The new 'swimmable' fresh water target: Nick Smith defends his plan

LAWRENCE SMITH/Stuff.co.nz

Prime Minister Bill English and Environment Minister Dr Nick Smith announce a plan to clean up New Zealand's waterways out at Riverhead NW of Auckland.

Environment Minister Nick Smith has come under fireover his new policy that sets a target of 90 per cent of rivers and lakes "swimmable" by 2040. On Friday he sat down to put his side of the debate.

Q: You have been under fire from the Greens and others - to use the United States phrase for "alternative truths" - over the new water targets and for shifting the goalposts. Have you? 

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22022017 News Photo:Lawrence Smith/Fairfax NZ
Prime Minister Bill English and Environment Minister Dr Nick Smith ...
Lawrence Smith

22022017 News Photo:Lawrence Smith/Fairfax NZ Prime Minister Bill English and Environment Minister Dr Nick Smith announce a plan to clean up New Zealand's waterways out at Riverhead NW of Auckland.

Nick Smith: There's no question we want to improve water quality. We are not in dispute with the Greens about that. What we are in dispute over, is whether the Government's classification of rivers is fair and reasonable for an average person. We have classified the swimmable category into three areas: fair, good and excellent.

Look at the Hutt River. It is in the middle of the "fair" category. Under the policy by 2040 you would have to lift it up into the "good" category.

The "fair" category says it has to be compliant with the (less than) 540 E.coli/100mls of water standard between 80 and 90 per cent of the time. The good category is 90-95 per cent and "excellent" is above 95 per cent of the time.

Critics are using "junk science" to attack his clean water plan,:says Environment Minister Nick Smith.

Critics are using "junk science" to attack his clean water plan,:says Environment Minister Nick Smith.

For the Hutt River we have really good data at Silverstream over 15 years, hundreds and hundreds of data points. The river has a median E.coli of 100. It exceeds the 540 standard for 85 per cent of the time - so it is right in the middle of that band.

Q: Don't you mean it's lower than 540, 85% per cent of the time?

Nick Smith: Correct, that's right. The last three months is really typical. The median has been the same as for the last 10 years so I am not picking some cute date. It's tested every week. So if you look at the data for the last three months it goes 28 (E.coli), 61, and then 920 on December 19 - a big rainfall event that brings all the crap in. Now the moment you go over half you have to do an extra test the next day and it dropped back to 29. Then (in the following weeks) 8, 40, 11, 38, 54, 57, 160, 168.

Massey University freshwater ecologist.Mike Joy says the Govenrment is "trying to pull a swifty" with its new swimmable ...
WARWICK SMITH/FAIRFAX NZ

Massey University freshwater ecologist.Mike Joy says the Govenrment is "trying to pull a swifty" with its new swimmable waterways plan.

Q: So relate that to the level of risk for swimmers. 

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Nick Smith: At 540 you have a one in 20 chance (of infection). At the 130 level you've got a one in 1000 chance. So every time when that number is less than 130 the risk is less than one in 1000. On one day, in the last three months, it went above that level. 

Q: So how would you describe the river at Silverstream?

Nick Smith: The Government says it's swimmable but it's in the bottom category of swimmable. To describe the risk of getting an infection at one in 20 in the Hutt River is grossly unfair. For more than 50 per cent of the time it's actually less than one in 1000. My challenge to those who say the categorisation system is unfair - such as Green co-leader James Shaw - what does he think is a fair description of the Hutt River? Is he saying it should be described as unswimmable? There are 8500km of rivers in exactly the same class. Our description of those rivers is "fair". If you are in doubt check the LAWA (Land Air Water Aotearoa) website. If I was a family living in Wellington I'd safely swim in the Hutt River any day, but if I'd had a big rainfall event - like around that date in mid-December - I'd check.

Q: Are those categories any different from what they were before Thursday's announcement?

Nick Smith: Under the 2014 policy it would have been an "A" - because the standard in 2014 was "wadeable". In the new standard it is classified as a "C". That's why I take offence at people saying "your new standards are softer and making it easier for water bodies to meet it". That's not correct. Mike Joy is being a bit cute. The 540 E.coli level was set by the previous government and by the WHO. We all agree if you go over 540 the level of infection gets to one in 20 and you shouldn't swim. What he is doing is taking the worst case scenario on those water bodies and saying that's the level of infection that applies all the time. That's very unfair, and not true and in my view "junk science".

Q: But the Ministry of Health recommendation is 260 E.coli - how does that relates to the 540 level?

Nick Smith: The 260 level is new. It says if you get a 260 reading you need to upgrade monitoring to daily. We accepted that with weekly monitoring, when you are getting close to that 540 limit, [above which the Ministry of Health considers it unswimmable], that risks you going for a swim with your family. (So monitoring is stepped up.)

This bit is very nerdy. We are saying at 540 E.coli the risk is one in 20 (of getting sick).  But that one in 20 is at the 95 per cent confidence level. So there is an extra level of cautiousness. Even if you put 20 people in water and it has a 540 E.coli level it's not saying on average one person gets sick out of 20. It's saying one in 20 of 20 groups will have one in 20 get sick.

Q: So when your critics say you have moved the level from 260 E.coli to 540 that is what they mean? There was no other prior 260 level?

Nick Smith: Yes there is. The old wadeable standard had a 260 annual median. To be in A, B or C (the new swimmable categories) not only do you have to not exceed the 540 level 5, 10 or 20 per cent of the time, it has to be less than a median of 130.

If you want to compare the annual median of the old standard with the annual median now - that was wadeable and this is swimmable. When you put your head under you need to have an extra level of cautiousness.

 - Stuff

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