Keʻehi Lagoon Mangrove Removal

Mangroves are a fast-proliferating form of vegetation in the intertidal zones of tropical estuaries, lagoons, and sheltered shorelines all around the world. Mangroves, when occurring naturally, can perform positive ecological functions such as water quality improvement and sediment stabilization, they can also have unintended negative impacts.

Mangroves did not exist in Hawaiʻi before the 1900s.  They were introduced on Molokaʻi in 1902 for the purpose of stabilizing coastal mud flats but are now are well established across all major Hawaiian Islands. In many cases, mangroves negatively impact the local ecosystem: providing shelter for other invasive species inadvertently or purposely introduced to Hawaiʻi and reducing natural habitat size and quality for native species, such as the Hawaiian Stilt bird.  Mangroves can also negatively impact local drainage from above the tidal zone into the estuaries or lagoons.

Invasive Mangrove trees, proliferating in the Keʻehi Lagoon, serve as a habitat for several non-native bird species, which have the potential to cause bird strikes for planes during takeoff and landing at the nearby Daniel K. Inouye International Airport. Bird strikes can be extremely dangerous, so to prioritize safety, the Department of Transportation Airports Division is overseeing the removal of the invasive mangrove trees.

Oceanit is providing construction management, environmental consulting, and coastal engineering services for this project. Responsibilities include project documentation; tracking schedule, budget, and compliance; site inspections; and safety oversight. As many native endangered species also live in the lagoon, Oceanit also implements regular surveys of endangered species to ensure that only non-native trees and birds are being removed from the location.

Several challenges have arisen throughout the course of this project including the COVID-19 pandemic. In response to the pandemic, Oceanit quickly adapted inspections and implemented a set of protocols to ensure maximal safety. Additionally, five of the six project areas are located on islets in the lagoon, and the inter-tidal nature of the job site requires work to be executed around the changing tide tables.

The project is still on track to be completed on time in January 2022.