New Zealand's cow population is rapidly increasing as record high milk prices lure a growing number of farmers to convert dry stock farms into dairy operations.
The number of cows has doubled to six million in the last 30 years in the same time the national sheep population has halved to 35 million.
Farming experts say the trend is the result of farmers eager to take advantage of record high dairy prices.
ANZ chief economist Cameron Bagrie said the dairy industry has seen a lot of investment as dry stock farms, where animals are raised for their meat, are switched to dairy operations.
"If you look at the underlying returns to the dairy sector over the past five to seven years, they've been pretty strong," said Bagrie.
"What you've naturally seen is a lot of investment, a lot of conversions, a lot people chasing this so called 'white gold'".
The trend is likely to continue with another 70 dairy conversations estimated in the Canterbury region alone which is expected to boost employment opportunities.
Farmers estimate for every 250,000 cows, an extra 1000 jobs are created in the dairy sector.
However, the Greens say the economic benefits of dairy farming are not worth the detrimental effects to New Zealand's waterways.
They are calling for a cap on cow numbers and for farmers to be charged for irrigating farms.
"With six million cows, that's the equivalent of 80 million people without the sewerage treatment," said Green Party MP Eugenie Sage.
Each cow is estimated to produce 14 times more waste than a human being which can pollute rivers and lakes if a dairy farm is not properly irrigated.