HONOLULU -- Heavy rains prompted evacuations over fears that a dam might breach on the Hawaiian island of Maui, and officials asked people to not to return to their homes on Tuesday because flood advisories were still in effect.

Officials initially thought that the Kaupakalua Dam in the community of Haiku was breached by flood waters, "but after closer inspection, county officials determined there was no structural damage," said a statement from Maui County late Monday.

Those living near or below the dam are asked to continue evacuations until the all clear is given, county officials said Tuesday.

The National Weather Service reported that 13.2 inches (33.5 centimetres) of rain fell in the Haiku area of Maui's north coast between 7 a.m. and 3 p.m. on Monday. Maui and all of Hawaii's islands are under a flash flood watch amid heavy rains expected to last through Wednesday morning.

About six homes on Maui and two bridges were heavily damaged or destroyed, Maui County Mayor Michael Victorino's office said Tuesday. He urged people to be vigilant because there were fears that landslides could happen.

"This has been unprecedented flooding, and we will be making damage assessments today," Victorino said in a statement Tuesday. "I ask everyone to stay vigilant and be safe."

The Maui Fire Department said it responded to more than a dozen calls for help from residents trapped by rising waters.

Water flowed over the top of the dam's reservoir, but the dam itself did not fail, said Shan Tsutsui, the chief operating officer of Mahi Pono, a co-owner of the dam.

Officials monitored the reservoir overnight. County officials said water levels remained above normal, roughly 3 feet below the top of the dam.

One evacuation centre remained open Tuesday for anyone needing shelter.

He also urged tourists to stay in their hotel rooms or wherever they were staying.

Maui County spokesman Brian Perry said he did not know how many people lived downstream of the dam.

A state website says the earthen dam was built in 1885 and is 57 feet (17.4 metres) in height and 400 feet (122 metres) in length.

The state Department of Land and Natural Resources said the dam is scheduled to be removed this summer. The agency notified the dam's owners in February 2020 that it needed a water-level gauge with readings accessible on the internet and ordered the owners to keep the reservoir empty. The owners have done so, except during storms when water is passed through, the agency said.

East Maui Irrigation Company, which was created to divert water from streams to sugar plantations, owns the dam.

Mahi Pono, which grows a variety of crops on former sugar cane land, co-owns East Maui Irrigation with Alexander & Baldwin Inc., a commercial real estate developer with roots in the sugar industry.

The state regulates 132 dams across Hawaii, most of them built as part of irrigation systems for the sugar cane industry, according to a 2019 infrastructure report by the American Society of Civil Engineers. The number of regulated dams fell to 131 the following year, likely because one had been taken out of service, Dan Dennison, a spokesman for the Hawaii Department of Land and Natural Resources, said in an email to The Associated Press.

Of the 132 dams listed in the 2019 report, 93% are classified as high hazard potential, which means a failure could result in significant loss of life or property, the report said.

A dam failure turned fatal in Hawaii in 2006, when seven people were killed after the Ka Loko dam on the island of Kauai collapsed and water rushed downhill.