Hawke's Bay Fish and Game officers are keeping a close eye on the algal bloom problems at Lake Tutira but believe there is no threat to the lake's trout population.
Officer Tom Winlove said there had been some speculation about the impact of the algal bloom on the 2750 young trout released into the lake in September.
"There have been no reports or evidence to suggest that fish are dying in any numbers which fits with what's happened when previous blooms have occurred.
"And the Hawke's Bay Regional Council has found that overall, water quality hasn't been impacted [in the lake]."
Mr Winlove said there was no doubt the lake was experiencing one of the worst algal blooms of recent times but he was optimistic for the trout's survival, based on what's occurred in past years.