By Angus Grigg

It's one of the worst environmental disasters to strike Australian waters, but it's a story that's hardly registered for much of the country.

For the last year a toxic algal bloom has flared along the South Australian coastline, wiping out vast populations of marine life, closing parts of the fishing industry, and prompting some beachgoers to question whether it's making them sick.

While the toxic bloom might only be affecting SA, it's a warning for the entire country.

As climate-driven environmental disasters become more frequent and more severe, how governments respond and communicate with the public has never been more important.

On tonight's Four Corners we reveal how the SA government continued to insist the bloom posed minimal risk to humans, despite early signs pointing to the fact it contained a potentially harmful toxin.

It would take four months for health advice to change, potentially putting asthmatics and those with compromised immunity at risk.

We hope you can watch tonight as we talk to those living and working alongside this continuing environmental disaster.

Watch Four Corners: Toxic Tide tonight from 8:30pm on ABC TV and ABC iview.