Take your time and watch it in full. This Documentary is 25 min. long and about an invasive, extra cellular form of algae, which invades in this case a tailwater river.
Jason du Pont who is a Fly Fishing Guide since 7 years, filmed and documented the progress of the Didymo (Didymosphenia geminata) Algae Invasion in his home river: The Gunpowder River (Maryland, USA)
Thanks to Jason du Pont for uploading this film on vimeo and thanks to Owl Jones for sharing this. ( stumbled upon this, through his website owljones.com )
Spread the word and not the algae! (Clean, Dry, Repeat)