The paper analyzed and proposed a solution to the problem of meeting safety conditions at temporary work sites for the rehabilitation of the supply tunnels of RHE Velebit, HPP “Orlovac”, HPP Zakucac and HPP Kraljevac. For each individual hydroelectric power plant, the most favorable (safe and economical) solution to the mentioned problem of meeting the safety conditions during operation in the very unfavorable (difficult to access and wet area) conditions of the supply tunnels of the mentioned hydroelectric power plants was offered.