A riparian strip is the piece of land alongside a river or stream. The name comes from the Latin word ‘ripa’, meaning a river bank, and it’s an important piece of land for lots of reasons. Caring for it well can improve water quality, help with soil conservation, minimise fertiliser runoff from pasture, and provide habitats for wildlife.
In the past, farmers often allowed livestock to have direct access to streams. This caused a lot of problems, and we now know that keeping stock out of these areas, at least for most of the time, is important to prevent contamination with urine and dung, sedimentation, and erosion caused by trampling of the banks. Fencing off and planting your river and stream banks can have many positive effects, and it doesn’t have to be a huge chore.
The kind of fence needs to be appropriate to your conditions. An 8- or 5-wire fence may be ideal in some situations, but if your waterway is prone to flooding, more adaptable and cheaper options such as moveable electric fences may work better. Fencing is the first step because it allows you to keep livestock away from the banks and the water and lets you establish suitable plantings.
Once the fence is in place, even just leaving an area in undisturbed grass is better than nothing, and some farmers are now experimenting with systems where they allow occasional grazing under careful control so that weeds are kept down, fire hazards are reduced, and the area is more accessible for recreational use. Other areas lend themselves to the planting of native trees and shrubs, which reduce erosion by stabilising the banks with their roots, and provide shade to suppress waterweed growth and keep the water cooler, favouring all sorts of aquatic animal life. Often it is best to avoid (or remove) willows, which can accumulate silt around their roots and stimulate erosion on the opposite banks. However, in some situations willows may be useful, particularly if you want your riparian strip to help you with providing extra fodder for your livestock. Riparian strips can be handy places to grow fodder trees such as willow, poplar and tagasaste (tree lucerne), which can either hang over the fence to allow browsing, or can be harvested and fed out to the stock.
Get advice before planting, as your plans need to make allowance for the width of your riparian strip and the type of waterway you have – wider strips may be good sites for taller species, while in narrow strips, low-growing sedges and tussocks may be preferable. If erosion is a major problem, planting shrubs and trees with fibrous root systems which tolerate moist soil and silting is a sensible approach. You may also need advice about what is suitable for each side of your waterway: north-facing and south-facing environments can be quite different.
Different regions in New Zealand have different regulations regarding the planting and management of riparian strips. If you want to see the details, a good starting point is a website called Quality Planning, The RMA Planning Resource. It contains links to Best Practice examples for each of New Zealand’s District Plans. As one example, the Waikato region has an online resource called Clean Streams. For your particular area, start with your Regional or District Council, who should be able to provide basic advice – such as this guide from the Auckland Regional Council.
There’s plenty of information out there, and of course, it’s often a good idea to get together with your neighbours and form a stream or river care group. There are many of these around the country already; here's an example. A coordinated local effort will be cheaper, more efficient, and probably a lot more fun! And there are bigger advantages: water quality in rivers and streams is a cumulative thing. How bad it is downstream is a result of the actions of lots of individual landowners along the way, so group action keeps longer bits in better condition.