Water has been moved from the Colorado Basin to the Great Basin for the last 100 years to meet central Utah’s water needs. Once in Utah, the water was transferred from Strawberry Reservoir to urban areas of Utah County through previously existing rivers and streams. At the onset of this endeavor, the headwater tributary, which likely was intermittent with flows that rarely exceeded 10-15 cubic feet of water per second (cfs), was exposed to flows of 400 cfs. These excessive flows resulted in drastically altered erosion and sedimentation rates as well as severely altered natural flow regimes that ramified through the ecosystem. Since the onset of the project, a series of tunnels have been constructed that would allow the Bureau of Reclamation to reduce flows entering the streams and rivers. I am a part of an interdisciplinary team evaluating the effects of altered flow regimes on Sixth Water Creek and Diamond Fork River, UT, tributaries of Spanish Fork River, UT. Collectively, our research team is evaluating the effect of flow on temperature, geomorphology, biology, and ecosystem metabolism. Our laboratory’s efforts focus on the effect of altered habitat, temperature, and prey base on the production potential of the fish community and the quality of the fisheries.
Our team has the goal of identifying optimal flows to meet stakeholder (water-users, anglers, managers, and conservationists) goals. From a fish-centric perspective, stakeholders have identified two goals for the future of this watershed:
- To develop and maintain and Bonneville cutthroat trout fishery in the higher elevation reaches of Sixth Water Creek
- To maintain the unique mid-sized brown trout angling opportunities provided by Lower Diamond Fork River
We surveyed the watershed under experimentally reduced flows in 2016 and preliminary analyses have indicated that reduced flows (i.e., 18 cfs in Sixth Water Creek) are 1) associated with the highest Bonneville cutthroat trout recruitment on record (Figure 1, above) without 2) compromising the brown trout fishery (Figure 2, below).