Fish and Game Otago is to appeal to its national body to support research into the impact of didymo on the Upper Clutha.
The council is concerned the issue of didymo had "disappeared" , yet anglers were concerned about its impact on the Upper Clutha fishery.
Cr John Jillett said recently a lot of money had been "thrown at didymo" when it was first discovered but that funding seemed to have disappeared.
Chief executive Niall Watson said research was being carried out in the Waitaki Valley on why didymo did not grow in spring water.
Cr John Barlow said for the first two or three years there did not seem to be a great change to waterways with didymo, but now didymo seemed to be trapping silt.
"It seems to have been a two stage thing."
Cr Dan Rae said it was a major problem for the upper Clutha fishery and he would like to see a study done on the river.
The council agreed to write to the New Zealand council asking for its support for research into the impact of didymo on the Upper Clutha.
