New Zealand Federation of Freshwater Anglers spokesman Ken Sims said those responsible for the waterway had been lethargic and shown "an alarming lack of vigilance".
The federation represents several thousand anglers in about 30 clubs.
Mr Sims, from Manawatu, said reports of a suspected outbreak of lake snow in Lake Hawea were "disappointing", considering it had been identified in Lake Wanaka in 2004, Lake Coleridge in 2012 and Lake Wakatipu this year.
"Commercial fishing guides taking tourists fishing in Lake Wanaka had virtually given up guiding operations because the lake slime accumulated quickly on fishing lines and lures."
Mr Sims said council plans to monitor water in the affected lakes this year was "disappointingly belated".
"What makes it frustrating is that similar slowness occurred back in 2004 when didymo was discovered in Southland’s Waiau River.
"It has since spread to many South Island rivers."
Mr Sims said in addition to the inconvenience to trout anglers, the outbreak of lake snow was damaging New Zealand’s ‘‘much vaunted’’ 100% pure image.
The council’s engineering, hazards and science director, Dr Gavin Palmer, told the Otago Daily Times the council had been proactively dealing with water-quality issues across the whole region through rules introduced in its plan change 6A.
In respect of Lakes Wanaka, Hawea and Wakatipu, water sampling that would run for several months would begin next week.
The samples would be DNA tested in the hope the origin of the lake snow algae could be identified.
Also, more precise monitoring methods than usual would be used to provide greater detail of water quality in the lakes.
Dr Palmer said lake snow was not, as yet, confirmed in Lake Hawea.
