The heaviest floods in 15 years have forced the closure of several businesses in the commercial heart of Khiri Mat district in Sukhothai.
Despite the flood, the irrigation agency has dismissed a chance of the country facing a repeat of the 2011 flood crisis.
Shops and businesses in the downtown municipality were closed as floodwaters rose rapidly on Sunday.
The water level in the central area of the district surged as a result of floodwater flowing from upstream Phran Kratai district of nearby Kamphaeng Phet province combined with runoff from mountains in Ramkhamhaeng Sukhothai National Park.
The downtown area was under 60cm of water. Owners of small cars were told to keep off the flooded roads as residents raced against time to create sandbag embankments around their homes and shops.
Authorities said the flood in the Khiri Mat district's main commerce zone was the heaviest in 15 years.
The floods also spread to 10 tambons, affecting about 5,500 households in the district. Worst-hit was the Thung Luang municipality where the entire community suffered a complete inundation.
Disaster mitigation officials were on hand to assist flood victims as they surveyed damage from the floods.
Sukhothai governor Piti Kaewsalabsee said the disaster mitigation office, the provincial internal security command and the border patrol police distributed aid to affected families in tambons Thung Luang and Sam Phuang.
Ban Huay Nam Sai in tambon Samphung is under one metre of water which cut off roads connecting to 144 homes. The flood has also devastated wide areas of farmland and stranded farmers and livestock in several neighbouring tambons.
Khiri Mat district chief Uthai Lertwut warned motorists to avoid the Sukhothai-Kamphaeng Phet road which was partially flooded. The worst-hit section of the road was submerged in 40cm of water.
In Phran Kratai district of Kamphaeng Phet, two crocodiles escaped from their flooded farms. One of them, two metres long and weighing 20kg, was caught in a fish pond in Ban khao Kaew village. The other was still on the loose.
Meanwhile, the Royal Irrigation Department said the heavy rainfall over the North last week did not exceed the average rate for this time of year.
Department deputy chief Thongplew Kongchan has ruled out a repeat of the disastrous flood of 2011 affecting most parts of the country including Bangkok.
He said no signs, including the threat of tropical storms, have indicated an excessively wet year ahead.
Calling for calm, he said state agencies have prepared measures to fight heavy floods and urged people to monitor weather reports.
However, he expressed concerns over areas in the Yom River basin where there is no large dam to retain excess water and cushion the impact of flood water.
Also Sunday, the Chao Phraya dam in Chai Nat began discharging more water downstream as run-off from the torrential rains in the North fed into the Chao Phraya River, an official said.
Suchart Charoensri, director of the 12th Irrigation Office, said the water gauge at the Jiraprawat Military Camp in Nakhon Sawan showed the water level in the Chao Phraya dam had risen from 16.03 metres to 16.75m above sea level Sunday.