Daugava

Geography

The total catchment area of the river is 87,900 km² (33,900 mi²), of which 33,150 km² (12,800 mi²) are in Belarus.

Tributaries

The following rivers are tributaries to the river Daugava (from source to mouth):

• Left: Mezha, Kasplya, Dysna, Laucesa, Berezauka, Eglona, Pikstere, Ņega
• Right: Usvyacha, Palata, Drysa, Dubna, Aiviekste, Pērse, Dīvaja, Ogre

History

Humans have settled at the mouth of the Daugava and along the shores of the Gulf of Riga for millennia, initially participating in a hunter-gatherer economy and utilizing the waters of the Daugava estuary for fishing and gathering. Beginning around the sixth century CE, Viking explorers crossed the Baltic Sea and entered the Daugava River, navigating upriver into the Baltic interior.

In medieval times, the Daugava was part of the trade route from the Varangians to the Greeks, an important route for the transport of furs from the north and of Byzantine silver from the south. The Riga area, inhabited by the Finnic-speaking Livs, became a key location of settlement and defence of the mouth of the Daugava at least as early as the Middle Ages, as evidenced by the now destroyed fort at Torņakalns on the west bank of the Daugava in present-day Riga.

From the end of the Livonian War great part of the Daugava formed the northeastern border of Duchy of Courland and Semigallia separating it initially from the Kingdom of Livonia, later Swedish Livonia and Riga Governorate. After the incorporation later in the Russian Empire the river formed a border between governorates of Courland on the western bank and Livonia and Vitebsk on the eastern bank.

From 1936 to 1939 Ķegums Hydroelectric Power Station was built on the Daugava river in Latvia. Pļaviņas Hydroelectric Power Station was put into operation in 1968 and Riga Hydroelectric Power Plant in 1974.

Settlements

The following are some of the cities and towns built along the Daugava:

Russia

• Andreapol
• Zapadnaya Dvina
• Velizh

Belarus

• Ruba
• Vitebsk
• Beshankovichy
• Polotsk (home to the Boris stones)
• Navapolatsk
• Dzisna
• Verkhnedvinsk
• Druya

Latvia

• Krāslava
• Daugavpils
• Līvāni
• Jēkabpils
• Pļaviņas
• Aizkraukle
• Jaunjelgava
• Lielvārde
• Ķegums
• Ogre
• Ikšķile
• Salaspils
• Riga

Environment

The river began experiencing environmental deterioration in the Soviet era due to collective agriculture (producing considerable adverse water pollution runoff) and hydroelectric power projects. This is the river that the Vula river flows into.

Water quality

Upstream of the Latvian town of Jekabpils, the river's pH has a characteristic value of about 7.8 (slight alkaline). In this area, the concentration of ionic calcium is around 43 milligrams per liter, nitrate is about 0.82 milligrams per liter, ionic phosphate is 0.038 milligrams per liter, and oxygen saturation is 80%. The high nitrate and phosphate load of the Daugava has contributed to the extensive buildup of phytoplankton biomass in the Baltic Sea; the Oder and Vistula rivers also contribute to the high nutrient loading of the Baltic.

In Belarus, water pollution of the Daugava is considered moderately severe, with the chief sources being treated wastewater, fish-farming, and agricultural chemical runoff (such as herbicides, pesticides, nitrates, and phosphates).