Ronald Irvine raised concerns in mid-March about the damaged caused by flooding along the Curdies River because of the mouth had been blocked since November.

Residents also raised concerns if nothing was done they could end up with blue-green algae in the river and by early April, signs warning of an outbreak had been erected at Peterborough.

"That's exactly what we said would happen," Mr Irvine said.

Heaving earth moving equipment was last week brought in by Parks Victoria to remove the sand berm blocking the estuary, with recent rainfall and increasing water levels cited as the the reason.

Corangamite Catchment Management Authority said it had conducted a risk assessment prior to the opening, which determined freshwater inflows from recent rainfall had reduced the likelihood of a fish death event.

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Mr Irvine said the river was opened because it reached the 1.3-metre level, just slightly above the level it had reached in November when he believes it should have been opened.

"It got so close about 1.2 something metres in November, " he said.

"They need to be aware of exceptional circumstances - 1.3m is not necessarily the right level."

Mr Irvine said if the authorities had opened the river in November when it had only been closed for two days it would have been quicker and easier to do, and not caused the flooding destruction along the river.

If they had opened it in November, he said, it would have been through a sandbar of about two-feet deep and 10 to 12 metres long.

The delay of months meant heavy machinery was needed to dig a channel at least 50 metres long through a sandbar 10 to 15 feet deep.

"That's what I call exceptional circumstances," he said.

"It shouldn't have been allowed to have been left there at that height for so long when they could have opened it straight away."

Mr Irvine said the problem with having a greater amount of fresh water trapped in the river system for so long was that it caused blue-green algae.

He said it was spotted in the river towards the end of March and now the water had been let out it had left behind a mess.

"All I've got along my river frontage now is mud and tussocks covered in dried blue-green algae," he said.

"It just becomes a stinking mess."

Mr Irvine said the flooding had wiped out four or five years' worth of tree planting in the area.

He has written to those who oversee the river to try and get a meeting where they can discuss streamlining the process of opening the mouth.

Mr Irvine said the number of people involved in trying to open the river included two shire councils, Parks Victoria and the Corangamite Catchment Management Authority, which has the final say.

"It shouldn't be a process that involves so many things," he said.

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