It is one of twelve constituencies in Kiambu County which comprises four wards: Kiamwangi, Kiganjo, Ndarugo, and Ng'enda.
It's located inside Kinale Forest, its being constructed across Theta River in Gatundu South constituency.
The project includes construction of a 17-meter-high compacted earth fill dam, Construction of a reinforced concrete spillway and Laying of a 3.5 km long 500mm diameter steel pipeline up to the Mundoro forest edge.
On completion, Theta dam reservoir will have a storage capacity of 2 million cubic meters (2 Billion liters).
This will improve water supply to the upper parts of Gatundu such as Gachika, Kiamuoria, Kiganjo, Gatitu of greater Kiganjo location and upper parts of greater Ndarugu locations.