 I'm on the banks of the River Wye, I'm just downstream of Hereford at a place called Hom Lacey. I went canoeing along exactly this stretch of river a few years ago and I can vouch for it, it really was gorgeous, clear, fast flowing, teeming with life. But not today. It's murky, tea brown, every stone at the river's edge is deeply furred over with a coat of sludgy green algae.