Mount Rainier from Pulford Road  Tanwax Creek

   Creek Health

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Healthy streams have several key components
Water Substrate Riparian Vegetation Large Woody Debris

  • Oxygen-rich, pollution free environment

  • Adequate stream flow all year; stable flow for at least part of the year; higher flows during fish spawning.

  • Good pool/riffle ratio: food producing areas (riffles) are interspersed with resting areas (pools)

  • Good bug populations

  • The mud, silt, gravel, cobbles, boulders or bedrock

  • Best if sorted

  • Silt-free gravel is best for spawning

  • Balanced quantity--not too much or too little

  • Stable--no large scour or deposition

  • Vegetation beside or along the bank of a stream or river

  • Shades the water and lowers water temperature

  • Supplies nutrients

  • Protects banks

  • Supplies large woody debris

  • Creates habitat
     

  • Creates pools

  • Forces meanders and side channel development

  • Supplies carbon

  • Protect banks & regulates sediment input

  • Causes turbulence

  • Stabilizes and sorts the substrate
From NPS website Silt-free Gravel
 From NPS website		 Riparian Vegetation
From WDFW website		 Large Woody Debris (LWD)
From NPS website
Tanwax Creek Shows Symptoms of Declining Health
 Tanwax Creek has been studied using a system known as Ecosystem Diagnosis and Treatment, or EDT.  The current EDT analysis shows a loss of watershed productivity according the following major factors:
 
  • High sediment load
  • Accentuated summer low flows
  • Decline in habitat diversity
  • Decline in channel stability
In all of the stream reaches in the Tanwax watershed, low flows are now lower than they were historically, and high flows are higher than they were.  EDT analysis shows that this problem, along with a lack of high quality habitat, has a negative effect on fry, rearing juveniles, and a pre-spawning adult coho, steelhead, and chinook.  Maximum summer temperatures have gotten warmer throughout the basin, especially in the upper Tanwax and Tanwax Lake reaches.  These high temperatures are harmful to juvenile coho and steelhead that rear in the creek.
In all of the stream reaches of the creek and its tributaries, especially the upper Tanwax and Rapjohn Creek reaches, there is less woody debris and poorer riparian function than there was historically.  Riparian function is a measure of the linkages between the stream and its floodplain, such as overbank flows, streamside vegetation, and groundwater interactions. 
These factors, along with the bed scour in the lower Tanwax, Mud Creek and Trout Creek reaches, and ditching of the creek in all reaches except the lower Tanwax, have led to poor channel stability.  This lowered channel stability lowers the productivity of egg, fry and juvenile coho, chinook and steelhead.  The lack of wood and poor riparian function also leads to a lack of habitat diversity, which negatively affects spawners, pre-spawners and rearing juveniles in all reaches.  Increases in the percentage of find sediment present in the substrate of the creek and increases in the turbidity in all reaches have increased the sediment load.  This is detrimental for the egg incubation life stage of al salmon species, and is also a problem for fry and juvenile steelhead that rear in the creek
The EDT model also indicates that changes in the types of habitat available in the creek have been detrimental.  There has been a decline in pool and pool tailout habitat and and increase in glide habitat throughout the creek and its tributaries.  There has also been a decline in small cobble riffles for spawning in the Tanwax upper and lower reaches.  Some reaches also show large declines in the amount of beaver dam pools, backwater pools, and off channel habitat available compared to historic conditions.  Other problems noted included the presence of introduced species, especially in the lake and upper tributaries, increases  of predation, pathogens, and harassment, lack of food (decline of salmon carcasses), lowered dissolved oxygen in Mud Creek, and impacts from water withdrawals.
Suggested Projects to Address Factors of Decline

Lower Tanwax (Hwy 7 to Nisqually River)

  • Reed Canary Grass removal in upper half
  • Large Woody Debris (LWD) addition
  • Riparian Enhancement in selected areas

Upper Tanwax (Hwy 7 to Eatonville Cutoff Road)

  • LWD addition for fish cover
  • Riparian enhancement in selected area
  • Cranberry and Rapjohn lake outlet restoration
  • Reduce negative effects of logging roads

Upper Tanwax (Eatonville Cutoff Road to Tanwax Lake)

  • Channel restoration in Eatonville Cutoff Road section
  • Riparian Enhancement throughout
  • Tanwax Lake Screen installation
  • Eatonville Cutoff Road culvert modification

Tributaries

  • Riparian Enhancement
  • Large Woody Debris addition
  • Assess potential for restoring spawning habitat upstream of Rapjohn Lake
  • Assess Cranberry Lake rearing potential
  • Eliminate non-native species in Rapjohn and Cranberry Lakes
  • Assess potential restoration of other tributaries and lakes
                                       Overall
  • Limit water use/ irrigation especially in summer months
  • Protect lower Tanwax wetlands
  • Assess habitat potential in all lakes, especially Cranberry and Rapjohn Lakes
  • Riparian project locale prioritization will result from riparian assessment