Brooklands Dam Joint Venture

About 11 years ago the Bygrave and Anderson families (Bill and Christine Bygrave and John and Audrey Anderson) formed a joint venture to build a large dam to supply irrigation water on their drought-prone Northland dairy farms. The result has been a significant increase in summer production. About three years ago they offered their excess water to the Fonterra plant at Maungaturoto, which had become seriously short of water in summer. The 6km of pipeline is just about completed. Thus a major speculative venture has become a key element in the profitability of two farms and the continued viability of the dairy factory and surrounding township.

Detail:

11 years ago Bill was a director of what was then the Northland Dairy Company. The Company wanted to find ways in which Northland dairy farmers could overcome drought conditions that affected seven out of ten summers, so they organised a trip to Victoria and Tasmania looking at drought-proofing strategies. Irrigation from dams was one of them, and Bill returned very enthused. An Australian expert subsequently visited Bill but could find no suitable dam sites on his property. However, Bill’s neighbour, John Anderson, had a very good site on a run-off 3 km away in the southern Brynderwyns.

They planned a very large structure that would occupy 20 ha, have a wall height of 25m, be 28m at the deepest point and have a capacity of 1.3 million m³. It took six months to build the dam at a cost of nearly $600,000 which was a lot of money in those days. Resource consent cost $30,000, and gaining it meant lots of consultation with local people and iwi, and addressing concerns about its effect on streams and wildlife.

It was a huge undertaking – the dam is essentially a valley that has been blocked off and flooded, and the structure is listed in the New Zealand Register of High Dams. Water is gravity fed down a creek from the runoff to the Anderson property about 1.5km away, where it goes into a holding pond. The pond overflow goes back into the creek and another 1.5km to the Bygrave’s holding pond. Irrigation water is pumped from the ponds.

It has proved to be a success – the ability to irrigate has drought-proofed both farms and boosted production.

Says Bill: “Christine compared records of the five years prior to our starting irrigation with the three years after, and she estimates that we increased production by 50 kgMS per cow per year. We typically irrigate for 12 to 14 weeks a year, and this gives certainty to our summer production.”

Even in the driest of summers the two farms use only about half of the available water, so they had plenty to spare. Some years ago Bill read in a local paper that the Maungaturoto dairy factory was running short of water in summer. Pressure was being put on Fonterra to reduce its intake from local streams so that minimum flows could be maintained. They had looked at constructing dams but had not found a suitable location.

When John and Bill approached the factory manager he was very interested, and they set about negotiating a contract and working out how water supply to the factory could be achieved. A major sticking point was meeting local Council requirements, and it took three frustrating years to come to an agreement.

However, that was finally achieved, and construction of 6km of pipeline (cost $1.3 million, paid for by Fonterra) is now almost completed. Through the local Council Fonterra will this summer have the option to take up to 270,000 m³ per year and possibly more if there is water available.

Looking back, although there have been problems, John is pleased they took their original decision.

“It has guaranteed my production, and I haven’t had the ups and downs that I experienced prior to putting in irrigation. That’s been a great benefit particularly with the good payout in the last couple of years. The initial investment was a large sum at the time, but it has certainly been well worth the effort and expense”, says John.

When the project first started there was some controversy locally over what was going to happen to the creeks, but Bill says that the scheme has actually improved them.

“We have had a commercial eel farmer coming onto our land for the past 30 years and since we have had the dam with the water running through the creeks, keeping everything moist and the drains running even in summer, he says that he has never seen such beautiful eels, so the wetland areas and life in the drains have been enhanced,” he says.

John agrees. “The dam is in a very protected spot with bush around 60% of it right down to the waterline, and we are just in the process of planting around the remainder. It attracts quite a lot of birdlife, although paradise ducks and Canadian geese can be a problem,” he says.

“In the past we have had people come in with kayaks and canoes, practising for canoe races. We have also contemplated putting in fish and even generating electricity from the overflow, and these are possibilities for the future.”