The Ngiep River originates in the mountains of Xieng Khouang Province, flowing through Khoun District into Thathom District of Xaysomboun Province, through Hom District and into Bolikhan District of Bolikhamxay Province. The Nam Ngiep (nam is the Lao word for river) meets the Mekong River just upstream from Pakxan city in Bolikhamxay.
The project will create two dams on the Nam Ngiep. The main dam, 9 km upstream of Hat Gniun village in Bolikhan District, will create a 70-km-long, narrow reservoir that extends up the Ngiep valley as far as Thathom District. At almost 150 m high the dam will be the second tallest in Laos. The Power Station at this dam will generate up to 272 MW of electricity for export to Thailand.
Around 6 km below the main dam a 20 m high re-regulation dam will control water flows to avoid sudden large releases of water to the river downstream. A second power station at this re-regulation dam will be able to produce around 18 MW of power for sale to the national utility, Electricité du Laos (EDL).
With a combined capacity of 290 MW, Nam Ngiep 1 will generate around 1,620 GWh of electricity annually. Two transmission lines will be required to transport the electricity generated by the project. From the main power station a 230-kV line will run for 125 km to the Nabong outside Vientiane. A 115-kV transmission line will be constructed by EDL from the Re-regulation Power Station to Pakxan, over a distance of 40 km.