american samoa - University of Hawaii at Manoa Botany Department

TABLE 4-5COMPARATIVE EVALUATIONWETLAND RESTORATION AND ENHANCEMENT OPPORTUNITIESAOA WETLANDOptionProjectCostResidentialLand UsesSubsistenceAgricultureFish &InvertebrateHabitatWetlandVegetationHabitatStormwaterDetentionFloodHazards &PropertyDamage1 SC SC MC LB SB LB LC2 SC MC LC SB SB NBC MC3 MC MC LC SB SB LB SC4 LC LC NBC SB SB NBC LBNotes:Potential project benefits were rated by PPC as follows:SB Significant project benefitsLC Limited undesirable consequencesMB Moderate project benefitsMC Moderate undesirable consequencesLBNBCLimited project benefitsNo anticipated project benefits orundesirable consequencesSource: Pedersen Planning Consultants, 2000SCSignificant undesirable project impactsThe biggest risk associated with Option 4 is that frequent storm waves entering Aoa Bay willoccasionally transport sand that will partially or completely block future tidal exchange. In theabsence of regular tidal exchange, a significant change in the water quality of the estuary canadversely impact the health of mangroves. However, the same risk is associated with Option 2.While past encroachment has been made on the west side of the Aoa wetland, the potentialdevelopment costs associated with the implementation of options 1 and 3 appear unattractive inlight of limited to moderate benefits. Limited to moderate to significant disruptions in existingresidential land uses and subsistence agriculture would be generated by the development ofoptions 1,2 or 3. Such change would likely annoy most residents who would be directlyimpacted by the project. Further, there is a limited to moderate probability that options 1, 2 or3 would occasionally generate some flooding problems in the adjoining residential area.Significant benefits associated with the planting of red and oriental mangroves are anticipatedfrom options 2 and 3. The establishment of mangroves would desirably establish a coastalswamp forest and, at the same time, create new habitat for fish and invertebrates.Recommended Option and Estimated Project CostThe restoration of the mangrove forest immediately upstream of the Puna Stream and TapuaStream mouths (Option 4) is recommended for implementation. This wetland restorationproject is recommended because the project can provide multiple benefits to the Aoa wetlandand Aoa Village for considerably lower project costs.The costs associated with the restoration of the mangrove forest would primary be associatedwith the initial clearing of the Puna Stream mouth, as well as the subsequent collection andplanting of mangrove, fau, and milo tree cuttings by the ASCC Land Grant Program. Theseestimated cost associated with the initial clearing of the Puna Stream mouth would beapproximately $3,056 (Table 4-6). The planting of mangrove and riparian trees would requirean expenditure of approximately $2,721 (Table 4-7). Consequently, the total project wouldcost an estimated $5,777.American Samoa Wetland/Stream Restoration and Enhancement PlanFebruary 2001, Aoa Wetland, Page 4-14