Supervision of dams
The practice of public control and supervision of dams in Norway started in 1909 with the foundation of the Control Department in the former Norwegian Water Administration, which was succeeded by the Norwegian Water Resources and Energy Administration (NVE) in 1920.
NVE, which is now a directorate under the Ministry of Petroleum and Energy, is still the governmental authority on dam safety in Norway. Today the function of the former Control Department is taken care of by the Supervision and Contingency Planning Department, Section for Dam Safety. The dam owners are fully responsible for the safety of their dams and appurtenant structures, while the main responsibility of the Section for Dam Safety in NVE is to ensure that the dam owners comply with the safety requirements given in law and regulations. The main activities of the Section for Dam Safety are related to supervision of dams and appurtenant structures, including approval of plans for construction and rehabilitation, and administration of the legal framework for dam safety, including development of new technical guidelines.
The main goal of the public supervision is to ensure a uniform high level of safety on Norwegian dams and appurtenant structures, and thereby ensure that these structures are not posing a threat to life, property or the environment. The number of dams with significant failure consequences (class 4, 3, 2 and 1) are approximately 2400. However, also dams in class 0 with insignificant failure consequences are subject to public supervision according to the legal framework, and thereby included in the dam register held by NVE. So the total number of dams in the dam register is approximately 3600. More than 360 of these dams are classified as class 4 and 3 dams (very high and high consequences), and 343 are large dams (height > 15 m). The dam register also include some technical data for other structures such as intake structures, penstocks, tunnels and canals.
The dam safety regulation, which was revised in 2009, is based on a risk philosophy with consequence classification of dams and some differentiated requirements. Naturally, the most strict requirements are given to the dams in the highest consequence classes. NVE also give the highest priority to the dams in the highest consequence classes, i.e. consequence class 4, 3 and 2.