The Impacts of Climate Change and Water Supply Management on Fish in the Colorado River
The Colorado River and its major tributaries provide a crucial water supply for more than 40 million people in the American Southwest and in California. This water supply is primarily used in irrigated agriculture but also provides essential drinking water to many large metropolitan areas. Hydropower is also produced at many of the large dams on the river. River flows have declined during the past 15 years due to decreasing watershed runoff associated with a warming climate and ongoing drought. Climate projections indicate a continued decrease in future water availability as runoff continues to decline and temperatures warm. Water-users in the Colorado River basin are concerned about this declining water availability and are negotiating sustainable short- and long-term solutions that attempt to balance consumptive water use with the available supply. These water allocation decisions have the potential to play an important role in determining the future distribution of fish species in the Colorado River basin. These species include endemic and federally-listed species. Numerous studies suggest that streamflow and water temperature have a significant influence on fish populations in the basin. The goal of this project is to identify how fish populations in the Colorado River basin might respond to future changes in water allocation and reservoir storage. Researchers will synthesize the state-of-the-science on how fish communities respond to changes in water temperature, streamflow, and sediment in the basin, and then develop tools to predict how fish populations will respond to different possible temperature and flow conditions and water storage management decisions - such as storing water in Lake Powell in the Upper Basin or Lake Mead in the Lower Basin. Water allocation decisions in the Southwest are set to be renegotiated during the 2020s. As a result, numerous federal and state agencies are currently preparing foundational science to inform these upcoming water supply management decisions. The results of this project will uniquely contribute to this effort by providing water managers with information on alternative water storage scenarios under a changing climate and providing science on how the basin’s ecosystems might respond.