The effect would ultimately be the same as if an oil spill happened in the local river and/or ocean. Water and Oil do not mix and the oil becomes thick and remains on top of the water. Water ultimately drags the oil with it and eventually into the river and ocean. There the oil will cause oxygen from passing through the water, therefore killing all local plants in and near the rivers as well as causing harm to local animals that bathe and drink in the contaminated water
