Farmers already forced to ration dwindling supplies of vital irrigation water face further possible restrictions after a drought was formally declared for the east of England.

The Environment Agency has confirmed drought status for several regions following months without significant rainfall, including East Anglia's driest July on record.

Farmers in some catchments have already been asked to voluntarily reduce their abstraction from rivers and groundwater - and some have been ordered to stop to protect the environment.

So while reservoirs run dry and abstraction licences near their limits, they are being forced to choose which crops get the water they need from dwindling supplies.

As a result, they expect "significant" shortages of crops like potatoes, carrots and onions, while sugar beet and maize plants are also showing signs of heat stress.

Although the updated status does not automatically trigger further restrictions, it means that "the Environment Agency and water companies will step up their actions to manage the impacts".

Farmers questioned why a drought was not declared sooner - and why no domestic hosepipe bans have been introduced locally while food crops wilt in the parched fields.

Anglian Water said, despite the drought declaration, it still does not envisage needing a hosepipe ban this summer because of its investments in its infrastructure and resilience.

Jamie Lockhart, managing director of Brandon-based farming and fresh produce business Frederick Hiam, is also the Norfolk branch chairman of the National Farmers' Union (NFU).

He said the company, which farms across 7,000 acres including 2,000 acres of vegetables around the Norfolk-Suffolk border, is within 20pc of its limit on water supplies from reservoirs, boreholes and abstraction licences.

He said any future restrictions on public water users have come too late to help the food sector.

"It is shutting the stable door after the horse has bolted," he said. "We have been in this situation for the last month.

"We have had restrictions imposed and no access to extra water. If a drought order had been made some time ago, then the water saved could have been redistributed to where it was needed. That is the frustration.

"We know of people who have had licences revoked and we have had 25 hectares of onions on land that we rent in the Brecks that we had to stop watering. They had a surface water abstraction licence which was withdrawn three weeks ago.

"So why have there not been hosepipe bans from some time ago? Is it really that important to wash your car or water your lawn?"

Mr Lockhart is expecting yields to be 15-20pc down across the board - with later-season parsnips being a particular concern.

But he said the fixed contracts with retailers meant it was difficult to recoup the financial costs of a drought-hit season, exacerbated by soaring production costs.

"The retailers acknowledge the inflationary pressures we are under, and we acknowledge that retailers are supplying a consumer that is struggling at the moment, so they are unwilling to give us the scale of price rises we need to get back to parity," he said. "We need 20pc, but they are offering 5pc."

Andrew Francis is farms director at the Elveden Estate near Thetford, where the reservoirs are empty and there is "a few more weeks of licensed water available" from boreholes.

He is also making "difficult decisions" on which crops to prioritise for water, and is worried about potato crops which need water to lift them out of the ground without bruising.

He said it was "amazing" that there had been no local restrictions on public water use, and called for a more detailed specific drought plan for agriculture.

"Water for food is so important, but when these [drought status] bands come in it does not free up water for agriculture to cope," he said.

"It always hits us first because our licensed abstraction rates can be restricted and then the water just runs out. We have all of that long before other sectors will see restrictions come in.

"The conversations need to happen with all parties having an equal share."

What drought status means for farms

The drought declaration does not automatically trigger added water restrictions - but it indicates the increasing severity of a situation which could require further action.

The Environment Agency's decision followed a meeting of the National Drought Group, made up of senior decision-makers from the government, water companies and industry bodies.

It was based on regional assessments of rainfall, river flows, groundwater levels, reservoir levels, and the dryness of soils, as well as the impacts on public water supply, abstractors and the environment.

And it means the agency will "step up actions", which have so far included "managing abstraction licences" and requesting voluntary reductions in water taken by farmers.

Kelly Hewson-Fisher, the Newmarket-based national water specialist for the National Farmers' Union (NFU), attended the meeting.

She said drought status won't automatically mean enforced emergency variations of water licences - known as Section 57 notices - although these become increasingly likely as the dry weather continues.

"The drought status does not change the restrictions specifically for farmers, and it does not automatically mean Section 57 notices are issued - it is not as clear cut as that," she said.

"What it means is continued monitoring of the situation and looking at water companies as well to ask if everything is being done to ensure efficient water usage.

"There are conversations happening in some catchments to ask for voluntary restrictions, whether it is reducing quantity or only abstracting four nights out of seven.

"We cannot say there will be no Section 57s, but it certainly means more monitoring of the situation in these local areas and further restrictions may be imposed."

Alison Parnell a drought manager for Environment Agency in East Anglia, said: “We’ve already been taking action to protect the environment; monitoring rivers and groundwaters, working with water companies and sending teams out to help wildlife in difficulty.

“We’ve also been working with farmers, businesses and other abstractors to manage water availability and ensure that they get the water they need while maintaining our protection of the environment.

“Please report any environmental concerns to our help line on 0800 807060.”