The Suviana and Brasimone lakes regional park () is a regional park and protected natural area in the Bolognese Apennines, in Emilia-Romagna, northern Italy. It lies in the Metropolitan City of Bologna, near the border with Tuscany, and extends around the artificial reservoirs of Lake Suviana and Lake Brasimone, together with the surrounding forests, ridges, villages and hydroelectric infrastructure.
The park was established by Regional Law no. 38 of 14 April 1995 and covers 3,329.89 hectares in the municipalities of Camugnano, Castel di Casio and Castiglione dei Pepoli. Its territory includes two large reservoirs created for hydroelectric purposes, a largely forested mountain landscape, historical settlements such as Bargi, Baigno, Badi, Stagno and Chiapporato, and the Natura 2000 site IT4050020 "Laghi di Suviana e Brasimone".
The park is unusual among protected areas of the Apennines because its landscape is closely connected with twentieth-century energy infrastructure. The difference in elevation between Brasimone and Suviana is used by the Bargi hydroelectric power station, a pumped-storage plant commissioned in the 1970s. The southern shore of Lake Brasimone is also the site of the ENEA Brasimone Research Centre, one of Italy's main facilities for research on advanced energy systems, liquid-metal technologies, fourth-generation nuclear fission, fusion-related technologies and experimental systems for nuclear and non-nuclear applications.
Geography
The park occupies a central sector of the mountains south of Bologna, between the valleys of the Brasimone stream and the Limentra di Treppio. Its southern boundary follows the watershed near the Tuscan border. The ridge between the two principal reservoirs is formed by Monte Calvi, the highest summit of the park at , and by Monte di Stagno.
The two main lakes are artificial reservoirs at different elevations. Lake Suviana lies at about above sea level, while Lake Brasimone lies at about . This difference in altitude later became central to the pumped-storage hydroelectric system linking the two basins.
The landscape is mostly wooded. Mixed oak woods, beech woods, chestnut groves and conifer plantations cover much of the slopes, while open meadows and former cultivated areas occur within the forest. Sandstone outcrops and steep wooded walls are visible along the western side of the main ridge and below the Brasimone basin, especially in the area known as the Cinghi delle Mogne.
Geology and scenic features
One of the most characteristic scenic features of the park is the rocky front of the Cinghi delle Mogne, immediately downstream from the Brasimone dam. Here the left bank of the stream is dominated by steep cliffs showing regular stratification of turbiditic sandstones, with sparse vegetation of European hop hornbeam, manna ash, oak, sweet chestnut, beech and shrubs.
The cliffs of the Brasimone gorges provide habitat for raptors such as kestrels and peregrine falcons. Along the ridge, at about above sea level, is the Grotta delle Fate, a natural cave formed along a fracture in the sandstone layers, about long and deep, with specialised subterranean fauna.
Monte Calvi, the highest mountain in the park, has a steep western slope above the Limentra di Treppio valley, where mixed broad-leaved woods and conifer plantations are interrupted by sandstone outcrops. On the gentler eastern side, former fields and pastures are now colonised by bracken, shrubs and broom, while stone walls still mark old meadows and rural settlements.
Monte di Stagno is another major panoramic point. Its flat and windy summit offers views over Lake Suviana, the Limentra di Treppio valley, the Reno valley and several Apennine peaks, including Corno alle Scale, Monte Cimone, Monte Vigese and Sasso Balinello.
History
The park was created in 1995 to protect the natural and historical landscape around the two reservoirs and the surrounding Apennine territory. Traditional settlement in the area was based on small mountain villages, chestnut groves, woodland management, pastoral activity and local routes across the ridges. For centuries the local economy relied mainly on livestock, timber, charcoal production and chestnut cultivation.
From the early twentieth century the area was transformed by large public works connected with hydroelectric production. In 1910 works began on a dam near the Scalere mill, where the Brasimone valley narrowed and the stream formed a series of drops. The dam was also used for a new road linking Castiglione dei Pepoli with Riola through Camugnano, improving access to the Porrettana road and the Bologna–Pistoia railway.
The hydroelectric plant connected with the Brasimone reservoir was built farther downstream, near the old church of Santa Maria, where a second dam was built in 1917 to increase production. Ten years later the State Railways completed the Pavana reservoir, in the nearby Limentra di Sambuca valley, to provide electricity for the electrification of the Porrettana railway.
In 1928 works began on the damming of the Limentra di Treppio near Bargi and Suviana. The Suviana dam, completed in 1933, was described by the park authority as the highest dam then existing in Italy, at . New roads and a cableway between Suviana and Porretta railway station were built to support construction and to transport cement. Water from Pavana was also conveyed into the new reservoir through an underground conduit.
At the beginning of the 1970s the two basins of Brasimone and Suviana were connected by penstocks and a plant capable both of generating electricity and of pumping water back to the upper reservoir. In the 1960s construction had also begun on the PEC experimental nuclear reactor project on the southern shore of Lake Brasimone; the project was abandoned after the Italian nuclear referendum of 1987.
Reservoirs and hydroelectric system
Lake Suviana
Lake Suviana is one of the largest bodies of water in the Emilian Apennines. It has an approximate surface area of , a maximum depth of about and a capacity of about 46 million cubic metres. The reservoir was built between 1928 and 1932, taking advantage of the form and geology of the valley, which allowed a large quantity of water to be stored.
The lake has steep shores in many sections, and its water level varies according to the operation of the hydroelectric system. It is the more visited and equipped of the two main lakes. Tourist sources describe picnic areas, seasonal accommodation, bathing areas and outdoor activities such as windsurfing, sailing, rowing and sport fishing, subject to local regulations.
Lake Brasimone
Lake Brasimone is smaller and higher than Suviana. It has an approximate surface area of , a maximum depth of about and a capacity of about 6 million cubic metres. Its waters are held by the Scalere dam, about high.
The dam was built at a narrow section of the valley, where the Brasimone stream enters its gorge and the valley sides are formed by solid sandstone. The reservoir flooded a broader basin where mainly clayey terrains crop out.
Compared with Suviana, Brasimone has a quieter and more wooded character. Its shores include small rest and picnic areas, and the lake is closely associated with forest walks, the surrounding mountain landscape and the ENEA research facilities on its southern side.
Bargi hydroelectric power station
The two reservoirs are connected by the Bargi hydroelectric power station, a pumped-storage hydroelectric plant owned by Enel. The plant was commissioned in 1975 and has an installed capacity of about 330 MW. It uses the difference in elevation between Lake Brasimone and Lake Suviana, with a gross head of about .
In generation mode, water descends from the upper Brasimone basin to the lower Suviana basin through the turbines. In pumping mode, water can be moved back from Suviana to Brasimone, allowing the system to store energy and support grid management. The hydroelectric system gives the park a strong connection not only with landscape conservation and recreation, but also with the history of energy infrastructure in the northern Apennines.
On 9 April 2024 an explosion and fire occurred at the Bargi plant during works at the hydroelectric facility. Seven workers died in the accident. The incident concerned the power station rather than the dams themselves.
ENEA Brasimone Research Centre
The ENEA Brasimone Research Centre is located at Brasimone, in the municipality of Camugnano, on the southern shore of Lake Brasimone. It is one of the most distinctive scientific sites in the Bolognese Apennines and forms a major technological element in the landscape of the park.
ENEA describes Brasimone as one of the main national and international research centres devoted to the study and development of technologies for fourth-generation nuclear fission and magnetic-confinement nuclear fusion. Its activities include innovative energy systems, green technologies and environmental monitoring, nuclear safety technologies, liquid-metal technologies, advanced materials, ionising radiation technologies, radiation protection, and the prototyping of systems and components for energy applications.
The centre covers more than 400 hectares, of which about 100 hectares are urbanised and the rest is mainly woodland. The urbanised area contains 17 buildings and several experimental halls, with about 31,000 m² of usable space, including more than 19,000 m² equipped for experimental activities.
Origins and conversion
The centre originated in the 1960s as a facility of the CNEN, the Italian National Committee for Nuclear Energy. It was initially intended to host the experimental reactor known as PRO, or Progetto Reattore Organico, a project that was later abandoned.
In the early 1970s, during the Italian-French fast-reactor programme, Brasimone was selected for the PEC project, or Prova Elementi Combustibili, an experimental reactor intended for fuel-element testing. From 1972 onwards, major infrastructure works were carried out, including service buildings and four large technological halls known as ESPRESSO, ISI, CPC-1 and RSA, which hosted experimental plants for tests on components and materials.
The PEC was designed as a sodium-cooled fast experimental reactor with a thermal power of 118 MWth. Its main purpose was to study the behaviour of fuel elements under thermal and neutron conditions comparable with those of fast power reactors. The reactor core included a central test channel for an experimental fuel element of 3 MWth, served by independent sodium circuits.
The complex was designed with a metallic containment building surrounded by three main buildings: the sodium and gas building, the control and services building, and the fuel handling building. In 2017 ENEA began, in collaboration with Italian universities, a project to recover and digitise part of the paper archive of the PEC reactor project. ENEA describes this archive as a unique record of the detailed design of a sodium-cooled nuclear reactor whose construction had begun and was then permanently halted after the 1987 referendum.
In 1985 the centre employed about 240 ENEA staff members, while construction activities involved more than 1,000 workers from external companies. After the Chernobyl disaster in 1986 and the Italian nuclear referendum of 1987, the PEC programme was halted and the centre was gradually converted to other research fields. By 1990 its activities had been redirected mainly towards controlled thermonuclear fusion technologies and, later, towards advanced nuclear systems and fourth-generation fission technologies.
Fourth-generation nuclear research
One of the main areas of activity at Brasimone is research on fourth-generation nuclear systems, especially lead-cooled fast reactors. ENEA considers heavy liquid-metal technologies, particularly liquid lead, one of the centre's strongest fields of expertise.