Projects by Discipline / Water Resources Planning and Management

Drought Plan for the City of Boulder, Colorado

Boulder's water supply system serves approximately 110,000 people from surface water supplies obtained from Boulder Creek and the upper Colorado River. While Boulder's Raw Water Master Plan determined that the City's water supply system was highly reliable, it recognized the uncertain nature of streamflows in Colorado and recommended that Boulder develop a drought plan to provide for rational and organized responses to extraordinary droughts.

In 2000, City staff engaged Hydrosphere to develop a plan to effectively: (1) identify impending droughts, (2) respond with appropriate supply and demand management strategies, and (3) communicate with the public. The Drought Plan was based on a sophisticated examination of the climatic and hydrologic aspects of droughts that could affect Boulder's water supply system. Historical climate and streamflow records were augmented using tree ring data, which allowed for reconstruction of climate and streamflows as far back as 1703.

Drought recognition triggers were tailored to regional climate and snowmelt-driven hydrology. Drought response strategies were tailored to the specifics of Boulder's water supply system and water use patterns. Four levels of drought response were developed to correspond to increasing severities of drought. Each response level included a range of supply management strategies and indoor and outdoor water use reduction goals. These strategies were developed with input from a wide range of water customer and public interests.

A computer model of Boulder's water supply system was used to test the effectiveness of various combinations of drought recognition triggers and drought response strategies against 300 years of historical and tree ring-based hydrology.

The combination of drought recognition triggers and drought response strategies was also tested against the city's water utility managers' decision-making preferences to incorporate human dimensions of risk-aversion behavior.

Extraordinary drought conditions were unfolding as Boulder's Drought Plan was being completed, culminating with record-low streamflow conditions in 2002. The Drought Plan allowed Boulder to respond quickly and effectively to these impending drought conditions.