I am writing to clarify and dispute a recent article regarding the rotenone treatments on the Fremont River in Wayne County. I disagree with the statement "the stoneflies eaten by trout apparently will not recover for years, if ever."
First, adult stoneflies are winged insects quite capable of recognizing the Fremont River from adjacent streams or from upstream reaches. Second, the stoneflies and other aquatic insects can access microhabitats under the rocks and mud to escape the rotenone during the treatment. Third, the concentration of rotenone used was designed to kill trout, not all aquatic life.There is a monitoring program spearheaded by Richard Denton of the Utah Bureau of Water Pollution Control that has been assessing aquatic insect diversity and abundance in the Fremont River for years. In addition to the sites monitored in Bicknell (Egan Bridge) and in Capitol Reef (Hickman Bridge), the division of Wildlife Resources has been funding additional sampling at two other points on the river.
Results from the Hickman Bridge site this spring indicated that the biomass or weight of aquatic insects had actually increased. The Bicknell site biomass had dropped during this same period, indicating that the treatment had affected the insect populations but that they were still present. Stoneflies were also present.
Sampling this spring in Capitol Reef also showed that there were still abundant populations of nongame fish. Rotenone treatments this fall also showed that even in the treated stretches, nongame fish (Utah and leatherside chubs, mottled sculpin, speckled dace, redside shiner) had survived last year's treatment.
Regarding a discharge permit (Clean Water Act), rotenone is a registered chemical with the Environmental Protection Agency, approved for aquatic use Therefore, a permit was not required for the treatment.
Treatments this fall will hopefully control a serious threat to wild fish (whirling disease) and also provide an opportunity to reintroduce some native cutthroat into upper reaches of the Fremont drainage.