SALT LAKE CITY — Even if you are not a fly fisher, there's reason to be concerned with the loss of salmonfly in Utah rivers and streams. This giant stonefly, a large aquatic insect, is an indicator of water quality. It can only live and thrive in cold, clean, well-oxygenated water. Its dwindling numbers and possible extirpation from river systems could have detrimental effects on other aquatic insect species, fish and birds that share the river environment, and even a river's aesthetic value decrease for people. Provo and Logan rivers Salmonfly extirpation from rivers such as the Logan and sections of the Provo has been studied and documented.