HAWAII RESERVOIR REPORT

Last Updated: February 5, 2026

The United States' network of dams and reservoirs plays a crucial role in water storage, flood control, hydroelectric power, and recreation. Observations from the latest dataset reveal a complex picture of varying storage levels across the nation, with some reservoirs experiencing surpluses while others face drought conditions.

In the Northeast, Lake Winnipesaukee at Weirs Beach, New Hampshire, is below its average storage level, indicative of potential water shortages if the trend continues. Similarly, in the West, concerns rise as major reservoirs such as Lake Powell in Arizona and Lake Mead in Nevada report significantly lower storage levels than their historical averages, reflecting prolonged drought conditions and increased water demand. Conversely, reservoirs like Lake San Antonio in California and Lake McConaughy in Nebraska show higher than average storage, possibly due to recent heavy precipitation, efficient water management, or reduced local demand.

The variability in reservoir levels can often be linked to regional climatic conditions, such as snowpack levels and river flows. For instance, the higher storage in Colorado's Vega Reservoir may correlate with increased snowmelt, while the low levels in New Mexico's Elephant Butte Reservoir could be attributed to scarce precipitation and high evaporation rates. These disparities underscore the challenges of managing water resources amid changing climate patterns and emphasize the need for adaptive water management strategies to ensure sustainable water availability for all uses.

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.