Return to Aorere Catchment

May 2011

Progress in a catchment trying to improve water run-off quality

Sue Brown is the leader of the Aorere Catchment Project, and Robert Haldane is an early adopter in the programme, taking theoretical science around effluent management and putting it into practice on his farm at Bainham.

As a result of the Aorere Catchment Project the local dairy farmers are a long way down the track towards understanding the land:water interface.

The Aorere Catchment has annual rainfalls from 2.5m at Collingwood up to almost 5m in the upper catchment. This high rainfall has a flushing effect on the catchment.

Most of the catchment is in native bush, with 3% scrub, 1% exotic forestry and 16% in pastoral farming, mostly dairying.

There are about 33 dairy farms, ranging in size from 120 cows to 1200 cows milked through one shed. Most average 250-450 cows.

On Pakawau beaches there is an export cockle harvesting business and just offshore there are export mussel farms.

The main problem for the catchment is when bacteria spikes or plumes occur in low to median rainfall events, when there is little change in river flows. (The high rainfall events – such as the recent major floods – can’t be controlled.)

Golden Bay is a shallow sandy bay with strong tidal flows bringing fresh ocean water in every seven hours. This results in good growth rates for shellfish.

However these bacteria spikes are a major problem for the marine farmers who can’t harvest mussels or cockles when there is any risk of contamination.

Both cockles and mussels are exported. Some of the cockles are exported live in their shells to restaurants, so high quality product is vital.

The mussel farmers spent 22 weeks fighting in the Environment Court for the right to farm where they are. But the effects of having them sited out from the river mouth – and the contamination possibilities – weren’t looked at during this process.

When the project started, shellfish harvesting was only possible about 30% of the time because of this problem.

The community project started in 2006 under the umbrella of the NZ Landcare Trust. Everybody in the community has had something to do with it.

“We worked out what we needed to concentrate on was management practices to mitigate the effects of our farming for small and medium rainfall events. The next question was what are we going to do?

Our project has proved you have to start with your catchment and the science about it. Catchment modelling was crucial to us. It was the key to us all understanding and allowed us to learn about the land/water interface with regard to our high rainfall, soil types and topography.”

Barry Robertson and Leigh Stevens of Wriggle Consulting in Nelson did the modelling work. Both have previously worked with the Cawthron Institute and Leigh was once a council compliance officer.

“We were dealing with scientists with an excellent understanding of the land, the estuaries and our dairying systems. What we learnt was the Tasman District Council didn’t need to change its rules, they just needed to define their regulations about storage and irrigation to land.”

Lots of science and modeling work helped come up with three solutions to the problem:

• Fencing stock from waterways

• Storage of dairy shed effluent when the soils are too wet to absorb irrigated effluent

• Low rate application of effluent to pasture.

Moving stock out of waterways was one step. In the catchment they now have fenced about 75% of what needs to be fenced. While this might seem low it’s simply a reflection of the myriad of waterways in the valley compared to other parts of the region.

For example the Haldanes have five significant creeks through their farm, and in only one paddock there are three waterways that need fencing.

The project to date has funded 19 of the 33 farms having farm environment plans done voluntarily on their properties. These whole farm environmental plans, undertaken with Jan Derks, are built around ways to mitigate the bacterial problems. (In other areas the problem is with nutrients running off from the land, but it’s not the problem in this catchment.)

This year a few more farms will get their plans completed.

This year Fonterra’s “Every Farm Every Year” risk based check of suppliers’ dairy farm effluent systems has also kicked in.

If an effluent system scores as at risk of becoming non-compliant, Fonterra provides technical assistance to these farms.

“It is usually really hard to get measurable outcomes without spending a lot of money on water testing. However we’ve been able to measure our success by the ability of the shellfish farmers to harvest, and the success is the result of farmers understanding the land:water interface, and how we need to store effluent, and how to apply it when the soil and weather conditions are right.

The key thing is our kids can play in the creeks.

It’s almost like a think global act local project. If each of us looks after the small tributary streams on our farms then the main river is healthy too. When the Aorere is clean the shellfishermen don’t get restricted days of harvest and it is safe for all of us to swim and gather kaimoana.

We’ve managed to do this work without ending up in the Environment Court.

And we think the results will keep getting better and better.”

But there are challenges: At Dall’s Creek, there was major damage in the recent floods. This was a site where the streamcare group had done some planting in conjunction with the landowner. There was a major wash-out, and only toetoe plantings have clung on.

“In flood prone spots we have found we should only plant toetoe, flax and cabbage trees. We have found we should plant intensively and hope the plants gain a grip before the next flood. It might be 50 years of trial and error before some of these spots come back. The knowledge we have learned to date has also enabled us make better decisions on the farm, which is helping future-proof the farm.

We never used to talk about effluent systems doing anything better than meet compliance. Now we’ve gone past that.

For example, because we have large storage ponds for effluent, in spring at calving time we can concentrate on calving, and we know the effluent will wait until the weather is fine.

Those who have upgraded their effluent systems have one thing less to worry about. We can easily store three months of effluent in our pond.

That is also attractive to management, sharemilkers and staff. There is nothing worse than having to shift a travelling irrigator spraying effluent onto soils that are too wet to irrigate onto.

So we are finding these other benefits down the track: the workload in spring has changed, it helps staff. Of course there are fertiliser benefits too. Low rate application systems mean the nutrients remain in the root zone, and more is available to plants.

And we have good relationships across the farming industries in our community. This was highlighted recently by our involvement in the movie The Water Whisperers. The project is a way to work together collaboratively.

And it allowed us to celebrate our success collaboratively. Now we are working with Rai Valley farmers who are facing similar issues, but on different soils and steeper hills.

That project is also under the Landcare Trust umbrella, funded by the MAF Sustainable Farming Fund and is supported by Rural Women, Federated Farmers, Dairy NZ and Fonterra, as well as the Marlborough District Council.

Our project has shown that working on best practice on a catchment basis to define the issues and appropriate tools is the key. A methodology I am hooked on: hook, line and sinker! It works for our ecology and our primary industry.

I have a vested interest in the dairy industry being successful for NZ Inc, just like the mussel and cockle farmers are all part of NZ Inc, and the urban population. We all have to work together.”

Interview with Robert Haldane :

Debbie and I share-milk for Haldane Farms, which is a family business we half own with my brother David and his wife Jo. The land has been in our family since it came out of bush, and I have been farming here for 18 years.

We milk on 214ha effective but our home block is 435ha, and this year our peak number of milking cows is 685. Some of the property is sheep and beef land run by my brother and some is native bush. The farm runs along the valley floor and there are creeks all through it.

We were activated by the Clean Streams Accord rather than the Aorere Catchment Group because the Accord was like a sledgehammer for us. I just hadn’t given it any consideration at all.

We had two old cow sheds on the farm, and when we built a new shed we made the creeks the boundaries of our paddocks. Since the Clean Streams Accord came out from Fonterra in 2003 we have fenced our whole farm again.

You hear people moaning about the Accord but for us it is really good, and it gave us time to get the work done.

We have built two and three wire fences, put in bridges and culverts – one cost $4000, the other $6000. The total cost of fencing and labour was $72,000, and the Tasman District Council supplied posts and wire which was really fantastic.

Our estimate of bridge and culvert costs is $205,000, some of which we have spent; some we are about to spend.

When we built the cowshed we had a travelling irrigator and no storage.

We had always been compliant even with our old sheds. So three years ago, we were feeling pretty good about ourselves.

Then the Tasman District Council came out and said: you have no storage, you have to build a three month storage pond. And they wanted us to irrigate over a larger area.

Some of the farm is free-draining gravels which are less likely to pond. But to get to these paddocks you have to pump the effluent uphill from the cowshed. That is easy, we thought, we’ll get a bigger pump. Then we had to get bigger power to the shed, which cost $35,000. So we went looking for alternatives, and John Scandrett showed us his work in Southland on really wet soils.

He developed a weeping wall and K line irrigation system for us. You have to get the fibre out of the effluent before it can be irrigated.

We used existing pipes and hydrants which were in place already. We used a transfer pump to transfer effluent from the sump to the weeping wall ponds.

This new effluent system cost around $50,000: made up of K-line pump and fittings of $12,700, a new effluent pipe to more paddocks costing $4400, $11,000 to construct the ponds, $1600 for the transfer pump, a spare pump which is a TDC requirement of $2750, and a pumpshed and weeping wall of $8000, with miscellaneous costs of $4500.

Then we had a field day at our place to look at the system, and that’s how we got involved in the Aorere Catchment Project.

We bank on 4.5m rain a year, much of it from July to the end of October. That means rainfall at that time can top up the storage ponds, so we have to monitor the pond levels all the time.

The real secret with our effluent system is the timer on it. The K-line irrigation might be on for 15 minutes and off for 45 minutes. The travelling irrigator, at its lowest rate would put on 25mm in a pass. The K-line puts on much less, with a smaller nozzle.

We irrigate about 60ha of the farm with it. Because the effluent has the solids taken out of it, it’s not as potent as a fertiliser, and the nitrogen response is lower than with the previous method.

Now we are also putting back the solid sediment as a fertiliser. Ross Patching of Golden Bay has an effluent solids spreader which he hires out to local famers.

Overall I have no regrets. The TDC wanted us to have storage but didn’t have a system that was working until this one turned up in the nick of time. It has been a really good system and the staff like it. The K line is really easy, and is pulled around behind a bike.

There are now other big storage ponds in the catchment.

Our kids play in the river and we kayak down the river with the kids; and our family lives off where the Aorere catchment goes: I love mussels and cockles.

Golden Bay is a small community; my manager’s brother in law is a fisherman. We want them to have a fair go too.

Gretchen Robertson at the Landcare Trust did a really good job pulling everyone together.