| Official Name: | Mayluu-Suu |
| Native Name: | Майлуу-Суу |
| Pushpin Map: | Kyrgyzstan |
| Pushpin Label Position: | bottom |
| Pushpin Mapsize: | 300 |
| Pushpin Map Caption: | Location in Kyrgyzstan |
| Subdivision Type: | Country |
| Subdivision Type1: | Region |
| Subdivision Name: | Kyrgyzstan |
| Subdivision Name1: | Jalal-Abad Region |
| Established Title: | City Status |
| Established Date: | 1946 |
| Area Total Km2: | 120 |
| Population As Of: | 2021 |
| Population Total: | 25892 |
| Population Density Km2: | auto |
| Coordinates: | 41.2457°N 72.448°W |
| Elevation M: | 1300 |
| Postal Code Type: | Postal code |
| Postal Code: | 721100 |
| Area Code: | (+996) 3744 |
Mayluu-Suu (Kirghiz; Kyrgyz: Майлуу-Суу, Russian: Майли-Сай Mayli-Say) is a mining town in the Jalal-Abad Region of southern Kyrgyzstan. It is a city of regional significance, not part of a district.[1] Its area is, and its resident population was 25,892 in 2021. It has been economically depressed since the fall of the Soviet Union. From 1946 to 1968 the Zapadnyi Mining and Chemical Combine in Mayluu-Suu mined and processed more than 10000ST of uranium ore for the Soviet nuclear program.[2] Uranium mining and processing is no longer economical, leaving much of the local population of about 20,000 without meaningful work. The town was classified as one of the Soviet government's secret cities, officially known only as "Mailbox 200".[3] Mayluu-Suu consists of the town proper, the urban-type settlement Kök-Tash and the villages Sary-Bee, Kögoy and Kara-Jygach.[1]
See also: 1958 Mailuu-Suu tailings dam failure.
The USSR left 23 unstable uranium tailings pits on the tectonically unstable hillside above the town.[4] A breached tailings dam in April 1958 released of radioactive tailings into the river Mayluu-Suu.[5] In 1994, a landslide blocked the river, which flowed over its banks and flooded another waste reservoir. A flood caused by a mudslide nearly submerged a tailings pit in 2002. Mayluu-Suu was found to be one of the 10 most polluted sites in the world in a study published in 2006 by the Blacksmith Institute.[6]
The World Bank approved a US$5 million grant to reclaim the tailings pits in 2004,[7] and approved an additional $1 million grant for the project in 2011.[8] However, grave threats still persist.[9]