The races take place on the River Thames on Sunday, April 2.
Drought Warning for Thames Valley
Thames Water says it's not a case of whether the Thames Valley will have a drought - but when and how bad it will be
It's after below-average rainfall for 18 months of the last 23 months across Oxfordshire, Berkshire and Buckinghamshire.
As the South East looks set to follow eastern England into drought, the Environment Department is convening a meeting of water companies, farmers and wildlife groups today to discuss potential water shortages.
It comes after an Environment Agency briefing said parts of eastern England continue to be drought-afflicted, while swathes of the South East are still affected by dry weather.
They would need well above average rainfall over the next few months for groundwater levels to recover, but the Midlands, Anglian region and South East all had below average rainfall in January.
Thames Water is urging people to save water, for example by turning off the tap while cleaning their teeth or taking shorter showers, fixing leaks and only washing full loads of laundry, in the face of potential shortages.
Mr Aylard said: "We all need to recognise that the water coming out of our taps comes from our local river or from the aquifer that feeds that river - and the less water we all use the less we need to take from the river.''
He added: "It is no longer a case of if we have a drought this year, but rather when, and how bad.''
He said 2010-2011 was the third driest two-year period in the Thames Valley and London since records began 128 years ago.
Ahead of the summit, Environment Secretary Caroline Spelman said: "All of our activity is going to be carefully coordinated so that we are able to minimise the effects of unpredictable water availability and support people in doing the right thing in taking sensible measures to save water.''
Two Lorries Involved In M40 Crash Near Bicester Which Closes Motorway.
21-Year-old Man Arrested On Suspicion Of Arson With Intent To Endanger Life.
Burglary On Radcot Road in Faringdon.
Recently Played Tracks
On Radio: James Merritt
1am - 6am
Text 'HEART' to 82122
Now playing: Non-stop hit music
Deposit £10 to get a £40 Welcome Bonus - That's £50 to play bingo, slots and more!*
Over 50 tracks to make you feel-good. New album out now...
Find your local four day weather report here.
What's happening on the roads where you are?
Make Heart the soundtrack to your day and you could be a winner with great prizes up for grabs throughout the day.
Find out more about some of the companies advertising on Heart.
Get some great ideas on how to advertise your business on radio, online and on mobile.