Most of Europe's lakes are still officially classed as failing – and yet the scientists who've spent decades beside these waters tell a more hopeful, more complicated story. So how do we actually know whether restoration is working? What gets lost when a single failing measure marks a whole lake as a failure? And, crucially, who is going to pay to bring our lakes back?

In this third episode, we meet two researchers from the FutureLakes project who have spent years trying to measure success – not just in nitrogen and phosphorus, but in birdlife, swimming, jobs, carbon and euros.

Lilith Kramer (Deltares) draws on a synthesis of six demonstration lakes to explain why real recovery is often hidden by EU scorecards, and why hope and complexity go hand in hand. Environmental economist Najla Kamergi (SEMIDE) makes the case for lakes' "bankab ...