american samoa - University of Hawaii at Manoa Botany Department

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flow velocities have apparently generated excessive erosion along the east bank of Papa Streamand littered the stream bed with considerable amounts of rock and debris.Due to the erosive nature of soils along the stream bank, aggressive bank stabilization practicesshould be used to help improve stream hydrology and reduce the amount of future stream bankerosion. While various construction options are available, it recommended that the east bank ofPapa Stream be armored with basaltic rock and grouted with a concrete slurry along theupstream and downstream sides of the Tauese Stream discharge (Figure 7-3). This approachwill enable the construction of a strong bank structure without increasing the velocity ofdownstream stream flows.Option 3: Restore Stream Path Upstream of Project AreaOption 3 would design and construct stream improvements that would:• restore the former single, stream path some 700 to 800 feet upstream of station 11+80;• somewhat reduce stream velocities downstream of the basaltic wall that has generatedsignificant downstream bank erosion;• reduce further downstream bank erosion along east and west banks of Papa Stream; and,• provide potential opportunities for planting wetland trees such as ifi along the 100-150-footlength of the stream bank that has been impacted by stream modification.ASEPA/ASDOC would need to retain a professional engineer to design conceptual,preliminary, and final construction drawings, as well as preliminary cost estimates, for thisstream improvement project. Once funds are secured for this project, a building contractorwould be selected for construction of the proposed design.Comparative Benefits and ImpactsPPC’s evaluation of the three alternate restoration and enhancement strategies is summarized inTable 7-6. Option 1 provides somewhat greater benefits to wetland vegetation and fish andinvertebrate habitat for a reasonable cost. Option 2 provides some needed improvementsbetween station 5+00 and 6+00 that would help reduce bank erosion and potential floodingalong a portion of lower Papa Stream.Option 3 would address a significant bank erosion and stream hydrology upstream of theproject area. This project would provide some benefits to wetland vegetation, as well as fishand invertebrate habitat. However, the potential significant cost associated with this projectmakes this project less desirable despite its need.TABLE 7-6COMPARATIVE EVALUATIONWETLAND RESTORATION AND ENHANCEMENT OPPORTUNITIESLOWER PAPA STREAMOption Project Residential Subsistence Fish & Wetland/ StreamCost Land Uses Agriculture Invertebrate Riparian BankFlood Hazards& PropertyDamageHabitat Vegetation Stability1 LC LB NBC MB SB NBC LB2 MC NBC NBC MB LB NBC MB3 SC MB NBC LB LB NBC LBNotes: Potential project benefits were rated by PPC as follows:SB Significant project benefitsLC Limited undesirable consequencesMB Moderate project benefitsMC Moderate undesirable consequencesLB Limited project benefitsSC Significant undesirable project impactsNBC No anticipated project benefits orundesirable consequencesSource: Pedersen Planning Consultants, 2000American Samoa Wetland/Stream Restoration and Enhancement PlanFebruary 2001, Papa Stream, Page 7-11
Figure 7-3Option 2: Reduction of Erosion at East Bank of Papa StreamAmerican Samoa Wetland/Stream Restoration and Enhancement PlanFebruary 2001, Papa Stream, Page 7-12
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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
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Onsite InvestigationsNovember 1999G
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Where appropriate, stream cross sec
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Chapter TwoTULA WETLANDLOCATIONTula
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Figure 2-2Tula WetlandExisting Cond
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Improved channelization of stormwat
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LAND USES IN THE VICINITY OF TULA W
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Figure 2-3Option 2: Detention of St
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Figure 2-4Option 3: Expansion of Ta
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Comparative Benefits and ImpactsPPC
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TABLE 2-4PRELIMINARY COST ESTIMATEP
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TABLE 2-5LONG-TERM RESOURCE MONITOR
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TABLE 2-6 (CONTINUED)FIELD MONITORI
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Chapter ThreeALAO WETLANDLOCATIONAl
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Figure 3-2Taufusi MarchExisting Con
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Figure 3-3FEMA 100-Year Flood Plain
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East Portion of the MarshThe impact
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WETLAND RESTORATION AND ENHANCEMENT
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The availability of new, blight-res
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Long-Term Monitoring and Site Maint
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TABLE 3-7FIELD MONITORING WORKSHEET
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Recommended monitoring stations or
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Figure 4-1Location MapAoa Village W
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No stream flow estimates are availa
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Fresh-Water SwampThe fresh-water sw
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ecome dominant if there is a nearby
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Relative Abundance and Diversity of
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Option 4: Restore Mangrove Forest U
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TABLE 4-5COMPARATIVE EVALUATIONWETL
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Long-term resource management activ
Page 71 and 72: TABLE 4-9FIELD MONITORING WORKSHEET
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
Page 115 and 116: Stream flow, in some cases, is cons
Page 117 and 118: Stormwater Discharges and Related F
Page 119 and 120: AQUATIC FISH AND INVERTEBRATESGener
Page 121: Opportunities and StrategiesOption
Page 125 and 126: TABLE 7-8PRELIMINARY COST ESTIMATEP
Page 129 and 130: TABLE 7-10 (Continued)FIELD MONITOR
Page 131 and 132: More specific monitoring of stream
Page 133 and 134: Figure 8-1Location MapSauino Stream
Page 135 and 136: Stream FlowsHistorical Stream Flows
Page 137 and 138: AQUATIC FISH AND INVERTEBRATESGener
Page 139 and 140: Figure 8-3Option 1: Construction of
Page 141 and 142: FIGURE 8-5OPTION 2: PLANT NATIVE RI
Page 143 and 144: Long-Term Monitoring and Site Maint
Page 147 and 148: TABLE 8-8 (Continued)FIELD MONITORI
Page 149 and 150: LOCATIONChapter NineLEAFU STREAMLea
Page 151 and 152: Figure 9-2Leone Pala and 300-Foot L
Page 153 and 154: However, during and following heavi
Page 155 and 156: Vegetation TrendsThe lower Leafu St
Page 157 and 158: LAND USES ADJACENT TOLOWER LEAFU ST
Page 159 and 160: Option 2: Construct Basaltic Wall,
Page 161 and 162: Figure 9-5:Stabilize East Stream Ba
Page 163 and 164: TABLE 9-7PRELIMINARY COST ESTIMATEP
Page 167 and 168: TABLE 9-9 (Continued)FIELD MONITORI
Page 169 and 170: Chapter TenASILI STREAMLOCATIONAsil
Page 171 and 172: 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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