People used to gravitate toward the Rhine River for all sorts of play -- even swimming despite the dangerous currents. Legend has it that in winter, part of the Rhine used to freeze over, and people would walk across the mighty waterway.

The river begins in Switzerland. Passing through the city of Basel, it forms the border between Germany and France, flows into Germany and the Netherlands and ends in the North Sea.

But in the wake of an environmental disaster 20 years ago in Switzerland, many stayed away from the water, with experts wondering if it would ever be clean again. At a recent press conference, an international commission said the Rhine is a "living" river once more.

Polluted with pesticides

In 1986, a fire broke out in a production plant storage room at the pharmaceutical company Sandoz in the Swiss city of Basel. As a result, huge amounts of pesticides were released into the Upper Rhine, killing a multitude of fish and micro-organisms.

The accident turned the river into Europe's biggest sewer.

Fritz Holzwarth, head of the Bonn-based International Commission for the Protection of the Rhine, said that it was this catastrophe that triggered concern about the river's health.

"We can say that the Sandoz incident was basically the worst possible scenario at the time so it contributed a great deal to making the protection of water an important issue in politics," he said.

A huge task

It would take a lot of effort before the river could be transformed into a place where people could swim again. Ultimately, it was pressure from an outraged public that forced politicians to take fast action.

Since then, investments in industrial and public water purification plants have amounted to 60 billion euros (over $75 billion), with local governments investing a yearly amount of one billion euros in water purification.

The risk of another dramatic accident has been minimized since the companies located along the Rhine have taken precautions, Holzwarth said, adding that a pro-active approach is necessary to keep the river clean.

"The International Commission for the Protection of the Rhine, together with those who live near the river's banks, want to advance a perspective that allows people to live with and enjoy the river," he said. "We want to include the river in our lives and in those of our children," he added.

To that end, a 320-kilometer-long (nearly 200-mile) hiking trail called the Rheinsteig was recently completed between Bonn and Koblenz.

In addition, the Rhine, Europe's most densely populated river, is a UNESCO World Heritage Site. It has become a home again to over 60 different species of fish.