Nam Ngum 4 Dam Hydropower Info by Hobo Maps - Go to Hydropower Projects Page - - Home
Electricite Du Laos (EDL) is developing the 240 MW Nam Ngum 4 Hydropower Project in Phoukout/Pek Districts, Xieng Khouang Province, Lao PDR. The site is not too far south of Nam Chat town on National Road 7 near the Nam Ngum river.
Nam Ngum is pronounced like "Nam Nyum".
Nam Ngum 4 dam site location in images below at coordinates - 19°27'12.0"N 103°00'39.0"E (19.453333, 103.010833)
Map below shows partial diversion of Nam Ngum river through cutoff tunnel & Nam Ngum 4 Powerhouse with all discharged back into Nam Ngum river about 25 km downriver.
Nam Ngum 4 powerhouse site location in old image below at coordinates - 19°25'21.1"N 102°51'04.3"E (19.422520, 102.851194). Too bad in 2025 we can't find a more recent satellite image that shows the powerhouse construction activity.
The government initially granted permission for a local Lao company to build the Nam Ngum 4 hydropower project with construction expected to take five years. After the company failed to make progress the government handed it over to EDL to carry out development under an Engineering, Procurement and Construction model.
EDL is now the 100% owner of Nam Ngum 4 hydropower project.
The project has three 80 MW turbine/generator units for a total capacity of 240 MW with ability to produce 872 GWh of output per year (maybe 884 GWh).
Be aware that some publications, including Wiki sites, have the wrong coordinates putting Nam Ngum 4 project very close to Nam Ngum 5 HPP, far to the west of where Nam Ngum 4 actually is. In 2024 some EDL web pages also had the locations of Nam Ngum 4 & 5 reversed with 5 wrongly close to the Plain of Jars and 4 far to the west.
Nam Ngum 4 layout image below:
Nam Ngum 4 powerhouse site images below during construction.
Nam Ngum 4 dam structure images below.
Intake structure below.
Nam Ngum 4 powerhouse site images below during construction at coordinates - 19°25'21.1"N 102°51'04.3"E (19.422520, 102.851194)
In 2016 the Lao government and China signed a $600 million loan agreement for construction of the Nam Ngum 4 hydropower project.
The Nam Ngum 4 Hydropower Project is estimated to cost US$ 760 million and is constructed by China National Heavy Machinery Co. (CMHC), an affiliate of Sinomach Heavy Equipment Group Co., Ltd.
Construction began Feb. 2018 and should be completed in 2024.
In 2025 it looks like the project is finished and may have already started commercial production. See 2025 EDL video that shows a completed project with nice images but only in Lao and not in English.
It seems that all output from Nam Ngum 4 HPP will be used inside Laos for domestic consumption and not for export.
Nam Ngum 4 location is shown at top of Nam Ngum Basin map below.
The project includes the construction of a roller-compacted concrete gravity dam with 10 sections. The dam structure is 74 meters high and 252 meters long.
The surge chamber of the project is 121 meters in length with maximum excavation diameter of 24 meters.
The project also involves the construction of a 17.5 km diversion tunnel.
Full supply level of the reservoir is to be at 1,040 meters above sea level. Reservoir capacity is 107.4 million cubic meters.
In July 2025 image below we see a controlled release of excess water showing that impoundment is complete.
Photos below from Facebook posting of Nam Ngum 4 Impounding Start Ceremony Feb. 1, 2024
July 29, 2024 celebrated succesful 72 hour tests for all 3 turbine generator units below.
In August 2021 an agreement was reached pursuant to a Memorandum of Understanding in which Electricity Vietnam (EVN) would purchase all of the project's 240 MW electric output when the plant is finished. But in Feb. 2023 a Vientiane Times report said the planned sale to Vietnam would not be effective and was apparently cancelled.
As of December 2025 we have no info regarding a current plan for export of the project's output.
Spiral case installation image below:
Images below from a generator stator installation April 2022
Nam Ngum 4 control images below:
Nam Ngum 4 switchyard image below:
The rough excavation of the 17.5 km underground diversion tunnel was completed in October 2021 after 4 years of construction. Geologic and hydrologic conditions of the tunnel excavation were complex and the stability of the surrounding rock was poor.
Nam Ngum 4 tunnel construction image below:
Nam Ngum 4 reservoir elevation at 1,040 meters above sea level in chart below:
Nam Ngum 4 Dam shown in upper part of map below:
