Over the years the mouth of the river has shifted about two kilometres to the east, creating a sand spit causing increased flood risk and reduced water quality.

In 1945, three local men used a horse-drawn scoop and shovels to cut a channel and clear the sand spit, returning the mouth to its historical position.

The mouth has now closed again, and earlier this year Augusta-Margaret River Shire councillors voted to cut a channel to the sea before next winter if the mouth had not opened naturally in the interim.

However, third generation Blackwood River fisherman Trevor Price says conditions at the mouth are the worst he’s seen in his 42 years of working on it and in recent weeks it hasn’t been worth setting his nets.

“There’s been nothing for about six months, last week I caught a single whiting,” Mr Price said.

His theory is that run off from agricultural fertilisers have accumulated in the shallow mouth, allowing the algae to flourish as temperatures warm.

The algae has attached to the sea grass, starving the river of oxygen, depleting fish stocks and destroying the traditional whiting nursery.

While he agrees these long term issues must be addressed, he said the immediate solution would be to cut the river mouth to allow the salt water to flush the algae out to sea.

“Ten years ago this was a beautiful pristine, healthy river; now it’s just a stinking, dead heap of water,” he said.

“And, as the temperatures rises the situation will only get worse – this stuff can double its mass in a week.

“Something needs to be done within the next couple of weeks or the river will take years to recover.

“There’s nothing for recreational fishermen, the whole town will suffer if tourism drops off.”

Mr Price said the water quality could also cause health problems for children who often swim near the Colourpatch Cafe.

“The town is dying with the rivermouth,” he said.

James Austin, who operates Blackwood River Houseboats, said his business was also suffering, as did Jan Hughes who runs eco tours on the river.

Shire president Ray Colyer visited the area last week, and agreed the Blackwood problem needs prompt attention; however, he said there were a number of State Government hurdles to get over before any action can be taken.