Star Valley residents and anglers are confronting a new wildlife health crisis on the Salt River. Wyoming Game and Fish biologist Darren Rhea reported that hundreds of mountain whitefish have been found dead this summer, the first confirmed case of proliferative kidney disease (PKD) in the river.
Low water and warm temperatures set the stage
Rhea, the Jackson Region fisheries supervisor, noted that the Salt River has been flowing at roughly half its normal volume for months, forcing him to wade during a late‑August float. “I don’t ever remember floating it this low,” he said. The reduced flow, combined with higher water temperatures, creates the perfect environment for the microscopic parasite Tetracapsuloides bryosalmonae, which causes PKD.
PKD has devastated whitefish populations in the Snake River’s South Fork and the Yellowstone River in 2016. Laboratory testing this week confirmed the same pathogen is responsible for the current die‑off on the Salt River.
Impact on the fishery and future monitoring
Whitefish are considered a bellwether for stream health because they require cold, clear water. Rhea estimates that the observed hundreds of dead fish likely represent thousands overall. “We have historic trend monitoring data for trout and whitefish, so we’ll know the full impact next year,” he said.
The Wyoming Game and Fish Department has already asked anglers to avoid catch‑and‑release fishing between noon and sunset from July 29 through Aug. 14, citing warm water conditions in the adjacent Snake River.
Long‑standing water‑quality challenges
The Salt River has also struggled with an E. coli impairment for years. A 2015 Total Maximum Daily Load (TMDL) plan aimed to cut fecal bacteria by 60%, but recent statements from Wyoming Department of Environmental Quality lead analyst Ron Steg indicate concentrations have not significantly improved.
Livestock grazing remains a major source of contamination, with up to 95% of E. coli attributed to the 32,000 sheep and 10,000 cattle that graze in the watershed.
Looking ahead
Researchers at the University of Idaho are studying the disease to better understand why PKD outbreaks occur under specific temperature and flow conditions. Wyoming fisheries managers will continue to track the whitefish and trout populations, using the Salt River’s extensive monitoring data to assess long‑term effects.
Local stakeholders, including the Salt River Watershed Group, are working to improve water quality and habitat conditions, but the current PKD outbreak underscores the vulnerability of the river’s ecosystem when water resources are stressed.
Original reporting: Oil City News (Casper WY) — read the source article.
