Waimea Dam Update
Ensuring a sustainable water supply to the communities and businesses on the Waimea Plains
Since the drought of 2001 there’s been a move in the Nelson region to find a way to make sure there is enough water in the Waimea catchment for the community and its businesses. Since 1985 more water has been used on the Waimea Plains than the river can provide, and water has been rationed for years, however it has been recognised that rationing will not be enough in the long term.
Climate change is expected to bring slightly more rainfall, in heavier bursts, but is also tipped to double the time spent in drought each year. Aquifers will also be more at risk from saltwater contamination from rising sea levels.
After 12 years of research the best solution that has been identified to these issues is the Waimea Community Dam, and along with the Waimea Water Augmentation Project, its believed these will provide a secure water supply for the expected demand.
Murray King is chair of the Waimea Water Augmentation Committee.
He says the catalyst for the dam was the 2000 to 2001 drought, when the lower reaches of the Waimea River went dry. There are two arterial routes crossing the river, one at Appleby, the other at Brightwater, so it was front of mind for people every day.
“The Tasman District Council needed to consider minimum flows in the river, and the minimum flow set then was unsustainable.”
“They realised they had over-allocated water by up to 70% in some areas. So they were keen to increase the minimum flow, but at the same time, realised the water was over-allocated.”
“In the absence of augmentation, we have invested heavily in our properties, and we are going to make the water supply even more unreliable.”
“That was the catalyst for a multi sector group approach to the problem, which included water zone representatives, both the TDC and Nelson City Council, DOC, iwi, and Fish and Game. This group was formed in 2003, and its recommendation was that the solution to the problem was a dam on the Lee River.”
“In the mid 1980s the Waimea East Irrigation community took water for 1000 ha directly from the river. All of the other takes are from groundwater. It’s a hugely well understood resource. We have had water meters in place for 30 years. “
“The other thing that gave us confidence was the small Kainui Dam which is in the Wai-iti Catchment, and which we know works. It releases water into the river, supplementing the direct takes. Like the proposed dam, it doesn’t use pipes or channels to deliver the water.”
“It took a couple of years to identify options and select sites, then carry out feasibility studies and a lot of geotech work and investigations were done. Some geotech issues meant the footprint of the dam was shifted further up the river. “
“A lot of design work and detailed drawings to 85% of completion have been done. This all led to a resource consent to dam the river being granted just over two years ago. Since then the concern is who pays for the dam, and how much they pay. The process since then has been slowed due to council consultation requirements.”
“Construction is expected to start later this year or early next year and take two years, with a further 18 months to fill the dam.”
“It’s a concrete faced rockfill dam, with just under 60 ha of water behind it. It will be constantly spilling water, and will also be able to release water for flushing flows to clean out algae from the river.”
“Water will be able to be taken from different levels of the dam to maintain water quality. And it’s designed for around a one in 24 year drought security.”
“The dam is 52m high and will hold 13.4m cubic metres of water, big enough for the current shortfall and demand for the next 100 years. About 5000ha of land will be able to be irrigated from the dam.”
“For irrigators, the cost will be a $5000/ha one-off capital charge with approximately a $500/ha annual operating cost which will cover insurance, rates operating finance costs.”
Murray says the dam is not just about irrigation of high value horticultural crops but also provides for urban water and environmental and recreational benefits.
John Palmer is well known for his roles in business and governance in horticulure and other business sectors. He is also an orchardist and strategic advisor to the irrigation company. He has first hand experience of what such a scheme brings to an area at his Waimea West orchard.
John says getting this dam built is probably the single most important thing that should happen in the region as a long term investment for water security.
“The water quality of the river will now be mandated, and water security for land users is essential for both food production and the industrial supply for the Tasman District and Nelson City Council.
“Without a major investment all of this is in peril. There’s a feeling that ratepayers are subsidising irrigators. The community depends on the economic activity of the region. Intensive land use on the Waimea Plains is a critical economic and social driver.”
“The sole reason we expanded our business to Tapawera was because of the availability of water we didn’t have here. The only reason we have been able to intensify here in the last 15 years is because of the Kainui Dam. Water security is the basis for investment. That enables taking very low returning land, and intensifying it by a factor of 20 at the farm gate. We have moved from dryland farming to horticulture.”
“There are two guarantees; the first is that if there is no dam and no augmentation, there will be no more investment in land use intensification and hence economic activity.”
“You don’t plant apple trees hoping that they will survive. You need water as the basis for that investment. The things the region is really good at growing – apples, kiwifruit, berryfruit are long term crops, as are glasshouse crops. They require substantial investment. If they lose water for a day, they lose substantial income. Water is critical for our economic and social well being.”
“It is also certain that at individual property levels, in the absence of water supply, there will be disinvestment and landowners will have to reduce the intensity of their businesses, even where they are 100% developed. The economic cost of that is enormous.”
“A report in late 2016 estimated a cost to the community of $700 million without the dam. That includes the impacts on existing water users, the cost of alternative water supplies for the Tasman District Council and Nelson City Council and the cost of environmental improvements in the Waimea River.”
“That is because without augmentation, the water allocation and permits will reduce because water is over allocated, and minimum flow levels for the river will be introduced. As a result of the increased minimum flows, without a dam, and in a normal year, irrigators can expect a 30% rationing, but in a bad drought year, it will go as high as 70% rationing. No new water permits will be possible.”
“The most recent bad drought in the catchment was in 2001, when parts of the river dried up.”
“There is also a pressing need for more water in the urban areas around Richmond and the communities around the edge of the Waimea Plains, for example like Ruby Bay and Mapua, which do not have enough water to expand. In the absence of a secure water supply that will constrain the growth of the region.”
“There is also a long term problem for Nelson City in terms of supply and quality of urban water. The eastern hills catchment that flows into the Lee catchment is critical to that.”
“The review of water rights in the catchment was going to happen this year but has been extended a year to enable irrigators to sign up for the dam.”
“If the dam is going ahead then people who are shareholders in Waimea Irrigators who have affiliated water permits will be able to continue to take water when the river level at the Wairoa Gorge drops to 1200 litres/second. But if you are unaffiliated, you will have to cease your water take.”
“If there is no dam, there will be very little water anyway, and if there is a dam and you are not a shareholder in most years you won’t have any water.”
“For lifestyle block owners with a two to five hectare lot, it would only cost them $5000/ha to protect the value of their lifestyle investment. It’s a complete no-brainer.
“The dam is already consented, but we have already gone two years out of that seven year consent time frame. If we don’t take this opportunity as a region it may be lost forever, and irrigators and everyone in the region will be poorer as a result.”