefficient Alteration; Water: Storage or Withdrawal, Channelization, Management Juveniles Frequency and magnitude of high flows are not sufficient to create and maintain channel complexity and provide nutrients from floodplain areas. Additional flow reductions are associated with irrigation diversions in many watersheds.
FALL CHINOOK
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Biological Viability Criteria Diversity -- Artificial Propogation Straying Adult spawners Large numbers of stray fall Chinook spawning with indigenous populations pose serious genetic risks.
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; Filling; Riparian Degradation; Wetland Loss Juveniles Land use practices have led to losses of wetlands and floodplain function.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practicies; Forest Management; Dam or Hydropower Facility Management Diking; Filling; Wood/Structure Removal Juveniles Reduction of off-channel habitat and limited wood in the Clackamas River Watershed have reduced the frequency and depth of pools, limiting rearing. Hydro operations on the Clacakamas River result impaired gravel recruitment, and channel incision.
Instantaneous Mortality Anthropogenic Mortality -- Fishery Management Harvest Adults Fall Chinook are subject to both ocean and freshwater harvest.
Water Quality Temperature -- Agricultural Practicies; Forest Management; Dam or Hydropower Facility Management Water: Temperature and Gas Alteration; Riparian Degradation Juveniles Stream temperatures in many watersheds exceed criteria for summer maximum for juvenile salmonid rearing. Hydro operations on the Clacakamas River result in elevated water temperatures
Water Quantity Decreased Water Quantity -- Agricultural Practicies; Dam or Hydropower Facility Management Water: Runoff Coefficient Alteration; Water: Storage or Withdrawal, Channelization, Management Juveniles Frequency and magnitude of high flows are not sufficient to create and maintain channel complexity and provide nutrients from floodplain areas. Additional flow reductions are associated with irrigation diversions in many watersheds.
OREGON CHUB
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Habitat Quantity and Quality Morphological Changes Freshwater-Floodplain Agricultural Practices; Urbanization Diking; Filling; Riparian Degradation; Wetland Loss All Land use practices have led to losses of wetlands and floodplain function.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Forest Management; Agricultural Practices; Urbanization Impervious Surfaces (Road Density); Riparian Degradation All Land use practices have resulted in loss of riparian vegetation and off-channel habitats.
Instantaneous Mortality Predation -- Fishery Management Species Introduction All Introduced predaceous fish threaten existing populations of Oregon chub, and inhibit re-colonization of formerly occupied habitat.
Sediment Conditions Increased Sediment Quantity Freshwater-Instream Agricultural Practices; Forest Management Sediment: Bank Destabilization; Sediment: Upland Disturbances; Impervious Surfaces (Road Density); Riparian Degradation All Logging practices in the Middle Fork Willamette watershed contribute sediment to ponds that contain Oregon chub. Land use practices have resulted in increasing sedimentation.
Water Quantity Altered Flow Timing -- Agricultural Practicies; Dam or Hydropower Facility Management Water: Runoff Coefficient Alteration; Water: Storage or Withdrawal, Channelization, Management All Altered hydrograph resulting from hydro operations prevents the formation of chub habitat and natural dispersal of the species.
SPRING CHINOOK
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Biological Viability Criteria Diversity -- Artificial Propogation Straying Adult spawners Large numbers of stray spring Chinook spawning with indigenous populations pose serious genetic risks.
Habitat Quantity and Quality Access and Availability Freshwater-Instream Dam or Hydropower Facility Management Migration Impediments Adults Dams block access to 80% of the historical spring Chinook salmon habitat in the Middle Fork Willamette watershed. Complete barriers also include Detroit and Big Cliff dams in the North Santiam watershed. Dams in the McKenzie and Clackamas watersheds also restrict access.
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; Filling; Riparian Degradation; Wetland Loss Juveniles Land use practices have led to losses of wetlands and floodplain function.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Forest Management; Agricultural Practices; Urbanization Impervious Surfaces (Road Density); Riparian Degradation; Wetland Loss Juveniles Removal of streamside vegetation and road building in the Clackamas River Watershed have reduced habitat. Losses of wetland, floodplain, and off-channel habitats have reduced the quantity and quality of adult salmonid holding areas in the Molalla and Calapooia watersheds. Invasive plants limit the growth of native vegetation needed for habitat and channel formation processes.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practicies; Forest Management; Dam or Hydropower Facility Management Diking; Filling; Wood/Structure Removal Juveniles Limited wood in many watersheds has reduced the frequency and depth of pools, limiting rearing. Channel complexity has been reduced by reduced peak flows.
Water Quality Temperature -- Agricultural Practicies; Forest Management; Dam or Hydropower Facility Management Water: Temperature and Gas Alteration; Riparian Degradation Juveniles Stream temperatures in many watersheds exceed criteria for summer maximum for juvenile salmonid rearing. Hydro operations on the Clacakamas River result in elevated water temperatures
Water Quantity Decreased Water Quantity; Increased Water Quantity; Altered Flow Timing -- Dam or Hydropower Facility Management Water: Runoff Coefficient Alteration; Water: Storage or Withdrawal, Channelization, Management Juveniles Hydro operations result in elevated flows during spawning and subsequent dewatering of redds. Reduced peak flows reduce channel complexity and diversity, and elevated water temperatures cause premature hatching and emergence.
WINTER STEELHEAD
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Biological Viability Criteria Diversity -- Artificial Propogation Straying Adult spawners Large numbers of stray steelheadk spawning with indigenous populations pose serious genetic risks.
Food Competition -- Artificial Propogation Intraspecific Interaction Juveniles Hatchery releases lead to competition with naturally produced juveniles.
Habitat Quantity and Quality Access and Availability Freshwater-Instream Dam or Hydropower Facility Management Migration Impediments Adults Complete barriers include Detroit and Big Cliff dams in the North Santiam watershed. Dams in the McKenzie and Clackamas watersheds also restrict access.
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; Filling; Riparian Degradation; Wetland Loss Juveniles Land use practices have led to losses of wetlands and floodplain function.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Forest Management; Agricultural Practices; Urbanization Impervious Surfaces (Road Density); Riparian Degradation; Wetland Loss Juveniles Removal of streamside vegetation and road building in the Clackamas River Watershed have reduced habitat. Losses of wetland, floodplain, and off-channel habitats have reduced the quantity and quality of adult salmonid holding areas in the Molalla and Calapooia watersheds. Invasive plants limit the growth of native vegetation needed for habitat and channel formation processes.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practicies; Forest Management; Dam or Hydropower Facility Management Diking; Filling; Wood/Structure Removal Juveniles Limited wood in many watersheds has reduced the frequency and depth of pools, limiting rearing. Channel complexity has been reduced by reduced peak flows.
Instantaneous Mortality Predation -- Fishery Management Species Introduction Juveniles Non-native species introductions have lead to community shifts and predation issues.
Water Quality Temperature -- Agricultural Practicies; Forest Management; Dam or Hydropower Facility Management Water: Temperature and Gas Alteration; Riparian Degradation Juveniles Stream temperatures in many watersheds exceed criteria for summer maximum for juvenile salmonid rearing. Hydro operations on the Clacakamas River result in elevated water temperatures
Water Quantity Decreased Water Quantity; Increased Water Quantity; Altered Flow Timing -- Dam or Hydropower Facility Management Water: Runoff Coefficient Alteration; Water: Storage or Withdrawal, Channelization, Management Juveniles Hydro operations result in elevated flows during spawning and subsequent dewatering of redds. Reduced peak flows reduce channel complexity and diversity, and elevated water temperatures cause premature hatching and emergence.