The Rakaia River – Canterbury’s troubled water

In 2016 the Rakaia River was judged to be the highest ranking braided river within the Canterbury region for UNESCO World Heritage or Ramsar international status.–status,-using-multiple-combined-ranked-metholdogies.pdf

A Protected River

Recognizing the threat of “death by a thousand cuts” due to incremental increases in the allocation of Rakaia River water for irrigation, the Ashburton and North Canterbury Acclimatisation Societies fought a long and arduous battle in the courts to obtain New Zealand’s second National Water Conservation Order NWCO for the Rakaia River.

Sadly the status of Canterbury’s WCOs were debased by the Environment Canterbury (Temporary Commissioners and Improved Water Management) Act 2010

Amendments to the Rakaia NWCO to provide an additional 40 m3 for Central Plains Water CPW and the Barrhill Chertsey Irrigation BCI scheme have resulted in the loss of an outstanding recreational salmon and sea trout fishery, the virtual disappearance of the regionally restricted, (Red Listed), and once locally abundant Stokell’s Smelt, and reduced breeding success of several endangered sea bird colonies including White Fronted Terns and Black Billed Gulls.

If Stage III of the Lake Coleridge Project proceeds, a further 30 m3 will be lost.

The middle and lower braids have been radically modified by annual aerial defoliating herbicide applications of glyphosate together with eco-toxic surfactants by ECan. The reason given by ECan is to remove weeds invading the flood plain due to the loss of environmental (variable) flows. Variable flows are an essential element of braided rivers not some arbitrary minimum flow negotiated by lawyers set below the 7 year mean monthly low flow. It is likely that the river engineers are attempting to compensate for leaving the Rakaia River with insufficient flow to transport the 4.3 million tons of gravels eroded annually into the headwaters of this catchment – the river is no longer in ”equilibrium” risking potential building up of the flood plain and loss of coastal armouring.

The North Rakaia River now has its flow artificially managed and no longer exists within an open shingle flood plain. Once a prime sea trout nursery, the North Rakaia River has become a virtual “dead zone”. The North Rakaia River is now restricted to a single braid requiring periodic cross channel bulldozing and herbicide applications to compensate for the lack of environmental (variable) flows.

Thousands of hectares of (protected) riparian margins and special purpose reserves have been given over to agricultural encroachment at the behest of an undemocratic government appointed and controlled regional council – “Environment Canterbury” ECan.

The Original NWCO:

National Water Conservation (Rakaia River) Order 1988

The Rakaia River is the: • largest braided river, (NZ 9th largest overall); • mean flow = 215.9 cumecs; • mean annual flood = 2,520 cumecs; • 7 day mean annual low flow = 92.1 cumecs;

The National Water Conservation (Rakaia River) Order was gazetted 10 Oct 1988.

Recognised the Rakaia River and it’s tributaries include and provide for: (a) An outstanding natural characteristic in the form of a braided river; (b) Outstanding wildlife habitat above and below the Rakaia River Gorge, outstanding fisheries, and outstanding recreational, angling and jet boating features

Retention of natural waters in a natural state – upper Rakaia upstream of Wilberforce confluence includes Lake Heron.

Partial retention of natural waters – To protect Rakaia River values down stream of Wilberforce confluence to the sea: – the quantity and rate of flow of natural waters in the Wilberforce River and tributaries are to be retained in their natural state – the quantity and level of natural waters in Lake Coleridge and quantity and rate of flow of natural water in its tributary streams are to be retained in their existing state – the quantity and rate of flow of natural waters in the Rakaia River downstream of the Wilberforce confluence to the Recorder site (Rakaia Gorge bridge) is to be retained in their natural state (no mention of tributaries) – minimum gorge flow and allocation limit and sharing set for abstraction downstream of the gorge – minimum flow varies monthly (from 139 cumecs in November to 91 cumecs in July) – below the gorge flow in the river is not to be reduced by abstraction by more than 70 cumecs – abstraction not to reduce flow by more than half the of the excess of the gorge flow over the minimum gorge flow. (i.e. 1 to 1 sharing) (So for 70 cumecs to be allowed to be abstracted there must be 140 cumecs + the minimum flow at the gorge.)

The WCO allows water permits in and above the gorge only to replace/renew existing water permits on similar terms, and allows permitted activities only as applied in 1988.

The “gorge flow” is the mean daily flow. Consents indicate this as noon to noon but usually this is determined for the 24 hours up to about 4pm on the day prior.

The WCO states the “right to dam not to be granted”.

No specific reference to groundwater takes and stream depletion effects.

Water quality standards for any discharges.

Water permits to take water (including divert as appropriate) = 76.283 cumecs.

The Rakaia River NWCO post Environment Canterbury Temporary Commissioners and Improved Water Management Act:

National Water Conservation (Rakaia River) Order 1988 (Amended 2013)

Clause 3. Outstanding characteristics and features

It is hereby declared that the Rakaia River and its tributaries include and provide for—

(a) an outstanding natural characteristic in the form of a braided river:

(b) outstanding wildlife habitat above and below the Rakaia River Gorge, outstanding fisheries, and outstanding recreational, angling, and jet boating features.

Clause 9A Lake Coleridge Project

(1) Nothing in this order shall restrict the granting of resource consents, or variation of existing resource consents, to enable the Lake Coleridge Project as defined in clause 2, provided that the outstanding characteristics and features recorded in clause 3 are recognised and sustained and provided that:

(a) the Coleridge HEPS continues to operate,

(b) the Lake Coleridge Project be operated such that the discharge from the Lake into the Rakaia River at or above the Coleridge HEPS shall not fall below 45% of the inflows to Lake Coleridge, both inflows and outflows being calculated as the 2-yearly rolling average of daily flows; and

(c) whenever the Coleridge HEPS ceases to discharge water to the Rakaia River for more than 24 hours and the Rakaia River flow is within 30 cumecs of the minimum gorge flow prescribed in this order, the operator shall take immediate steps to shut off the Harper and Wilberforce diversions.

(2) Subject to clause 2A, the maximum rate at which water can be discharged from Lake Coleridge through any canal constructed as part of the Lake Coleridge Project is 25 cubic metres per second, and the total maximum discharge rate from Lake Coleridge through the Lake Coleridge Hydroelectric Power Scheme and any canal constructed as part of the Lake Coleridge Project is 65 cubic metres per second.

(2A) If the flow as measured at the recorder site maintained by the National Institute of Water and Atmospheric Research Limited at Fighting Hill (map reference K35:997437 on Map series NZMS260 for the preceding day is more than 10 cubic metres per second below the minimum flow set out in clause 7 then, during the next calendar day, only stored water may be released from Lake Coleridge along the canal referred to in clause 9A(2).

(2B) Prior to applying for any resource consents pursuant to clause 9A(1), the enhancement fund must be established and an agreement must have been concluded with Canterbury Regional Council for the receipt, on an annual basis, of the hapua management fund.

(3) Records shall be kept by the operator of the Lake Coleridge Hydroelectric Power Scheme enabling the calculation of the—

(a) stored water within Lake Coleridge;

(b) stored water that has been discharged from Lake Coleridge;

(c) water (including stored water) being diverted into any canal from Lake Coleridge.

(4) For the purposes of this order, and except as specified in clause 7(5), any abstractions or diversions of any water (including stored water) from any conveyance infrastructure constructed as part of the Lake Coleridge Project (other than water being discharged back into the Rakaia River from any such conveyance infrastructure) shall be treated as if those abstractions or diversions were from the Rakaia River between the Rakaia Gorge Bridge referred to in clause 2 and the sea.

Clause 9A: inserted, on 7 March 2013, by clause 11 of the National Water Conservation (Rakaia River) Amendment Order 2013 (Gazette 2013, p 443).

The Parliamentary Counsel Office

Clause 9 Resource consents

(1) Resource consents under the Act shall not be granted in respect of any part of the Rakaia River or its tributary streams for the purposes of constructing or maintaining stock barriers or facilitating agricultural encroachment into those bodies of water.

(2)Resource consents under the Act shall not be so granted for any discharge into the Rakaia River downstream of its confluence with the Wilberforce River or any part of the bodies of water specified in clause 4, if the effect of the discharge would be to breach the following provisions and standards:

(a) any discharge is to be substantially free from suspended solids, grease, and oil:

(b) after allowing for reasonable mixing of the discharge with the receiving water—

(i)the natural water temperature shall not be changed by more than 3 degrees Celsius:

(ii)the acidity or alkalinity of the water as measured by the pH shall be within the ranges 6.5 to 8.3, except where due to natural causes:

(iii) the waters shall not be tainted so as to make them unpalatable, nor contain toxic substances to the extent that they are unsafe for consumption by humans or by farm animals, nor shall they emit objectionable odours:

(iv) there shall be no destruction of natural aquatic life by reason of a concentration of toxic substances:

(v) the natural colour and clarity of the water shall not be changed to a conspicuous extent:

(vi) the oxygen content in solution in the water shall not be reduced below 6 milligrams per litre:

(vii) based on not fewer than 5 samples taken over not more than a 30-day period, the median value of the faecal coliform bacteria content of the waters shall not exceed 200 per 100 millilitres.

(3) Subject to subclause (4), resource consents under the Act shall not be granted in respect of any part of the Rakaia River or its tributary streams, or of Lake Heron or Lake Coleridge or their tributary streams, where the effect of such resource consents would be that the provisions of this order cannot remain without change or variation.

(4) Resource consents under the Act may be granted and general authorisations may be made in respect of any part of the waters specified in this clause for all or any of the following purposes:

(a) research into, and enhancement of, fisheries and wildlife habitats:

(b) the maintenance or protection of roads, bridges, pylons, and other necessary public utilities:

(c) soil conservation and related matters undertaken pursuant to the Soil Conservation and Rivers Control Act 1941 or the Act:

(d) the diversion, taking, and discharging of water from and to the Rakaia River to enable the Selwyn District Council to continue to provide for its rural water supply in accordance with, and on the same terms and conditions as, the water rights granted to it and in force on the date of commencement of this order:

(e) clause 7 shall not apply to any take of water up to 680 litres per second from the Rakaia River at map reference NZTopo50 BX22: 228 547 that is granted to the Ashburton District Council to provide for the continuation of its domestic and stock water supply:

(f) the Lake Coleridge Project, as provided for in clause 9A(1).

The amount of water abstracted for irrigation has been increased from 76 m3 to 116 m3 at present with a further 30 m3 allocated for the yet to be completed stage III of the Lake Coleridge Project.

Apparent Non Compliance with the Rakaia River NWCO

  1. Diversion of main braids

, The Rakaia River – Canterbury’s troubled water

  1. Agricultural Encroachment

When the Chinese took over ownership of Synlait Farms, (in addition to the Synlait Factory), it was discovered unconsented agricultural encroachment had occurred on several of the purchased farms – riverbed held under the Conservation Act 1947, Selwyn District Council roads, etc.

The Overseas Investment Office’s OIO response was to “regularize” the titles for the new Chinese owners.

Angler access through these properties disappeared along with public ownership.

, The Rakaia River – Canterbury’s troubled water

, The Rakaia River – Canterbury’s troubled water

Image shows landowner flood protection has extended out to the main river bed wiping out native riparian margins well beyond existing fence lines – see below

, The Rakaia River – Canterbury’s troubled water

Special purpose (public) reserves under the Soil Conservation Act vested with Ecan. Now part of Rakaia Island Dairies’ intensively farmed irrigated dairy platform

C:\Users\Peter    Toshiba\Pictures\2020-04-22\DSC_1333 (2).JPG

ECan reply to LGOIMA request date 3 September 2018 p.2

  1. Toxic Substances – Glyphosate

Photographs taken of lower North Rakaia River two years after aerial glyphosate application in 2012

, The Rakaia River – Canterbury’s troubled water

, The Rakaia River – Canterbury’s troubled water

Post aerial spray 2010. Photograph taken 2012

, The Rakaia River – Canterbury’s troubled water

, The Rakaia River – Canterbury’s troubled water

, The Rakaia River – Canterbury’s troubled water

Juvenile salmon feed on terrestrial insects as they grow and migrate to the sea.

Glyphosate at high application rates destroys soil ecology and insect life.

Young salmon live and grow in the deep backwater pools. Defoliation has largely eliminated these structures.

Jet boating is adversely affected by lack of channel structure

Young salmon rely on vegetation for shelter from predation

Sustained low flows means higher water temperature = higher metabolic rate = higher feed requirements for the young fish

Survival of salmon smolt entering the sea is influenced by size – smaller starved fish = poor survival = poor returns of adult salmon

  1. Sediment

, The Rakaia River – Canterbury’s troubled water

Defoliating the islands and banks of the riverbed with glyphosate releases fine sediment which coats the gravels and coarse sand of the lower Rakaia River braids smothering the spawning habitat of Stockell’s Smelt.

A coating of fine sediment over eggs and larvae is a likely explanation for the disappearance of this once abundant Rakaia River native fish that once underpinned the ecology of the hapua or river mouth zone.

No smelt = poor breeding success of Black Billed Gull and White Fronted Tern breeding colonies.

No smelt = few sea trout entering the lower braids. Poor condition and poor growth rates

No smelt = diminished coastal fishery (Stokell’s Smelt are a marine species that only enter freshwater to spawn. [Less kawhawai, short finned eels, flounder, Hectors Dolphins, and Shag spp.]

No smelt probably removes a source of food for the marine life stage of salmon

[See also Rex Gibson’s article “I have Seen Armageddon” on the NZFFA website]

, The Rakaia River – Canterbury’s troubled water

, The Rakaia River – Canterbury’s troubled water

, The Rakaia River – Canterbury’s troubled water

, The Rakaia River – Canterbury’s troubled water

Selected from a file of (78) images of dead Black Billed Gull chicks of varying size and age found in over 90% of nests after the birds departed their breeding colony summer 2019. Black Billed Gulls are the most endangered species of gull in the world. Without the presence of the once abundant Stokell’s Smelt, starvation is the most likely explanation.

  1. North Rakaia River – a river no longer in its “Natural State”

Following the conversion of the Rakaia Island farm with its patchwork of special purpose reserves into a 17.5 km2 dairy platform carrying 5,600 cows, and the adjacent Faraday’s Island consent to take water for electricity generation, the North Rakaia river is no longer in its natural state.

Both flood protection works carried out by Ecan and the Rakaia Island farm(s) and the managed flow regime for irrigation and power generation have reduced the North Rakaia River to a single channel for much of its length.

The once open shingle flood plain has been invaded by woody scrub consisting of willow, broom, alders, gorse, lupins, thistles, coarse grass species and a few isolated clumps of Manuka.

Periodic cross-blading by large bulldozers and aerial spraying is carried out to mitigate the risk of spill over on to farm land during severe flood events.

The North Rakaia River used to be a very productive nursery for the sea trout fishery due to its connected upwelling groundwater flows maintaining high water quality in several deep cut holes through the winter months. Large trout could be viewed in their hundreds on calm winter sunny dates hanging in the water in these pools which often experienced periods of no inflowing surface water during periods of low winter river flows.

On warm summer evenings the lower pools came alive with small trout taking mayflies and other insects at the surface.

Sadly the North Rakaia River has become a dead zone with silt and algal mats choking the life from the channel bed.

, The Rakaia River – Canterbury’s troubled water

, The Rakaia River – Canterbury’s troubled water

, The Rakaia River – Canterbury’s troubled water

6. Nutrient enriched springs

Clear Stream, (once used for spawning by a small run of wild salmon), and other small spring fed creeks that once played an important nursery role for salmon, trout and native fish entering the Rakaia River lagoon have been affected by both sediment and nutrient enrichment. Toxic algae and luxuriance growths of algae and large aquatic plants have reduced the productivity of these streams.

The photographs below were taken in 2012 and then in April 2020 at the same point where Clear Stream enters an old flood channel of the North Rakaia River.

These images record the resulting nutrient enrichment from adjacent dairy farm conversions.

, The Rakaia River – Canterbury’s troubled water

, The Rakaia River – Canterbury’s troubled water

Fish kills have been observed in the lagoon and connected springs, (both Clear Stream and Mathias Creek), after hot summer weather and low flows in the main river reduce tidal flushing of the lagoon.

The cause of these fish deaths has not been determined but is likely to be associated with water quality – temperature, &/or low oxygen saturation due to nutrient enrichment.

The NZFFA purchased an instrument to test water nitrate (NO3-N) levels after learning Ecan had stopped monitoring the local streams. Mathias Creek which has its source from the Rakaia Island dairy farms had shown readings of up to 6.9 mg/L No3-N before Ecan monitoring ceased “due to a lack of funds and a priority given to addressing the ineffective fish screens mandatory on irrigation intakes”.

[Mathias Creek continues to give the highest results but has remained under 3.0 mg/L NO3-N since NZFFA began their own monitoring from August 2019. There are no longer trout in Mathias Creek but the farm environment plan appears to be helping to reduce nitrate leaching.]

, The Rakaia River – Canterbury’s troubled water

  1. Nitrate Leaching

Nitrate leaching from the out of river use of Rakaia River flows used for irrigation in Central Canterbury is a growing source of pollution of the region’s aquifers and lowland spring fed rivers and streams that threatens both public health and aquatic ecosystems.

Deposed (elected) Ecan councillor Eugenie Sage, (2007 -2010), wrote in a submission to a 2012 Ecan Hearing, that it would be reckless and irresponsible to give consent to the Central Plains Water irrigation scheme until the regulations and a means to manage nitrate leaching was developed. Sage did not re-present her submission under revised rules of the Hearing following the death of one of the three Hearing commissioners. Given the importance of this advice it is fair to ask why not?

The ex-councillor included in her initial submission the observation that salmon and trout anglers risked losing their protected fishery without any compensation or mitigation from TrustPower.

A growing number of rural Central Canterbury wells used for drinking have nitrate levels that exceed New Zealand’s and the WHO’s MAV for NO3-N (11.3 mg/L).

  1. TrustPower

The prime beneficiary of the Ecan 2012 Lake Coleridge Hearing to amend the Rakaia River NWCO was TrustPower.

By simply defining water comprising of around 40% of the entire Rakaia River catchment that is diverted through Lake Coleridge as part of an existing consent for the Coleridge HEPS and is returned to the natural river flows as “stored water”, TrustPower was awarded the right to sell water newly defined as “stored water” under a complex set of conditions proscribed in the amended WCO to both CPW and BCI.

Other than the (tax deductible) costs of the consent hearing, TrustPower now has public water for sale without any need construct any additional storage means, simply time its electricity generation the requirements of the irrigation schemes.

Trustpower is entrusted to manage the sale and storage of this (public?) water – Clause 9A Lake Coleridge Project (3)(a)(b)(c)

Rakaia salmon and trout anglers believe this cosy arrangement is very opaque and have asked Ecan that accounting of this water be made public. ECan has not replied to NZFFA’s initial request which included concerns about consents allowing sediment to be discharged into the Rakaia River by both TrustPower and CPW. Anglers are also concerned about the wide swings in Rakaia River flow recordings since this regime commenced including the potential effect of sudden de-watering of affected reaches of the river.

The CRC consent TrustPower holds to divert water into Lake Coleridge has conditions relating to the amount of sediment entering Lake Coleridge.

Do these conditions have meaning?

, The Rakaia River – Canterbury’s troubled water

, The Rakaia River – Canterbury’s troubled water

  1. North Canterbury Fish & Game

North Canterbury Fish & Game’s involvement relating to the Rakaia River NWCO Amendment contrasted starkly to the passion and success of the previous Ashburton and North Canterbury Acclimatisation Societies. The then NCFG CEO altered F&G’s position from opposing the consent applicant to approving the Lake Coleridge Project after TrustPower offered F&G the use of Whiskey Creek for a hatchery.

When questioned on his action, the CEO explained that as a lawyer he saw no chance of influencing the decision and as a result took the option above to save wasting F&G resources. He since became an ECan councillor.


The 2013 amendments to the Rakaia River NWCO (1988) caused significant harm to the Rakaia River and its fisheries. The expert opinion of Trustpower’s expert witnesses at the, (Ecan managed), Lake Coleridge Project (LCP) irrigation Hearing that the effects of the LCP would be “minor or less than minor” has been found wanting. Now we have witnessed the effects of Stage 1 & II it is evident that these expert witnesses were not expert.

Construction of the consented Stage III has yet to commence and will involve the abstraction of a further 30 m3 from an already badly compromised Rakaia River.

If the Rakaia River NWCO has any meaning then Stage III of the Lake Coleridge Project should be re-examined in the Environment Court before any work on Stage III commences.

Ecan, together with its government masters, appears to have paid scant regard to the once outstanding features of the Rakaia River and its NWCO in their hell bent race to increase GDP.

What we lost

, The Rakaia River – Canterbury’s troubled water

Dr Peter Trolove BVSc MSc MBA


New Zealand Federation of Freshwater Anglers

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