Sparkling clear freshwater is one of the most striking and memorable things about New Zealand. However, many of our lowland freshwaters have become degraded, and this process is continuing.
In particular, as discussed on our webpages on Sustainable Land Use, there is a large and growing impact of agricultural activity on our streams, rivers, lakes and estuaries.
The main sources of impact are:
- Intensification of agriculture, especially in dairying and cropping, is causing excessive amounts of nutrients to leach into waterways, promoting algal and weedy growths which then rot. Nutrient-enriched lakes and waterways thus tend to become unattractive and smelly; the natural freshwater ecosystem can die off from oxygen deprivation; and toxic organisms often grow in the degraded waters.
- Land use practices that cause sediment to enter waterways also degrade water quality. In particular, unfenced and unplanted stream banks, and erodible hillsides maintained in pasture without protective trees plantings, produce a lot of fine sediment which washes into streams. This accumulates on the stream bed, smothering the natural stream bed ecosystem. The silt also creates turbid conditions in the water, making it unattractive for swimming, while the loss of light penetration through the water column kills off most freshwater-dwelling species, other than those adapted to living in murky waters.
- Irrigators are often allowed to take too much water out of rivers and streams, leaving waterways with only a trickle of flow during the summer season. Such practices degrade the freshwater ecosystem, and prevent the movement of fish up and downstream. The impact is felt during the months when our waterways are most valued for fishing, swimming and family picnicking activities. Many waterways have become permanently degraded as a result of over-commitment to irrigators.
The Government’s Sustainable Water Programme of Action is designed to address a number of issues in the management of freshwater, including improving the allocation of water to users, and reducing degradation by non-point sources of contamination such as agricultural activities.
Read about Ecologic's proposals for Freshwater Policy, including our draft National Policy Statement on Freshwater Management, and our attempts to get Environment Waikato (a regional council) to control Waikato farm runoff that is causing significant deterioration in the quality of many rivers, lakes, streams and wetlands.