It’s the second natural disaster in less than a week.
Hundreds drowned and more than five villages were swamped by the rising Omo River and tributaries that feed Lake Turkana, which straddles Ethiopia and Kenya.
Fueled by heavy rain in the highlands, the latest floods washed away 872 head of livestock and property, including granaries, according to police spokesman Inspector Daniel Gezhegn.
"Rescue teams are struggling with the help of helicopters and boats to save some of the people who are in serious danger," he said.
Local officials appealed for equipment and other items to assist rescue work to help desperate survivors move to higher ground after their homes were deluged in the week-long rains.
Television reports said bad weather had grounded some helicopter flights.
The meteoroligical department warned that more rain would hit the area in the coming days and alerted residents to take precautionary measures.
Devastating wet season
The latest deaths bring the toll to at least 386 people drowned in Ethiopia in less than two weeks as the June-September wet season takes hold.
Earlier this month, two rivers burst their banks and swept through east Ethiopia's Dire Dawa township, killing 256 people and displacing around 10,000.
Some 250 people are still missing.
Officials in Dire Dawa, where residents were continuing to search for missing relatives, have declared the area a disaster zone and banned the rebuilding of new stettlements.
The World Food Programme, which has been coordinating delivery of supplies, has described the situation as a humanitarian crisis and urged the world to help the displaced.
They have been forced to take shelter in tents and at makeshift camps in crowded schools, raising the risk of disease.
Ethiopia, home to some 70 million people, has suffered heavy floods and droughts in recent years.
In the past few years, flooding has affected large areas of eastern and southern Ethiopia, displacing tens of thousands of people and causing damage running into millions of dollars.
Last year at least 200 people were killed and more than 260,000 displaced when heavy rains pounded the region.