Along some stretches water levels are such that companies offering pleasure cruises are even considering putting their passengers in coaches and taking them by road.
The falling levels, which are mainly found upriver from Kew in south- west London, are making navigation more difficult because islands are appearing in the river. Some boat trips have already been cancelled and one company is running 70 per cent fewer excursions than usual because of the increased risk of accidents and grounding.
"We need 350 million gallons of water to flow over Teddington Weir every day, but currently it is only getting about 100 million gallons," said Colin Davis from the Port of London Authority. "We have issued a warning to boat-owners because of the low levels."
According to the authority, extraction by Thames Water upriver from Teddington is causing much of the problem. "We are writing to Thames Water to see if we can have a meeting to discuss what we can do about this," said Mr Davis.
Beyond Teddington the Thames is run by the Environment Agency and it issues extraction licences to Thames Water. "We accept they need to extract water, but we have to see if there is a way they can take it at different times which do not affect the level of the river quite so badly," added Mr Davis.
Companies which run boats on the river have noticed the falling volume. "We have been forced to change our schedule," said a spokeswoman for WPSA Upriver, which normally ferries around 600 passengers a day along the Thames during the summer. "At certain times of day we can't make it all the way to Hampton Court without the boat running aground. It makes things very difficult for tourists."
Although WPSA Upriver is considering running a coach service for its customers, the spokeswoman admitted that this would obviously defeat the point of taking a river trip.
According to the Environment Agency, many rivers are at less than 50 per cent of their normal levels for this time of year, partly due to declining annual rainfalls, but the level on the Thames at Kingston, Surrey is down to 37 per cent of normal.
Some vessels can now only travel safely at high tide and there are concerns for the survival of birds and other wildlife which inhabit the river and banks.
With more hosepipe bans and water restrictions predicted for parts of Britain later this year, the disappearing Thames is symptomatic of continuing drought conditions. January was the fourth driest on record, and after two years of low rainfall, groundwater has been severely depleted.Reuse content