Over the last 100 years, the cumulative impact of decades of unrestricted cattle grazing (finally removed in 2001), excessive sedimentation, riparian degradation, invasive species (muskrats), noxious weeds, and over fishing decimated the Hat Creek Wild Trout Area.
- Today, more than 95% of the riparian corridor in the upper WTA—mainstem and tributaries—lacks adequate vegetation and structure.
- 60,000 cubic yards of excessive sediment blankets the river bottom disrupting native aquatic plant cycles (likely originated from collapsing lava tubes).
- Invasive muskrats continue to burrow into streambanks causing bank instability and collapse.
- Existing recreation trails and parking areas, which are not maintained, continue to deteriorate and erode into the river.
- According to the CADFW, trout population estimates over the last 20 years have ranged from as high as 6,500 per mile in 1973 to less than 1,000 in 2007 (DFG, 2010).
The Hat Creek fishery declined in the late 1920’s and early 1930’s following many years of thriving trout populations. Declines in trout in the 1960’s may have been caused by dam construction at Lake Britton and associated increases in warm water fishes in Hat Creek (Deinstadt and Berry, 1999).
Decades of active restoration efforts began with the construction of a fish barrier in 1968 followed by chemical treatment and re-stocking (Deinstadt and Berry, 1999). Following the treatment and restocking, the fishery improved throughout the 1970’s, but declined again in the late 1980’s, ostensibly due to a large body of sediment that moved through the WTA over a 20 year period.
This sediment likely disrupted aquatic vegetation cycles and caused decreases in insect and fish productivity (HatRAC, 2013).