The Ohinemuri River, which turned bright orange on Friday afternoon, is likely to be contaminated with metals from the old Comstock mine in the Karangahake Gorge.
Locals have sent us photos of the mine shaft from this site in what is known as “Scotsman’s Gully” which show the orange sludge pouring out and running down hill to the main river.
We will not know the extent of any pollution damage until we see the results of the Waikato Regional Council water tests, but we are very concerned given what we already know about the Comstock mine.
A study on effects of past mining on aquatic environments by the National Soil and Water Conservation Authority in 1987 showed the Comstock mine site had elevated heavy metals in the water including the highest arsenic levels of more than 20 sites tested, including the infamous Tui Mine.
“Until we see the test results we wont known the damage, but we already know that toxic heavy metals persist in the environment and that the impact on the Ohinemuri river and the species living in will not be good.
The Ohinemuri River also runs into the Waihou River and thus into the Hauraki Gulf. Dilution does not solve the problem, it merely redistributes it further afield.
Elders of the local hapū and iwi have told us that from the 1890s to the 1950s the miners used the river as a sludge channel discharging up to 800 tonnes per day, but as this week event shows, it’s not over.”
Watchdog is calling on the Waikato Regional Council to release test results as soon as possible and monitor the Comstock and other old sites.
Whether it is toxic heavy metals from old mining, or the legacy of long term risk being created from the huge Waihi tailings dams, this problem should be avoided.
We need to stop this kind of mining which creates toxic mine waste as a long term and serious risk.