Canada‘s prime minister, Stephen Harper, faces a widening revolt by the country’s leading scientists against sweeping cuts to government research labs and broadly pro-industry policies.

The scientists plan to march through Ottawa in white lab coats on Tuesday in the second big protest in a month against the Harper government’s science and environmental agenda.

Harper is accused of pushing through a slew of policies weakening or abolishing environmental protections – with an aim of expanding development of natural resources such as the Alberta tar sands.

His government is also accused of jeopardising Canada’s scientific reputation by shutting down the Experimental Lakes Area (ELA), a research station that produced critical evidence to help stop acid rain.

“In my view there are a lot of attempts in this country, and other countries too, to push through resource-based economies,” said Prof John Smol, a freshwater lake biologist at Queen’s University in Kingston, Ontario. “People working at ELA are constantly finding reasons why you can’t just put a pipeline here, or an industry there, because there are going to be environmental costs.”

Andrew Weaver, a climate scientist at the University of Victoria in British Columbia, was even more pointed. “It’s not about saving money. It’s about imposing ideology,” he said. “What’s happening here is that the government has an ideological agenda to develop the Canadian economy based on the extraction of oil out of the Alberta tar sands as quickly as possible and sell it as fast as it can, come hell and high water, and eliminate any barriers that stand in their way.”

However, a spokeswoman for Gary Goodyear, the minister of state for science and technology, said the government remained committed to funding science. “Our government has made historic investments in science, technology and research to create jobs, grow our economy, and improve the quality of life for Canadians,” she said.

But Canadian government officials also indirectly confirmed scientists’ charges that Harper was far more interested in funding research with direct industry applications, than in funding pure science or environmental research.

“As a country we have been lagging behind our peer nations on applied research and commercialisation and our government is taking steps to correct that,” the official said.

The official provided a list of new projects supported by the government. Among the largest was $105m for marketing forest products.

The showdown between the government and scientists was set late last month by the passage of a budget bill that weakened or abolished scores of environmental laws.

The government claims the cuts are intended to shift more resources towards monitoring development of the Alberta tar sands, the core of Harper’s economic strategy.

Critics say the changes gut the country’s strongest environmental law, the Canadian Fisheries Act, by easing earlier requirements on mining and other industries to protect fish habitat.

In addition, the C-38 budget bill cut dozens of jobs for government scientists, scrapped research projects, and pollution control programmes. It abolished the unit in charge of monitoring emissions from power plants, furnaces, boilers and other sources, for a net saving of about $600,000.

It cut funding entirely for two-well established bodies: the National Round Table on the Environment and the Economy, an advisory panel, and the Canadian Foundation for Climate and Atmospheric Science, which awards research grants. It also cut other research grant programmes.

The Harper government has clashed regularly with environmental groups over its strategy of developing the tar sands and shipping the oil to America and China.

Earlier this year, the natural resources minister, Joe Oliver, accused foreign radicals and “jet-setting celebrities” of trying to hijack the country, by opposing development of the tar sands.

The government has also directed the tax authorities to investigate the funding of environmental groups.

There were protests, too, when government scientists were banned from speaking to media without an official “minder”, and when news of the cost-cutting proposals first trickled out.

More than 500 groups took their websites down for 24 hours last month in protest at the budget cuts, which they claim were an excuse to weaken environmental protections.

But the cuts that seem to have galvanised the protests on Tuesday was the government’s decision to shut down the Experimental Lakes Area in March 2013.

“It’s a culmination of all of the cuts to government science and environment,” said Diane Orihel, a PhD candidate at the University of Alberta, leading the campaign to save the labs. “The ELA is one small little morsel in a much broader problem.” But she added: “We are starting to see momentum.”

Since the decision first trickled out – as a government leak – the Harper government has faced widening criticism in Canadian media.

Scientists say the closure, due in March 2013, would rob researchers of a rare chance to conduct science on a real-life scale – not just in a laboratory flask, said Smol.

Over the years, it has provided critical evidence on the causes of acid rain, and the effects on fish and their habitats of dumping fertilisers, detergents, or mercury.

“Any water quality problem we have on the planet, the research started out there,” Smol said. “I think we need that information to get solid policy to deal with our environmental problems.”

The government argues it can no longer afford the research station, which costs about $2m a year to run.

Critics dismiss that argument, pointing to the Harper government’s promotion of the Alberta tar sands and its opposition to the Kyoto protocol agreements on climate change.

“The Harper government is the most environmentally hostile one we have ever had in Canada. Harper pulled Canada out of the Kyoto protocol, gutted the Fisheries Act (our strongest freshwater protection law), and hollowed out our environmental assessment legislation, making it easier for extractive industries to get licences to exploit,” said Maude Barlow, a former UN advisor on water and chair of the Council of Canadians. “It is heartlessly shutting down a programme that costs very little to run given the incredible benefits it brings, in order to silence the voices who speak for water.”

More than 200 flood warnings and alerts were issued by the Environment Agency on Saturday as torrential rain swept the country, causing havoc in many areas.

In East Tynedale, Northumberland, a man in his early 20s was killed after his car plunged off the A68 between Broomley Grange and Healy in heavy rain.

In Yealmpton, Devon, the Yealm burst its banks, flooding more than 40 homes, including some that had six feet of water inside, police said.

The rain led to flooded homes, road closures and havoc on public transport across parts of the country as the latest downpours continued to fall on ground already saturated after three months of record-breaking rainfall.

The RSPCA urged farmers to move livestock from low-lying fields and ensure that animals had access to food and shelter, and told pet owners to keep their animals safe at all times.

Thousands of motor-racing fans heading to the F1 British Grand Prix were warned not to attend the Silverstone race track in Northamptonshire for race qualifying on Saturday after the deluge left car parks unusable and caused long traffic jams near the circuit.

Officials said that they would have the car parks ready for use on Sundayand be able to accommodate all ticket holders.

Craig Woolhouse, the Environment Agency’s head of flood incident management, urged people to remain on alert for flooding, especially in Devon, Cornwall and Somerset.

“It has been raining heavily and the situation could escalate quite quickly. We would also ask people to remember to stay away from flood water, and do not walk or drive through it, as it is often fast-moving and can contain sewage and other debris.”

Many parts of the country received more than half the average rainfall for July in one day, and the Met Office warned that heavy rain was expected to move east overnight, reaching Sussex and Kent on Sunday.

In Yealmpton, Tony Stearn, whose house backs on to the Yealm river, said that he had been telephoned by a neighbour warning him of danger. “He said you better have a look out your window. Our garden was completely under water.”

A spokesman for the Dorset Fire and Rescue Service said that it been called to incidents – mainly flooding of houses and cars stuck in flood water – in more than a dozen places, including Bridport, Maiden Newton and Bradpole.

Monday’s horse racing meeting at Newton Abbot in Devon has been cancelled due to a waterlogged track, while Dorset police have warned people to stay away from the base of cliffs in Lyme Regis, as mud slides are making them unstable.

Several residents in the Leicestershire village of Sheepy Magna were evacuated from their homes. According to a Red Cross official, a total of 13 houses were involved in the rescue.

In Scotland, 13 flood warnings were issued in Edinburgh, the Lothians and in the Borders.

The A720 Edinburgh city bypass was closed between Hermiston Gait and Straiton and the Taste of Edinburgh festival was cancelled after its site at The Meadows was flooded. Emergency teams have been sent from Moscow.

Highways buckled in Wisconsin, water use was cut back in Indiana and those who had power in the mid-Atlantic were urged to conserve it, but the heat gripping much of the country was only expected to worsen Saturday.

Temperatures of more than 100 degrees were forecast in Philadelphia, authorities warned of excessive heat in the Midwest and the power outages surpassed a week in the mid-Atlantic, where extreme heat was expected into the weekend.

A major storm in the area last week left behind damage, which combined with the high demand for power to stress the electrical system’s capabilities, a Washington-area utility said.

Hundreds of thousands remained without power Friday night in the Appalachians and mid-Atlantic.

Tens of thousands were still without power in the Midwest as well after storms there this week.

Utilities hoped to restore service over the weekend in Michigan, where temperatures were forecast in the 90s.

The heat wave has so far been blamed for at least eight deaths.

In Ohio, a man in his 70s and two women – one in her late 60s, the other in her 80s – were found dead this week inside stifling hot houses.

Doctor Jeff Lee, deputy coroner in Licking County in central Ohio, said all three were suffering from heart disease but died from stress caused by high temperatures.

In two cases, temperatures inside the homes – with windows shut and no ventilation – were in the 90s. The houses lacked electricity because of recent power outages.

“If they had gotten cooling, we would have expected them to survive,” he said.

Three deaths in Wisconsin and two in Tennessee were also reported to be heat-related.

Record temperatures were set Friday in the Indiana cities of Indianapolis, South Bend and Fort Wayne, where temperatures could reach 106 degrees but feel more like 114.

In central Arkansas, Russellville reached 106 degrees, breaking a record set in 1964.

Relief was on the way in the form of a cold front as the weekend ends, but forecasters expected it to bring severe weather, too.

The rain should help dry spells in many places.

Much of Arkansas is enduring brown grass and seeing trees lose their green, and farmers in Ohio are growing concerned about the dry conditions, considered among the worst of the past decade.