At least eight people were killed and hundreds of families displaced after Patel Dam in Solai, Nakuru County, burst its banks Wednesday night.
The dam breached its banks, sweeping away hundreds of homes in the neighbourhood, including those on the expansive Nyakinyua Farm, which borders the water reservoir.
Rescue operation by Kenya Red Cross and Nakuru County disaster management teams went into Thursday morning and up to 40 people have been rescued from the mud and taken to hospitals. Many are feared trapped at the mud as rescue mission goes on.
Officials said the dam water and mud spilt out of the reservoir and submerged homes, extending to a radius of nearly two kilometres.
In a statement, Nakuru Governor Lee Kinyanjui said: "We assure residents that we will do our best to take affected families to safety and help them get medical attention."
He asked the public to be careful during this season of heavy rains.
At least 140 people have died in the last two months and more than 260,000 displaced as raging floods wreak havoc across the country.
And yet weather experts are warning of more heavy rains in the next few days in an unusual departure from traditional weather patterns.
The government, the United Nations office in Nairobi and the Red Cross say 32 counties are the worst affected.
Interior Principal Secretary Karanja Kibicho said they had distributed food worth Sh600 million to those affected.