A regional council spokesman said in the interim the river was not being cleaned by anyone, but nature was taking its own course.
"The continuous flow of the river will clean itself as part of a natural process. Recent rain will have assisted this to occur. No workers are involved in this natural process."
The source and cause of the effluent discharge have been identified and an investigation is under way.
"This could lead to a prosecution but it is too early to confirm at this stage," he said.
Hawke's Bay District Health Board Medical Officer of Health Rachel Eyre said it was important the public followed the no-swim warning and avoided the Tutaekuri River for at least three days after the Tuesday incident.
The district health board was working with Hawke's Bay Regional Council with the investigation under way, she said.
Hawke's Bay Federated Farmers president Jim Galloway said it was disappointing to see it happen and that farmers and others working with waste systems around waterways needed to make sure a general upkeep in maintenance was met.
For a farmer to discharge farm dairy effluent, a resource consent is required.
This applies regardless of whether they have an oxidation pond system or apply the effluent directly to land.
Under council rules a farmer must not discharge untreated farm dairy effluent to streams, rivers or lakes.
