The periodic scourge of tar balls affecting the west coast is not a new phenemenon but has been going on for years due to the tankers and other ships pumping out sludge and other petroleum products into the sea as there is no proper satellite surveillance in this area. Ships after discharging their cargo of crude oil in the far east head back to the middle east and before loading do their tank washing in the Arabian Sea before loading their next liquid cargo consignment. They dare not do it in the south China sea or the Mallaca Straits because of the strict surveillance and heavy fines including the arrest of the Master and Chief Engineer. Tar balls are in the sea round the year but during a certain period due to favourable currents, swell and other factors of the sea are washed ashore. The only way to avoid this is to keep a strict watch on the errant ships like they do in the USA, Europe and Australian waters where the Master and Chief Engineer is held culpable, fined and in worse cases jailed.
