River-Lab

The headwaters of Blind Horse Creek originate in the highest point of the Trinity Alps. It is a tributary to the South Fork Salmon River located in the Klamath National Forest. In the summer of 2021, wildfires burned 114,433 acres in the Salmon River watershed. For this subbasin of the greater Klamath River Basin (KRB), this was the greatest number of acres burned in a single year on record. The River Complex was a large-scale, high-severity wildfire that burned all around the South Fork Salmon River leaving steep drainages barren of any vegetation. The following year, 2022, summer rains brought 1-2 inches of rainfall to the landscape and triggered a debris flow within the Blind Horse Creek drainage. Although initially a major disturbance to the river system, over time the new sediment moving through the system deposited behind Large Woody Debris, boulders, and eddies, creating new beaches and sand bars distributed throughout the river. The delivery of fine sediments to streams post-fire can initially degrade salmonid-rearing habitat, however, these new sand deposits have the potential to be viable rearing habitats for other native fish species, such as Pacific Lamprey (Entosphenus tridentatus), and their larval stage, ammocoetes. Having a baseline of how the sediment is distributed throughout the system can indicate habitat change and distribution for these evolutionarily primitive and culturally significant fishes. Our work documents the current distribution of sediment and identifies potential lamprey rearing habitat through cross-sectional elevation surveys, facies map documentation, and the measurement of viable sand bars. The description of current site conditions after a large disturbance can help inform restoration strategies for the river and perpetuation of habitat for sensitive species such as salmonids and Pacific lamprey.