US authorities: Floodwaters are ‘the worst we’ve seen’ in years

US authorities have warned that floodwaters in the Colorado River have “the worst flooding we’ve ever seen” and urged people to stay away from the area.

US National Guard troops have also been dispatched to help the federal government manage floodwaters.

President Donald Trump signed an executive order last week declaring a state of emergency for the Colorado.

A separate emergency order, issued on Wednesday, also calls for an emergency declaration in New York City and parts of Maryland and Virginia.

Colorado is the largest river in the US, with an annual volume of more than 5.2 million cubic metres.

The Colorado River is a tributary of the Missouri River.

The river flows through the US state of Colorado.

The water level of the Colorado is about 10 feet higher than it was at its peak in April.

The area of the river in Denver was under water on Thursday morning, said USGS meteorologist Michael Osterberg.

Floodwaters had risen to a depth of about 8 feet in Boulder, and the river level was about 1.5 feet higher, according to Osterburg.

In New York, water was at about 7 feet in the city, according the National Weather Service.

In Washington state, at least nine homes were damaged by flooding and at least four people were taken to hospitals.

The floodwaters are believed to be the worst in years, and authorities are urging people to avoid the area, the Washington Post newspaper reported.

The New York Department of Environmental Conservation warned on Thursday that flood waters in parts of the city were at “record levels”.

Authorities said that “in some areas, the river is at its highest levels in decades, leading to extensive damage and destruction”.

Floodwaters in parts at least 10 feet high in Boulder have inundated homes, leaving the city under a state-wide state of evacuation, officials said.

The city has said it will reopen on Monday to allow for the recovery of residents affected by the flooding.

A spokeswoman for the US Army Corps of Engineers said that the floodwaters had reached “high-water mark”, with the river reaching an area of about 7.4 miles (13 kilometres) in a few areas, said Colleen Seitz, a spokeswoman for US Army officials.

“We expect the floodwater to recede, but it’s going to take some time,” she said.