Perils of fecal contamination in Golden Mile of the Mount Lavinia beach: are we circumspect enough?
Figure 1: People flocking the Mount Lavinia beach for recreational activities (Source:http://visitcolombo.com/content/5-mount-lavinia-beach)
Figure 2: Google Earth view of the golden mile of Mount Lavinia beach with developments in the neighborhood
Figure 3: Unprecedented release of fecally contaminated water
The fecal pollution could not easily be identifiable, as the water and beach sand do not depict a unique color or a pungent smell. In Sri Lanka, fecal pollution is usually characterized by the presence of fecal coliforms, which are a group of bacteria generally originated in the intestines of warm-blooded animals and people. The presence of fecal coliforms in both beach sand and near-shore water may not be harmful if present in levels less than the threshold levels recommended by the relevant authorities and does not necessarily warrant the presence of feces. Sri Lanka is yet to regulate the popular bathing sites, such as Mount Lavinia in terms of fecal contamination, though many such sites have been heavily polluted. Nevertheless, it is a general practice in many countries that for primary recreational activities, including bathing and swimming, maximum fecal coliform levels are to be less than 150 MPN/100 mL in which the likelihood of inflicting health hazards seems to be remote. The water directly mixed with raw feces without any dilution may contain fecal coliforms in the order of 106-107 MPN/100 mL. According to a study carried out by Jeffery Soller and co-workers in 2010, the human exposure to fecally contaminated water may instigate health hazards, including, but not limited to, gastrointestinal symptoms, eye infections, skin irritations, ear, nose and throat infections, and respiratory illness. Qian Zhang and co-workers in 2015 have manifested, that fecal bacteria in beach sand are at levels 10 to 100 times higher than those in the near-shore water, as the decay of microbial communities is much sluggish, indicating that the fecal contamination remains in the beach sand at high levels for a longer period.
When the fecal coliforms enter the near-shore water under episodes of calm coastal regime their decay over time (90% over two to three hours) is responsible for warranting low levels in areas far from the point of receipt. Nevertheless, the near-shore water is often dynamic giving rise to episodes of the rough coastal regime, where alongshore currents bring about the movements of fecal coliforms along the beach towards the direction of currents depending on the prominent wind direction. Mount Lavinia experiences both northbound and southbound currents over the year. The rock-outcrop on which the Mount Lavinia hotel is located usually hinders the smooth movements of currents, as it juts out towards the sea. This phenomenon makes the fecal coliform movement pattern complex in the neighborhood of the hotel with incidences of reflection and refraction of waves, creating local zones of profoundly high fecal coliform levels. It is observed that during spring tides with atmospheric wind speed more than 10 m/s there exists an exceptionally high risk of fecal contamination being spread and persists in the so-called golden mile causing greater havoc. The authors of this article are, for the past couple of years, engaged in monitoring of numerous popular near-shore bathing sites of which Mount Lavinia is one of them. Table 1 depicts the maximum fecal coliform levels recorded in one of the many individual sites of Mount Lavinia subjected to long-term monitoring during northeast and southwest monsoon periods.
Table 1: Maximum fecal coliform levels recorded in near-shore water at the golden mile stretch of Mount Lavinia (all measurements done at spring tide under high wind conditions; permissible level for primary recreational activities is 150 MPN/100 mL)
The results of both monsoonal measurements over the years indicate that there has been alarmingly high fecal contamination and that the near-shore water has not been amenable for recreational activities (fecal coliform levels > 150 MPN/100 mL). Fecal coliforms always show higher levels during the northeast monsoon compared to those of southwest because of the southbound currents bringing in fecally contaminated water along the coast and presence of high densities of beachgoers during January to March. The fecal contamination seems to be on the rise over time for which the real reasons are not apparent. Prima facie evidence suggests that the golden mile of Mount Lavinia depicts the highest levels of fecal coliforms compared to other popular near-shore bathing sites, making it the most fecally polluted popular bathing site in Sri Lanka. Nevertheless, one needs to comprehend that the most polluted scenarios prevail when the favorable conditions (spring tide and strong winds coupled with fecally contaminated runoff) for the fecal bacterial decay are encountered. Such scenarios do not occur every day nor every hour, but nobody could predict safe periods during which recreational activities be practiced without the fecal contamination being pronounced to have instigated health hazards.
The tourism industry spurted in Mount Lavinia may not strategically be advocated as long as the fecal contamination has been incredibly engulfing the golden mile. Properly instituted a sewerage network in the areas of Mount Lavinia, Dehiwela, and Ratmalana is of paramount importance in promoting the Mount Lavinia beachfront among beachgoers. On the other hand, the health cost of getting exposed to rather polluted-water at Mount Lavinia has not been estimated but would be prohibitively high. The responsibility of keeping the Mount Lavinia golden beach free of fecal contamination should be borne by all of us merely because the progressive nature of vanishing pristine beaches may unwittingly deprive of future opportunities of economic boom as a whole. Let all of us strive forward collectively, proactively, and unanimously towards protecting our beachfront and near-shore water in Mount Lavinia from fecal pollution for the benefit of future generations.
Eng. (Professor) Mahesh Jayaweera
B.Sc (Civil Eng), PhD (Env Eng)
Professor, Department of Civil Engineering, University of Moratuwa
Chartered Engineer, Member of IESL, IWA, and SLAAS-Section C
Eng. (Dr) Buddhika Gunawardana
B.Sc (Civil Eng), M.Eng(st), M.Eng, PhD (Env Eng)
Senior Lecturer, Department of Civil Engineering, University of Moratuwa
Associate member of IESL, Member of IWA, Secretary-SLAAS-Section C