Data published in 2013 suggested that it was not safe for people to submerge themselves in 60% of New Zealand’s waterways. “We used to swim in these rivers,” says Sam Mahon, the artist. “Now they’ve turned to crap… [T]he real villains behind New Zealand’s deteriorating water quality are still at large…intensive dairy farms…
The first concern is bovine urine, which is rich in nitrogen. Nitrogen can cause toxic algae to grow when it leaches into water. Nitrogen fertiliser, used to increase fodder yields so that more cows can be raised on less land, exacerbates the problem….
At many of the sites where the government tests the groundwater it contains too much nitrate to be safe to drink—a particular problem in New Zealand, since water in much of the country has long been considered clean enough that it is used as drinking water with only minimal treatment. In Canterbury, one of the most polluted areas, expectant mothers are told to test tap water to avoid “blue baby syndrome”, a potentially fatal ailment thought to be caused by nitrates. The poisonous blooms have killed dogs.
An even greater concern for human health comes from cow dung, which contains nasty bacteria such as E.coli….And then there is the damage to native flora and fauna. The algal blooms suck the oxygen from rivers. Sediment washed from farmland can also choke the life out of streams. Almost three-quarters of native species of freshwater fish are under threat.
…One recent tally suggested that just 2,000 of the thirstiest dairies suck up as much water as 60m people would—equivalent to the population of London, New York, Tokyo, Los Angeles and Rio de Janeiro combined. …
Dairies are trying to clean up their act. Farmers have fenced off thousands of kilometres of rivers to prevent livestock from wading in. Some have planted trees along waterways to curb erosion; others remove animals from muddy fields during winter. Some parts of the country are using more sophisticated techniques: around Lake Taupo, the country’s biggest lake, farmers can buy and sell nitrogen allowances in a cap-and-trade scheme. A technique called “precision irrigation” may curb both water consumption and the leaching of nitrogen.
Earlier this year the National Party launched a plan to make 90% of rivers “swimmable” by 2040. Yet it ignored several recommendations of a forum of scientists and agrarians established to thrash out water policy….Environmentalists argue that the national dairy herd should be cut to prevent further damage…And pollutants moving through groundwater can take decades to emerge in lakes. The worst may still be to come.
Excerpts from Cows and seep: New Zealand’s Water, Economist, Nov. 18, 2017