HYDROELECTRIC POWER STATIONS ON DAUGAVA

The Daugava River is main un-fossil source of electrical energy available in Latvia. For this reason, the hydroelectric potential of Daugava was explored already since the late 19th century. Daugava is a typical low land river with average annual discharge of 20 – 22 million m3 and 1/3 of these water resources are collected in the territory of Latvia. The unique geological feature of the river is the unusual division of its gradient: the lower part of Daugava had the biggest concentration of its rapids and natural slope of 90 m gradient in a distance of 160 km. Considering these conditions three HPS were built in this stretch of the river in the 20th century comprising some 70% of the whole hydroelectric potential of Daugava today.

The first projects of HPS on Daugava designed before 1914 had their goal in constructing a waterway (3 m in depth) for civil and military transport by building a cascade of six dams. Production of electric power would be only a byproduct of this enterprise then. The Bolshevik government of Latvia in 1919 planned to build a HPS at Dole Island for development of chemical and engineering industry establishing for this purpose a state company „Daugavbūve” [«Двинастрой»]. Technical experts of this company continued to work in the Republic of Latvia providing in 1921 a concept of seven dams on Daugava, five of them intended for production of electric power. In 1932, the Foundation Company carried out hydrologic and geologic investigations of the Daugava valley in order to pick up places suited for construction of six HPS working on basic or required flow conditions. The amount of power available in each HPS would be ca 350 MW. The necessity to keep water transport and migration of fish in Daugava was also considered in this concept. However, until 1940 only construction of one HPS in Ķegums was completed.

After the World War II Soviet engineers designed another concept of HPS cascade on Daugava focused on production of electric power only. The cascade was meant to function in a different mode accumulating water resources to cover maximum demand of power in national power supply system based on thermoelectric centrals working in Riga. No considerations to ecological or heritage protection issues opposing the total reconstruction of Daugava valley in the course of this project were taken to any notice. The general concept was designed already in 1955 foreseeing construction of four HPS at Pļaviņas (1966), Dole (1975), Daugavpils (from 1979, suspended after public protest campaign in 1987 for ecological reasons) and Jēkabpils (not implemented). The total amount of power produced in this cascade would be 1475 MW calculated according to Soviet plans for economic development.