Traditional weirs are heavy to operate but all weirs are dangerous
Historic wooden weirs on the River Thames and River Kennet may be replaced under a new flood management scheme.
The Environment Agency (EA) wants to replace weirs in Northmoor, Radcot and Mapledurham in Oxfordshire, Molesey in Surrey and at Blakes Lock in Berkshire.
It said mechanised weirs would be safer to use and help reduce the flood risk.
Retired Oxfordshire lock keeper Colin Mullineux said these weirs were among the only intact wooden paddle and rymer weirs left in Europe.
Traditional weirs work by placing large wooden posts (rymers) into the bottom of the river and paddles of different lengths are placed against them to hold back the water.
They are used in conjunction with locks to raise the water level and make rivers easier to navigate.
Mr Mullineux, who looked after Northmoor lock, said the weirs were part of the River Thames' history and had not changed much since the signing of the Magna Carta.
He said: "You could put them in a museum, but they're like steam engines, they're dead in a museum. But if you have an operating steam engine it attracts thousands of visitors."
Simon Hughes, from the EA, said climate change meant a higher risk of the Thames flooding and it had to balance the weirs' heritage value with the need to install modern equipment that could be operated safely and efficiently during a flood.
A public consultation exercise is being held until 14 August with work expected to start in summer 2010.