ARTIFICIAL RESERVOIRS

The current national regulatory framework (Presidential Decree 1363/59 and subsequent provisions supplementing the same Regulation: Ministry of Public Works Circulars of 28 August 1986 No. 1125 and 4 December 1987 No. 352; Law No. 584 of 21 October 1994; Prime Minister’s Circular of 13 December 1995 No. DSTN/2/22806; Ministry of Public Works Decree 24 March 1982; Law No. 183/1989; Decree Law No. 507/1994 converted into Law No. 584/1994; Law No. 139/2004; Legislative Decree No. 152/2006; Ministerial Decrees of 14 January 2008 and 26 June 2014) governs the technical standards for the design and construction of dams, defines the rules for their operation, establishes implementing provisions, and allocates responsibilities for Large and small dams.
It also identifies urgent safety measures for Large Dams following revisions in national seismic risk legislation (Law No. 64/1974; Law No. 139/2004; OPCM No. 3519 of 28 April 2006) and sets out operational guidelines for the management of hydrogeological and hydraulic critical conditions (Prime Minister’s Decree of 27 February 2004; Prime Minister’s Directive of 8 July 2014).

Underground or elevated storage tanks are not subject to dam legislation, as they lack dam structures. Also excluded are all dam works creating reservoirs used exclusively for the storage, settling, or washing of industrial residues, which, under Law No. 584/1994, fall under the authority of the former Ministry of Industry, Commerce and Crafts, now the Ministry of Enterprises and Made in Italy (MIMIT).

In the field of seismic safety, several circulars have been issued (DG Dighe Circulars of 27 September 2017 No. 21530; 8 November 2017 No. 25157; 18 March 2019 No. 6660; 3 July 2019 No. 16790), providing guidance on methodologies and contents for the assessment of seismic hazard at dam sites and updating procedures for extraordinary inspections following seismic events.
The recent Director’s Decree DG Dighe No. 510/2025 defines criteria and technical procedures for classifying retention structures based on dam typology, dimensional characteristics, operational behaviour, seismicity, and other site features, as well as downstream territory characteristics, in compliance with Article 4 of Ministerial Decree No. 94 of 14 May 2024.

For small dams, Article 1 of Law No. 584/1994 (and subsequent Legislative Decree No. 112/1998) assigns responsibility to the Regions and Autonomous Provinces of Trento and Bolzano for dams not exceeding 15 m in height or creating reservoirs not exceeding 1,000,000 m³.
Article 2, paragraph 2-bis, of Law No. 584/1994 required Regions to adopt their own regulations within six months of the issuance of the national regulation, while maintaining the application of Presidential Decree No. 1363/1959 until the new regional regulations entered into force.
Several Regions and/or Provinces have enacted legislation on small reservoirs and implementing provisions governing project approval and operational control (Basilicata, Sardinia, Veneto, Piedmont, Aosta Valley, Tuscany, Abruzzo, Campania, Molise, Umbria, Emilia-Romagna, Lombardy, the Autonomous Provinces of Trento and Bolzano, and the Civil Engineering Office of Catania).
Some regional laws define reservoir risk categories based on the guidelines issued by the Presidency of the Council of Ministers – Department of Civil Protection (31 July 1991).

EU Directive 2000/60/EC establishes the obligation to prepare river basin management plans to achieve good ecological and chemical status of waters. Legislative Decree No. 152/2006 defines:

• Artificial water body: a surface water body created by human activity.
• Heavily modified water body (HMWB): a surface water body substantially altered by physical modifications due to human activity.

HMWBs are typically created by dams or weirs for civil, industrial (e.g., hydropower), and agricultural uses.