above natural ground level and/or a minimum height of dam. Legislation
must also adequately prescribe responsibility for enforcement and for the
proper supervision of design, construction and operation, and must detail
arrangements for surveillance, periodic major inspections and abandon-
ment.
7.4.2 Representative national approachesIllustrative examples of legislative and administrative approaches are
summarized below.
In France, the initial legislation of 1898 has been extended and
revised at intervals, notably following the Malpasset disaster of 1959. A
standing technical committee advises on the design and construction of
major dams, and all significant dams are subject to annual inspection by a
government department. The provisions are detailed and quite prescrip-
tive, and apply to dams exceeding 20 m height.
In Switzerland, regulations originated in 1934 and have been modi-
fied at intervals subsequently. Application of the legislation is entrusted to
a federal department operating in conjunction with consultants and mili-
tary authorities.
The qualifying criteria for national legislation to apply in Italy are set
at a height of 15 m or storage capacity of 1 106 m^3 , with smaller dams
subject to control by the regional authorities. Spanish dam safety legisla-
tion sets the same qualifying criteria at national level. Legislation across
Europe is summarized and discussed in Charles and Wright (1996).
In the United States of America federal dams are subject to control
through the appropriate government agency, e.g. the Corps of Engineers
and the Bureau of Reclamation. Non-federal dams are the subject of state
legislation, but the degree of control exercised at state level is very vari-
able. A US national survey completed in 1983 identified 68 000 dams, of
which approximately 40% were considered to present a significant poten-
tial hazard. Of 8818 dams subjected to further screening and inspection,
33% were classified as technically inadequate, with 2% categorized as
‘emergency unsafe’ (Duscha, 1983).
International guideline recommendations covering the safety of
dams have been published (UNESCO, 1967). These provided a suggested
framework for use in drafting appropriate national legislation. The recom-
mendations favoured a national authority empowered to examine and
approve all proposals to construct, enlarge or repair dams and be respons-
ible for approving operating and surveillance schedules.