A MULTI-TRACER APPROACH FOR EVALUATING THE TRANSPORT OF WHIRLING DISEASE TO MAMMOTH CREEK FISH HATCHERY SPRINGS, UTAH

The Utah Division of Wildlife Resources operates 10 fish hatcheries in Utah that derive water from large springs and has been concerned about the vulnerability of these hatcheries to whirling disease, caused by the microscopic parasite Myxobolus cerebralis. Whirling disease is typically transmitted from one water body to another by birds or fisherman. However, the triactinomyxon spores (TAMs) that cause the disease can potentially migrate along underground pathways in areas where aquifer permeability is high, such as in karstic and volcanic terranes, and the movement of ground water is sufficiently rapid to allow viable passage of the spores. Mammoth Creek fish hatchery in southwestern Utah tested positive for whirling disease in 2002. Because adjacent Mammoth Creek also tested positive, the U.S. Geological Survey began a study to evaluate potential hydrologic connections and determine ground-water travel times between the creek and the hatchery springs.

Fluorescent dye-tracer studies indicate that water lost through the channel of Mammoth Creek, about 3,000 feet west of the hatchery, discharges from the west and east hatchery springs. Ground-water travel time from Mammoth Creek to the springs was about 8 hours and time to peak concentration occurred about 8 hours later. Ground-water travel time between the creek and the hatchery springs is well within the 2-week timeframe of viability of whirling disease spores; however, results of studies using soil bacteria (Acidovorax) and club moss (Lycopodium) spores as surrogate particle tracers to simulate the size (10 to 100 microns) of the parasite, indicate that the potential for transport of the parasite through the basalt aquifer may be low. Substantial losses of the particle tracers occurred during infiltration through the streambed sediments and during transport. Bacteria concentrations in water samples from the springs were generally below reporting limits and club moss spores were recovered from only a few samples. However, peak concentrations of the particle tracers in water from the east hatchery spring coincided with peak dye recovery, indicating likely breakthrough of these particles.