Here are some facts about waterways around the world:

• Each year, plastic waste in water and coastal areas kill up to 100,000 marine mammals, 1 million sea birds, and countless fish
• 95% of the worlds cities still dump raw sewage into their water supplies
• In one week, a typical cruise ship generates:
  • 795,900 litres of sewage
  • 3.8 million litres of 'grey water' from showers, sinks, dishwashers and washing machines
  • 149,230 litres of oily bilge water and
  • More than 8,128 kgs of solid waste
• The chemicals found in one cigarette butt can leach out contaminate approximately 7.5 litres of water within one hour. This contaminated water is lethal to small crustaceans and other aquatic life.

So, what is polluting them? Well, That question has an easy answer: Agriculture. And this link between agriculture and water pollution isn't a recent occurence either - its been happening since the 1800's.

As mentioned before, only 25% of New Zealands forests remain, with the majority of the land being cleared and used in agriculture, and in particular, farming industries. We've also cleared 95% of our native wetlands, which if we hadn't taken away, would play a major part in protecting waterways from pollution.
Dr Mike Joy teaches enviromentla sustainability at Massey University, and says that "When we get heavy rainfall we also get huge amounts of fine material from deforested areas, called sediment. This then comes of the land and clogs up rivers making them brown and dirty"