Sack is a public utility dam located on the San Joaquin River in Madera, California, with a primary purpose of flood risk reduction. Built in 1946, this buttress-type dam stands at 9 feet high and spans 100 feet in length, providing a storage capacity of 165 acre-feet. Despite its low hazard potential, Sack is state-regulated and subject to regular inspections to ensure its satisfactory condition.

Being a critical infrastructure for water management in the region, Sack serves multiple purposes including flood risk reduction, hydroelectric power generation, irrigation, and water supply. The dam is under the jurisdiction of the California Department of Water Resources and falls under the oversight of the Safety of Dams regulatory agency. With a surface area of 36.7 acres, Sack plays a crucial role in managing the water resources of the San Joaquin River watershed.

As an essential component of the water resource system in California, Sack contributes to the overall water management efforts in the state. With its strategic location and design, Sack not only helps in mitigating flood risks but also supports various water-related activities, highlighting its significance in ensuring water security and sustainability in the region.