Calleguas MWD Plans for Emergencies with the CaDC

For Dan Drugan, Manager of Resources at Calleguas Municipal Water District, planning for both predicted and unforeseen changes in the District’s water supply is an essential part of the job. In addition to managing the annexations of new territory to the District, water use efficiency, legislative affairs, public outreach, and other programs, Dan and his team are in the process of developing an Imported Water Outage Protocol (IWOP) to manage water access for purveyors during outage events.

One of the biggest risks for the District is the potential for a failure of the Santa Susana Tunnel, the District’s access point for imported water, and a vital link between the people of Ventura County and water from the Metropolitan Water District. Calleguas was concerned that an emergency event (such as a tunnel collapse) could lead to a severe, long-term outage that would require a more robust system for allocating limited stored supplies.

This image (provided by Calleguas) illustrates Calleguas’ main water provision pipeline. Because the majority of the District’s water resources are imported from Northern California, they must travel across the State, to the Metropolitan Water District, and through a single tunnel east of Simi Valley before being distributed to the Calleguas service area. The collapse of this tunnel during an earthquake could effectively eliminate Calleguas’ main source of supply for 3–6 months, leaving more than 650 thousand residents dependent on a limited volume of stored water.

Having worked closely with the Metropolitan Water District of Southern California (another CaDC member agency), Dan knew that the CaDC could use data to optimize allocation methods for an urban water supply agency like Calleguas. Dan reached out to the CaDC and began working towards an allocation system that could conserve the District’s limited stored supplies over the duration of the outage, meet the health and safety water needs of residents, and achieve Calleguas’ goals.

During the project, the CaDC worked closely with Dan to develop a robust allocation model for Calleguas’ IWOP based on stored supplies, past water purchases by purveyors, and local differences in the availability of groundwater. By developing and demystifying the formulas for allocating scarce emergency supplies, the CaDC helped provide Dan with the tools needed to prepare for and respond to an extreme event in an informed, data-driven manner.

For Dan, working with the CaDC highlighted a need to incorporate additional measures to verify purveyor production data and improve communication throughout the District. By establishing a closer connection with water users, Calleguas can feel more confident in the quality of their data and better manage adaptation strategies during outage events.

By refocusing Calleguas’ approach to contingency planning, Dan can extend water resources substantially and limit negative impacts during an interruption to the District’s imported water supply. As a result, Dan and his team can feel confident and encouraged to leverage their data in future contingency and conservation plans.

Work With The CaDC

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Sarah Wingfield

Aspiring water resources analyst and senior studying water management policy at Georgetown University.