Freshwater is apart of our everyday lives. It is used for drinking, food gathering, recreational/tourism activities and to produce goods and services. Therefore it is essential for New Zealand to maintain our freshwater resources for future generations. However this is becoming a problem due to the clearing of vegetation, draining of wetlands, urbanisation and most importantly the increase in agricultural activities. These activities are placing a large amount of pressure on our water bodies and their ecosystems and as the population grows this pressure will continue to increase.
Agricultural based activities (mainly dairy farming) can cause excess amounts of nutrients (nitrate-nitrogen) to enter our waterways through run off. These nutrients come from the animal waste/urine as well as fertilisers. While nutrients often occurs naturally and are essential for plant growth, high nutrient concentrations result in algae growth. Too much algae in the water leads to the decrease in oxygen levels and will prevent light from entering the water. High concentrations of nitrogen can also be toxic to species and will make the water unsafe to drink. “In monitored rivers, nitrate-nitrogen was worsening (55%) at more sites than improving (28%)” (The Ministry for the environment 10). Many farmers have been moving towards more intensive dairy farming, as dairy products have become more profitable over the years. “In 2015, New Zealand farmed around 29 million sheep, 10 million cattle (6.5 million for dairy) and 900,000 deer” (The Ministry for the environment 27). With the increase in dairy or any type of farming the amounts of nitrate-nitrogen run off will continue to enter our waterways.
E.coli also has an effect on our waterways. E.coli comes from either animal or human faeces that has made it’s way into the freshwater, this can increase the risk of illness for swimmer in the area. “E.coli concentration was 22 times higher in the urban land cover class and 9.5 times higher in the pastoral class, compared to the native class (2009-2013), (The Ministry for the environment 11).
Freshwater fish are also effected by our polluted waterways as numerous species migrate between the sea and freshwater each year to complete their life cycles and breed. “Of the 39 native freshwater fish species we report on, 72% were either threatened (12 species), or at risk of (16 species) extinction in 2013” (The Ministry for the environment 14).
- Ministry for the Environment & Stats NZ (2017). New Zealand’s Environmental Reporting Series: Our fresh water 2017.