The detritus washing into our waterways from roads, farms and new subdivisions is wreaking havoc on our fresh water. So what to do?

Dirty water. There's a lot of it about, despite a growing clamour to clean it up.

According to the Auckland Council's latest State of the Environment report, 54% of the 100 or so streams and rivers it monitors are in a poor or degraded state.

Most of the streams in trouble are in urban catchments, where they are affected by inputs of metals, other contaminants and sediment.

Many urban streams have been put in channels and concreted to cope with stormwater overflows, or piped underground as a result of urban developments.

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That means there is little opportunity for ecological communities to develop.

Mayor Len Brown says while air quality has improved, the report shows the challenges around water.

"Because of how quickly we are growing, our residential development in some of our greenfields sites, the challenge we put on our local waterways, our creeks, our streams our estuaries, you can see it in the Tamaki and Oruarangi estuaries where high sediment levels from subdivision, metals coming off cars and tyres off the roads through the stormwater into the local creeks, all means we are doing better but we have to do a lot better than that," he says.

In the lakes, the council reports a major invasion of the aquatic weed hornwort, which threatens biodiversity, water quality, utility and recreation. It grows up to 10 metres tall, blocks water intakes and out- competes desirable native aquatic vegetation.

Eradication options could include manual removal, introduction of grass carp or selective herbicides.

Things aren't much better below ground. The nitrate concentrations in the south Auckland volcanic aquifers exceed drinking water and environmental standards.

This groundwater emerges at various springs in the Franklin area, introducing high nitrate concentrations to Franklin's streams.

The council says it is involved in research projects to better understand the nitrogen cycle in the area, which could lead to science-based management to reduce the nitrate concentrations.

"The key objective with freshwater is to manage the life-supporting capacity of fresh water, in other words maintain its ecological health."

Nitrates and phosphates are a problem nationally, driven by an expansion in fertiliser use that makes New Zealand one of highest percentage users of fertilisers in the OECD.

The excess fertiliser going into streams increases the phosphorus level, but it's what the fertiliser is used for that creates the nitrogen problem.

The lush pasture it produces means more cows can make more milk over a longer season. While sheep urinate in small amounts, which the grass treats as fertiliser, cows gush litres of urine at a time. The grass can't take it up, and it passes through the soil into the groundwater.

According to an update report on water quality by the Parliamentary Commissioner for the Environment, between 2008 and 2012 the amount of land used for dairying increased by 157,900 hectares.

That accounts for most of 151,000 hectares no longer used for used for sheep and beef farming, as well as some of the 9600 fewer hectares in plantation forest.

While the commissioner's earlier modelling predicted a large increase in both forest and scrub land by 2020, it's now clear that won't happen, and the felling of forest on the Volcanic Plateau for dairy conversions is going to mean lots more nutrient loss into the upper Waikato River catchment.

Other land use activities such as open-cast mining and urban expansion are also sources of diffuse water pollution. It all serves to negate the gains made from improved wastewater treatment and the 30 year crack down on point-source pollution.

According to Robert Davies-Colley from the National Institute of Water and Atmospheric Research, about 40% of New Zealand's land area is used for grazing livestock.

So while river water quality coming out of New Zealand's conservation estate may be described as 'very good' when compared with Europe, North America and Asia, the rivers draining pastoral catchments are only fair.

A year ago the government released under a under the Resource Management Act national policy statement for freshwater management, setting minimum requirements for regional plans.

Regional and unitary councils must set water quality targets for each water body or "freshwater management unit" in their area based on the value their community places on it.

The starting point is to account for all water taken out of rivers, lakes and groundwater, and the sources and amounts of contaminants going into them.

"Ecosystem health" and "human health for recreation" are compulsory national values and must be provided for everywhere, even if the national bottom lines set in the statement are lower than many of the critics would have liked.

Wading and boating is the national bottom line, and it's up to councils to say if a river or lake should also be swimmable, let alone drinkable.

The deadline for compliance was brought forward to 2025, and councils need to file annual progress updates.

Environmental Defence Society chair Gary Taylor says the national policy statement is immature and needs a lot more work before it will be effective.

"It's a start, at least there is some national guidance, but the statement includes ambiguities and uncertainties and the national objectives framework, the numbers in there are incomplete," Taylor says.

The statement has already been tested and found wanting in the case of the proposed Ruataniwha irrigation scheme, where the Environment Court found the "unders and overs" approach to water purity being taken by the Hawkes Bay Regional Council was unlawful."

"The key objective with freshwater is to manage the life-supporting capacity of fresh water, in other words maintain its ecological health," Taylor says.

The key attributes for doing that aren't in the NPS yet. It will be reviewed next year with the Land and Water Forum having a hand in it and science panels already squirreling away to see what to do with it.

"What the Land and Water Forum has done is get agreement across the board, including from farmers, that we need to manage water within limits, but what limits and when, what is the pathway? If you have an over-allocated catchment, how long do you give people to get it back into an underallocated state?

"Under the (Resource Management) Act there is a first-come, first-served entitlement. The Land and Water Forum has been looking at that, trying to develop policy approach between existing and potential and new and more efficient users, which might require some tradability."

That comes up against the government's contention that water can't be owned, even though the current regime creates de facto property rights.

"Iwi rights and interests are also a wrinkle - to what extent is a settlement for the crown and to what extent should regional councils managing water make allowance for iwi?" Taylor says.

"We are making progress on fresh water but it is tricky. It is hard to get national guidance right and regional councils' performance is uneven. Some are doing a good job, some are doing a second rate job."

EDS is meeting one of the regional councils next month to study its approach, because it suspects it is flouting the law.

"A lot of regional councils are dominated by farming interests who look after their own."
He says things should improve once the recommendations of the Land and Water Forum start being implemented.

"The way to improve fresh water is to set limits that will protect ecological health and then drive the implications of that up into the land with stocking rates and so on," Taylor says.

He sees three immediate challenges: fixing the national policy statement and national objectives framework to give clear, complete and effective national direction; having regional councils upskilling and, if necessary, retraining people to implement that national direction effectively; and for the science community to reach agreement on what to measure and how to measure ecological health.

The bio-augmentation solution

There are a lot of trees being planted in the name of cleaning up New Zealand's lakes and streams.

There are also chemicals like aluminium sulphate or alum being dumped into lakes to make them look clear, even if the by-product is a toxic sludge on the bottom.

A Waiheke woman believes councils and communities could do better by looking at what waterways do anyway to clean themselves up.

Claudine Kitson says bio-augmentation is widely used overseas, yet seems largely unknown in New Zealand.

She says the addition of bacterial additives to accelerate nutrient removal is one of the key approaches recommended by the North American Lake Management Association.
"I see instead a lot of work in various regions around reducing nutrient levels off farms through riparian planting and fencing off buffer zones between stand-off grounds and streams.

"There is also a lot of money being spent trying to sort out septic tanks, but it will take decades and really hard to manage."

That time lag is an issue with many forms of diffuse pollution, the effects of which can take decades to show up.

We don't have the time, she says, with councils having to implement the National Policy Statement for Freshwater Management by 2025.

Her company Unblok (unblok.co) has taken an agency for Eco-Fix, which is a controlled release of micro-organisms) to break down contaminants.

She says it enhances the existing microbial community in the waterway, which makes the treatment method organic, safe and ecologically sustainable as well as being in tune with Maori cultural values on water management.

"It has been proven to work really well overseas and there are decades of results.
"The other thing is it is really low cost," Kitson says.

She says a draft budget for treating the lagoon at Little Oneroa on Waiheke would be $2000 for an initial shock with maintenance of about $4000 a year to refresh monthly or after heavy rain.

Bio-augmentation can even be used in sewage systems. The small Spanish town of Villalba de los Barros, injects bacteria into its sewer pipes to start the treatment process before the waste hits its treatment plant.

It has halved the sludge normally produced by the treatment plant and made the whole system better able to cope with the seasonal increase in activity during the peak processing season for grapes and olives, which producing a fivefold increase in wastewater.

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