The Ilek River is a steppe river at the southern end of the Ural Mountains. It is a tributary of the Ural River

Ural River

The Ural or Jayıq/Zhayyq , known as Yaik before 1775, is a river flowing through Russia and Kazakhstan. It arises in the southern Ural Mountains and ends at the Caspian Sea. Its total length is 1,511 mi making it the third longest river in Europe after the Volga and the Danube...

 and lies in the Orenburg Oblast

Orenburg Oblast

Orenburg Oblast is a federal subject of Russia . Its administrative center is the city of Orenburg. From 1938 to 1957, it bore the name Chkalov Oblast in honor of Valery Chkalov...

 in Russia

Russia

Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

 and Republic of Kazakhstan

Kazakhstan

Kazakhstan , officially the Republic of Kazakhstan, is a transcontinental country in Central Asia and Eastern Europe. Ranked as the ninth largest country in the world, it is also the world's largest landlocked country; its territory of is greater than Western Europe...

. It rises just south of Orsk

Orsk

Orsk is the second largest city in Orenburg Oblast, Russia, located on the steppe about southeast of the southern tip of the Ural Mountains. The city straddles the Ural River. Since this river is considered a boundary between Europe and Asia, Orsk can be said to lie in two continents. It is...

, flows south a short distance and then flows westward south of and parallel to the Ural River, with many meanders and oxbow lakes, and joins the Ural about 75km west of Orenburg

Orenburg

Orenburg is a city on the Ural River and the administrative center of Orenburg Oblast, Russia. It lies southeast of Moscow, very close to the border with Kazakhstan. Population: 546,987 ; 549,361 ; Highest point: 154.4 m...

. Two main cities lie on the banks of the Ilek River: Sol-Iletsk

Sol-Iletsk

Sol-Iletsk is a town in Orenburg Oblast, Russia, located on the right bank of the Ilek River , south of Orenburg. Population: 22,000 ; 11,802 ....

 and Aqtöbe (alternate spelling: Aktöbe, Aktyubinsk). The Ilek River remains the most polluted water body in the Ural-Caspian basin. The content of boron and chromium in the river is caused by the tailing ponds of former chemical plants via ground water. The quality class of water in the Ilek River changes from 4 – “polluted water” to 6 – “very polluted water” ("Water resources of Kazakhstan in the new millennium," Water Resources Committee of RK, 2002).
A further tributary of the Ilek River is the Bol'saja Chobda. It is also of archeological significance since it has been discovered as the site of certain Kurgan

Kurgan

Kurgan is the Turkic term for a tumulus; mound of earth and stones raised over a grave or graves, originating with its use in Soviet archaeology, now widely used for tumuli in the context of Eastern European and Central Asian archaeology....

 (Indo-European) burials. http://www.iras.ucalgary.ca/~volk/sylvia/Kurgans.htm.

Tributaries include the Kargala River

Kargala River

The Kargala is a river of Kazakhstan, It flows through Aktobe Province. It flows into the Ilek River near Aktobe City....

.