Why is the Bighorn so phenomenal?

A convergence of the most ideal conditions has created a trout habitat that is unrivaled in its consistency and quality. The perfect conditions start with the enormous reservoir, Bighorn Lake. This lake is created by yellowtail dam which was completed in 1967. This reservoir’s geologic composition makes for high alkalinity which in turn allows freshwater invertebrates (a.k.a trout food)  to thrive in impressive and consistent numbers.

Not only does the geologic composition of the dam enhance the habitat for freshwater invertebrates, but the consistent flow from this reservoir wards off events that severely damage non regulated rivers.  Damaging events that happen on unregulated streams do not occur on the Bighorn. Events such as extremely high runoff’s in the spring, high water temperatures in the summer, dangerously low flows in the fall, and anchor ice in the winter.

Yellowtail dam is a hydroelectric dam and many rivers below these dams have a suffering trout habitat due to the flows that fluctuate daily due to power demands. However; the Bighorn below Yellowtail Dam benefits from a large afterbay. This afterbay is a sizeable second reservoir below Yellowtail Dam which is kept low. This second reservoir has its own flow regulating gates so when power demands increase and flows from the reservoir increase there will not be a sudden surge of water through the river, but the afterbay will fill and flows will increase gradually. Many rivers below hydroelectric dams struggle to maintain a healthy trout population due to the sudden changes in flow, but this is not a problem on the Bighorn.
The past five years have had below average snowpack and reservoir levels, but 2005 saw the end of this drought. While many dire predictions were made for the future of the Bighorn, none of them came true. There were several fish counts by the Department of Natural Resources (DNR) that indicated a drop in numbers of fish. However, these fish counts were inaccurate due to the fact that the DNR could not get their boats to the areas of the river that they historically use to count fish. Therefore the fish counts were not comparable to previous year’s fish counts because as any angler knows different stretches of river hold different numbers of fish, and as any scientist Should know data that was collected with different methods, practices, and locations should not be grouped or listed with other dissimilar data.

The fish numbers are not quite at their once estimated 10,000 fish per mile, but the slight drop in numbers of catchable trout per mile has been more than made up for in the great increase in size.

For more information please check our other site: www.BighornRiverFlyFisher.com.