Water Resources Research Act Program

Principal Investigators: Vicki Watson, Vicki Watson

Abstract: In Montana and other parts of the arid west, diversion of water can create environmental challenges for downstream fish populations. Many diversions take place over the summer months, primarily for crop irrigation. Some are year-round, including the fall and winter months when instream flows are naturally reduced. The latter can have particular implications for fish that spawn in the autumn, such as the brown trout, by reducing water levels with a potentially critical effect on environmental parameters essential to trout egg survival. This two-year study will examine the effects of an overwinter diversion on brown trout egg redds in Warm Springs Creek, Montana. Three years ago, a local industry began a year-round diversion of water from Warm Springs Creek. The diversion of water noticeably lowers stage and streamflow levels in the spawning areas of the creek during the fall and winter months, which are critical to brown trout spawning and egg development. This fall and winter, 2005-2006, there will not be an overwinter diversion of water. Next winter, this diversion will resume.