Province Summary


Cowlitz Subbasin Summary

The Lower Cowlitz basin is the Cowlitz watershed below Mayfield Dam, not including the Toutle and Coweeman basins. The Cowlitz enters the Columbia at RM 68, approximately 3.5 miles southeast of Longview, WA. The Coweeman and Toutle are the two largest tributaries. These basins are covered in separate chapters. Other significant tributaries include Salmon Creek, Lacamas Creek, Olequa Creek, Delameter Creek, and Ostrander Creek.

Mayfield Dam (RM 52), constructed in 1962, blocks all natural passage of anadromous fish to the upper basin. The Cowlitz Salmon Hatchery Barrier Dam (RM 49.5), located below Mayfield Dam, is a collection facility for trapping and hauling fish into the upper basin, a practice that has been in effect since 1969. Below the Barrier Dam, the river flows south through a broad valley. Much of the lower mainstem Cowlitz suffers from channelization features related to industrial, agricultural, and urban development.

The Toutle River, which enters the Cowlitz at RM 20, is a major lower tributary that drains the north and west sides of Mount St. Helens. The Toutle River was impacted severely by the 1980 eruption of Mount St. Helens and the resulting massive debris torrents and mudflows, which also impacted the Cowlitz mainstem downstream of the Toutle confluence. Following the eruption, the lower mainstem Cowlitz was dredged and dredge spoils were placed in the floodplain.

Forestry is the dominant land use in the subbasin. Commercial forestland makes up over 80% of the Cowlitz basin below Mayfield Dam. Much of the private land in the lower river valleys is agricultural and residential, with substantial impacts to riparian and floodplain areas in places. Population centers in the subbasin consist primarily of small rural towns, with the larger towns of Castle Rock and Longview/Kelso along the lower river.

Source: Lower Columbia Province Plan

Status and Trends of Focal Species in Cowlitz Subbasin
 
Species ESU MPG Population Biological Objective (s) Biological Status Federal Status Data / Charts
Fall Chinook Lower Columbia  Cascade Fall  Lower Cowlitz, Upper Cowlitz, Toutle, Coweeman  Draft Recovery Plan Criteria :
Natural Adults
Upper Cowlitz - no objective; Lower Cowlitz - 3,000; Toutle - 4,000; Coweeman - 900 298
 
NOSA Estimate
2015:
Toutle River - 440 spawners474
Coweeman River - 1,430 Adults474
2013:
Upper Cowlitz River - 3,287 spawners474
Lower Cowlitz River - 3,587 Adults474
Juvenile Outmigrants
2017: 32,459 juveniles474
Threatened Status & Trends
Spring Chinook Lower Columbia  Cascade Spring  Upper Cowlitz, Cispus, Tilton, Toutle  Draft Recovery Plan Criteria :
Natural Adults
Upper Cowlitz - 1,800; Cispus - 1,800; Tilton - No Objective; Toutle - 1,100 298
 
NOSA Estimate
2014: 227 spawners (natural)474
Threatened Status & Trends
Chum Columbia River  Cascade  Cowlitz  Draft Recovery Plan Criteria :
Fall Run - 900 natural adults; Summer Run - 900 natural adtuls 298
 
9 adults collected at Cowlitz Salmon Hatchery 513 Threatened No Data
Coho Lower Columbia  Cascade  Lower Cowlitz, Coweeman, South Fork Toutle, North Fork Toutle, Upper Cowlitz, Cispus, Tilton  Draft Recovery Plan Criteria :
Natural Adults
Lower Cowlitz - 3,700; Coweeman - 1,200; South Fork Toutle = 1,900; North Fork Toutle - 1,900; Upper Cowlitz - 2,000; Cispus - 2,000; Tilton - No objective 298
 
NOSA Estimate
2012: Tilton River (early) - 2,744 spawners474
2013: North Fork Toutle River (early and late) - 1,425 spawners474
2015: Lower Cowlitz(late) - 5,132 spawners474
Upper Cowlitz(early and late) - 381 spawners474
Coweeman (late) - 767 spawners474
South Fork, Toutle River (early and late) - 1,537 spawners474
Threatened Status & Trends
Winter Steelhead Lower Columbia  Cascade Winter  Lower Cowlitz, Coweeman, South Fork Toutle, North Fork Toutle, Upper Cowlitz, Cispus, Tilton  Draft Recovery Plan Criteria :
Natural Adults
Lower Cowlitz - 400; Coweeman - 500; South Fork Toutle - 600; North Fork Toutle - 600; Upper Cowlitz - 500; Cispus - 500; Tilton - 200 298
 
NOSA Estimate 2015: Upper Cowlitz River - 151 adults 474
2013: Tilton River - 445 spawners474
Adult Escapement (natural)
2015: 940 adults (natural) 111
2014: Cowlitz River - 24 spawners 111
Green River - 310 spawners 111
Juvenile Outmigrants
2017: 11,567 juveniles474
Threatened Status & Trends
    
View abundance data for Cowlitz Subbasin
 
Hatcheries located in Cowlitz Subbasin
**Hatchery data will be updated in 2016**

Hatchery / Acclimation Pond Hatchery Info Releases / Returns Program Reviews(APRE / HSRG / HGMP / USFWS) Map
Coweeman Rearing Pond #1 View View   View
Coweeman Rearing Pond #2 View     View
Cowlitz Game and Anglers View   View  
Cowlitz Salmon View View View  
Cowlitz Trout Hatchery View View View View
Flyfishers Acclimation Ponds View   View  
Friends of Cowlitz View View    
Green River Salmon Hatchery View   View View
Lou Reebs Net Pens View   View  
Mill Creek Hatchery View     View
Mossyrock Trout Hatchery View View View View
North Toutle View View View  
Toutle Hatchery View   View View
Upper Cowlitz Restoration View View    
 
Hatchery Releases and Returns to Cowlitz Subbasin363, 359, 360
**Hatchery data will be updated in 2016**

Some releases into subbasins may be from hatcheries located in other provinces and subbasins. Hatchery releases of anadromous fish, within the geographic range of an ESU/DPS, are listed accordingly.
 
Hatchery / Acclimation Pond Species ESU/DPS Released in 2009 Returns to Collection Facility in 2009 Data as of
Clark PUD Coho Lower Columbia River Coho ESU 38,695 8 / 30 / 2010
Coweeman Rearing Pond #1 Winter Steelhead Lower Columbia River Steelhead DPS 5,055 8 / 30 / 2010
Cowlitz Salmon Coastal Cutthroat 5,224 8 / 30 / 2010
Coho Lower Columbia River Coho ESU 2,822,159 77,858 8 / 30 / 2010
Fall Chinook Lower Columbia River Chinook ESU 5,104,829 4,309 8 / 30 / 2010
Spring Chinook Lower Columbia River Chinook ESU 880,607 1,895 8 / 30 / 2010
Summer Steelhead Lower Columbia River Steelhead DPS 5,218 8 / 30 / 2010
Summer Steelhead Lower Columbia River Steelhead DPS 94,124 8 / 30 / 2010
Winter Steelhead Lower Columbia River Steelhead DPS 5,233 8 / 30 / 2010
Cowlitz Trout Hatchery Coastal Cutthroat 160,442 2,971 8 / 30 / 2010
Summer Steelhead Lower Columbia River Steelhead DPS 466,489 1,623 8 / 30 / 2010
Winter Steelhead Lower Columbia River Steelhead DPS 797,483 1,313 8 / 30 / 2010
Friends of Cowlitz Coastal Cutthroat 10,075 8 / 30 / 2010
Goldendale Trout Hatchery Brook Trout 91 8 / 30 / 2010
Brown Trout 1,896 8 / 30 / 2010
Rainbow Trout 20,149 8 / 30 / 2010
Tiger Trout 1,394 8 / 30 / 2010
Krause Project Coho 1,000 8 / 30 / 2010
Meseberg Hatchery Tiger Muskie 1,463 8 / 30 / 2010
Mossyrock Trout Hatchery Brown Trout 19,125 8 / 30 / 2010
Golden Trout 1,034 8 / 30 / 2010
Rainbow Trout 150,572 8 / 30 / 2010
Westslope Cutthroat 1,519 8 / 30 / 2010
North Toutle Coho 489,641 32,824 8 / 30 / 2010
Fall Chinook 1,468,609 1,586 (mixed) 8 / 30 / 2010
Summer Steelhead Lower Columbia River Steelhead DPS 25,124 63 8 / 30 / 2010
Trout Lodge Commercial Rainbow Trout 1,996 8 / 30 / 2010
Upper Cowlitz Restoration Spring Chinook Lower Columbia River Chinook ESU 300,718 8 / 30 / 2010
Recovery Status for ESA-Listed Salmon and Steelhead in the Cowlitz Subbasin369

Updated : 5/27/2010

Species Population Abundance Threshold Mean Abundance Major Spawning Area Growth Rate Recruits / Spawners Current Viability
Winter Steelhead Lower Cowlitz River 540 350 -- -- -- Low
  Upper Cowlitz River -- <50 -- -- -- Very Low
  Cispus River -- <50 -- -- -- Very Low
  Tilton River -- <50 -- -- -- Very Low
  South Fork Toutle River 450 350 -- -- -- Medium
  North Fork Toutle River 590 120 -- -- -- Very Low
  Coweeman River 470 350 -- -- -- Low
Fall Chinook Lower Cowlitz River 3,150 500 -- -- -- Very Low
  Upper Cowlitz River -- 0 -- -- -- Very Low
  Toutle River 2,350 <50 -- -- -- Very Low
  Coweeman River 700 100 -- -- -- Very Low
Spring Chinook Upper Cowlitz River -- 300 -- -- -- Very Low
  Cispus River -- 150 -- -- -- Very Low
  Tilton River -- 100 -- -- -- Very Low
  Toutle River -- 100 -- -- -- Very Low
Coho Lower Cowlitz River 3,680 500 -- -- -- Very Low
  Upper Cowlitz River -- <50 -- -- -- Very Low
  Cispus River -- <50 -- -- -- Very Low
  Tilton River -- <50 -- -- -- Very Low
  South Fork Toutle River 1,900 <50 -- -- -- Very Low
  North Fork Toutle River 1,900 <50 -- -- -- Very Low
  Coweeman River 1,200 <50 -- -- -- Very Low
Chum Cowlitz River Fall -- <300 -- -- -- Very Low
  Cowlitz River Summer -- -- -- -- -- Very Low
Limiting Factors in the Cowlitz Subbasin 362

CHUM
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 chum 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 Juveniles 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 Fry Extensive diking has disconnected the floodplain.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Agricultural Practices; Forest Management; Urbanization Diking; Filling; Riparian Degradation Adults Riparian areas are severely degraded in the lower 20 miles of the Cowlitz. Buffers are inadequate between river miles 20 and 52. Channel stability is a problem in the North Fork Tilton and Upper Cowlitz. In the Coweeman, land use has resulted in poor bank stability from river miles 4 to 7.5, and 17 to 26.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practices; Forest Management; Urbanization Diking; Filling; Impervious Surfaces; Riparian Degradation Eggs, adults Most side-channel habitat has been eliminated from the Lower Cowlitz. Large woody debris levels are low throughout the subbasin.
Instantaneous Mortality Pathogens -- Artificial Propogation Disease Amplification and Transfer Eggs, adults Pathogens from hatcheries may limit productivity.
Sediment Conditions Increased Sediment Quantity Freshwater-Instream Mass Wasting;Erosion Control, Flood Prevention & Over-water Structures; Urbanization Landslides; Impervious Surfaces (Road Density); Beach Alteration; Sediment: Bank Destabilization Eggs, adults Most streams are sediment impaired. The Cispus River (Upper Cowlitz watershed) experiences excessive sedimentation due to mass wasting and roads. A sediment retention structure in the North Fork Toutle River is a major source of sedimentation.
Water Quality Temperature -- Agricultural Practices; Forest Management; Urbanization Water: Temperature and Gas Alteration Eggs, adults The Lower Cowlitz is on the Washington state 303(d) list for exceeding pH, temperature, and fecal coliform standards. Silver and Willame creeks (Upper Cowlitz watershed), Green River and Harrington Creek (Toutle watershed), and the Lower Coweeman River are 303(d) listed for temperature.
Water Quantity Decreased Water Quantity -- Agricultural Practices; Forest Management; Urbanization Water: Storage or Withdrawal, Channelization, Management Eggs, adults Low flows limit adult holding and spawning, and egg survival.
COASTAL CUTTHROAT
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 Juveniles Extensive diking has disconnected the floodplain.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Agricultural Practices; Forest Management; Urbanization Diking; Filling; Riparian Degradation Juveniles, adults Riparian areas are severely degraded in the lower 20 miles of the Cowlitz. Buffers are inadequate between river miles 20 and 52. Channel stability is a problem in the North Fork Tilton and Upper Cowlitz. In the Coweeman, land use has resulted in poor bank stability from river miles 4 to 7.5, and 17 to 26.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practices; Forest Management; Urbanization Diking; Filling; Impervious Surfaces; Riparian Degradation Juveniles, adults Most side-channel habitat has been eliminated from the Lower Cowlitz. Large woody debris levels are low throughout the subbasin.
Sediment Conditions Increased Sediment Quantity Freshwater-Instream Mass Wasting;Erosion Control, Flood Prevention & Over-water Structures; Urbanization Landslides; Impervious Surfaces (Road Density); Beach Alteration; Sediment: Bank Destabilization All Most streams are sediment impaired. The Cispus River (Upper Cowlitz watershed) experiences excessive sedimentation due to mass wasting and roads. A sediment retention structure in the North Fork Toutle River is a major source of sedimentation.
Water Quality Temperature -- Agricultural Practices; Forest Management; Urbanization Water: Temperature and Gas Alteration All The Lower Cowlitz is on the Washington state 303(d) list for exceeding pH, temperature, and fecal coliform standards. Silver and Willame creeks (Upper Cowlitz watershed), Green River and Harrington Creek (Toutle watershed), and the Lower Coweeman River are 303(d) listed for temperature.
Water Quantity Decreased Water Quantity; Increased Water Quantity -- Agricultural Practices; Forest Management; Urbanization Water: Storage or Withdrawal, Channelization, Management Juveniles, adults Most streams in the Upper Cowlitz watershed experience increased peak flows. Low summer flows in Outlet Creek (Toutle watershed) limit juvenile fish rearing.
COHO
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage(s) Description
Food Competition -- Artificial Propogation Intraspecific Interaction Summer parr Hatchery releases lead to competition with naturally produced juveniles.
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 Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practices; Forest Management; Urbanization Diking; Filling; Impervious Surfaces; Riparian Degradation Juveniles, adults Most side-channel habitat has been eliminated from the Lower Cowlitz. Large woody debris levels are low throughout the subbasin.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Agricultural Practices; Forest Management; Urbanization Diking; Filling; Riparian Degradation Juveniles, adults Riparian areas are severely degraded in the lower 20 miles of the Cowlitz. Buffers are inadequate between river miles 20 and 52. Channel stability is a problem in the North Fork Tilton and Upper Cowlitz. In the Coweeman, land use has resulted in poor bank stability from river miles 4 to 7.5, and 17 to 26.
Instantaneous Mortality Anthropogenic Mortality -- Fishery Management Harvest Adults Coho are subject to both ocean and freshwater harvest.
Instantaneous Mortality Predation -- Fishery Management Species Introduction Summer parr Non-native species introductions have lead to community shifts and predation issues.
Sediment Conditions Increased Sediment Quantity Freshwater-Instream Mass Wasting;Erosion Control, Flood Prevention & Over-water Structures; Urbanization Landslides; Impervious Surfaces (Road Density); Beach Alteration; Sediment: Bank Destabilization All Most streams are sediment impaired. The Cispus River (Upper Cowlitz watershed) experiences excessive sedimentation due to mass wasting and roads. A sediment retention structure in the North Fork Toutle River is a major source of sedimentation.
Water Quality Temperature -- Agricultural Practices; Forest Management; Urbanization Water: Temperature and Gas Alteration All The Lower Cowlitz is on the Washington state 303(d) list for exceeding pH, temperature, and fecal coliform standards. Silver and Willame creeks (Upper Cowlitz watershed), Green River and Harrington Creek (Toutle watershed), and the Lower Coweeman River are 303(d) listed for temperature.
Water Quantity Decreased Water Quantity -- Agricultural Practices; Forest Management; Urbanization Water: Storage or Withdrawal, Channelization, Management Juveniles Low flows impede Chinook and coho salmon in the Coweeman River.
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 Agricultural Practices; Urbanization Diking Fry Extensive diking has disconnected the floodplain.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Agricultural Practices; Forest Management; Urbanization Diking; Filling; Riparian Degradation Juveniles, adults Riparian areas are severely degraded in the lower 20 miles of the Cowlitz. Buffers are inadequate between river miles 20 and 52. Channel stability is a problem in the North Fork Tilton and Upper Cowlitz. In the Coweeman, land use has resulted in poor bank stability from river miles 4 to 7.5, and 17 to 26.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practices; Forest Management; Urbanization Diking; Filling; Impervious Surfaces; Riparian Degradation All Most side-channel habitat has been eliminated from the Lower Cowlitz. Large woody debris levels are low throughout the subbasin.
Instantaneous Mortality Anthropogenic Mortality -- Fishery Management Harvest Adults Fall Chinook are subject to both ocean and freshwater harvest.
Instantaneous Mortality Pathogens -- Artificial Propogation Disease Amplification and Transfer Eggs, adults Pathogens from hatcheries may limit productivity.
Instantaneous Mortality Predation -- Fishery Management Species Introduction Summer parr Non-native species introductions have lead to community shifts and predation issues.
Sediment Conditions Increased Sediment Quantity Freshwater-Instream Mass Wasting;Erosion Control, Flood Prevention & Over-water Structures; Urbanization Landslides; Impervious Surfaces (Road Density); Beach Alteration; Sediment: Bank Destabilization All Most streams are sediment impaired. The Cispus River (Upper Cowlitz watershed) experiences excessive sedimentation due to mass wasting and roads. A sediment retention structure in the North Fork Toutle River is a major source of sedimentation.
Water Quality Temperature -- Agricultural Practices; Forest Management; Urbanization Water: Temperature and Gas Alteration All The Lower Cowlitz is on the Washington state 303(d) list for exceeding pH, temperature, and fecal coliform standards. Silver and Willame creeks (Upper Cowlitz watershed), Green River and Harrington Creek (Toutle watershed), and the Lower Coweeman River are 303(d) listed for temperature.
Water Quantity Decreased Water Quantity -- Agricultural Practices; Forest Management; Urbanization Water: Storage or Withdrawal, Channelization, Management Juveniles Low flows impede Chinook and coho salmon in the Coweeman River.
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 Juveniles, adults Extensive diking has disconnected the floodplain.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Agricultural Practices; Forest Management; Urbanization Diking; Filling; Riparian Degradation Juveniles, adults Riparian areas are severely degraded in the lower 20 miles of the Cowlitz. Buffers are inadequate between river miles 20 and 52. Channel stability is a problem in the North Fork Tilton and Upper Cowlitz. In the Coweeman, land use has resulted in poor bank stability from river miles 4 to 7.5, and 17 to 26.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practices; Forest Management; Urbanization Diking; Filling; Impervious Surfaces; Riparian Degradation All Most side-channel habitat has been eliminated from the Lower Cowlitz. Large woody debris levels are low throughout the subbasin.
Instantaneous Mortality Pathogens -- Artificial Propogation Disease Amplification and Transfer Eggs, adults Pathogens from hatcheries may limit productivity.
Sediment Conditions Increased Sediment Quantity Freshwater-Instream Mass Wasting;Erosion Control, Flood Prevention & Over-water Structures; Urbanization Landslides; Impervious Surfaces (Road Density); Beach Alteration; Sediment: Bank Destabilization All Most streams are sediment impaired. The Cispus River (Upper Cowlitz watershed) experiences excessive sedimentation due to mass wasting and roads. A sediment retention structure in the North Fork Toutle River is a major source of sedimentation.
Water Quality Temperature -- Agricultural Practices; Forest Management; Urbanization Water: Temperature and Gas Alteration All The Lower Cowlitz is on the Washington state 303(d) list for exceeding pH, temperature, and fecal coliform standards. Silver and Willame creeks (Upper Cowlitz watershed), Green River and Harrington Creek (Toutle watershed), and the Lower Coweeman River are 303(d) listed for temperature.
Water Quantity Decreased Water Quantity -- Agricultural Practices; Forest Management; Urbanization Water: Storage or Withdrawal, Channelization, Management All Most streams in the Upper Cowlitz watershed experience increased peak flows. Low summer flows in Outlet Creek (Toutle watershed) limit juvenile fish rearing. Low flows impede Chinook and coho salmon in the Coweeman River.
WINTER STEELHEAD
Key Limiting Factor Impairment Habitat Affected Threat Type Threat Name Life Stage(s) Description
Food Competition -- Artificial Propogation Intraspecific Interaction Summer parr Hatchery releases lead to competition with naturally produced juveniles.
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 Juveniles, adults Extensive diking has disconnected the floodplain.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Riparian Agricultural Practices; Forest Management; Urbanization Diking; Filling; Riparian Degradation Juveniles, adults Riparian areas are severely degraded in the lower 20 miles of the Cowlitz. Buffers are inadequate between river miles 20 and 52. Channel stability is a problem in the North Fork Tilton and Upper Cowlitz. In the Coweeman, land use has resulted in poor bank stability from river miles 4 to 7.5, and 17 to 26.
Habitat Quantity and Quality Small-Scale Structural Complexity; Morphological Changes Freshwater-Instream Agricultural Practices; Forest Management; Urbanization Diking; Filling; Impervious Surfaces; Riparian Degradation All Most side-channel habitat has been eliminated from the Lower Cowlitz. Large woody debris levels are low throughout the subbasin.
Instantaneous Mortality Predation -- Fishery Management Species Introduction Summer parr Non-native species introductions have lead to community shifts and predation issues.
Sediment Conditions Increased Sediment Quantity Freshwater-Instream Mass Wasting;Erosion Control, Flood Prevention & Over-water Structures; Urbanization Landslides; Impervious Surfaces (Road Density); Beach Alteration; Sediment: Bank Destabilization All Most streams are sediment impaired. The Cispus River (Upper Cowlitz watershed) experiences excessive sedimentation due to mass wasting and roads. A sediment retention structure in the North Fork Toutle River is a major source of sedimentation.
Water Quality Temperature -- Agricultural Practices; Forest Management; Urbanization Water: Temperature and Gas Alteration All The Lower Cowlitz is on the Washington state 303(d) list for exceeding pH, temperature, and fecal coliform standards. Silver and Willame creeks (Upper Cowlitz watershed), Green River and Harrington Creek (Toutle watershed), and the Lower Coweeman River are 303(d) listed for temperature.
Water Quantity Decreased Water Quantity -- Agricultural Practices; Forest Management; Urbanization Water: Storage or Withdrawal, Channelization, Management All Most streams in the Upper Cowlitz watershed experience increased peak flows. Low summer flows in Outlet Creek (Toutle watershed) limit juvenile fish rearing.