News

Information as of 9 January 2026, on the condition of the dams and facilities managed by NEK EAD in the Arda cascade.

At 12:00 p.m. on 9 January 2026, the inflow to the Arda cascade had already decreased tenfold and amounted to 131 cubic meters per second. A water volume of 94 cubic meters per second passes through the spillway. The total volume of the high wave passing through the reservoir was 100 million cubic meters, which is more than the total usable volume of the reservoir, i.e., it is not possible to regulate the incoming water quantities without overflowing. During the high wave period, Ivailovgrad HPP operates around the clock.

Arda Cascade consists of Kardzhali, Studen Kladenets, and Ivailovgrad reservoirs. As of 9 January 2025, the cascade is operational under subsiding complex meteorological conditions, with high storage volumes and a passing high wave through the Ivailovgrad reservoir.

Arda River is characterized by significant fluctuations in discharge and high winter flows, requiring increased attention to dam management in view of the frequent passage of high waves through the cascade and the associated safe overflow through the spillways.

The volumes stored in the reservoirs are as follows:

1. Kardzhali Reservoir – 87% of its total volume
2. Studen Kladenets Reservoir – 94% of its total volume
3. Ivailovgrad Reservoir – full capacity with water overflowing through the spillway.

On 7 January 2025, a sharp increase in the inflow to the Ivailovgrad reservoir was observed as a result of intense torrential rains in the Krumovitsa River basin. After analyzing the data, a procedure was initiated to transfer the dam under high wave conditions. The necessary steps were taken in a timely manner to notify all institutions, agencies, and local authorities involved in the disclosure process. At 22:00 that same evening, a peak high wave of 1,156 cubic meters per second was recorded. With this volume of water, the reservoir quickly fills to capacity and at midnight begins to overflow through its relief facilities. The operational staff on duty at NEK EAD begins reporting information on the condition of the dam every two hours, around the clock.

In conclusion, Ivailovgrad dam fulfilled its purpose and played an important role in controlling the torrential nature of the Arda River, reducing the peak of a high wave of 1,100 cubic meters per second by about 70% to 330 cubic meters per second released downstream of the dam.

National Electricity Company (Natsionalna Elektricheska Kompania) approaches the water management of its multipurpose and significant dams with a high level of responsibility.

Five decades after the construction of Vacha dam and Orpheus pumped-storage hydropower plant, NEK marked the anniversary of the two facilities with a festive event dedicated to the people who created and preserved this significant hydropower heritage.

"I would like to express my sincere gratitude to the teams at Vacha Dam and Orpheus pumped-storage power plant for their professionalism, dedication and outstanding achievements over the years," emphasized NEK Executive Director Georgi Dobrov. " Since their creation, these impressive hydraulic structures have been of strategic importance – not only for the region and its inhabitants, but also for the energy security of the whole country," he said.

Among the guests at the event were Deputy Minister of Energy Georgi Samandov, Plovdiv Regional Governor Prof. Dr. Hristina Yancheva, and Mayor of Krichim Municipality Atanas Kalchev, as well as veterans—engineers, technicians, and managers who participated in the construction in the 1970s. They recalled the scale and challenges of the project, and today their work is continued by new generations of energy professionals who maintain the facilities in excellent technical condition and ensure their reliability in the current conditions of energy transition. The first manager of Orpheus PSHPP, Atanas Chelebiev, was also an honored guest at the ceremony. His professional career at the plant is a true inspiration for young energy professionals. 

During the ceremony, honorary plaques were presented to the managers of Vacha dam service area and Orpheus pumped-storage hydropower plant, Vlado Boyarov and Plamen Dimitrov. The guests viewed a photo exhibition presenting key moments in the construction and development of the facilities – a bridge between the past and the present of Bulgarian hydropower.

Located in the Rhodopes, about 15 km from the town of Krichim, the enchantingly beautiful Vacha Dam is part of the Dospat-Vacha cascade, a key energy scheme with a storage capacity of over 675 million m³ of water. The construction of Vacha reservoir was carried out between 1968 and 1975. The reservoir, which is about 10 km long, was built as an annual flow-control reservoir with a total storage capacity of 226.2 million m³ and a flooded area of 5.0 km².

With a height of 144.5 m, Vacha dam is the highest in Bulgaria. It is built as a concrete gravity structure with buttresses, 420 m long at the crest. Its main purpose is the energy use of water as part of the overall cascade operation.

The Orpheus pumped storage plant, built into the body of the dam, has been in operation since 1975. It has four units with an installed capacity of 160 MW in the generating mode and 47 MW in the pumping mode, producing approximately 229 GWh annually. The plant can process up to 168 m³/s at an average head of 120 m.

Half a century after their commissioning, Vacha Dam and Orpheus PSHPP continue to be examples of engineering precision and sustainability, providing reliable energy and stability to the power system of Bulgaria.