Fish and Game policy analyst Dr John Hollows told a meeting of the Fish and Game Otago Council at Clyde yesterday the number of dairy cows in the Maniototo district is likely to double from 3000 to 6000.
Three farms sold recently would be converted to dairying.
Councillors at yesterday's meeting were concerned the change of land use could have serious effects on waterways in the district. They agreed it was the job of the Otago Regional Council (ORC) and the Central Otago District Council (CODC) to monitor it.
Cr Donald Scott said one cow was equal to six or seven humans when it came to producing effluent. Putting that many dairy cows in the Maniototo would be equal to building a small city there.
Dr Hollows said it was inevitable that dairying would become more prevalent in the South.
"Where you get water, you get dairying,'' he said.
Farmers were splitting their farms and selling off the flat areas for dairying at a good price and leaving the high country, he said.
The ORC had put policies and objectives in place to protect the waterways, but rules were needed to back them up.
Fish and Game Otago chief executive Niall Watson said the agriculture and dairying were getting away with a cost of production (effluent disposal) that was not factored in.
"Water quality results would suggest that dairying isn't sustainable in the long term.''
Mr Watson called for a planning regime at a regional and district level to manage the effects of farming.
"We have industrial-scale dairying and traditional effluent disposal. Farmers should be factoring in the cost of buying water and disposing of effluent.''
Cr Adrian McIntyre said 23 farms in West Otago had converted to dairying in the past month. He was also concerned about farmers who were grazing heifers over the winter months.
"You are now going to have thousands of heifers grazing on sheep farms and many of the farmers have no idea how to deal with this, and the ORC doesn't seem to be pro-active in telling them how to go about doing the right thing. Even new dairy farmers seemed to have received very little information about the rules for dairy farming and effluent disposal.''
Council chairman John Barlow said people were not likely to change until they had to.
"They get free water and dispose of their effluent very cheaply and we pay the price. We had a gentlemen's agreement with Fonterra a few years ago that if these guys complied we wouldn't prosecute - but nothing's happened yet,'' he said.
Mr Hollows has met some land owners in the Maniototo and discussed the importance of fencing stock away from waterways and and the need for the creation of wetland areas at runoff points.
Stock must also be kept away from the the lower terraces alongside the Taieri River.
