“…There, the appearance of unpleasant-looking mucilage produced by the decay of algae caused a 40% reduction in tourism in that year's bathing season (WHO, 1995). A number of studies have provided a wide range of estimates of the value that beach users place on water quality changes, typically ranging from $4 to $39 per person (Bockstael et al, 1987;Choe et al, 1996;Feenberg and Mills, 1980;Georgiou et al, 1998;Le Goffe, 1995). This disparity valuation method used; the pollution indicators adopted; the percentage quality improvement that is being valued; and the units (of environmental improvement) to which values refer.…”