Ohinemuri Regional History Journal 32, September 1988
By Owen Morgan
A further stage in the progress of the Karangahake Gorge Walkway was opened on the 22 August 1987 when Miss Lilian Valder of Waihi Beach cut the ribbon and. declared the Waitawheta River Loop Track completed and ready for use. Mr. Jim Rowland, mayor of Putaruru and chairman of the South Auckland Walkway Committee, in introducing Miss Valder, explained how her very generous donation had made the construction of the suspension bridge over the Waitawheta River possible.
The East Coast Main Trunk Railway once snaked its way through this gorge too but the section from Paeroa to Apata was abandoned when a shorter route to the Bay of Plenty via the Kaimai tunnel was opened in September 1978.
The Ohinemuri is a remarkable river. Its source, northeast of Waihi is less than 2 km from the East Coast, but it sets out on a westerly course, and after wandering across the Waihi Plains it plunges through the Karangahake Gorge to join the Waihou River at Paeroa before meandering on to the Firth of Thames.
Strangely too, the range of hills it penetrates at Karangahake is much higher than the coastal range which excludes its headwaters from the sea. Geological evidence shows that while the Coromandel Range was slowly being uplifted over millions of years, the Ohinemuri River had sufficient force to gradually deepen its channel andsocontinue on its westward course.
After the discovery of gold in Coromandel and Thames it was always considered a possibility that it would also be present in the Ohinemuri district. And so on the 3rd March 1875, and after much negotiation with the Maori Elders, the area was opened for prospecting by Government Commissioner, James Mackay. At a given signal about 1500 hopeful miners raced from Mackaytown towards Mt. Karangahake to stake their claims and make their fortunes. But they were disappointed. Although gold was detected in many places, it was soon realised that the low-grade, mineralised gold-bearing quartz needed sophisticated machinery and a great deal of money and metallurgical skills in order to win payable quantities of the precious metal. So instead of individual miners being able to work their claims as had been done on the alluvial deposits of the South Island, companies had to be floated so as to purchase crushing machinery. Most of these companies were based in the financial centres of London, and today evidence of their endeavours can be seen on every hand, from crumbling building foundations to the remains of water races, tunnels and bridges. Many of the claims were given romantic names such as the Talisman, Woodstock, Sir Walter Scott, Kenilworth, Golden Dawn, Crown and Ivanhoe.
In July 1889, in a remote part of the Waitawheta Gorge at the original Crown Battery site, an event took place which was to change the course of gold-mining throughout the world. For it was here that the first experiments of extracting gold and silver by the cyanide process were tried. This process, developed in Glasgow, dissolved the precious metals from the finely ground ore by means of a weak solution of sodium cyanide. This was the break-through mining engineers had been waiting for, and overnight the Ohinemuri Goldfield changed from one of doubtful value to profitability beyond their wildest dreams.
Because of the treatment plants which sprang up on the banks of the rivers, the Ohinemuri was not the sparkling waterway it is today. It was gazetted by the Mines Department as a "Sludge Channel" and during the 60 years that the Martha Mine in Waihi was working, 800 tons of cyanide impregnated "tailings" were discharged into it every day from the Victoria Battery at Waikino. What is more, when the velocity of the river slowed after rushing through the Karangahake Gorge, these tailings settled and so added to the severity of flooding in Paeroa and the Hauraki Plains.
The Karangahake Gorge now marks the boundary between the Coromandel and the Kaimai/Mamaku State Forest Parks, and being within easy reach of about a million people it is popular not only for its scenery, but also for rock-climbing, canoeists and anglers. The Karangahake Historic Walkway too, is becoming a major attraction, made all the more exciting because it passes through the former railway tunnel.
Eventually this walkway will link with the Gold-fields Steam Train operations at Waikino and the river boats from the Maritime Park at Paeroa.