The Giona is a ‘torrent’, or

intermittent stream Intermittent, temporary or seasonal rivers or streams cease to flow every year or at least twice every five years. Such rivers drain large arid and semi-arid areas, covering approximately a third of the Earth's surface. The extent of temporary ...

, which rises on the slopes of

Monte Tamaro Monte Tamaro is a mountain of the Lugano Prealps, overlooking Lake Maggiore in the Cantons of Switzerland, Swiss canton of Ticino. Reaching a height of 1,962 metres above sea level, it is the highest summit of the chain located between Lake Magg ...

, in the

Swiss Swiss most commonly refers to: * the adjectival form of Switzerland * Swiss people Swiss may also refer to: Places * Swiss, Missouri * Swiss, North Carolina * Swiss, West Virginia * Swiss, Wisconsin Other uses * Swiss Café, an old café located ...

canton Canton may refer to: Administrative divisions * Canton (administrative division), territorial/administrative division in some countries * Township (Canada), known as ''canton'' in Canadian French Arts and entertainment * Canton (band), an It ...

Ticino Ticino ( ), sometimes Tessin (), officially the Republic and Canton of Ticino or less formally the Canton of Ticino, is one of the Canton of Switzerland, 26 cantons forming the Switzerland, Swiss Confederation. It is composed of eight districts ...

. After about , it enters the

Italian Italian(s) may refer to: * Anything of, from, or related to the people of Italy over the centuries ** Italians, a Romance ethnic group related to or simply a citizen of the Italian Republic or Italian Kingdom ** Italian language, a Romance languag ...

province of Varese The province of Varese () is a Provinces of Italy, province in the Lombardy region of Italy. Its capital is the city of Varese (population of 80,857 inhabitants), but its largest city is Busto Arsizio. The headquarters of AgustaWestland, the compa ...

, forming the Val Veddasca before entering

Lake Maggiore Lake Maggiore (, ; ; ; ; literally 'greater lake') or Verbano (; ) is a large lake located on the south side of the Alps. It is the second largest lake in Italy and the largest in southern Switzerland. The lake and its shoreline are divided be ...

at Maccagno. Its course passes through the communes of

Indemini Indemini () is a former municipality in the district of Locarno in the canton of Ticino in Switzerland. On 25 April 2010, the former municipalities of Caviano, Contone, Gerra Gambarogno, Indemini, Magadino, Piazzogna, San Nazzaro, Sant'Abb ...

in Switzerland and Veddasca, Curiglia con Monteviasco,

Dumenza Dumenza is a ''comune'' (municipality) in the Province of Varese in the Italian region of Lombardy, located about northwest of Milan and about north of Varese, on the border with Switzerland. The municipality of Dumenza contains the ''frazioni'' ...

and Maccagno in Italy. The fish found in the river are predominantly

Salmonidae Salmonidae (, ) is a family (biology), family of ray-finned fish, the only extant member of the suborder Salmonoidei, consisting of 11 extant genera and over 200 species collectively known as "salmonids" or "salmonoids". The family includes salmo ...

Cyprinid Cyprinidae is a Family (biology), family of freshwater fish commonly called the carp or minnow family, including the carps, the true minnows, and their relatives the barb (fish), barbs and barbel (fish), barbels, among others. Cyprinidae is the ...

ae and

Cottidae The Cottidae are a family of fish in the superfamily Cottoidea, the sculpins. It is the largest sculpin family, with about 275 species in 70 genera.Kane, E. A. and T. E. Higham. (2012)Life in the flow lane: differences in pectoral fin morphology ...

, in particular

brown trout The brown trout (''Salmo trutta'') is a species of salmonid ray-finned fish and the most widely distributed species of the genus ''Salmo'', endemic to most of Europe, West Asia and parts of North Africa, and has been widely introduced globally ...

, grayling,

chub Chub is a common fish name. It pertains to any one of a number of ray-finned fish in several families and general. In the UK, the term ''chub'' usually refers to the species '' Squalius cephalus''. In addition, see sea chub. In family Cyprinid ...

, vairone and

European bullhead The European bullhead (''Cottus gobio'') is a freshwater fish that is widely distributed in Europe, mainly in rivers. It is a member of the family Cottidae, a type of sculpin. It is also known as the miller's thumb, freshwater sculpin, common bu ...

. The river is put to use as a source of

hydropower Hydropower (from Ancient Greek -, "water"), also known as water power or water energy, is the use of falling or fast-running water to Electricity generation, produce electricity or to power machines. This is achieved by energy transformation, ...

Notes

Rivers of Italy Rivers of Ticino Rivers of Lombardy Rivers of the Province of Varese International rivers of Europe Rivers of Switzerland {{Italy-river-stub