Presence of boron in domestic wastewater has resulted in high B/CI ratio at some locations in the coastal water around Bombay. A widest range (0.215-0.281) of B/CI was observed at a location with high influence of wastewater release. The mean B/CI decreased at locations situated away from the polluting sources. In the histograms showing the frequency distribution of B/CI the range in which most B/CI values prevailed was same as that of unpolluted coastal water (0.224-0.230) whereas, at a location affectEd. by severe sewage pollution the range of the most frequent B/CI occurrence was higher (0.230-0.236). Nearly 45-71% of B/CI values at all stations were higher than the highest limit (0.230) for unpolluted coastal water, giving a graphic clue to B addition through external sources. Among the higher values, the frequency of occurrence decreased with the magnitude of B/CI range, indicating a slow rate of removal of the externally added B. A negative intercept on the B axis after the linear least square regression analysis of B and CI data pairs revealed B loss at one location perhaps due to absorption by clay minerals. However, at other locations, the positive intercept on the B axis increased directly in line with the severity of pollution at those locations