Introduction and Background
Pouhala Marsh is a 70-acre tidal wetland located in Waipahu on the southwestern coastline of the island of O‘ahu, Hawai‘i (see Figures 1-1 and 1-2). The US Fish and Wildlife Service (USFWS) identified Pouhala Marsh as a “wetland of critical concern” for protection and habitat enhancement. The marsh is owned by the State of Hawai‘i (State) and the City and County of Honolulu (City). The State parcel consists of 24 acres and the City parcel contains 86.5 acres. The State Department of Land and Natural Resources (DLNR), Division of Forestry and Wildlife (DOFAW) manages the area as a wildlife sanctuary through a land lease agreement with the City (USFWS 1995).
Figure 1–1. View of Pouhala Marsh Looking Mauka.
Figure 1–2. Location Map of Pouhala Marsh Project Site.
Pouhala Marsh is the largest remaining wetland habitat in the Pearl Harbor complex and was historically considered as a potential landfill site because of the site location across from a City Waste Convenience Station. In the past, the marsh may have been flushed with freshwater during high flows from Waikele Stream into Kapakahi Stream. About an 8-acre area was disturbed by the importation of fill material when the site was being prepared for use as a landfill. This disturbed area currently remains dry under most conditions and is the area targeted for restoration of waterbird habitat ponds.
Development, water pollution, and invasive plants, such as mangrove and pickleweed, have degraded Pouhala Marsh (see Figure 1-3). Currently, efforts are being made to restore the original wetlands through invasive plant removal, refuse removal, native outplantings, fencing to prevent predation, trespassing, and illegal dumping. Wetland restoration would provide a naturally functioning ecosystem with suitable habitat for four endangered Hawaiian waterbirds. Restoration of the site and adjacent Kapakahi Stream would allow for environmental education programs, such as vegetation identification, avian surveys, and water quality studies.
Figure 1–3. View of Pickleweed and Mangrove in Marsh.
Previous studies conducted include an “Environmental and Enhancement Plan for Pouhala Marsh” (Ducks Unlimited 1997) that was prepared for USFWS, DOFAW, and City and presents general wetland restoration recommendations for the site. Oceanit also prepared an Engineering Study (2009) to identify the areas of the wetlands that would be restored for waterbird habitat.