By ,

Rajagopalan, BalajiÌý1Ìý;ÌýNowak, KennethÌý2Ìý;ÌýPrairie, JamesÌý3Ìý;ÌýHoerling, Martin4Ìý;ÌýHarding, BenjaminÌý5Ìý;ÌýBarsugli, JosephÌý6Ìý;ÌýRay, AndreaÌý7Ìý;ÌýUdall, BradleyÌý8

2ÌýPresenting Author

1ÌýDepartment of Civil Environmental and Architectural Engineering, University of Colorado, Â鶹¹ÙÍø, CO 80309 USA
2ÌýDepartment of Civil Environmental and Architectural Engineering, University of Colorado, Â鶹¹ÙÍø, CO 80309 USA
3ÌýBureau of Reclamation, University of Colorado, Â鶹¹ÙÍø, CO 80309 USA
4ÌýNOAA Earth System Research Laboratory, Â鶹¹ÙÍø, CO 80305 USA
5ÌýAMEC Earth & Environmental, Inc., Â鶹¹ÙÍø, CO 80302 USA
6ÌýNOAA Earth System Research Laboratory, Â鶹¹ÙÍø, CO 80305 USA
7ÌýNOAA Earth System Research Laboratory, Â鶹¹ÙÍø, CO 80305 USA
8ÌýCooperative Institute for Research in Environmental Sciences, University of Colorado, Â鶹¹ÙÍø, CO 80309 USA

With climate change looming, continued population growth, and the likelihood of multi-year droughts, the future reliability of Colorado River water supply is in question. We assess the risk to Colorado River water supply for the next 50 years (2008-2057). Under current practices in the absence of climate change we find a 5% risk of reservoir depletion through 2026 increasing to 9% by 2057, demonstrating resilience to demand growth and natural climate variability. A 20% reduction in Colorado River average flow due to climate change by 2057, increases risk through 2026 to less than 12%, but greatly increases risk to 52% in 2057. However, we find management alternatives can greatly reduce risk – under aggressive management the risk reduces to 32%. A lower rate of climate change induced flow reduction, demand adaptation and aggressive management can further reduce the risk to around 10% - suggesting substantial flexibility in existing management could mitigate the increased risk.