River Wye at Hereford Bridge now 2cm deep amid dry spell

The top of the River Wye's level has dropped from 3.3m to 2cm deep

The River Wye is now 2cm deep along a stretch in Hereford amid a heatwave warning, Environment Agency data shows.

Monitoring equipment at Hereford Bridge showed water levels had fallen to 2cm (0.8in), well below the top of the river's normal range of 3.3m (10.8ft).

Charles Watson, from campaign group River Action, said the UK's rivers faced an "ecological emergency" if the government did not act urgently.

Water temperatures have already reached 22C (71.6F), an expert said.

Retired Environment Agency manager and Herefordshire river expert Dave Throup added the water temperatures were expected to rise further in coming days.

During last month's heatwave, Natural Resources Wales opened the Caban Coch reservoir to increase the Wye's levels to save the river's salmon population.

"You can do that once," Mr Watson said. "You can't do that every time there's a drought."

• Wildlife under stress as dry spell shrinks rivers

• Four-day extreme heat warning in England and Wales

• Fishing ban as low rainfall sees river levels drop

Many fish were found dead in the Wye in July due to hot weather dissolving oxygen levels in the water.

Anglers have now been asked to to stop fishing for salmon and trout until temperatures have dropped sufficiently, a spokesperson for the Environment Agency said.

"Our teams are conducting flow monitoring and we are working with water companies and other abstractors to monitor resources," they added.

There is currently no evidence of low oxygen levels for prolonged periods, which can be harmful to fish, occurring alongside an algal bloom, the spokesperson continued.

Fish were found dead in the River Wye in July

Previously, River Action has largely campaigned about pollution, raising concerns about the impact of intensive farming on the Wye.

With the flow of rivers now drying up as well, it has become "disastrous" for wildlife, Mr Watson said.

The low water levels have become "disastrous" for wildlife, the River Action group has said

"If the flows really slow down, the ecology of the rivers is being killed and, meanwhile, the concentration of the pollution that's all still there will increase," he said.

The group has called on the government to act to resolve what Mr Watson called "an ecological emergency".

Some water companies have introduced a hosepipe ban after the country saw the driest July in England since 1935.