Resident Shaun Swanton said the water disappeared very quickly
The Environment Agency has begun an investigation after a small Hampshire lake was drained leaving fish dead and dying on the mud.
North Lake in Bishops Waltham usually has five to six feet (1.5 to 1.8m) of water but nearly all of it has disappeared in the past two weeks.
Wildlife experts said it had also left other animals fighting for survival.
Portsmouth Water, which extracts water upstream, said it had to continue in order to keep up its public supplies.
Shaun Swanton, who lives nearby, said: "Two days ago we were down to about a foot of water and then within about 24 hours of that we had various puddles around the pond with dying fish.
We cannot say that there is no impact at all but the reality is we've got public there who want their public water supplies
Andy Neve, Portsmouth Water
"This is a wildlife calamity. Where are the guardians who are supposed to look after this?"
The pond was created in the 12th Century to provide fish and water power.
It is now now split in two by a road and while the lower pond, which is actively managed, has kept its water, the north pond is now dry.
David Rumble, from Hampshire and Isle of Wight Wildlife Trust, said: "It's catastrophic in the short term.
"If they haven't managed to complete their life-cycles, immature frogs and toads, dragonflies, they will die or be picked off by predators.
"The same goes for young birds."
The pond was created in the 12th Century to provide fish
Upstream from the pond, Portsmouth Water abstracts water from the chalk below, which acts like a big sponge and causes the pond to dry out.
Andy Neve, from Portsmouth Water, said: "Sadly what happens is that when that ground water level reduces, towards the end of the summer and during the autumn, then the water drops out of the bottom of the pond.
"We cannot say that there is no impact at all but the reality is we've got public there who want their public water supplies.
"We have got to give them to them, there aren't many alternatives to us."
The Environment Agency said it was talking to Portsmouth Water about abstracting water from alternative areas during times of peak demand.
Birds and amphibians are struggling to survive after the pond was drained
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