Spencer 1990). Fire ash from the fire may increase aquatic nutrient levels 

 by 2-3 times present levels the first year after fire and decline over time. 

 Concentrations of both phosphorus and nitrogen are expected to increase 

 in streams draining severe burned areas. Many published studies show 

 elevated levels of these nutrients immediately following wildfires and 

 during subsequent spring runoff (Spencer and Hauer 1990, Salminen and 

 Beschta 1991). 



The risk of sediment deposition and increased nutrient loads to streams is 

 expected to decrease by 2005 as ground cover vegetation continues to 

 recover. Vegetative regrowth is expected to help reduce additional 

 delivery from summer and fall rain events. This is due to the natural 

 buffering and sediment trapping that occurs along vegetated surfaces 

 versus bare soils. 



Another indirect impact to water quality is increased summer maximum 

 stream temperatures. Within the Deer and Thompson Creek watersheds, 

 most streamside trees and shrubs were consumed in those stream reaches 

 affected by stand replacement fire. Streams with mixed burned severity 

 and partial shade on bank-edges and deeper stream pools should have less 

 temperature affect. 



There will be substantial inputs of large woody material into creeks as 

 burned trees continue to fall across streams. This woody material input 

 may create short-term bank scour by deflecting flows but will have a long- 

 term effect of stabilizing the channel. Large woody material creates 

 sediment storage and reduces the erosive power of streams. This input 

 will also benefit fish habitat over the long term. Due to the stand 

 replacement nature of the fire on Deer Creek and segments of Thompson 

 Creek, the large woody material left by the fire will be the only 

 recruitment of large woody debris for 80 to 100 years. 



3.2.1.1.3 Water Quantity 



There is extensive literature and observations that water yield and stream 

 flows will increase following fire. Increased water yield is a function of 

 vegetative cover loss, reduced evapo-transpiration, snowmelt 

 modification, and bum area severity in a watershed. Summer storms 

 present the highest risk of flood damage. During post-fire survey efforts 

 there was concern that hydrophobic (water repellant) soils may occur that 

 would limit water infiltration and further increase surface runoff. 

 Hydrophobic soils in the Fish Creek watershed are limited in extent 

 following the fires (refer to soils section) and are not expected to affect 

 runoff as greatly as initially modeled following the fires. Extensive 

 ground surveys found only low to moderate soil bum severity. The soil 

 hydrophobicity observed was limited in area and degree and more a 

 function of soil drying by the fire, rather than fire altering the soils. This 



Fish Creek Salvage Environmental Assessment 3-8 



