Seym (river)

Seym
Seym at Bupel in Kursk Oblast
Native nameСейм
Location
Regions Russia: Belgorod, Kursk
 Ukraine: Sumy, Chernihiv
Physical characteristics
Sourcenear Morozovo
  coordinates51°09′50″N 37°13′58″E / 51.16389°N 37.23278°E / 51.16389; 37.23278
MouthDesna
  coordinates
51°27′34″N 32°33′50″E / 51.45944°N 32.56389°E / 51.45944; 32.56389
Length748 km (465 mi)
Basin size27,500 km2 (10,600 sq mi)
Discharge 
  average99.6 m³/s
Basin features
ProgressionDesnaDnieperDnieper–Bug estuaryBlack Sea
Tributaries 
  leftReut, Vyr
  rightTuskar, Svapa, Kleven

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.

Places on the river include Kursk, Kurchatov, Rylsk, Glushkovo, Putyvl, Baturyn, and the junction with the Desna, which continues west and south past Chernihiv to Kyiv.

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.

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