Land drainage

Southland has an extensive land drainage system in place. This system consists of artificial drainage canals and community drains. These drains periodically require maintenance work to be carried out to ensure that they perform the function they were designed for.

Some waterways flow constantly and others intermittently (ephemeral), but they are all part of a catchment and contribute to water quality.

Waterways on hill country farms are mostly unmodified natural waterways. On more intensively farmed properties, the natural waterways have been highly modified to improve drainage. In some cases artificial drains have been created to drain wetlands and to channel tile drain flows into waterways.

Waterways and artificial drainage not only transport water to the sea, but also carry sediment, bacteria and nutrients. While this is a natural process, intensive land use has significantly increased these amounts, which can impact both farm productivity and the life-supporting capacity of our waterways.

Ideally, all farmers should know which waterways on their farm are at risk of receiving excess sediment and nutrients, and how to minimise these amounts. Every waterway on a farm needs to be considered, as even smaller waterways and ephemerals have the capacity to transport these materials.

Good management practices

• Environment Southland encourages excluding stock from waterways by permanent or temporary fencing to maintain water quality.
• Wherever possible, place your fences at least five metres away from the water's edge. Wider buffers of up to 10 metres may be required on sloping land.
• Crop preparation and stock grazing should be undertaken away from waterways - in some conditions a riparian buffer of more than five metres is required to protect water quality.