Dams & Cascades Enterprise

"Dams & Cascades" is an enterprise within the structure of Natsionalna Elektricheska Kompania EAD, which deals with operation and maintenance of dams and hydraulic facilities.

The Dams & Cascades Enterprise operates reservoirs with total storage capacity of 3.5 billion  m3, which is 55% of the total regulated volume of water storages in the Republic of Bulgaria.

The reservoirs provide water resources for NEK's HPPs and PSHPPs with total installed capacities of 2737 MW in turbine mode and 931 MW in pumping mode.

The main activities of Dams & Cascades Enterprise include:

  • Carrying out of technical control and monitoring of the operational safety and stability of 46 dams and their facilities, 671 km of derivations, tunnels and canals and over 500 water catchments. These are extremely complex and diverse facilities, which operation is subject to high requirements related to security and economy.
  • Annual technical inspections are conducted to establish the operational condition of the dams and their facilities. In regular intervals, in accordance with the regulations, inspections of derivations and underwater inspections of facilities are performed.
  • The D&C Enterprise provides high quality of current and major repairs and maintenance of all hydraulic, construction, mechanical and electrical equipment and facilities from the hydro power cascades and hydro units.
  • It performs activities related to dams operation, provides design and technical solutions, as well as maintenance of the accompanying infrastructure – accommodation and office buildings, workshops, communications, labour protection, etc.
  • It prepares daily, 10-day, monthly and annual water balance assessments of the operated reservoirs.
  • It performs hydrometric observations and maintains a database for the purposes of analyses on water efficient use.

  • It carries out systematic and continuous technical monitoring of all hydraulic facilities in accordance with approved technical control programmes, strictly observing the requirements of the relevant regulatory documents.
  • In regular intervals the D&C Enterprise prepares analyses on the condition of the dams operated by NEK EAD, and makes conclusions about the technical and operational condition of the facilities, basing on the behaviour of the dams and the results of their operation, including financial results. The need of current and major repairs is assessed. The analyses are reviewed by an expert technical council of Natsionalna Elektricheska Kompania EAD, including also external specialists in the field of dam design, construction and operation, who make decisions related to the future operation of these facilities.
  • An internal database of documents regulating the activities related to the operation, security and reliability of the dams and other hydraulic facilities is being developed.
  • Action plans are prepared for emergency situations and in case of high waters, coordinated according to the active regulations with the institutions concerned - Fire Safety and People Protection Divisions, Regional Authorities and Municipalities, and Owners of hydraulic facilities long the rivers.
  • Carrying out of new construction works related to the facilities technical and economic operation.

A number of activities are performed within the technical control:

  • Control of displacements of the dams, their foundations and slopes by using geodetic methods and precise control & measuring systems;
  • Control of infiltration through the dams, their foundations and slopes;
  • Monitoring of chemical and mechanical suffusion of water;
  • Water management, hydrological and meteorological observations and measurements at the dams and in the catchments of the hydro power cascades, related to complex analyses and rational use of waters.
  • Measurement of sediments in the reservoirs and developing erosion processes;
  • Control of the technical and operational condition of machines and electrical equipment in the dams;
  • Control of technical and operational condition of water catchments and derivations.

Up-to-date and highly professional equipment is used for all these observations and measurements: devices for geodetic measurements, instruments for remote measurement and reading of the parameters of deformation and infiltration processes and phenomena in the dams, automatic meteorological stations, level gauges, flow meters for pressure and                   non-pressure water facilities, hydrometric propellers, echosounders with GPS systems.

Among the large reservoirs operated by the Dams & Cascades Enterprise are Iskar Dam, Belmeken Dam, Batak Dam, Vacha Dam, Krichim Dam, Chaira Dam, Golyam Beglik Dam, Dospat Dam, Studen Kladenets Dam, Ivailovgrad Dam, Ovcharitsa Dam, Rozov Kladenets Dam, Koprinka Dam, Alexander Stamboliyski Dam.


The Dams & Cascades Enterprise plays a leading role in our country with its activities in the sphere of hydraulic facilities maintenance and operation.

The Dams & Cascades Enterprise is a collective member of the Bulgarian Society of Large Dams (BUNCOLD) and its active participant.