Emergency Situations Ministry spokeswoman Jamila Tilloeva told RFE/RL's Tajik Service today that the accident happened while repairs were being made to a drainage tunnel.
She said the accident was the result of a failure to heed safety regulations.
Another person was hospitalized with serious injuries.
Experts of the Interior Ministry and Energy Ministry were dispatched to the site.
The Nurek facility is the largest hydroelectric power plant in Tajikistan.