Angler blames dam for algae
A concerned angler says the growth of phormidium toxic algae in the Opihi River is a flow-on effect of the Opuha Dam.
Barry Stone, of Timaru, said although the dam had given the district "a much required boost to the local economy", the increase in phormidium in the river was a result of how the dam company took its water, which was by a single take and not a multiple take system.
Mr Stone had been examining the river for more than 10 years, and said, if anything, the problem had got worse, not better.
"There has been a total degrading of the Opuha and Opihi rivers," he said.
"This situation is now entering its 13th year and in my opinion getting worse not improving.
"We were originally informed that five to 10 years would see this situation remedied with a much improved water quality of a more acceptable standard."
Mr Stone said the fish were too putrid to eat, and for the first time in more than 50 years, he decided not to renew his licence.
He had made several presentations to various groups on the matter over the last five or so years.
"Unfortunately the constant denials by Central South Island Fish and Game in regards to this situation, and the many problems we now have regards water quality, prove a total lack of responsibility by this body," he said.
"Trout, salmon, eels or whitebait should never be inedible. But this is not just about fishers, this is about the people who swim in the water, or picnic there. "
Mr Stone's remarks follow similar concerns raised by fishermen in the Herald this summer.
CSI Fish and Game chief executive Jay Graybill said it was not the responsibility of his organisation to monitor the dam company's consent.
"That is a matter for the regional council. Our role is one of advocacy, we do not issue or monitor the consents," he said.
"The situation [with phormidium] is not ideal, and it is certainly a nuisance that the algal growth does occur, particularly in times of high summer under stable flow conditions and high air temperature."
Mr Graybill said that in general, in many parts of the Opihi, the fishery had actually improved as a result of the higher minimum flow provided by the dam.
"Contrary to what Mr Stone said, the condition of the Opihi has actually improved. The trout and salmon fishery has responded particularly well, and the mouth is blocked far less often," he said.
Mr Graybill said the Opuha environmental flows advisory group had done a lot of good collaborative work with the dam company, such as managing the lake level and arranging a system to release flushing flows when appropriate conditions permit.
Environment Canterbury surface water and ecosystems manager Tim Davie said phormidium was naturally occurring and grows in rivers both with and without dams.
Dr Davie said that about a decade ago, a consent review was undertaken as a result of two reports which raised concerns about the declining water quality.
"We consider the work done to aerate the water within Lake Opuha has solved the water quality issues raised by the reports, and so long as the aeration consent conditions are continued to be adhered to, the water quality in the Opuha will remain of high quality."
The Timaru Herald