|Primary inflows||underground springs, Scarpia, Pellino, Plesna, Qualba, Fiumetta, Pescone|
|Catchment area||116 km2 (45 sq mi)|
|Max. length||13.4 km (8.3 mi)|
|Max. width||2.5 km (1.6 mi)|
|Surface area||18.2 km2 (7.0 sq mi)|
|Average depth||71.6 m (235 ft)|
|Max. depth||143 m (469 ft)|
|Water volume||1.3 km3 (1,100,000 acre·ft)|
|Residence time||8.9 years|
|Surface elevation||290 m (950 ft)|
|Islands||Isola San Giulio|
It has been so named since the 16th century, but was previously called the Lago di San Giulio, after Saint Julius (4th century), the patron saint of the region. Its southern end is about 35 kilometres (22 miles) by rail, to the northwest of Novara on the main Turin-Milan line, while its north end is about 6 kilometres (4 miles) by rail south of the Gravellona-Toce railway station, halfway between Ornavasso and Omegna.
Its scenery is characteristically Italian, while the San Giulio island has some very picturesque buildings, and takes its name from the local saint, who lived in the 4th century.
It is supposed that the lake is the remnant of a much larger sheet of water by which originally the waters of the Toce flowed south towards Novara. As the glaciers retreated the waters flowing from them sank, and were gradually diverted into Lake Maggiore.
- This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Orta, Lake of". Encyclopædia Britannica (11th ed.). Cambridge University Press.
- CNR - ISE: Laghi (in Italian)
- LIMNO Banca dati dei laghi italiani: Orta (in Italian)