A survey of beach pollution at a seaside resort

Abstract

Bacteriological surveys of beach pollution were made at a seaside resort before and after the installation of a new sewer outfall.The presumptive coliform count on samples of sea water was found to be a satisfactory index of contamination, and showed good agreement with sanitary survey and with the results of float-test observations. The faecal coli count was in general constantly related to the results of the presumptive test, but there was some indication that coliform bacilli of the I.A.C. groups persisted or multiplied in the sand around the outfall.The degree of contamination of the sea water at a given sampling point was shown to depend not only on its distance from the outfall but on various meteorological and tidal factors.For bacteriological surveys of beach pollution, it is suggested that a large series of tests by a relatively simple technique is preferable to a more limited investigation by more complex methods.The possibility of laying down bacteriological standards for bathing beaches is discussed. An upper permitted limit of the order of 1000 coliform organisms per 100 ml. would discriminate between areas on the beach investigated which were unsatisfactory by sanitary survey before and after the installation of the new sewerage scheme, and those parts of the beach which were apparently not subject to serious pollution with sewage.I am greatly indebted to Lt.-Col. J. M. Linton Bogle, consulting engineer responsible for the sewerage scheme described, for his interest in and practical help with this investigation; to members of the staff of the local authority concerned for help with sampling, and to Dr A. F. Ollerenshaw and Mr A. Partridge, who were in local charge of the temporary laboratory where the presumptive tests were carried out, in 1950 and 1948 respectively.