A bridge off Peahi Road above the Kaupakalua Reservoir and Dam (Kehaulani Cerizo/The Maui News Via AP)

The State of Hawaii has not shown up on this blog before, but last week’s dam breach and evacuations have earned it a coveted spot.

On March 8, the Kaupakalua Dam in Maui overtopped, prompting evacuation orders downstream. The 138-year-old earthen dam overtopped during heavy rains and is scheduled to be removed this summer.

According to the state’s Department of Land and Natural Resources, the dam’s owner was sent a notice of deficiency in early 2020 that set a schedule for addressing its deficiencies, and in October the owner submitted an application to remove it entirely. In February 2021, the Department issued a formal Notice of Violation for failing to install a real-time reservoir water level gauge with readings accessible on the internet. This is required by state statutes. Apparently, the previous gauge was stolen in 2018.

Because of the deficiencies in the dam, the Department has required that the reservoir, which holds up to 68 million gallons of water, remain empty. This was apparently not possible during storm events like the one experienced last week.

According to the Department, 126 of Hawaii’s 130 state-regulated dams are classified as high or significant hazard potential due to their proximity to people and structures downstream. Most have Emergency Action Plans on file with the Department, and last week’s public alerts and evacuations were in line with that plan for this particular dam.

It appears that emergency planning helped to reduce the risk of the Kaupakalua Dam’s overtopping; such planning is a critical piece of reducing the risks associated with aging infrastructure, and California’s Central Valley is not a stranger to emergency planning in the context of flood safety. The Central Valley has embarked on a $1B plus effort to rehabilitate levees over the past couple of decades, coupled with substantial emergency planning efforts that we saw play out in 2017 with the Oroville Dam and spillway.