Fencing farm waterways

Fencing to keep animals out of waterways leads to better water quality by reducing the amount of faecal matter and sediment deposited directly into it. This will contribute to a better habitat for fish and other freshwater life, improve the appearance of the waterway and reduce drain maintenance costs. 

Many regional councils provide free guidance on fencing and other aspects of waterway management. Most provide free locally focused and helpful publications. Be sure to contact them in the early planning stages. Along with professional guidance, council staff can alert you to regulations and funding opportunities.  

In the meantime, here are some key things to consider.

Fence set-backs and options 

Consider the overall layout of your farm when planning for waterway fences. Along with protecting waterways, new fencing could improve subdivision for grazing management and stock control. 

For fence placement: 

Go for a minimum set-back of 1m where the paddock slope toward the waterway is less than 10 degrees (the set-back should be greater if you are going to be planting).

Go for a 3m set-back of ungrazed vegetation where the slope is greater than 10 degrees.

Where banks are unstable, set it further back. 

Weigh up straight lines (less materials and labour to install) versus following the waterway course (possibly less grazing land lost).

Choose fencing that suits your budget and your current set-up. Ensure it’s stock-proof.

Seven to nine wires with battens is best for permanent fences.

A two- or three-wire electric fence with permanent posts is satisfactory to prevent cattle entering the waterway.

For a single wire fence on a 1m set-back, increase the margin a little to allow for the grazing that will occur under the fence. 

Allowing for access

Be sure to allow for access when needed. For margins retired permanently, removable wooden rails in a convenient spot will make it easy to free stock that might get in.

For areas that require drain clearing, an electric fence that can be removed or dropped will allow easy access. Where fencing is more permanent, adequate spacing should be left between the waterway and fence for digger access. 

Coping with floods

Simple one-wire or two-wire electric fences are good choices in flood prone areas. They are less likely to collect debris or be swept away in floods. They are also easier to stand back up after a flood event.

Here are some more ways to reduce damage and repair costs in areas prone to flooding:

Place fencing a greater distance from the waterway (especially on the outside of bends) and place posts further apart than normal.

Put fence wires on the paddock and/or downstream side of posts so they pop their staples and drop, rather than breaking.

Use un-barbed staples so wires can pop more easily.

Construct separate ‘blow-out’ sections across flood channels.

You should also think about the height of the bottom wire relative to expected flood levels. Recording flood heights will be helpful with placement of fences in the future. 

Finally, temporary electric fences can be helpful to protect sensitive areas at critical times. You can run a hot tape around wet areas and seeps in winter, for example, to keep stock out and avoid pugging. 

• This article is adapted from the third in a series of nine DairyNZ Farmfacts on managing waterways on farms. They can be viewed at www.dairynz.co.nz in the Farmfacts – Environment section.