Isfana River

The Isfana River (Исфана суусу; Isfana soyi; река Исфана), also called Andarsoy in its lower course, is a north-flowing transboundary river in Central Asia. It is approximately 69 km long and flows through Razzakov, which was also called Isfana until 2022. The river's course runs through Kyrgyzstan and Tajikistan, from the Turkestan Range into the Syr Darya. Most of the river's water is diverted for irrigation or seeps into the ground, and as such it rarely reaches the Syr-Darya.

The Isfana is fed by unnamed glaciers on the northern flank of the Turkestan Range as well as groundwater. It has 31 tributaries, most of which meet in and around Razzakov. One of the several transboundary rivers in the Syr-Darya basin, the Isfana River flows parallel to the Khojabakirgan River. International donor organizations have supported the establishment of small basin councils in the Isfana River basin, particularly in Tajikistan.

Name
The word "isfana" is believed to have come from the Sogdian word asbanikat, asbanikent or aspanakent which means "the land of horses". In Kyrgyz, the river is called Isfana suusu (Иcфана суусу), and in Uzbek it is called Isfana soyi, which means the "Isfana Creek". In its lower course, the River is also called Andarsoy, since it passes through the village of Andarsoy in Tajikistan.

Course
The headwaters of the Isfana are several unnamed glaciers at roughly 2500 m elevation in the northern region of the Turkestan Range called Altynbeshik (Алтынбешик; Oltinbeshik). The upper portion of the river flows roughly north and northwest. As it passes through the Dagana Gorge (Дагана; Dahana) into the Toojayloo basin (Төөжайлоо; Tuyayaylov), the river disappears underground. The dry riverbed runs through the Isfana-Kara-Bulak basin and reaches eastern Razzakov, where it reemerges and is fed by several artesian wells.

The Isfana River has 31 tributaries. The portion of the river that runs west from the Dagana Gorge to eastern Razzakov is called Tegirmenlik (variously spelled as Тегирмелик and Тегермалик in Kyrgyz; Tegirmonlik), and the portion that flows through Razzakov is called the Say (Сай; Soy), which literally means a "creek". In central Razzakov, the Say receives the Cholgan Creek (Choʻlgan soyi), also fed by an artesian well, from the right.

In the north-west of Razzakov, the Say joins the Taylan Creek, forming the Isfana River proper. The Taylan Creek is also fed by several unnamed glaciers at roughly 1800 m elevation in Kekche-Tau Mountain (Кекче-Тау; Quchchi) in the Turkestan Range. The portion of the Taylan Creek that runs from the eponymous village through Razzakov until it merges with the Say is called the Uzunsay (Узунсай; Uzunsoy).

After travelling north from Razzakov for roughly 40 km, the Isfana River enters Jabbor Rasulov District of Tajikistan.

Tributaries
Tributaries of the Upper Isfana include:
 * Tegirmenlik / Say (which in turn receives Cholgan Creek from the right in central Razzakov)
 * Taylan / Uzunsay

Hydrology
Sources differ on the length of the Isfana River, putting it from 35 km to 69 km long. Most of the annual runoff of the river occurs from May to June, with lowest water levels from February to March.

The Isfana River has an average discharge of anywhere between 0.2 m3/s-0.3 m3/s to 3.1 m3/s. In the spring, the Isfana River often overflows, causing flash floods. Flash floods in the river's basin have become more common since the late 1980s.