HAWAII RESERVOIR REPORT

Last Updated: December 19, 2025

In a comprehensive overview of the nation's dams and reservoirs, the latest observations reveal a diverse array of storage levels, with some water bodies experiencing surpluses and others facing drought-like conditions. Notably, Lake Mead in Nevada and Lake Powell in Arizona are significantly below their average storage levels, reflecting the ongoing water scarcity challenges in the southwestern United States. Conversely, reservoirs such as Lake Almanor and New Bullards Bar in California are reporting storage levels above average, indicating a surplus that benefits local water supply and ecosystem management.

Diving deeper into specifics, Colorado's Blue Mesa Reservoir and New Mexico's Elephant Butte Reservoir are experiencing low storage levels compared to historical averages, underscoring the impact of prolonged drought and climate variability in these regions. On the other hand, reservoirs like California's Lake Almanor and New Bullards Bar have seen an increase in storage, likely influenced by recent precipitation events that have somewhat alleviated the water stress in their respective watersheds. These insights reflect the complex and dynamic nature of water resource management, as hydrologists and researchers work to balance ecological needs with human consumption, agricultural demands, and the challenges posed by changing climatic conditions.

Hawaii has several reservoirs and dams that provide water for irrigation, hydroelectric power generation, and domestic use. The largest reservoirs in the state are Wahiawa and Kealia, which are located on the islands of Oahu and Kauai, respectively. Both reservoirs are fed by streams that originate in the mountainous regions of the islands, and they can hold up to tens of billions of gallons of water. Snowpack is not a significant factor in Hawaii's hydrology, as the state is located in a tropical region and does not experience significant snowfall. Instead, rainfall is the primary source of water for the reservoirs and rivers in Hawaii. Drought conditions can be a concern in Hawaii, particularly during El Niño years when rainfall is reduced. In 2016, Hawaii experienced a severe drought that affected agricultural production and led to water restrictions. Overall, the hydrology of Hawaii is closely tied to its mountainous topography and tropical climate, with rainfall and streamflow playing a critical role in the availability of water for the state's residents and industries.

Hawaii has several reservoirs and dams that provide water for irrigation, hydroelectric power generation, and domestic use. The largest reservoirs in the state are Wahiawa and Kealia, which are located on the islands of Oahu and Kauai, respectively. Both reservoirs are fed by streams that originate in the mountainous regions of the islands, and they can hold up to tens of billions of gallons of water.

Snowpack is not a significant factor in Hawaii's hydrology, as the state is located in a tropical region and does not experience significant snowfall. Instead, rainfall is the primary source of water for the reservoirs and rivers in Hawaii.

Drought conditions can be a concern in Hawaii, particularly during El Niño years when rainfall is reduced. In 2016, Hawaii experienced a severe drought that affected agricultural production and led to water restrictions.

Overall, the hydrology of Hawaii is closely tied to its mountainous topography and tropical climate, with rainfall and streamflow playing a critical role in the availability of water for the state's residents and industries.