Much of northern England faces a drought within weeks, according to new figures published this week. The combination of recent high temperatures, one of the sunniest Aprils in a century and five months of below-average rainfall is the reason, the Environment Agency said.

Weekly river flow and rainfall data (pdf) shows that the flow in major rivers including the Lune, Wharfe, Wyre, Swale, Conwy, Dee and Taff are already "notably" and in some cases "exceptionally" below-average levels for the time of year. There is little prospect of the levels being replenished in the immediate future with the present "mostly dry" weather forecast set to continue.

In the last four months, says the agency, north-west England and Wales have received at most 80% – and sometimes little more than 13% – of their long-term average rainfall. It is the driest new year spell since 1964 in England and 1976 in Wales.

"Potentially, north-west England could be reaching full drought status by the end of June," said an agency spokesman. "Continued below-average rainfall will increase pressure on water resources and we continue to monitor the situation closely. Water is a precious resource, and we urge people and businesses to use water responsibly at all times of the year."

But there is little chance of widespread water shortages in England or Wales, he said, because groundwater and reservoir levels are close to average for the time of year. "Low summer flows are a likely prospect in many rivers but the overall water resources position remains fairly typical of the late spring."

Most unusually for Britain, rainfall over the normally wet winter months has been heavy in southern and eastern areas rather than in the west. While Wales and the Lake District have been far drier than usual, most rivers south and east of a diagonal line between the Humber and the Severn estuary have been running at normal levels. The hot, dry spell after the Easter and the recent mini heat wave increased temperatures significantly with rainfall down by up to 80%. During April, Britain basked in 222 hours of sunshine – compared to the monthly average of 141.3 hours.

The situation is remarkable because the last three summers have been exceptionally wet, leading to a rise in water tables and an increase in the flow of some groundwater-fed rivers. Towns like Cockermouth, which last year experienced some of the worst floods in a century, are now witnessing near record-low river levels.

Conservation group WWF today warned that many rivers are in danger of drying out completely during a hot summer because an increasing amount of water is being taken by water companies and farmers who have licences dating back nearly 50 years. This, said the group, is threatening local ecosystems and having serious consequences for wildlife.

"The northern rivers are suffering already this year. These are the warning signals that we should use less water. When river flows reduce there are ecological consequences all the way up the food chain," said Rose Timlett, WWF's freshwater policy officer.

In many cases the abstraction licences are not fit for purpose as the amount that can be taken bears no relation to the impact on the environment".

A WWF report issued last month, Riverside Tales, said progress on abstraction licenses "has not gone far enough, and opportunities continue to be missed."

The Environment Agency, which regulates the amount of water that can be taken from rivers, has warned that demand from growing populations and climate change could reduce river flows in some areas by 80% by 2050 and that ecosystems in one-third of British river catchments are in danger of drying out in a hot summer.

"We are reviewing abstraction licences. Some rivers are over-abstracted and over-licenced. [The changes] will affect farmers and some water companies as well as some small-scale industries," said the agency.