Limiting Factors



Intermountain Province

Spokane Subbasin 408

KOKANEE
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 The development of hydropower facilities without fish passage facilities limits genetic exchange, distribution, and habitat connectivity for fish species.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practices; Forest Management; Urbanization Impervious Surfaces (Road Density); Riparian Degradation Juveniles, adults Embedded substrate and reduced habitat complexity, due to anthropogenic activities, limits native salmonid populations.
Sediment Conditions Increased Sediment Quantity Freshwater-Instream Agricultural Practices; Forest Management; Urbanization Impervious Surfaces (Road Density); Riparian Degradation All Fine sediment is the most common problem throughout the watershed.
Toxic Contaminants Water; Biota -- Pollution and Contamination Pollution: Heavy Metal; Pollution: Biological Wastes, Fertilizer, & Pharmaceuticals All Excessive nutrients exist in the Spokane River below Spokane Falls providing conditions for aquatic vegetation to thrive in low velocity habitats. Accumulation of decaying aquatic vegetation creates biological oxygen demands exacerbating already low oxygen concentrations. dissolved oxygen levels fall below 4 mg/L in the summer.
Water Quality Temperature; Oxygen -- Dam or Hydropower Facility Management; Agricultural Practices; Forest Management; Urbanization Riparian Degradation; Water: Storage or Withdrawal; Water: Temperature and Gas Alteration All In the Spokane River above Spokane Falls, increased water temperature and low dissolved oxygen concentrations are on the 303(d) list. High levels of total dissolved gas is a major problem below Long Lake Dam. Due to the continual series of reservoirs, dissolved gas cannot reach equilibrium. Approximately half of the Little Spokane drainage has impaired water quality throughout the year. Water quality in Hangman Creek is generally poor and state standards for fecal coliform, temperature, pH, and dissolved oxygen are often not met. In Upper Hangman Creek, low dissolved oxygen, high levels of total suspened solids, and high temperatures impair stream conditions and salmonid distribution. During the spring, total dissolved gas saturation often exceeds the standard in the Little Falls Pool, whereas dissolved oxygen levels fall below 4 mg/L in the summer.
Water Quantity Altered Flow Timimg -- Agricultural Practices; Dam or Hydropower Facility Management Water: Storage or Withdrawal; Water: Runoff Coefficient Alteration Adults Land uses, water diversions, and dams have altered the spring freshet such that the current annual peak flow event occurs rapidly rather than the natural condition of gradual run-off, which consequently creates low, late summer base flows that limit habitat area and complexity.
LARGEMOUTH BASS
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Water Quantity Altered Flow Timing -- Dam or Hydropower Facility Management Water: Storage or Withdrawal Juveniles Annual drawdowns at Lake Spokane limit the stability of warmwater species by increasing the proportional stock density of predatory fish and reducing cover and shelter for juveniles that leads to increased stress for juvenile fish.
MOUNTAIN WHITEFISH
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 The development of hydropower facilities without fish passage facilities limits genetic exchange, distribution, and habitat connectivity for fish species.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practices; Forest Management; Urbanization Impervious Surfaces (Road Density); Riparian Degradation Juveniles, adults Embedded substrate and reduced habitat complexity, due to anthropogenic activities, limits native salmonid populations.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Agricultural Practices; Forest Management; Urbanization Impervious Surfaces (Road Density); Riparian Degradation Juveniles, adults Riparian zones have been severely impacted by agriculture, grazing, forest management, road construction and other activities.
Sediment Conditions Increased Sediment Quantity Freshwater-Instream Agricultural Practices; Forest Management; Urbanization Impervious Surfaces (Road Density); Riparian Degradation All Fine sediment is the most common problem throughout the watershed.
Toxic Contaminants Water; Biota -- Pollution and Contamination Pollution: Heavy Metal; Pollution: Biological Wastes, Fertilizer, & Pharmaceuticals All Excessive nutrients exist in the Spokane River below Spokane Falls providing conditions for aquatic vegetation to thrive in low velocity habitats. Accumulation of decaying aquatic vegetation creates biological oxygen demands exacerbating already low oxygen concentrations. dissolved oxygen levels fall below 4 mg/L in the summer.
Water Quality Temperature; Oxygen -- Dam or Hydropower Facility Management; Agricultural Practices; Forest Management; Urbanization Riparian Degradation; Water: Storage or Withdrawal; Water: Temperature and Gas Alteration All In the Spokane River above Spokane Falls, increased water temperature and low dissolved oxygen concentrations are on the 303(d) list. High levels of total dissolved gas is a major problem below Long Lake Dam. Due to the continual series of reservoirs, dissolved gas cannot reach equilibrium. Approximately half of the Little Spokane drainage has impaired water quality throughout the year. Water quality in Hangman Creek is generally poor and state standards for fecal coliform, temperature, pH, and dissolved oxygen are often not met. In Upper Hangman Creek, low dissolved oxygen, high levels of total suspened solids, and high temperatures impair stream conditions and salmonid distribution. During the spring, total dissolved gas saturation often exceeds the standard in the Little Falls Pool, whereas dissolved oxygen levels fall below 4 mg/L in the summer.
Water Quantity Altered Flow Timimg -- Agricultural Practices; Dam or Hydropower Facility Management Water: Storage or Withdrawal; Water: Runoff Coefficient Alteration Adults Land uses, water diversions, and dams have altered the spring freshet such that the current annual peak flow event occurs rapidly rather than the natural condition of gradual run-off, which consequently creates low, late summer base flows that limit habitat area and complexity.
REDBAND TROUT
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage (s) Description
Biological Viability Criteria Diversity -- Fishery Management Species Introduction Adults Non-native rainbow trout releases lead to hybridization with native redband trout.
Habitat Quantity and Quality Access and Availability Freshwater-Instream Dam or Hydropower Facility Management Migration Impediments Juveniles, adults The development of hydropower facilities without fish passage facilities limits genetic exchange, distribution, and habitat connectivity for fish species.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practices; Forest Management; Urbanization Impervious Surfaces (Road Density); Riparian Degradation Juveniles, adults Embedded substrate and reduced habitat complexity, due to anthropogenic activities, limits native salmonid populations.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Agricultural Practices; Forest Management; Urbanization Impervious Surfaces (Road Density); Riparian Degradation Juveniles, adults Riparian zones have been severely impacted by agriculture, grazing, forest management, road construction and other activities.
Instantaneous Mortality Predation -- Fishery Management Species Introduction Juveniles, adults Predation by non-native fishes has depleted native fishes in the Spokane arm of Lake Roosevelt.
Sediment Conditions Increased Sediment Quantity Freshwater-Instream Agricultural Practices; Forest Management; Urbanization Impervious Surfaces (Road Density); Riparian Degradation All Fine sediment is the most common problem throughout the watershed.
Toxic Contaminants Water; Biota -- Pollution and Contamination Pollution: Heavy Metal; Pollution: Biological Wastes, Fertilizer, & Pharmaceuticals All Excessive nutrients exist in the Spokane River below Spokane Falls providing conditions for aquatic vegetation to thrive in low velocity habitats. Accumulation of decaying aquatic vegetation creates biological oxygen demands exacerbating already low oxygen concentrations. dissolved oxygen levels fall below 4 mg/L in the summer.
Water Quality Temperature; Oxygen -- Dam or Hydropower Facility Management; Agricultural Practices; Forest Management; Urbanization Riparian Degradation; Water: Storage or Withdrawal; Water: Temperature and Gas Alteration All In the Spokane River above Spokane Falls, increased water temperature and low dissolved oxygen concentrations are on the 303(d) list. High levels of total dissolved gas is a major problem below Long Lake Dam. Due to the continual series of reservoirs, dissolved gas cannot reach equilibrium. Approximately half of the Little Spokane drainage has impaired water quality throughout the year. Water quality in Hangman Creek is generally poor and state standards for fecal coliform, temperature, pH, and dissolved oxygen are often not met. In Upper Hangman Creek, low dissolved oxygen, high levels of total suspened solids, and high temperatures impair stream conditions and salmonid distribution. During the spring, total dissolved gas saturation often exceeds the standard in the Little Falls Pool, whereas dissolved oxygen levels fall below 4 mg/L in the summer.
Water Quantity Altered Flow Timimg -- Agricultural Practices; Dam or Hydropower Facility Management Water: Storage or Withdrawal; Water: Runoff Coefficient Alteration Adults Land uses, water diversions, and dams have altered the spring freshet such that the current annual peak flow event occurs rapidly rather than the natural condition of gradual run-off, which consequently creates low, late summer base flows that limit habitat area and complexity.