BWS Initiatives > Watershed Partnerships

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Rainfall is Oahu's primary water resource for streams and groundwater supply. Ideally, within a healthy watershed, there are multi-layered canopy forests that capture and retain rainfall, allowing it to seep into the underground aquifers. On Oahu, these groundwater aquifers are our primary source of drinking water constituting almost 100 percent of the municipal water supply. If forests and watersheds become degraded, the amount of vegetation holding the soil is reduced, less rainfall is captured and there is more chance of soil erosion and landslides, which can then lead to polluted waterways and reduced groundwater recharge. Healthy watersheds sustain the quality and quantity of Oahu's streams and groundwater supplies and we must care, protect and preserve these areas for future generations.

Only a portion of the prime watershed areas on Oahu are owned by the Board of Water Supply. There are many landowners, both public and private, and we all need to work together to enhance the health of our watersheds. Most of the prime watershed lands are protected by State Conservation Districts, which were established many decades ago. But recharge lands also consist of urban and agricultural zoned lands, and therefore, awareness, education, and best management practices in these areas are very important.

One of the primary concerns is to protect the watersheds to ensure there is enough groundwater recharge of drinking water for the people of Oahu.


One of the ways the BWS is protecting these important areas is by entering into watershed partnerships that protect and enhance our watersheds through resource management. Watershed partnerships come in all shapes and forms ranging from studies to Memorandum of Understandings (MOU) to actual on the ground projects. The BWS has partnered with local and federal government agencies, private landowners, schools, and community groups. Watershed partnerships in Hawaii had their start in East Maui in 1991 to control pigs and goats that were destroying the plant life and ruining watershed lands in that district.

BWS Watershed Partnerships and Projects


nature conservancy partnership

ala wai watershed association koolauloa ahupuaa

Watersheds encompass lands from the mountain ranges to the coral reefs. This is the traditional Hawaiian land management system called the ahupuaa. And while primary recharge areas consist of our forested lands, we must also focus on the urban and agricultural lands lower in the watershed. Land uses and management practices in these areas also impact our groundwater aquifers. Many BWS main pumping stations, for example, are located just mauka of King Street, Moanalua Road, and Farrington Highway. Residents should understand that if they live in the valleys, ridges, and in the Central Oahu areas, their practices impact the quality and quantity of our aquifers and streams.