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Vacoa Village ST Algal growth Water quality deterioration,leakage into marshBeau VallonST Algal growth Water quality deteriorationBungalowGeogina’a cottages ST Algal growth Water quality deteriorationVilla de Rose ST Unknown UnknownPti Payot GuestST Unknown UnknownHouseLe Meridien fisherman’s ST (installed AS in Algal growth Water quality deteriorationCove1997)Notes: ST: Septic tank, AS: Activated Sludge Treatment, Source: Shah, 1998The Quality of Environmental ResourcesGround and Surface WaterPollution levels can be measured at different sites in the study area, one being the fresh waterof the rivers and another being the seawater of the bay. A simple method used in 1996 bySOGREAH to give orders of magnitude of monthly mean values for river flow andgroundwater infiltration. Regular water analyses were carried out on the main water sourcesrunning into the Bay to measure BOD and SS concentrations. The following tables present anoverview of river water quality at different sites:River area PH Resist. SC/cm Total coliform/Faecalstreptococci1 Northolme 7.5 12720 3200/602 Upper St Loius 7.2 21890 350/503 Lower St Loius 6.8 14820 700/804 Mare Anglaise 7.1 5565 6000/305 Danziles 7.3 11110 18000/1206 Upper Niol 7.2 38485 10/67 Lower Niol 7.0 21730 150/248 1 Sullivan 7.1 10685 1200/16Source: SOGREAH, 1996River area Faecal coliform count/100 ml NH4Mg/lNO2Mg/l1 Northolme 160 0 0.042 Upper St Loius 110 0.1 0.023 Lower St Loius 240 0 0.034 Mare Anglaise 40 0 0.055 Danziles 250 0 06 Upper Niol 2 0 0.027 Lower Niol 16 0.1 0.028 Sullivan 1000 0 0.04Source: SOGREAH, 1996Dissolved inorganic nitrogen: The two main forms of inorganic nitrogen are ammonium (NH4)and nitrates (NO3). Ammonium originates from animal or human waste and from the bacterialdecomposition of organic nitrogen. The rivers give NH4 values of between 0.1 to 0.4 mg/l,thus indicating contamination. The analyses therefore proved contamination of human/animalorigin which is harmful to the marine environment.Phosphates: High concentration indicates pollution of domestic and agricultural origin. Thehighest concentration was found in the Sullivan River. (SOGREAH, 1996).1 Short explanation for above/below cited river areas:1 abandoned farm2 relatively clean3 high pollution level caused by human waste4 high pollution level caused by human waste5 high concentration of faecal coliform6/7 low mineral contents8 high pollution level caused by human wasteFinal Draft Report – Cost Benefit Case StudiesGPA Strategic Action Plan on Sewage, October, 200092
Bacteria content of naturally occurring water is found to be important in the riversBOD and SS: The water from an unpolluted river have values ranging from 3 to 5 mg/l BODand 30 mg/l for suspended solids. The river water analysis was found to be of very poorquality in terms of BOD.River area PO3 Mg/l MO Mg/l1 Northolme 0.02 2.72 Upper St Louis 0 2.13 Lower St Louis 0.03 3.74 Mare Anglaise 0.05 2.55 Danziles 0 06 Upper Niol 0 1.37 Lower Niol 0.01 2.48 Sullivan 0.03 2.6Source: SOGREAH, 1996Freshwater analysis from different rivers sources confirm that these sources are polluted to avariable degree, mainly attributed to human activities.Marine watersBacterial pollution of seawater concerns essentially bathing water and shellfish cultivationwater. Bacterial contamination is a major factor for urban sewage being disposed into the sea.Appropriate European regulation define the threshold levels to be respected in bathing waterand in the flesh of shellfish destined for human consumption.Organic pollution materials are well received in the marine environment on condition that theyare practically all biodegradable. Organic pollutants may have harmful effects only ifinsufficiently dissolved with oxygen or if they are disposed off in stagnant water areas.The coastal areas close to the two river outlets, namely the Mare Anglaise and the SullivanRiver have the highest level of faecal contamination at l<strong>east</strong> for 1.3 months in each year anddeemed unbatheable according to European standards for bathing water. The unsuitablelevels are expected to occur after periods of heavy rains. In only 2 months on average peryear are the levels of faecal coliform at its lowest level. The best area for swimming is locatedin front of Coral Strand Hotel. (Payet, 1996)Indicators of sea water quality in terms of faecal coliform values around the Beau Vallon coastshowed 60% of values unsatisfactory for recreational use by WHO standards (Payet, 1996).The level of faecal coliform in the water is depended upon rainfall and the inputs dischargedby hotels. The observable trend of faecal coliform along the Sullivan river shows that there isa contribution of faecal coliform from the hotels. There is also a relatively rapid decay offaecal coliform close of the coast, probably as a result of the wetland area present at the riveroutlet. The relative contribution of point source pollution (e.g. from hotels) in terms of faecalcoliform to the overall quality of the coastal waters is estimated to be about 43%. The poorturn-over of water in the bay induces a decrease in seawater sodium chloride concentration,itself highly detrimental to coral life, and therefore to all marine organisms associated with thecoral reef ecosystem and trapping of nutrients and polluting substances.Coral ReefsThe coral reefs of Beau Vallon are poor with little diversity. The special conditions in the bayhave led to the formation of poorly developed structures forming two embryonic fringing reefs.The coral reefs consist of an inner reef flat, a reef front and an outer slope. Under presentconditions good coral populations are located only in the southern part of the bay. Other coralreefs are also present at depths of 7 to 20 m beyond the outer slope. Unfortunately, soft coral,which thrives on organic matter enrichments, are thought to be competing with existing coralspecies. The coral reefs are poorly developed in the bay due to the desalinisation of theseawater from inland fresh water. There is also an extensive seaweed bed between thebeach and the reef flat. Its role is very important, especially in the Beau Vallon bay. TheseFinal Draft Report – Cost Benefit Case StudiesGPA Strategic Action Plan on Sewage, October, 200093
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TABLE OF CONTENTSPageTable of Conte
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The Report includes four Annexes wi
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4.2 Programme ObjectivesTo facilita
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TERMS OF REFERENCEThis Report has b
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CHAPTER 1. ECONOMIC ANALYSIS AND EN
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aesthetic and recreational value, i
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marginal benefit of pollution reduc
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loss of labour force productivity.
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Population connected to sewerage in
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Threats to the Coastal and Marine E
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fall disposal in deep sea at Kilind
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There are three main categories of
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Child mortality, and death in gener
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6. Estimated Annual Cost of Environ
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2.2 DAR ES SALAAM CASE STUDY2.2.1 I
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Dissolved solids 83,940 45,280 9,83
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4. Institutional Capacity Building
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Table 8: Classification of ValuesTy
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infrastructure. As shown above, the
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6. MangrovesMangroves are an exampl
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• The total cost in column (3) is
Page 44 and 45: 2.3 BEAU VALLON (SEYCHELLES) CASE-S
Page 46 and 47: In the marsh areas, various species
Page 48 and 49: Dissolved inorganic nitrogen: The t
Page 50 and 51: TourismSeychelles• Number of tour
Page 52 and 53: lossesHuman Health Indicator: Treat
Page 54 and 55: Dose-response data are not availabl
Page 56 and 57: Table 13: Estimated Potential Annua
Page 58 and 59: CHAPTER 3. ACTION PROGRAMME INPUTS3
Page 60 and 61: Property impacts are widely known t
Page 62 and 63: 3. Wastewater Treatment in Ismailia
Page 64 and 65: • Health costs• tourism income
Page 66 and 67: Annex IRegional OverviewThe Western
Page 68 and 69: • Degradation of coastal and mari
Page 70 and 71: • Resource over-exploitation• S
Page 72 and 73: Annex IIMombasa Regional and City P
Page 74 and 75: Population covered by sewerage infr
Page 76 and 77: Source: Mwaguni & Munga 1997Sewage
Page 78 and 79: 1628 people tested positive for cho
Page 80 and 81: Annex IIIDar-es-Salaam Regional and
Page 82 and 83: are extensively exploited by small-
Page 84 and 85: Solid wastes. It is estimated that
Page 86 and 87: Pollution load to surface water res
Page 88 and 89: Mtoni and Pugu. Existing lakes incl
Page 90 and 91: Annex IVSeychelles (Beau Valon Area
Page 92 and 93: labour force generating the major p
Page 96 and 97: sea grass beds are able to soak up
Page 98 and 99: Sewerage ManagementSewerage managem
Page 101 and 102: REFERENCESA. Background Regional En
Page 103 and 104: 7 GOK 1997: Mombasa District Fisher
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