Protecting farm waterways from sediment run-off is ''absolutely critical'' for stream health, and farmers are advised to leave a buffer zone near waterways, when cultivating paddocks for greenfeed crops.
Otago Regional Council manager community liaison and education Nicola McGrouther said she wanted to highlight issues linked to cultivating paddocks for next winter's greenfeed crops.
Under the council's new water quality rules, measures must be put in place when disturbing land to control sediment runoff into waterways. Having no effective sediment control measure is a prohibited activity.
''Where there is no filtering margin such as rank grass, rainfall and its resultant runoff over grazed paddocks readily transports sediment and contaminants into waterways,'' Mrs McGrouther said.
This was also ultimately damaging to the interests of farmers, because it could result in the loss of valuable topsoil.
Another negative result was increasing levels of nutrients, bacteria, and pathogens polluting streams and rivers.
A buffer zone of long grasses, fenced off with electric fences and left ungrazed, provided an effective trap within the paddock to maintain water quality during subsequent winter grazing. This also prevented stock falling into waterways and dying.
''Farmers need to put in buffer zones wide enough to minimise sediment runoff. The width needed will vary depending on the slope, contours, soil, and buffer vegetation,'' she said.
ORC staff had recently seen positive examples of good farming practice, but some farmers, including in South Otago, had not yet picked up on the requirements of the new water quality rules.
A buffer of at least 3-4m was recommended for very flat land, while steeper land would need a considerably larger buffer to trap animal waste and sediment runoff.
''If farmers follow some simple practices as they cultivate for next year's greenfeed crops, they will substantially reduce their impact on water quality as well as ensure environmentally-sound grazing during the 2016 winter,'' she said.
''It's a win-win for the farmers, their stock, and the waterways,'' she said.
Small waterways and tributaries played a vital role in overall water ecology and in the health of larger waterways.
Keeping an eye on farm waterways while the land was bare was important to ensure the buffer was effective.
Farmers had a good feel for what was happening on their properties, and a visual check would show if anything was wrong.
Plumes of sediment in the nearby waterway showed something was going wrong and farmers should then step in and fix it, she said.
Sediment badly damaged stream health, smothering key fish spawning areas, and damaging environments favoured by mayflies and other key insect species needed by fish.
Adverse effects could be long-lasting.
By building these buffer zone measures into their farm management, farmers should be compliant with the Otago water plan.
They would be taking a practical steps to support good water quality in waterways, she said.
