The water resources in Turkmenistan can be subdivided into surface and underground water. Among the surface water resources in Turkmenistan, the most important are the AmuDarya, Murgab, Tedjen and Atrek rivers. The small rivers are insignificant and depend on groundwater. [Diagram]
The AmuDarya plays a key role in the water supply of Turkmenistan. The largest man-made waterway, the Karakum River takes annually 10-12 km³ of water from the AmuDarya and delivers it to the poor in water or waterless regions of Turkmenistan. The AmuDarya is the main, vital water source covering nearly 90% of the water demand in the country. [Table and Diagram]

Other relatively large rivers in Turkmenistan (Murgab, Tedjen, and Atrek) have a total average annual flow of 2.7 km³, and a flow of 90% probability - 1.4 km³. Thus, the total water resources of the average annual river flow of big rivers, small rivers and springs are 27.1 km³/year, while a flow of the 90% probability is 22.8 km³/year.
The extensive network of irrigation canals is built on the plains, especially in the oases. The largest of these is the Karakum River, which is more than 1,100 km long. Its average annual water intake can reach 340-380 m³/s, which is 3-4 times more than the total flow of the Murgab, Tedjen, Atrek rivers and rivers on the northeastern slope of the Kopetdag.
In comparison to other Central Asian states, Turkmenistan has the lowest operational resources of groundwater, 60% of which are formed from the runoff lost through infiltration. As of 01.01.1999, the approved groundwater resources for the entire country were 3.36 million m³ a day.
The largest reserves of drinking water are concentrated in the piedmont areas of the Kopetdag and territorially they belong to the Akhal velayat; Mary and Dashoguz velayats drinking water reserves are very insignificant. Uneven distribution of operational resources of the groundwater creates great difficulties in water supply for the population and economic objects in the western etraps of Turkmenistan. [Table]