Dozens of houses built on riparian land in Kisii town were on Wednesday demolished by a multi-agency task force.
Locals claimed they were caught by surprise in the demolition of more than 100 houses along Nyakomisaro river.
Police presence was heavy during the exercise that began in the morning, their role being to maintain order.
"Our landlord did not give us a notice on the demolitions," said a Mwembe estate resident, one of many who claimed their landlords had kept silent.
The exercise was in the evening extended to Daraja Moja.
The multi-agency team is made up of the National Environment Management Authority, Kisii County, national security, National Youth Service, the National Disaster Management Unit, the Water Resources Management Authority and the National Building and Construction Inspectorate.
More than five major hotels along the river are also targeted for demolition, following claims that they emit raw sewage into the river.
The exercise is expected to continue in the next one week.
The demolitions occurred just a month after the National Land Commission revoked 10 titles deeds which were fraudulently acquired in Kisii.
This followed the commission's public land audit in 2018, which showed that the ownership of at least 600 parcels of public land had been exchanged fraudulently in Kisii town alone.
In February, Land Cabinet Secretary Farida Karoney said more titles would be revoked.
Ms Karoney also announced that all land officials in the 66 registries around the country will soon be reshuffled in a bid to enhance service delivery.
"I am embarrassed that my ministry is famous for all the wrong reasons, ranging from missing files to fake seals and title deeds. How do files manage to 'walk away' from registries yet they have no 'legs'?" she asked in a media address after paying Kisii Governor James Ongwae a courtesy call.