Saturday, 10 February 2018

Wellington Water mandated to seriously degrade the Hutt River to ensure water supplies

Update on my update on the Hutt River

Yesterday I wrote an update on the state of the Hutt RIver.

I finished with the following question:

I ask our negligent authorities and media - what has changed since this was written 2 months ago and why have there been no updates?

It seems that I have my answer but it was not the answer I would have expected!

Sprinkler ban lifted for Wellington but restrictions remain

Wellingtonians will be allowed to turn their sprinklers on for the first time in more than two months, with restrictions to be lifted on Friday.

However, while sprinklers and irrigation bans have been lifted, other restrictions remain.

Sprinkler use will still only be permitted at odd-numbered houses on odd dates, and even-numbered houses on even dates, and only between the hours of 6-8am and 7-9pm.

The remaining restrictions would stay in place until April 1, except in Upper Hutt, where restriction remains in place year-round.

A sprinkler ban was imposed in late November after unusually low rainfall, but with emergency storage lakes at Te Marua, north of Upper Hutt, refilled to 90 per cent capacity, Wellington Water said there was enough in reserve to see out the summer.

"Thanks to the response from the community, and in spite of a record hot January, the region's storage lakes are now in good shape to last for the remainder of summer," a spokesman said.

"This is a good position to be in, but it's important that people keep being responsible with water usage. Sprinklers are actually a relatively wasteful way to water plants, and their use is limited by the garden watering restrictions still in place."

With restrictions easing it was a good time to check and refill emergency water supplies, he said.


Wanting a response from the Regional Council on why they might want to lift restrictions on using sprinkers  - there has been NO indication of any restrictions on corporate use of water - Ihave to assume there is none - I rang and got a prompt response from M.H who was very helpful in providing me with the information.

The next bit is mind-blowing.

When I told him that I was "perplexed" as to why the restrictions might be lifted when we are still in drought and the water levels are low he said, so are we!

He went on to explain that it is Wellington Water that is reponsible for these decisions and people in the Regional Council are "in the dark" and often talk about it at morning tea time!!

I was flabbergasted. 

The left hand doesn't know what the right hand is doing - or at least the functions are kept quite separate and I wouldn't mind betting this is to stop the greater good from prevailing.

I am unsure of the background of Wellington Water except for the following:

Wellington Water was established in September 2014 as a result of a merger between Capacity Infrastructure Services and Greater Wellington Regional Council's water supply group.
We're owned by the Hutt, Porirua, Upper Hutt and Wellington city councils and Greater Wellington Regional Council. The councils are all equal shareholders.
Our role is to manage the drinking water, wastewater and stormwater services of our council owners.

I suspect it was set up to keep functions seperate and to be operated along commercial lines to cater primarliy for the commercial sector.

I managed to get hold of a spokesperson from Wellington Water who told me that they have a consent to extract water for commercial and domestic use until the flow rate upstream at the Kaitoke weir reaches 600 lit/sec.

Current flow rates are now about 1700 m3/second. If I do what I was told to do and multiply by 1000 that's 1,700,00 litres /second

He did not send me the document, but a short note confrming what he told me:

Thanks again for getting in touch. The river certainly looks low from time to time, but it looks like it will get a top up this weekend.

The consent condition requires us to leave a minimum flow of 600 litres a second over the weir in Kaitoke river, from where we extract water.

Another measure point is the Hutt river at Birchville, where when the flow gets below 1600 l/s for 20 days, or 1300 l/s for five days (consecutive), we need to discuss garden watering restriction levels with Greater Wellington.

Hope that clears things up a bit for you


As I have previously pointed out, statistics come in two forms - cubic meters/second and litres/second.

Converting from one to the other should be a simple matter of dividing (or multiplying) by 1,000.  However, if I do this the results that don't make any sense at all.

Using this method to calculate the equivalent of 600 litres/second minimum flow in Wellington Water's consent I get the result of 0.6 cubic metres!!

Instead I will compare both sets of figures separately.

The following figures are in cubic metres/second:

Site Description Average flow for Feb 1st 2015 (litres/second) Average flow for January 2015 (litres/second) Average flow for January 2013 (litres/second) Longterm average flow for January (litres/second) Average flow (litres/second)
Hutt River at Kaitoke (NIWA site)
Upstream of water supply weir at Kaitoke
Hutt River at Birchville (NIWA site)
Mid-catchment just upstream of Totara Park footbridge
Hutt River at Taita Gorge
Lowest site in catchment.  Opposite Manor Park golf course
Source: Greater Wellington Regional Council

These were the comments I made at the time:

What this indicates is the river flows at Kaitoke where water is extracted for water supply, on February 1 2015 stood at 1215 litres/ second - 22% of the January average of 6710 litres/second.

The figures were similar further downstream.

Although river levels have not yet reached the low levels of 2013, it is unprecedented for levels to be so low
so early in the season (mid-summer).

Clearly there is a problem, especially if we look at the wider global situation.

However no one, at the official level at least, wants to see the bigger picture or to acknowledge there is a problem at all, although several people we have spoken to (as private individuals), acknowledge that this is an unusual situation.

I went back to the Council to ask for comparative figures for 2013 and 2014.

Site Description Average flow for February 2013 (litres/second) Average flow for February 2014 (litres/second) Longterm average flow for February (litres/second)
Hutt River at Kaitoke (NIWA site) Upstream of water supply weir at Kaitoke
Hutt River at Birchville (NIWA site) Mid-catchment just upstream of Totara Park footbridge
Hutt River at Taita Gorge Lowest site in catchment.  Opposite Manor Park golf course

From these figures, the average flow for February 2014 (another drought year) was 2832 litres/sec while the long- term average for the month was 4818 litres/sec

If Wellington Water are mandated to extract water to a minimum of 600 litres/second this means  they are allowed to extract to a point that is 21% of the February average for 2014 (roughly equivalent to the situation now) and only 12% of the average flow for the month.

To get a sense of the situation as it is now, I have compared the figures for the flow in cubic metres/second on one day (9 February) in successive years:

9 February, 2013 2794
9 February, 2014 1659
9 February, 2015 1270
9 February, 2016 1272
9 February, 2017 8832
9 February, 2018 1250

The following are figures were provided to me by Wellington Regional Council.
They are mean figures, so are affected by the one rain event which makes it looks as if there is more water in the river than there actually is.

"The flows are in cubic metres per second so multiply by 1000 to convert to litres per second if needed."

Hutt River at Kaitoke – mean February flow

February 2015 1.409 m3/s
February 2016 2.697 m3/s
February 2017 11.593 m3/s
February (up to 9th) 2018 3.695 m3/s
Hutt River at Birchville – mean February flow

February 2015 2.957 m3/s
February 2016 6.069 m3/s
February 2017 36.474 m3/s
February (up to 9th) 2018 7.506 m3/s

Hutt River at Taita Gorge – mean February flow
February 2015 3.467 m3/s
February 2016 8.802 m3/s
February 2017 41.054 m3/s
February (up to 9th) 2018 8.252 m3/s 


What all of this means is that the river is in a parlous state and has been for a few years now.

Already at 1250 litres/second we have a situation with toxic algal blooms that are occasionally flushed out by a rain event but are a more or less permanent feature. Gone are the days when someone could canoe the river.

Imagine then a situation where due to drought and the authorities drawing off water from the river the flow rate drops to 600 litres/second.

This is a mandate to destroy a river to provide water to corporates as well as to the community.

Wellington Water say there is nothing to worry about because they have NIWA’s forecasts of “ample rain”, when the same NIWA failed miserably to predict this situation and only talked about the ‘hot blob’ well after I had noticed it by simply following Climate Reanalyzer. They say that if the river fails they have other rivers (in a similar,if not worse state), and the aquifer.

Their mandate is a largely commercial one – of providing their mostly-commercial customers with water – and devising strategies to do this.

They do not appear to care about the state of the river and fail to see that a day might come when, due to their profligate policies, they are unable to deliver their mandate. 

Menawhile there are people in Greater Wellington Regional Council who have a genuine concern for the conservation of the river.

In my mind, it is  the very reason why this company was set up – to keep the commercial … paramount.

I will finish off with this article which reveals something that stopped me in my tracks.

In the case of earthquake or other disaster which takes out the water supply  Wellington has only enough reserves to supply the city for 19 hours at normal usage.

The majority of the city's water is supplied via a pipe running along State Highway 2, which lies right on a faultline.

If this line were severed, it is predicted the city and eastern suburbs could be without water for up to 100 days.....Wellington has only enough reserves to supply the city for 19 hours at normal usage.

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