WTI, in a partnership with Montana Department of Fish, Wildlife and Parks, is monitoring a newly constructed irrigation diversion on the Shields River in Montana. The structure was designed to improve water withdrawal and to act as an upstream fish barrier to protect native Yellowstone cutthroat trout from non-native trout species. An important product from this research will be an evaluation of existing hydraulic models used to design diversion structures and fish barriers, and the development of a preferred modeling approach for future diversion and fish barrier design.