Saturday, May 5, 2012

Bridges' Future Unaffected

Bridges' future unaffected
By Helena de Reus, on Friday 4 May 2012
Otago Daily Times

Contact Energy's recent announcement it is shelving plans for further development on the Clutha River will not affect the future of two Clutha bridges.

The 124-year-old bridge at Beaumont and the Clydevale Bridge, both one-lane bridges which span the Clutha River, are scheduled for replacement or upgrading.

Earlier this week, Contact Energy announced it had withdrawn plans for further hydro development on the Clutha River and it would review management and ownership of its land holdings near the river.

A search of property records by Clutha District Council staff showed Contact Energy held 37 properties in the Clutha district totalling 2989ha and with a capital value of $26.3 million (figures from 2008). It is unclear how much of this property was earmarked for use in potential dam projects at Beaumont and Tuapeka Mouth.

New Zealand Transport Agency acting Otago-Southland state highways manager Ian Duncan said Contact Energy's recent announcement it was shelving plans for the Clutha River would not make the replacement bridge at Beaumont a higher priority.

Mr Duncan said the agency was still looking at building a new bridge at Beaumont in the 2017-18 financial year. Investigation work was scheduled to begin by 2014.

The Beaumont Bridge is funded solely by the NZTA.

Clutha District Council district assets manager Jules Witt said the Clydevale Bridge already had "reasonably high priority" with the Otago Regional Transport Committee and he did not believe the bridge would have been affected even if Contact Energy's developments had gone ahead.

Last year the Clutha District Council decided to upgrade the Clydevale Bridge to class 1 load capacity. Strengthening the bridge to class 1 would cost about $974,000. The council's share was estimated to be $390,000. NZTA would foot the remainder of the bill. The decision whether to build a new bridge would be reconsidered in 20 years.

Mr Witt said the council had budgeted for the strengthening and repairs in the 2012-13 financial year.

More...

Thursday, May 3, 2012

Call For Ethical Repatriation Of Land

Call for ethical repatriation of land
By Marjorie Cook, on Thursday 3 May 2012
Otago Daily Times

Contact Energy's review of its Clutha River land bank has sparked calls for the electricity generator to be a "responsible corporate citizen" and repatriate land ethically, while securing critical public access easements.

Contact Energy confirmed this week it had withdrawn plans for further dams on the river and would include its land holdings in a review of its $100 million national property portfolio.

Contact group communications manager Janet Carson yesterday declined to comment on the value and size of the Clutha portfolio, but confirmed "all the land was inherited" from Electricity Corporation of New Zealand and "includes parcels in the Clutha, Central Otago and Queenstown Lakes regions".

The holdings would be "sold as appropriate over time" and there was no end date for concluding the process, Ms Carson said.

The Otago Daily Times understands Contact Energy owns 95 properties in the Central Otago and Queenstown Lakes districts and another 40 in the Clutha district.

They include everything from farms to town sections.

It is also understood some of Contact Energy's larger properties around Beaumont are in discussion and valuation for sale back to farmers, while smaller properties nearer the waterline are believed not to be on the market.

Clutha River Forum co-ordinator Lewis Verduyn, of Wanaka, said yesterday the land bank review "has the potential to become a highly contentious issue" and warned how Contact proceeded could "stir up further resistance, or calm the waters".

"Much of the approximately 4400ha of land held by Contact along the Clutha was seized in the 1980s and some has subsequently been leased or rented back to the original owners, who have been subjected to a considerable cost.

"These people were literally made tenants on their own land, and they could now be shafted again if Contact opts for a quick capital sell-off.

"Long-term tenants are in a similar situation, having invested in their leased properties, while for many years their corporate landlord ignored them.

"But Contact could also act as a responsible corporate citizen by building community relations through the ethical repatriation of land.

"The occupants of this land, including farmers, should be able to purchase it on fair terms that acknowledge their investment in it.

"Such terms should include the option to purchase on a lease-to-own basis, with consideration given to the significant moneys already paid.

"Much of the Contact land within the river corridor is also critical to public access and should be vested in the conservation estate to be managed by Doc, along with adjoining public conservation lands.

"This would add considerable surety to the viability and success of river trails presently being constructed by community groups.

"All this could be done while retaining rights for future hydro development, though I can't envisage that happening," Mr Verduyn said.

Upper Clutha Tracks Trust chairman Tim Dennis, of Wanaka, said yesterday Contact Energy had supported the trust's projects and provided access easements.

It was now time for anyone with informal public access across Contact Energy's land to "shore up" those easements, he said.

"But I can't imagine they will get rid of their land any time soon.

"They might decide they want to hold on to it for another 10 to 20 years.

"The consenting environment might change, the energy demand might change.

Once it is sold, it will be hard to get it back," Mr Dennis said.

Otago Federated Farmers president Mike Lord, of Outram, said farmers would be "waiting with interest" to see what Contact would do.

"These things can take quite a bit of time and it is not going to be a quick process.

"A lot of that land is leased out and not all the leases will expire tomorrow.

"It is an opportunity for those lessees to be able to buy in, too," Mr Lord said.

Former landowners who felt squeezed off the land might now feel some bitterness and it might well be that land could be offered back to those people, he said.

Other options might include selling the entire Clutha portfolio at once to another power generator, such as Meridian, entering into sale agreements with lessees, putting the land on the open market or offering it in a ballot, he said.

"If I was Contact, I would be looking for the best value that I could. I would be looking at all the different options," Mr Lord said.

Mr Lord said it would be prudent for Contact Energy to finalise access easements before selling the land, to avoid problems down the track.

More...

Wednesday, May 2, 2012

Windfall For Contact Shareholders

Windfall for Contact shareholders expected
Tuesday 1 May 2012
TVNZ ONE News

Contact Energy shareholders can expect a substantial boost to cash flow from 2014 onwards as the company completes geothermal projects, winds back major capital spending and seeks to sell some of its $100 million of development land holdings.

The company's decision to all but abandon long-held hydro-electricity developments on the Clutha River was part of a wider drive to strip capital project costs out of the business for the time being, said chief executive Dennis Barnes.

Contact cited weak national electricity demand, the challenge of gaining resource consents and better options elsewhere for putting on ice hydro-electricity projects that could potentially double its output from the Clutha River, and beginning a process of selling land holdings in the area.

The Clutha options were not commercially viable "in the foreseeable future".

Contact already has 752 MW of installed capacity at the Clyde and Roxburgh hydro stations on the Clutha, and inherited options for developments at Tuapeka Mouth, Beaumont, Queensberry, and Luggate totalling 763MW when it was corporatised in the mid-1990's.

Since then, the company has periodically examined its Clutha options, while fending off criticism from local communities that a lack of clarity about its plans was impeding economic development.

A review of calculations last made in 2008 had shown roading infrastructure costs would be far higher than originally estimated, while the size of each project was too large to consider building for the foreseeable future.

Asked whether the decision signalled the end of "big hydro" in New Zealand, Barnes said: "I don't believe so, but I can't answer the question for 15 to 20 years."

It would be 2025 "at the earliest" before any of the Clutha options made sense to re-examine.

"We will stop spending money on it," he said. "Project development pipelines need to show a return and we needed to take the community to an honest point.

We decided we wouldn't do any work for seven, eight or 10 years, and it was fair to tell them that."

Contact also had more attractive geothermal and wind development options than any of its large hydro prospects, although it has extended for one year its resource consents on a small hydro scheme attached to the control gates on Lake Hawea, the only controlled storage lake on the Clutha system.

Barnes said one of his chief tasks in the last year had been to strip out capital development costs from the business, and to start implementing a more active land management policy to rationalise the company's approximately $100 million portfolio of development and other land holdings around the country.

The Clutha decision is still a step away from complete abandonment, with Contact proposing in some cases to sell land with encumbrances either to allow a future hydro development or preventing sale to a competing hydro developer.

"A dammed river is a very significant energy resource and will have a value over a timeframe," he said.

The company is taking a similar approach to land purchased for its mega-wind farm development in the North Island, on the coast north of Raglan, selling property with a future development right attached.

Contact owned only about 20% of the land it required to build any of the proposed Clutha dams.

No decision had yet been made on exactly how much of its land holdings would be marked for disposal, Barnes said.

He conceded also that resource consents in the lower South Island were likely to take longer and be more costly to obtain than in some other parts of the country.

"Our view is that if you take your time and are transparent, they are consent-able," he said. "But in that part of the country, the community conversations take longer and cost more. It's different from Wairakei, where the community embraces geothermal development."

Barnes said that once the 166MW Te Mihi geothermal plant was completed in 2013 that would bring to an end four years in which Contact had committed an average of $500 million of capital annually.

"It will drop to $100 million or less. The balance goes to cash flow. You will see that very strongly in 2014."

Contact shares traded unchanged at $4.85 on the NZX and have declined about 8% this year.

More...

Contact Should Atone: Resident

Contact should atone: resident
By Lynda van Kempen, on Wednesday 2 May 2012
Otago Daily Times

Beaumont resident Margaret Healy says she can finally "chuck away the snorkel" after living for years with the threat of the area being flooded if a hydro dam was built on the Clutha River nearby.

Contact Energy announced on Monday it was dropping its plans for further hydro development on the river, saying none of the options for dams at Beaumont, Tuapeka, Luggate and Queensberry were viable "in the foreseeable future".

Beaumont residents and former residents who opposed further hydro development on the Clutha welcomed the decision as "long-awaited and absolutely marvellous", said Mrs Healy, who is the secretary-treasurer of the Beaumont Residents Group.

It had been daunting to live for the past 20 years with the prospect of a dam that might flood the area "hanging over" them.

Contact owed Beaumont some compensation for the impact that uncertainty had had on the community, she said.

"The threat of the dam has changed the whole area and influenced a lot of things over the years, including the population in the area. The local shop closed as well as the school, and people stopped buying land here and took out orchards. We feel Contact owes us some compensation to make up for all that."

Compensation could take the form of the community being "gifted" the former shop building, which was owned by Contact, or the company could contribute to a new roof for the Beaumont Hall, Mrs Healy said.

Asked whether Contact would offer any "compensation" to Beaumont, Contact group communications manager Janet Carson said: "We're part of this community and contribute where we can.

"We have been working with locals about the shop for some time and will continue to see what's possible.

"We have also, just today, received a request for assistance with other [Beaumont] community-related matters, which we are also considering," she said.

Contact was involved in community projects throughout the region but the contributions it made should not be viewed as "compensation", she said.

Mrs Healy said Beaumont was a special place and she had received a steady stream of emails and phone calls yesterday from people saying they were "delighted" at the cancellation of the dam plans.

"Lots of them were people who used to live here.

"One even said, 'Hooray, I can still be buried in the Beaumont cemetery when I die'."

Under the proposal for a dam at Tuapeka Mouth, the cemetery would have been flooded, along with the Beaumont township.

Mrs Healy and her husband have lived on a 0.4ha block of land near the Beaumont bridge for the past 35 years.

Plans for a Tuapeka dam were first mooted in 1965 by Contact's predecessor, the Electricity Corporation of New Zealand, and the project has been reconsidered several times since then.

"It appears that threat of a dam has been virtually removed now that Contact is concentrating on other energy projects like geothermal projects," Mrs Healy said.

"We used to joke we'd be well under the water here and we'd need a 30m snorkel ... well, now I can chuck away the snorkel."

There would be nothing holding back progress in the area now that uncertainty was gone, she said.

People would be able to plan for the future and buy and sell land freely.

More...

Decision On Dams No Surprise

Decision on dams no surprise
By Lucy Ibbotson, on Wednesday 2 May 2012
Otago Daily Times

Contact Energy's decision to drop its hydro development plans for the Clutha River has come as no surprise to local government leaders in the district.

Clutha Mayor Bryan Cadogan had been "semi-aware" of Contact's intentions for some time.

He said the prospect of dams on the Clutha River had "polarised the community", and it was good to have some closure on a long period of uncertainty.

"I suppose if nothing else it gives certainty now for the future because for so long we've been saying 'Imagine if the dam happened' ... It's better to be dealing with the facts and move on with reality ... so onwards and upwards."

Mr Cadogan said there would never have been a "ready acceptance" of hydro development from the community if the project had proceeded.

"To have development in the district is something that we're always looking for, but it's got to be the right development and it's got to have community support."

The news Contact had cancelled its dam plans was not unexpected for Central Otago Mayor Tony Lepper, either.

"Only because I thought they were expensive power projects to go through with and obviously they've come to the same conclusion," he said.

"It's probably disappointing to miss out on the economic benefits, but I'm sure there's other economic benefits to come out of that river and we'll just have to make the most of those."

Mr Lepper said on a personal level, he was "rapt" there would be no dam proceeding at Luggate, where he regularly kayaked.

"I think that's one of the nicest stretches of river in New Zealand and I play on it all the time.

"I'm very pleased that it's going to be around for a bit longer."

Queenstown Lakes deputy mayor Lyal Cocks said the decision was "appropriate", based on information Contact had provided throughout the process and the division the dam proposals had caused within the district's communities.

"It's been an issue that we've been on the edge of for a while watching the progress ... I think it's an appropriate decision looking at the way the numbers stack up as they've [Contact] indicated to us."

He said there were other options for power generation that were more feasible

More...

Contact Ditches Clutha Hydro Plans

Contact ditches Clutha hydro plans
By Che Baker, Tuesday 1 May 2012
Southland Times

Contact Energy has announced it will no longer proceed with developing hydro generation on the Clutha River.

Contact chief executive officer Dennis Barnes said investigations during the past three years at four different sites along the river, at Queensberry, Luggate, Tuapeka Mouth and Beaumont, have shown none of the options was viable.

"It has become clear that all future Clutha hydro options came in at a much higher cost per megawatt to build than the next available new geothermal and wind generation options,'' Mr Barnes said.

The decision to stop development of the hydro options was based on an assessment of the economics of each option and took into account a range of technical, environmental, social and cultural factors, he said.

As part of Contact's land management strategy, it will be reviewing its land holdings near the Clutha River.

More...

Tuesday, May 1, 2012

Contact Pulls Plug On Dams

Contact pulls plug on dams
By Lucy Ibbotson, on Tuesday 1 May 2012
Otago Daily Times

Contact Energy has withdrawn plans for further hydro development on the Clutha River and will review management and ownership of its land holdings near the river.

The decision, announced yesterday, comes after Contact signalled in February delays in its plans to develop a new hydro-generation facility on the Clutha River, saying the project was on the "back burner" and geothermal energy remained a priority.

Contact spokeswoman Janet Carson said at the time the four Clutha hydro-development options, at Tuapeka Mouth, Beaumont, Queensberry and Luggate, "remained open", but were "more likely to be further down the track, probably into the next decade".

Contact announced in 2008 it was revisiting plans for dams on the upper and lower Clutha, costing between $300 million and $1.5 billion, which were originally proposed more than 20 years ago by its predecessor, the Electricity Corporation of New Zealand.

Contact hydro projects manager Neil Gillespie confirmed last night he had notified "as many of the stakeholders and people that we've talked to over the last three years" of the formal decision to end the Clutha hydro-development project.

"Contact has decided not to proceed with any of the options being investigated for hydro-generation development on the Clutha at this time and has ceased all work pertaining to it," Mr Gillespie's email yesterday to affected parties said.

However, he told the Otago Daily Times last night he could not permanently rule out hydro development on the river, as "who knows what the future holds".

Contact will now review future management and ownership of all its land holdings near the Clutha River as part of its ongoing land management strategy.

Mr Gillespie was unable to provide details on the extent of that land, but confirmed selling it was "one of the options that could come out of [the review]".

In a media statement, Contact chief executive Dennis Barnes said the company's investigations during the past three years had shown none of the options considered were viable for development.

"It has become clear that all future Clutha hydro options came in at a much higher cost per megawatt to build than the next available new geothermal and wind-generation options. On current demand forecasts, the Clutha options are not economic in the foreseeable future," Mr Barnes said.

"Contact has a range of new generation in the pipeline, either confirmed, consented or under construction, to meet foreseeable electricity demand for our customers."

Clutha River Forum, an alliance of river and conservation groups opposed to "think-big" hydro development on the Clutha, was set up in 2009. Forum co-ordinator Lewis Verduyn, of Wanaka, said yesterday's announcement was not a surprise.

"For some time now, we have known that New Zealand energy companies have been experiencing a low-growth environment in the wake of the global financial crisis," Mr Verduyn said.

"Consumers are cutting back, capital costs remain high, lake storage levels remain erratic, and there is now sufficient new generation either coming online or consented for some years ahead.

This decision, then, must be welcomed as a sensible one for Contact shareholders and river communities alike.

"What we need most now are energy-smart technologies, since efficiency is less than half the cost of new generation. It would be reasonable to say that unless we return to pre-2008 economic growth, which isn't going to happen, that the era of large dams is over."

Mr Gillespie declined to comment about how much Contact had spent developing the Clutha project, as it was "commercially sensitive".

More...

Clyde Dam Highly Problematic

Since the filling of the Dunstan reservoir behind the Clyde dam was completed in 1993, the Clyde dam controversy has faded in the minds of most New Zealanders. But the woes of the last 'think big' project have not gone away. Despite extensive and costly mitigation measures, issues remain regarding gorge instability, faultlines, and reservoir sediment build-up.

The Cairmuir-Dunstan Fault cuts across the gorge just above the dam, and the River Channel Fault disects the dam and the powerhouse. The discovery of the River Channel Fault came as a surprise to dam workers, who uncovered the micro-fractured rock running in a wide band along the riverbed. Obviously, fissured rock is not suitable for dam foundations. The first solution was to pump vast amounts of slurry concrete into the fault, but concerns mounted over the extent and depth of the faultline, and the likely futility of 'dental' concrete.

Finally, experts were called in to determine the extent of the fault issue. It was calculated that the River Channel Fault was 12-15km deep. This lead to a dam re-design in 1982 (during which a sluice channel was omitted leading to later modifications that reduced the dam's MW output by one-third). Subsequent investigations carried out by a team of some 40 geologists revealed serious instability issues throughout the gorge. The result was an incredibly expensive gorge stabilization programme, costing $936 million dollars (2005 value), resulting in the total cost of the project blowing-out to $1.4-1.8 billion dollars. The exact cost is unavailable or unknown, suggesting the true cost could be even higher.

There was considerable doubt over whether or not the dam would be safe, but in the end the government of the day, under Prime Minister Robert Muldoon, refused to admit that the project had been botched, and it was finished, complete with a controversial 'slip-joint' to accommodate earthquakes up to, supposedly, 7 on the Richter Scale.

The 'slip-joint' was hailed as an engineering achievement, but one of New Zealand's most respected geo-technical scientists at the time, Gerald Lensen, insisted that it was designed incorrectly, because the River Channel Fault is 'tensional' (pulling apart) and not 'lateral' (slipping sideways). Needless to say, this fact has been kept quiet ever since.

Now, according to GNS scientists, the 'big one' is overdue along the Alpine Fault (bigger than the 7.8 Fiordland quake in July 2009). Meantime, the 6,500 measuring and monitoring stations quietly observe the landslide movements, reduced but not stopped, and visible silting up continues in the Kawarau Arm at an alarming rate estimated to be 1.46 million cubic metres per year, building up the reservoir bed profile by an estimated 1.85m annually.

The Decline of Large Hydro

In the 21st century, energy that is "renewable" is defined as energy from a source that is both naturally replenishing and environmentally safe and sustainable. The term “new” renewable energy has also been used to define the latest wave of renewable technologies that are truly environmentally sustainable.

By such standards, hydropower over 10 MW is no longer considered renewable because the negative impacts of large hydropower outweigh the so-called renewable benefits, which have inherent limitations.

In New Zealand, we are told that to maintain our present society and standard of living we need a minimum increase in power availability of 2.5% per annum (peak power), with 170 MW of new generation added each year. Based on this figure, we would need the equivalent of one Luggate dam (86 MW) every 6 months, or one Tuapeka dam (350 MW) every 25 months, or another Clyde dam (432 MW) every 29 months. Clearly, this is not a credible long-term solution.

World-wide, large hydropower declined in the 1990s because of mounting opposition that culminated in the World Commission on Dams report (2000), which acknowledged that large dams do not meet best practice guidelines in the water and energy sector. The global recession spurred more large dam projects, especially in developing countries, but the tide has turned and large hydro is again in decline as new renewable technologies sweep the world.

The intrinsic problems associated with large dams have long been glossed over. Hydroelectricity is often falsely promoted as cheap and reliable. While the operating costs of hydroelectric dams can be relatively low, their construction costs are extremely high, running into the billions of dollars for major projects. They are also prone to cost overruns. The WCD (World Commission on Dams, 2000) found that on average dams cost 56% more than forecast. And 55% of the hydroelectric projects studied by the WCD generated less power than planners promised.

New Zealand's Clyde dam is an obvious example of disastrous cost overruns. According to the public record, the 1982 winning bid from the joint venture of W. Williamson & Co. of Christchurch and Ed. Zublin AG of Stuttgart, was $102.6 million. Ten years later when the dam began producing power, the cost had climbed to $1.4 – 1.8 billion. Conversely, the planned generation of 612 MW had fallen to an actual capacity of 432 MW.

Typically, construction and mitigation costs are under-estimated, long-term costs are ignored, the value of the proposed dam and mitigation measures are inflated, while the value of the current and potential benefits from the existing environment are under-reported.

The proponents of large dams also invariably claim that large hydropower is "green" energy. However, the carbon footprint of a large-scale hydro project is anything but "green". A comparative study at the University of Auckland found that large hydro has a full-life carbon footprint that is 2.5 times larger than that of tidal energy.

A similar comparative study in the U.K. found that in terms of grams of CO2 equivalent per kWh of electricity generated, large hydro in the U.K. comes in with a carbon footprint 2 to 6 times larger than that of wind power. Specifically, large hydro has been measured at 10-30gCO2eq/kWh while wind has been measured at only 4.64gCO2eq/kWh, the lowest except for nuclear (Carbon Footprint of Electricity Generation, 2006).

It is easy to understand why large dams rate so poorly. For example, the Clyde dam contains 1 million cubic metres of concrete, equivalent to about 3 million tonnes. Manufacturing one tonne of cement requires 4.7 million BTU’s of energy, which is the amount contained in about 170 litres of oil or 190 kilograms of coal. Obviously, this combined with emissions from machinery involved in earthworks for foundations, roading, terrain forming, landslide mitigation, and through the loss of river corridor carbon sink forests or vegetation, adds up to an enormous carbon footprint.

There are over 54,000 large dams in the world, some 5,000 of which are over 50 years old. The typical design-life of such dams is 80 years, and an increasing number of old dams are being classified as high risk. It is a telling fact that more dams are being decommissioned than built in the U.S., but dam owners typically avoid decommissioning issues and try to evade the considerable costs associated with dam removal and river restoration. This scenario points to a looming dam safety crisis.

In the past, the benefits of large dams were viewed as outweighing their obvious short and long-term environmental impacts. That has changed.

Large hydropower once represented the epitome of 20th Century technology and a passport to prosperity, projecting a misguided belief that Nature could be controlled without consequences. In the 21st Century, we face a new reality, for which 20th Century energy solutions are unacceptable.

Roxburgh Dam Decommissioning?

The Roxburgh dam was commissioned in 1956, and it is New Zealand's oldest concrete gravity dam. Such dams have a design lifespan of 80-100 years, but the actual lifespan of a dam depends on the rate at which its reservoir fills with sediment. Assessing the remaining life of a dam and reservoir is complex, but reservoir flooding events indicate that time is running out.

When other issues are added to the picture, questions must be asked.

The Roxburgh dam - like the Clyde dam, has faultine and landslide issues that are potentially catastrophic (something which has been kept quiet). However, when the Roxburgh dam was built, there was minimal geotechnical investigation and mitigation undertaken, despite obvious evidence of major landslides in the Roxburgh Gorge, notably at Island Basin.

But reservoir sedimentation is the most problematic issue. In fact, within 15 years of the dam's commissioning, the dam's two low level sluice gates were inoperable, and since then the silt burden has filled much of the Roxburgh reservoir reaching back to Alexandra. In 1995, ECNZ estimated that 1.5 million cubic metres of silt had entered the Roxburgh reservoir every year before the Clyde dam was built, and that a total 50 million cubic metres of silt had accumulated in the reservoir, raising the bed profile 'considerably'. Attempts to 'flush' the silt have had little effect, and have not reversed this process. This is probably because of the 'Gates of the Gorge,' a narrow bottleneck just below Alexandra.

As a result, Alexandra has become flood-prone, and has installed flood defence walls along the river. But even these will not be high enough to prevent future flooding, because the riverbed will gradually keep rising. It was thought that by building the Clyde dam that this sedimentation problem would be largely solved, but some silt still gets through to continue choking the reservoir and river, and the Manuherikia River still contributes silt when it is high.

Efforts continue to "buy time" for the Roxburgh dam. More "flushing" will only move some of the sediment load further toward the dam. (Flushing has failed to remove sediment wherever it has been tried, including on the Colorado.) Physically removing millions of cubic metres of sediment is not practicable because of the costs involved. An interim measure is to remove some sediment from the Manuherikia confluence, and also from the Galloway area, but this does not address the major constriction at the 'Gates of the Gorge.'

The most desperate strategy is to raise the operating level of the Roxburgh reservoir, and this was done in 2009 when a rise of .6m was consented. While this allows water to reach the dam more easily, it also increases the risks associated with flooding events, both at Alexandra and the dam. In the life cycle of a dam, this is the "Russian roulette phase."

The dam owners and the Crown must face up to the fact that the Roxburgh dam and reservoir will not last forever, and that enormous risks are imposed on communities in the meantime. A feasibility study is needed to determine the most effective decommissioning and de-silting methodology. Where such dam removal projects have been undertaken overseas, the costs as a proportion of construction, range from 35% to 150%.

However, since there has been no provision for the ultimate decommissioning of the Roxburgh dam (typical of the hydropower industry), there is something of a head-in-the-sediment policy on this issue.

Questions should be asked, including the most difficult question of all ... when the time comes to decommission the dam, who will pay?

© Clutha River Guardian 2009-2012