Limiting Factors



Columbia Cascade Province

Lake Chelan Subbasin 403

Bull Trout
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Food Altered Primary Productivity -- Water Management Water: Nutrient Alteration All Levels of nitrates, chlorophyll a, zooplankton, and benthic organisms are low, especially in the Lucerne Basin. The productivity of the lake is also affected by elevated bacterial levels and pesticide residues.
Food Competition -- Species Management Species Introduction Juveniles, adults Competition between native fish species and introduced game fish has reduced or eliminated native fish populations.
Habitat Quantity and Quality Access and Availability Freshwater-Instream Agricultural Practices; Forest Management; Dam or Hydropower Facility Management Migration Impediments Adults Sediment deposits at the mouths of some tributaries have created barriers to spawning areas. Fish, Safety, Prince, Gold, Grade, Mitchell, and Rail Road creeks contain sediment barriers that block passage of during upstream spawning migrations.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practices; Forest Management Riparian Degradation; Bank Destabilization Juveniles, adults Large woody debris has been removed limiting cover and reducing in-stream complexity. Tributaries to Lake Chelan (from Manson to Stehekin) lack appropriately sized gravel for trout spawning as well as large woody debris.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Agricultural Practices; Forest Management; Dam or Hydropower Facility Management Riparian Degradation Juveniles, adults Vegetation is limited along the Lake Chelan shoreline due to the steep-sided configuration of the drainage, the thin, rocky soils, and heavy wave action. Riparian and wetland habitat have been removed or filled near the mouth of the Stehekin River. Grazing and lake level fluctuations have reduced riparian habitat. Large trees, snags, and woody debris are limited. From Mitchell Creek down the lake, large trees and mid– to low-level shrubs and forbs/grasses are limited in numbers. Most tributaries (Grade, Mitchell, Box, Big, Bear, Prince, and Fish) have narrow, steep-walled drainages, deeply-incised channels, narrow bands of riparian vegetation alongside the streams, and a lack of large woody debris.
Instantaneous Mortality Anthropogenic Mortality -- Fishery Management Harvest Adults Populations are subject to high levels of legal harvest.
Water Quality Oxygen; pH; -- Water Management Water: Temperature and Gas Alteration; All First Creek and the lower Chelan River (Chelan Falls and Hatchery) are on the EPA’s 303d list for impaired water quality due to dissolved oxygen. Mitchell Creek was listed for irregularities in pH.
KOKANEE
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Food Altered Primary Productivity -- Water Management Water: Nutrient Alteration All Levels of nitrates, chlorophyll a, zooplankton, and benthic organisms are low, especially in the Lucerne Basin. The productivity of the lake is also affected by elevated bacterial levels and pesticide residues.
Instantaneous Mortality Predation -- Species Management Species Introduction Juveniles, adults Competition between native fish species and introduced game fish has reduced or eliminated native fish populations.
Water Quality Oxygen; pH; -- Water Management Water: Temperature and Gas Alteration; All First Creek and the lower Chelan River (Chelan Falls and Hatchery) are on the EPA’s 303d list for impaired water quality due to dissolved oxygen. Mitchell Creek was listed for irregularities in pH.
WESTSLOPE CUTTHROAT
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Food Altered Primary Productivity -- Water Management Water: Nutrient Alteration All Levels of nitrates, chlorophyll a, zooplankton, and benthic organisms are low, especially in the Lucerne Basin. The productivity of the lake is also affected by elevated bacterial levels and pesticide residues.
Habitat Quantity and Quality Access and Availability Freshwater-Instream Agricultural Practices; Forest Management; Dam or Hydropower Facility Management Migration Impediments Adults Sediment deposits at the mouths of some tributaries have created barriers to spawning areas. Fish, Safety, Prince, Gold, Grade, Mitchell, and Rail Road creeks contain sediment barriers that block passage of during upstream spawning migrations.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practices; Forest Management Riparian Degradation; Bank Destabilization Juveniles, adults Large woody debris has been removed limiting cover and reducing in-stream complexity. Tributaries to Lake Chelan (from Manson to Stehekin) lack appropriately sized gravel for trout spawning as well as large woody debris.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Agricultural Practices; Forest Management; Dam or Hydropower Facility Management Riparian Degradation Juveniles, adults Vegetation is limited along the Lake Chelan shoreline due to the steep-sided configuration of the drainage, the thin, rocky soils, and heavy wave action. Riparian and wetland habitat have been removed or filled near the mouth of the Stehekin River. Grazing and lake level fluctuations have reduced riparian habitat. Large trees, snags, and woody debris are limited. From Mitchell Creek down the lake, large trees and mid– to low-level shrubs and forbs/grasses are limited in numbers. Most tributaries (Grade, Mitchell, Box, Big, Bear, Prince, and Fish) have narrow, steep-walled drainages, deeply-incised channels, narrow bands of riparian vegetation alongside the streams, and a lack of large woody debris.
Instantaneous Mortality Anthropogenic Mortality -- Fishery Management Harvest Adults Populations are subject to high levels of legal harvest.
Instantaneous Mortality Predation -- Species Management Species Introduction Juveniles, adults Competition between native fish species and introduced game fish has reduced or eliminated native fish populations.
Water Quality Oxygen; pH; -- Water Management Water: Temperature and Gas Alteration; All First Creek and the lower Chelan River (Chelan Falls and Hatchery) are on the EPA’s 303d list for impaired water quality due to dissolved oxygen. Mitchell Creek was listed for irregularities in pH.