1.3.1 Land-based Sources
Land-based, point and non-point pollution sources are important in causing marine pollution. The DOE categorises point sources into sewage treatment plants, manufacturing industries, agro-based industries, and animal farms. Recent studies of catchment pollutant loading estimates in Malaysian rivers indicate that non-point pollutant contribution may be equivalent or greater to that of point sources. About 83% of the population in Peninsular Malaysia have access to sewage treatment. The discharge from sewage treatment plants is mandated to a standard enforced by the DOE. However, many rural and older houses in urban areas still use an individual septic tank with kitchen wastes being directly discharged into storm drains. Industrial activities, particularly involving heavy metals, such as mercury and lead or cadmium, also cause pollution of coastal areas. In Malaysian coastal waters, oil and grease, suspended solids and Escherichia coli (E. coli) are identified, in the annual DOE Malaysia Environmental Quality Reports, as being the main contaminants of coastal waters.