Engineers breached Pakistan’s largest freshwater lake to divert water that was threatening nearby cities, officials said on Monday, as heavy rain left millions affected by the worst floods in the country’s history miserable.

Almost a third of Pakistan is under water – an area the size of the UK – after months of record monsoon rains that have killed 1,300 people and washed away homes, businesses, roads and bridges.

Officials say the repair bill will exceed $10 billion for a country already in an economic crisis and where hundreds of thousands are homeless as the monsoons end and winter approaches.

“There is no place to shower or go to the toilet,” said Zebunnisa Bibi, who was sheltering near Fazilpur in Punjab province, where 65 tents now house more than 500 people fleeing their flooded villages fled to higher ground.

Similar tent camps have mushroomed in much of southern and western Pakistan, where the rain has nowhere to drain as rivers are already in full swing due to torrential downpours in the north.

Sindh provincial information minister Sharjeel Inam Memon told AFP on Monday that engineers had to cut a canal in Lake Manchar to divert water that was threatening the towns of Sehwan and Bhan Saeedabad, which have a combined population of nearly half a million.

Still, thousands had to be evacuated from smaller settlements flooded by the rerouted canal.

“The floodwaters have been diverted, but the threat is far from over,” Memon said.

“We are trying our best to stop the flooding of other villages.”

Lake Manchar, lying west of the Indus, varies in size with season and rainfall, but currently covers as wide an area as can be remembered.

Much of Sindh and parts of Balochistan have become one vast stretch of water, with displaced locals huddled miserably on elevated roads, railroad tracks and other rises.

Human and animal waste in the stinky waters attract swarms of flies, while outbreaks of dengue from mosquitoes that breed in the swamp areas have been reported.

A pregnant woman at a camp in Punjab said she needed urgent medical attention for a baby that is due any day.

The mother-of-five knows it could be a difficult birth as the baby hasn’t moved from the breech position.

“I need a doctor or midwife. What if something happens to my child?” said Fahmidah Bibi.

The United Nations Population Fund said over the weekend there were at least 128,000 pregnant women in flood-hit areas in need of urgent care – with 42,000 expected to give birth in the next three months.

Pakistan receives heavy – often destructive – rains during its annual monsoon season, which are vital to agriculture and water supplies.

But such heavy downpours have not been seen in decades.

Pakistani officials blame climate change, which is increasing the frequency and intensity of extreme weather events around the world.

Pakistan is responsible for less than one percent of global greenhouse gas emissions, but ranks eighth on a list compiled by the NGO Germanwatch of countries considered most vulnerable to extreme weather conditions caused by climate change.

A massive army-led relief operation is underway, but the country’s leadership has admitted to being overwhelmed by the scale of the crisis and has called for international help.

The latest figures from the National Disaster Management Authority show that since June, when the monsoons began, nearly 6,000 kilometers (4,000 miles) of roads have been washed away, 246 bridges have been demolished and 1.6 million homes have either been destroyed or badly damaged.