PLUMMETING water levels in one of Oxford's most picturesque ponds caused the death of hundreds of fish. 

The tranquil pond in University Parks transformed into a boggy mess last week after the water level fell rapidly, leaving a shoal of perch thrashing for oxygen.

Walkers in the North Oxford park noticed the unusual lack of water in the pond last Tuesday, which was potentially caused by human error.

Headington resident Peter West was initially baffled by the sudden change, and even more so when it returned to its normal level the following day.

He said the pond was 'like a mud bath' while parts of the River Cherwell, which runs through the park, were so low he could see bikes and even a lawn mower lying on the river bed.

Peter West took these photos just one day apart. Slide to see difference (slider created via Flourish) 

An Oxford University spokesman said: "Water levels in the pond were affected by a rapid reduction of water levels in the River Cherwell. 

"Regrettably we did lose some fish, which have been removed, but pond levels were quickly returned to normal, working closely with the Environment Agency, and there has been no other adverse impact on wildlife. 

"River levels are controlled by gates and we are investigating the cause, which was not due to any action by University Parks staff.

"We don’t think the river was drained intentionally – it’s possible the river gates were opened by a third party to increase the depth of water downstream, without realising the implications this would have upstream.

"The fish were mostly small perch which are very sensitive to low oxygen levels. 

"It's really difficult to say how many [died] – an estimate is that it was in the low hundreds."

The pond was back to its normal level by Wednesday.