Seym (river)

The Seym or Seim (Russian: Сейм; Ukrainian: Сейм) is a river that flows westward in Russia and Ukraine. It is 748 kilometres (465 mi) long (250 km within Ukraine) and its basin area about 27,500 square kilometres (10,600 sq mi). It is the largest tributary of the Desna.^[2][3][1][4]

Seym
Seym at Bupel in Kursk Oblast
Native name	Сейм
Location
Regions	Russia: Belgorod, Kursk  Ukraine: Sumy, Chernihiv
Physical characteristics
Source	near Morozovo
• coordinates	51°09′50″N 37°13′58″E
Mouth	Desna
• coordinates	51°27′34″N 32°33′50″E
Length	748 km (465 mi)
Basin size	27,500 km2 (10,600 sq mi)
Discharge
• average	99.6 m³/s[1]
Basin features
Progression	Desna→ Dnieper→ Dnieper–Bug estuary→ Black Sea
Tributaries
• left	Reut, Vyr
• right	Tuskar, Svapa, Kleven

Places on the river include Kursk, Kurchatov,^{[citation needed]} Rylsk, Glushkovo,^[5] Putyvl, Baturyn, and the junction with the Desna, which continues west and south past Chernihiv to Kyiv.^{[citation needed]}

In September 2024, during the Russian invasion of Ukraine, Ukrainian officials accused Russia of polluting the river by dumping sewage from a sugar factory in Tyotkino, Kursk Oblast, resulting in environmental damage estimated at about Hr 186 million ($4.5 million) in Chernihiv Oblast that included a decrease in oxygen levels and fish kills downstream.^[6]

The river also serves cooling water for the Kursk Nuclear Power Plant in Russia.