Pictures show before and after as source of River Thames in Gloucestershire dries up entirely
Watch Ken Goodwin's report
The source of the river Thames has dried up due to extremely hot weather and drought.
During the past six months, the start of the world famous river has become no more than a dirt track.
"This should be full of crustal clear water," river campaigner Ashley Smith told ITV News West Country while walking through what used to be the Thames.
"I've seen it when it's like that it is a thing of absolute beauty. Today it is utterly depressingly dead," he added.
Ashley has hit out at what he describes as wilful neglect of the UK's rivers.
The weather is one main reason for the decline in the size of the river, but water companies also play a part.
Ashely said: "The cheap way for the water industry is to suck more and more water to a growing population, so what do we think is going to happen?
"We deprive the beautiful vibrant places that agriculture also relies on and here we are in this catastrophic situation."
The dried-up ground is lined by frogs, sitting in the rare damp spots as they try to absorb any amount of water they can. The frogs are just some of the creatures struggling to survive the falling water levels.
Alastair Knowles, from The Rivers Trust, said: "It's upsetting. I know the source of the Thames drys up regularly, it will even dry up in a dry winter, but often it's a little pond with a stone saying 'here start-eth the Thames'.
"To think that you can a good 10-15km to find anywhere me or you would recognise as a river is scary."
The water regulator OFWAT has been contacted for a comment.