Texas Governor Greg Abbott on Sunday said damage from Hurricane Harvey would exceed that of epic hurricanes Katrina or Sandy, likely reaching $150 billion to $180 billion.

Harvey, which came ashore on Aug. 25 as the most powerful hurricane to hit Texas in 50 years, has killed an estimated 47 people and displaced more than 1 million after causing wreckage in an area stretching for more than 300 miles (480 kms).

Abbott, who is advocating for US government aid to repair his state, said the damage would exceed that of Katrina, the storm that devastated New Orleans and surrounding areas in 2005, and Sandy, which overwhelmed New York city and the US Northeast in 2012.

‘Katrina caused if I recall more than $120 billion but when you look at the number of homes and business affected by this I think this will cost well over $120 billion, probably $150 to $180 billion,’ Abbott told Fox News, adding, ‘this is far larger than Hurricane Sandy.’

The administration of US President Donald Trump has asked Congress for an initial $7.85 billion for recovery efforts, which Abbott called a ‘down payment.’

‘This is a long road to hoe if we are going to rebuild the fourth largest city in the United States as well as the entire geographic region,’ Abbott said.

Houston was still struggling to recover on Sunday, when the city forced the evacuation of thousands of people on the western side of town who were affected by the release of floodwater that had built up in a reservoir.

The city cut off power to homes on Sunday morning to encourage evacuation of those who had been reluctant to leave their homes.

The US Environmental Protection Agency on Saturday raised concerns about 13 Superfund sites, heavily contaminated former industrial zones, that had been flooded and were in danger of spreading toxins.

‘People have to be very cautious as they go through the rebuilding process ... The EPA is monitoring that, the EPA is going to get on top of that,’ Abbott said.

The head of the US Federal Emergency Management Agency (FEMA) called federal aid a ‘ray of hope’ but said state and local officials also needed to do their part.

‘We need elected officials at all levels to sit down and hit the reset button and make sure they have everything they need to increase levels of self-sufficiency,’ FEMA Administrator Brook Long told CBS News.

‘They can't depend only on federal emergency management,’ Long said, declining to offer a figure for how much money the White House would eventually ask from Congress.

But Houston Mayor Sylvester Turner said his city was making progress on several fronts to recovery, resuming city services and helping get people into housing and out of emergency shelters.

‘This is a can-do city. We're not going to engage in a pity party,’ Turner told the same CBS News program before Long spoke.

Speaking from the city's George R. Brown Convention Center, which once housed 10,000 flood refugees, he said there were ‘significantly less than 2,000’ people staying there now.

Damage from the storm is also posing an economic and humanitarian challenge for Trump, who visited Houston on Saturday and met some of the thousands of people in evacuation shelters and rescue workers who have helped shuttle survivors to safety.

The visit gave Trump an opportunity to show an empathetic side, after some criticized him for staying clear of the disaster zone during a Texas visit on Tuesday. Trump said he did not want to hamper rescue efforts.

Late Saturday night, Trump tweeted ‘Just got back to the White House from the Great States of Texas and Louisiana, where things are going well. Such cooperation & coordination!’

Officials said at least 75 schools in Houston suffered severe or extensive water damage, or more than 25 percent of all those in the district.

At least one high school, with 2,700 students, was unlikely to open for nearly the entire school year, and the city was still evaluating some other school structures.

Many areas of Texas were still battling floodwaters from swollen rivers that were expected to remain for a week or more. In Beaumont, about 85 miles (140 km) east of Houston, officials were trying to repair a flood-damaged pumping station that caused the city of about 120,000 people to lose drinking water for days.

Nearly 200,000 homes have suffered flood damage and about 12,600 were destroyed, the Texas Department of Public Safety said on Saturday.

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