Art installation opens in tunnel that will become London's new super sewer

The video discusses a significant project aimed at protecting the River Thames from sewage pollution. It highlights the creation of Lou Gardens as a symbol of future progress and reflects on the project's impact. The initiative promises a cleaner river, marking a new era for the Thames' health.

What does the speaker mean by 'a big protection program for the river'?

In what way does the speaker believe the River Thames will change in the future?