The

river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...

Tresa leaves

Lake Lugano __NOTOC__ Lake Lugano ( it, Lago di Lugano or , from la, Ceresius lacus; lmo, Lagh de Lugan) is a glacial lake which is situated on the border between southern Switzerland and northern Italy. The lake, named after the city of Lugano, is situated ...

at a point between Lavena Ponte Tresa in Italy and

Ponte Tresa Ponte Tresa ( Lombard: ''Punt da Tresa'') is a former municipality in the district of Lugano in the canton of Ticino in Switzerland. On 18 April 2021 the municipalities of Croglio, Monteggio, Ponte Tresa and Sessa merged to form Tresa. Histo ...

in Switzerland and flows into

Lake Maggiore Lake Maggiore (, ; it, Lago Maggiore ; lmo, label=Western Lombard, Lagh Maggior; pms, Lagh Magior; literally 'Greater Lake') or Verbano (; la, Lacus Verbanus) is a large lake located on the south side of the Alps. It is the second largest la ...

near

Luino Luino (Western Lombard: ''Lüin'') is a small town and ''comune'' near the border with Switzerland on the eastern shore of Lake Maggiore, in the Province of Varese (Lombardy, northern Italy). Luino received the honorary title of city with a presid ...

, a few hundred metres after joining the

Margorabbia The Margorabbia is the river (Stream#Intermittent and ephemeral streams, intermittent stream) of Valtravaglia, a valley in the province of Varese, Lombardy, Italy. It is a tributary of the Tresa which it joins a few hundred metres upstream of Lak ...

. At the outflow from Lake Lugano the river is crossed by a bridge which unites the Swiss and Italian parts of Ponte Tresa; a customs post divides them. The river is about long, and for most of its course marks the boundary between the Italian

Province of Varese The province of Varese ( it, provincia di Varese) is a Provinces of Italy, province in the region of Lombardy in northern Italy. Its capital is the city of Varese (population of 80,857 inhabitants), but its largest city is Busto Arsizio. The head ...

and the Swiss canton

Ticino Ticino (), sometimes Tessin (), officially the Republic and Canton of Ticino or less formally the Canton of Ticino,, informally ''Canton Ticino'' ; lmo, Canton Tesin ; german: Kanton Tessin ; french: Canton du Tessin ; rm, Chantun dal Tessin . ...

. It passes through the Swiss communes of Ponte Tresa, Croglio and Monteggio, and the Italian communes of Lavena Ponte Tresa, Cremenaga and Luino. A dam on the river, known as the Creva dam serves two purposes: to use the difference in elevation between the lakes to produce

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

, and as far as possible to regulate the flow of water into Lake Maggiore in order to avoid or limit the dangers of flooding.

External links

Hydrological data of the Tresa
at

{{Authority control Rivers of Italy Rivers of Ticino Rivers of Lombardy Rivers of the Province of Varese Italy–Switzerland border International rivers of Europe Rivers of Switzerland