Waiawa Watershed Groundwater Recharge

Oahu is the most urban island in the state of Hawaii, supporting close to 1 million residents and almost 6 million visitors per year. The majority of domestic potable water in Hawaii comes from groundwater sources: aquifers that are recharged by native forests that are super-efficient at capturing and storing rainfall. The irreplaceable high mountain Hawaiian forest in the Waiawa watershed absorbs mist and rain, collecting and purifying fresh water that supplies the island, but it is under threat from damage caused by non-native and invasive feral pigs.  Left unchecked, these animals will significantly degrade the native ecosystem through browsing, digging and rooting. This destroys native vegetation and leaves openings for invasive plants to grow, soaking up water before it can recharge critical aquifers.

The Waiawa project is a collaboration among various state, county, and private partners of the Ko’olau Mountains Watershed Partnership to protect 1,400 acres of intact native forest in this critical water recharge area. The project focuses on the first step of long-term watershed protection: fencing. Fences are the best way to protect watershed forests in Hawaii by eliminating the damage from non-native feral pigs. The longer the forest is left unprotected, the costlier and more difficult it will be to restore.

The 6.6-mile fence at Waiawa will be made from highly durable galvanized steel panels, with an estimated lifetime of over 35 years. 9,600 feet of fence materials have been airlifted to the summit area and are currently staged along the proposed fence line. Additional funding is needed to complete the project costs involved in the labor-intensive installation in this remote – but hydrologically critical – area on the island. This project will preserve the region’s function as one of the most important areas for ground water recharge – protecting approximately 11 million gallons of water per day.

* Project restores natural hydrologic conditions to facilitate improved capture and infiltration of surface water and groundwater recharge


Honoulu County, HI

Start Up Date:


Project Benefits:

Environmental Flow Restoration & Protection

Green Infrastructure Investment

Groundwater Conservation & Replenishment

Securing Water for Communities & Food Production

Water Quality Improvement

Wildlife & Habitat Protection

Project Type:

Restoration of Natural Hydrology *


Funding Needed