The county government in conjunction with the national government will build a Sh9 billion mega dam at Pesi in Ndaragwa sub-county.
The 16 million cubic metres dam is expected to end the perennial water shortage in the county and especially the areas bordering Laikipia County.
Nyandarua Governor Daniel Waithaka yesterday toured the site and announced that construction will start before the end of the year.
He said the dam will also be a source of hydro-electric power, irrigation, eco-tourism, fishing and water for domestic consumption.
"We want residents to involve themselves in farming and that is why we found it wise to construct the dam here," he said.