The dam has stalled despite a Chinese contractor having been on the site for months.
On Monday, the farmers found anonymous leaflets scattered across Gituamba Ward warning them that the government, through relevant ministries, would evaluate and assess their land afresh.
Farmers from Kanyoni village, Gatundu North Constituency of Kiambu County are now calling on the government to compensate them fully before they can pave way for the construction of the Sh24 billion Kariminu II dam.
The new demand followed claims that some government officials were working behind the scenes to reduce the compensation amounts that were agreed on earlier.
The farmers were speaking Monday at Kiriko Coffee Factory during a meeting organised by nominated MCA Lawrence Gitau Kariuki ahead of another meeting set for Tuesday in Nairobi.
The Tuesday meeting will be attended by Lands Cabinet Secretary Farida Karoney, her Water counterpart Simon Chelugui and a host of Kiambu leaders led by Governor Ferdinand Waititu. The farmers said they want a one-off compensation before they can surrender their pieces of land.
Led by their welfare committee officials, the farmers said they are not opposed to the building of the dam but insisted that the process should be carried out in a fair manner to ensure that none of them is short-changed.
On Monday, the farmers woke up to find anonymous leaflets scattered across Gituamba Ward warning them that the government, through relevant ministries, would evaluate and assess their land afresh or reduce the monetary value of the crops on their farms in a bid to reduce their compensation amounts by more than half of what they have been waiting for.
The writer of the leaflets claimed to be a government official working with the Ministry of Land and is privy to the deliberations made by various committees concerned with the dam's compensation process.
Other than the anonymous leaflets, word on the ground is that plans to shortchange the farmers are in top gear and the rumours have caused panic among the residents who have been waiting for directions for eight years since the news that a dam would be built in the area reached them.
"We do not want surveys done in phases neither do we want compensation done in phases. Our fear is that, that could be a plan to divide us and make others miss out on their compensation as has happened in other parts of this country," said Joseph Ng'ang'a, a committee member.
Mr Ng'ang'a added that since they (residents) heard of the government's intention to build a dam in the area, they halted planned development projects in their homes, a move that has derailed them and risks derailing them even further if they are not all compensated at once.
The MCA said the leaflets are not only inciting but also meant to create panic and division amongst the 5,000 farmers targeted for compensation. He called on Gatundu North deputy county commissioner to investigate the source of the leaflets.
The dam, whose construction works were set to begin early this year, has stalled despite a Chinese contractor having been on site for months now.
Tuesday's meeting in Nairobi is set to address the issues affecting the farmers.