american samoa - University of Hawaii at Manoa Botany Department

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Two ASPA groundwater wells (wells 151 and 152) and several residences are situated betweenthe east margin of the Aoa wetland and the primary roadway to Aoa Village. At least twovehicular trails along the east side of the wetland provide access from the primary roadway tolocal residences.Residential and subsistence agricultural activitiesalso are located on the west side of the wetland.One home near the mouth of Vaitolu Streamcontains a small man-made pool that is fed via afresh-water spring. The presence of Macrobrachiumlar, poeciliads, and prawn traps in thepool indicate that, at least, one family is usingaquatic organisms as a food resource.WETLAND RESTORATION AND ENHANCEMENT STRATEGIESGeneralThere are four potential opportunities for the restoration and enhancement of Aoa wetland.Three of these opportunities were originally identified by Biosystems Analysis, Inc. in theComprehensive Wetlands Management Plan. A fourth option identified by BiosystemsAnalysis was refined by PPC based upon discussions with representatives of the ASCC LandGrant Program. The scope of these restoration and enhancement opportunities and relatedimplementation strategies are presented in the following paragraphs.The potential benefits and impacts derived from the implementation of each strategy aresubsequently compared and evaluated. This analysis provides the basis for the selection of arecommended restoration or enhancement strategy.Preliminary cost estimates are presented for the implementation of the recommended strategy.Long-term monitoring and site maintenance requirements associated with the recommendedstrategy are also identified.Alternate Opportunities and StrategiesOption 1: Expand the West Boundary of the WetlandOption 1 would expand the west boundary of the Aoa wetland and establish a stream channelthrough the middle of a 100 to 200-foot wide strip of land. Through considerable excavationand grading along the middle reach of Vaitolu Stream, the new stream channel would be fedfrom surface flow via Vaitolu Stream.Option 2: Widen the Mouth of Vaitolu StreamOption 2 would widen the mouth of Vaitolu Stream and extend the restored area roughly 250feet inland of the stream mouth. Excavation would be required to gain tidal flow from thestream mouth, as well as accommodate the construction of a new 36-inch diameter culvert andnew bridge over the existing shoreline vehicular trail.Option 3: Establish a Fresh-Water Wetland Along Vaitolu Stream ChannelOption 3 would be similar to Option 2 with the widening of Vaitolu Stream. The primaryexception would be that tidal exchange from the nearshore waters would intentionally beblocked to establish a fresh-water wetland along the stream channel.American Samoa Wetland/Stream Restoration and Enhancement PlanFebruary 2001, Aoa Wetland, Page 4-11
Option 4: Restore Mangrove Forest Upstream of the Puna Stream and Tapua Stream MouthsRestoration of the mangrove forest immediately upstream of the Puna Stream and TapuaStream mouths (Figure 4-3) would initially require the clearing of sand, vegetation and solidwaste material that presently blocks tidal exchange via the Puna Stream mouth. This effort willrequire clearing within the existing 12-foot wide x 3.5-foot high culvert upstream of the Punastream mouth, as well as on the upstream and downstream sides of the culvert. A backhoe willalso be needed to facilitate the excavation of sand and heavier solid waste material.Machetes and weed-eaters can be used to mow vegetation upstream and downstream of theTapua Stream and Puna Stream culverts. Lighter, solid waste material should be burned.Excess material should be bagged in plastic garbage bags; arrangements should be made withASPA for a special collection of this material.In November 1999, the double culverts underneath the shoreline vehicular trail were clear ofany obstructions that might impede tidal exchange via the adjoining Tapua Stream mouth.Consequently, no clearing is anticipated at the Tapua Stream mouth or the upstream culvertunderneath the shoreline trail.The second task of the restoration effort would involve the planting of red and orientalmangrove trees within and along the margins of the estuary in the fresh-water swamp, as wellas the banks of Tapua Stream and Puna Stream between the culverts and the fresh-waterswamp.Roughly 50 red mangroves should be planted within the streambed because this plant readilycolonizes in estuaries and can sustain itself in waters with somewhat higher salt waterconcentrations (Stemmermann, 1981). Propagules or seedlings should be plantedapproximately three feet apart. Within three years, the mangroves should be thinned to about asix-foot spacing between each plant (Steele, 1999).In contrast, 25 oriental mangroves would more desirably be planted along the stream banksbecause it is less tolerant of salt water. Propagules or seedlings should again be spacedapproximately three feet apart. Plants should be thinned to a spacing of six feet within aboutthree years.Other smaller trees, shrubs and grasses that can survive successfully in a brackish, estuarineenvironment would supplement mangrove plantings. In-stream plantings of red mangrovewithin the estuary, for example, would be supplemented with approximately 25 fao trees (beachhibiscus). Along stream banks, the planting of oriental mangrove trees would be interspersedwith about 25 milo trees (Thesepesia populnea). Salt resistant grasses would be planted in theestuary to increase the amount of available habitat of fish upstream of the Tapua Stream andPuna Stream outlets.Comparative Benefits and ImpactsPPC’s evaluation of the four alternate restoration and enhancement strategies is summarized inTable 4-5. Option 4 would achieve significant benefits to wetland vegetation, reduce floodpotential in the vicinity of the Puna Stream mouth, expand a fish spawning area in the estuaryupstream of the Puna Stream mouth, and create new habitat for invertebrates. These potentialbenefits can be derived for considerably lower project costs.American Samoa Wetland/Stream Restoration and Enhancement PlanFebruary 2001, Aoa Wetland, Page 4-12
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Asili StreamAMERICAN SAMOAWETLAND/S
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American SamoaWetland/Stream Restor
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American Samoa Wetland/Stream Resto
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Figure 1-1Location of Potential Wet
Page 13 and 14: Onsite InvestigationsNovember 1999G
Page 15 and 16: Where appropriate, stream cross sec
Page 17 and 18: Chapter TwoTULA WETLANDLOCATIONTula
Page 19 and 20: Figure 2-2Tula WetlandExisting Cond
Page 21 and 22: Improved channelization of stormwat
Page 23 and 24: LAND USES IN THE VICINITY OF TULA W
Page 25 and 26: Figure 2-3Option 2: Detention of St
Page 27 and 28: Figure 2-4Option 3: Expansion of Ta
Page 29 and 30: Comparative Benefits and ImpactsPPC
Page 31 and 32: TABLE 2-4PRELIMINARY COST ESTIMATEP
Page 33 and 34: TABLE 2-5LONG-TERM RESOURCE MONITOR
Page 35 and 36: TABLE 2-6 (CONTINUED)FIELD MONITORI
Page 37 and 38: Chapter ThreeALAO WETLANDLOCATIONAl
Page 39 and 40: Figure 3-2Taufusi MarchExisting Con
Page 41 and 42: Figure 3-3FEMA 100-Year Flood Plain
Page 43 and 44: East Portion of the MarshThe impact
Page 45 and 46: WETLAND RESTORATION AND ENHANCEMENT
Page 47 and 48: The availability of new, blight-res
Page 49 and 50: Long-Term Monitoring and Site Maint
Page 51 and 52: TABLE 3-7FIELD MONITORING WORKSHEET
Page 53 and 54: Recommended monitoring stations or
Page 55 and 56: Figure 4-1Location MapAoa Village W
Page 57 and 58: No stream flow estimates are availa
Page 59 and 60: Fresh-Water SwampThe fresh-water sw
Page 61 and 62: ecome dominant if there is a nearby
Page 63: Relative Abundance and Diversity of
Page 67 and 68: TABLE 4-5COMPARATIVE EVALUATIONWETL
Page 69 and 70: Long-term resource management activ
Page 73 and 74: • begin at the Tapua Stream mouth
Page 75 and 76: Figure 5-1Location MapSoutheast Wet
Page 77 and 78: Tufu Stream and two stream branches
Page 79 and 80: Mr. Whistler was part of a three-pe
Page 81 and 82: InvertebratesCrustacean densities w
Page 83 and 84: FIGURE 5-3OPTION 1: RESTORE RIPARIA
Page 85 and 86: TABLE 5-4COMPARATIVE EVALUATIONWETL
Page 87 and 88: Long term monitoring of the Vatia w
Page 91 and 92: More specific monitoring of stream
Page 93 and 94: Figure 6-1Location MapVaipito Strea
Page 95 and 96: Stream FlowsHistorical Stream Flows
Page 97 and 98: California grass (Brachiaria mutica
Page 99 and 100: FIGURE 6-3FISH AND INVERTEBRATE SUR
Page 101 and 102: Most of lower Vaipito Stream segmen
Page 103 and 104: Red mangrove should be planted with
Page 105 and 106: TABLE 6-7PRELIMINARY COST ESTIMATEC
Page 107 and 108: TABLE 6-9LONG-TERM RESOURCE MONITOR
Page 109 and 110: TABLE 6-10 (Continued)FIELD MONITOR
Page 111 and 112: Vehicular and pedestrian access to
Page 113 and 114: Figure 7-1Location MapLeele-Papa-Ta
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Stream flow, in some cases, is cons
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Stormwater Discharges and Related F
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AQUATIC FISH AND INVERTEBRATESGener
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Opportunities and StrategiesOption
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Figure 7-3Option 2: Reduction of Er
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TABLE 7-8PRELIMINARY COST ESTIMATEP
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TABLE 7-9LONG-TERM RESOURCE MONITOR
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TABLE 7-10 (Continued)FIELD MONITOR
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More specific monitoring of stream
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Figure 8-1Location MapSauino Stream
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Stream FlowsHistorical Stream Flows
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AQUATIC FISH AND INVERTEBRATESGener
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Figure 8-3Option 1: Construction of
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FIGURE 8-5OPTION 2: PLANT NATIVE RI
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Long-Term Monitoring and Site Maint
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TABLE 8-8FIELD MONITORING WORKSHEET
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TABLE 8-8 (Continued)FIELD MONITORI
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LOCATIONChapter NineLEAFU STREAMLea
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Figure 9-2Leone Pala and 300-Foot L
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However, during and following heavi
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Vegetation TrendsThe lower Leafu St
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LAND USES ADJACENT TOLOWER LEAFU ST
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Option 2: Construct Basaltic Wall,
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Figure 9-5:Stabilize East Stream Ba
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TABLE 9-7PRELIMINARY COST ESTIMATEP
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TABLE 9-8LONG-TERM RESOURCE MONITOR
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TABLE 9-9 (Continued)FIELD MONITORI
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Chapter TenASILI STREAMLOCATIONAsil
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Figure 10-2Asili Stream SegmentExis
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Stormwater Discharges and Related F
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Further downstream, the stream chan
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TABLE 10-4SUMMARY OF MACROFAUNAL OR
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American Samoa Wetlands/Streams Res
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CLEAN-UP OF LOWER ASILI STREAMLABOR
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TABLE 10-9LONG-TERM RESOURCE MONITO
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TABLE 10-10 (Continued)FIELD MONITO
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Vehicular and pedestrian access to
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Figure 11-1Location MapFusi Wetland
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WETLAND VEGETATIONNovember 1999 Sur
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The lack of stream flow entering th
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Figure 11-3Option 1: Remove Solid W
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Recommended Option and Estimated Pr
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TABLE 11-6FIELD MONITORING WORKSHEE
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Any future monitoring stations or s
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Project ManagerRepresentatives of a
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REFERENCESBiosystems Analysis, Inc.
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APPENDIX ASUMMARY OFPLANTSOBSERVED
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Species Family EnglishNameSamoanNam
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APPENDIX CSUMMARY OFAQUATIC MACROFA
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american samoa - University of Hawaii at Manoa Botany Department

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