NZ Farmer - Data shows humans, not cows, the biggest water polluter

Northland dairy farmer Merv Rusk writes that dairy farmers have made great progress to reduce their treated effluent to only 11 million tonnes a year – that's only 3 per cent of the equivalent human waste.

The common view is that dairy cows are the main source of effluent going into our nation's waterways, effluent being the principal source of faecal pathogens like E.coli that govern how safe water is to swim in.

However, a recent examination of the exact amount of effluent going into our rivers and the sea shows that it is humans, not cows, that are the bigger polluter.

The data, available to the public from government and industry, reveal we each contribute an average of 249 litres of treated waste per day to water, but dairy cows contribute an average of just six litres of effluent per day.

The difference here is that while human waste is generally treated to a higher standard, it is the average city dweller that puts 40 times more wastewater into waterways and harbours than the average dairy cow.

Compared to the 418 million tonnes a year of wastewater put directly into waterways by towns and cities, dairy farmers have made great progress to reduce their treated effluent to only 11 million tonnes a year – that's only 3 per cent of equivalent human waste by volume.

Differences remain even when added water is removed from the analysis. In this scenario a total of 2.5 million tonnes of effluent a year comes from humans, while only 1.2 million tonnes a year comes from cows. So, urban areas still contribute twice the effluent of dairy farms, this time by mass or tonnage headed for waterways.

There are large differences in how effluent is managed by dairy farmers versus how human waste is handled. Nearly 93 per cent of treated effluent from cities and towns was shown to go directly into waterways, while only 9 per cent of dairy farm effluent goes into rivers (because the rest on farms is returned to the pasture as valuable fertiliser).

Differences are reflected to some degree in measured water quality. A recent Ministry for the Environment report demonstrated that urban water quality results are far worse than those in rural areas.

That report reveals the urban levels of nitrate–nitrogen, dissolved reactive phosphorous and E.coli, were 80, 20, and 120 per cent respectively, above the benchmark, than in pastoral areas.

Yes, urban effluent is generally treated to a higher quality. Nevertheless, the ministry report still holds true and urban water quality is failing in those tests to keep up with rural water quality.

And as every farmer knows, human effluent is generally far more dangerous to humans than the cow stuff. They are not to be equated, according to the US Environmental Protection Agency.

Older effluent infrastructure in urban areas often can't cope during rainfall of a few millimetres or more where sewage and stormwater go into the same pipe, sending raw human sewage directly into the nearest harbour or river. For example, in Auckland there are reportedly 50 such outlets that spill more often than 52 times each year. That's 2600 spills a year of a billion litres of raw human sewage. This is expected to rise.

The evidence shows that our cities are actually polluting just as badly, or worse than, the dairy industry in many catchments.

The view that dairy cows are the single problem for water pollution is a myth.

I should also emphasise that while my focus here is on E. coli, water quality is complex, with a range of land uses contributing to the issue – and attitudes and policies need to match this reality.

For example, dairy farmers are subject to harsh penalties around effluent performance. Yet, the penalties for urban areas are less severe, if they exist. The typical fine for a farmer is about $30,000. If Auckland city was fined that figure for each of its 2600 spills, it would be liable for $78 million a year in fines, yet this issue receives little attention.

My opinion is that if we truly care about our nation's water quality, we need to address all sources of effluent and all pollution, and not simply make a scapegoat of the dairy industry. That means we need to address the effluent from urban areas with just the same urgency as is occurring in the dairy industry.

Dairy farmers have spent over $1 billion to improve their effluent performance, despite recent tough economic times. Now it's time for urban residents to recognise they also have an important role in improving water quality.

I've been a dairy farmer for 60 years, mostly retired now, and I see a real need for this country to regain its former spirit of co-operation. Division only leads to failure, and futile division has never been the New Zealand way. We can win in the sporting arenas because we use the team approach, so why are we so divided on this?

Let's work together to make progress for the benefit of the whole country, and the generations to come.