Po River
Overview
 
The Po is a river that flows either 652 km (405.1 mi) or 682 km (423.8 mi) – considering the length of the Maira
Maira
The Maira is an Italian river, a right tributary of the Po River, which runs through the province of Cuneo in eastern Piedmont. Its source is in the Cottian Alps near the Col de Mary on the French border...

, a right bank tributary – eastward across northern Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

, from a spring seeping from a stony hillside at Pian del Re, a flat place at the head of the Val Po under the northwest face of Monviso (in the Cottian Alps
Cottian Alps
The Cottian Alps are a mountain range in the southwestern part of the Alps. They form the border between France and Italy...

) through a delta projecting into the Adriatic Sea
Adriatic Sea
The Adriatic Sea is a body of water separating the Italian Peninsula from the Balkan peninsula, and the system of the Apennine Mountains from that of the Dinaric Alps and adjacent ranges...

 near Venice
Venice
Venice is a city in northern Italy which is renowned for the beauty of its setting, its architecture and its artworks. It is the capital of the Veneto region...

. It has a drainage area of 74,000 km² in all, 70,000 in Italy, of which 41,000 is in montane
Montane
In biogeography, montane is the highland area located below the subalpine zone. Montane regions generally have cooler temperatures and often have higher rainfall than the adjacent lowland regions, and are frequently home to distinct communities of plants and animals.The term "montane" means "of the...

 environments and 29,000 on the plain.
Encyclopedia
The Po is a river that flows either 652 km (405.1 mi) or 682 km (423.8 mi) – considering the length of the Maira
Maira
The Maira is an Italian river, a right tributary of the Po River, which runs through the province of Cuneo in eastern Piedmont. Its source is in the Cottian Alps near the Col de Mary on the French border...

, a right bank tributary – eastward across northern Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

, from a spring seeping from a stony hillside at Pian del Re, a flat place at the head of the Val Po under the northwest face of Monviso (in the Cottian Alps
Cottian Alps
The Cottian Alps are a mountain range in the southwestern part of the Alps. They form the border between France and Italy...

) through a delta projecting into the Adriatic Sea
Adriatic Sea
The Adriatic Sea is a body of water separating the Italian Peninsula from the Balkan peninsula, and the system of the Apennine Mountains from that of the Dinaric Alps and adjacent ranges...

 near Venice
Venice
Venice is a city in northern Italy which is renowned for the beauty of its setting, its architecture and its artworks. It is the capital of the Veneto region...

. It has a drainage area of 74,000 km² in all, 70,000 in Italy, of which 41,000 is in montane
Montane
In biogeography, montane is the highland area located below the subalpine zone. Montane regions generally have cooler temperatures and often have higher rainfall than the adjacent lowland regions, and are frequently home to distinct communities of plants and animals.The term "montane" means "of the...

 environments and 29,000 on the plain. The Po is the longest river in Italy; at its widest point its width is 503 m (1,650.3 ft). The Po extends along the 45th parallel north.

The river flows through many important Italian cities, including Turin
Turin
Turin is a city and major business and cultural centre in northern Italy, capital of the Piedmont region, located mainly on the left bank of the Po River and surrounded by the Alpine arch. The population of the city proper is 909,193 while the population of the urban area is estimated by Eurostat...

 (Torino), Piacenza
Piacenza
Piacenza is a city and comune in the Emilia-Romagna region of northern Italy. It is the capital of the province of Piacenza...

 and Ferrara
Ferrara
Ferrara is a city and comune in Emilia-Romagna, northern Italy, capital city of the Province of Ferrara. It is situated 50 km north-northeast of Bologna, on the Po di Volano, a branch channel of the main stream of the Po River, located 5 km north...

. It is connected to Milan
Milan
Milan is the second-largest city in Italy and the capital city of the region of Lombardy and of the province of Milan. The city proper has a population of about 1.3 million, while its urban area, roughly coinciding with its administrative province and the bordering Province of Monza and Brianza ,...

 through a net of channels
Channel (geography)
In physical geography, a channel is the physical confine of a river, slough or ocean strait consisting of a bed and banks.A channel is also the natural or human-made deeper course through a reef, sand bar, bay, or any shallow body of water...

 called navigli
Navigli
The navigli was a system of navigable and interconnected canals around Milan, Italy.The system consisted of five canals: Naviglio Grande, Naviglio Pavese, Naviglio Martesana, Naviglio di Paderno, Naviglio di Bereguardo. The first three were connected through Milan via the Fossa Interna, also known...

, which Leonardo da Vinci
Leonardo da Vinci
Leonardo di ser Piero da Vinci was an Italian Renaissance polymath: painter, sculptor, architect, musician, scientist, mathematician, engineer, inventor, anatomist, geologist, cartographer, botanist and writer whose genius, perhaps more than that of any other figure, epitomized the Renaissance...

 helped design. Near the end of its course, it creates a wide delta
River delta
A delta is a landform that is formed at the mouth of a river where that river flows into an ocean, sea, estuary, lake, reservoir, flat arid area, or another river. Deltas are formed from the deposition of the sediment carried by the river as the flow leaves the mouth of the river...

 (with hundreds of small channels and five main ones, called Po di Maestra, Po della Pila, Po delle Tolle, Po di Gnocca and Po di Goro) at the southern part of which is Comacchio
Comacchio
Comacchio is a town and comune of Emilia Romagna, Italy, in the province of Ferrara, 48 km from the provincial capital Ferrara.-Geography:...

, an area famous for eel
Eel
Eels are an order of fish, which consists of four suborders, 20 families, 111 genera and approximately 800 species. Most eels are predators...

s. The Po valley was the territory of the Roman Cisalpine Gaul
Cisalpine Gaul
Cisalpine Gaul, in Latin: Gallia Cisalpina or Citerior, also called Gallia Togata, was a Roman province until 41 BC when it was merged into Roman Italy.It bore the name Gallia, because the great body of its inhabitants, after the expulsion of the Etruscans, consisted of Gauls or Celts...

, divided in Cispadane Gaul (South of the Po) and Transpadane Gaul (North of the Po).

The river is subject to heavy flooding. Consequently over half its length is controlled with argini, or dikes. The slope of the valley decreases from 0.35% in the west to 0.14% in the east, a low gradient. There are 450 standing lakes.

Po Valley

The vast valley around the Po is called the Po Valley
Po Valley
The Po Valley, Po Plain, Plain of the Po, or Padan Plain is a major geographical feature of Italy. It extends approximately in an east-west direction, with an area of 46,000 km² including its Venetic extension not actually related to the Po River basin; it runs from the Western Alps to the...

 (Italian Pianura Padana or Val Padana); in time it became the main industrial area of the country. In 2002, more than 16 million people lived there, at the time nearly 1/3 of the population of Italy.

The two main economic uses of the valley are for industry and for agriculture, both major uses. The industrial centres, such as Turin
Turin
Turin is a city and major business and cultural centre in northern Italy, capital of the Piedmont region, located mainly on the left bank of the Po River and surrounded by the Alpine arch. The population of the city proper is 909,193 while the population of the urban area is estimated by Eurostat...

 and Milan, are located on higher terrain, away from the river bottom. They rely fortions in or on the flanks of the Alps, and on the coal/oil power stations which use the water of the Po basin as coolant. Drainage from the north is mediated through several large, scenic lakes. The streams are now controlled by so many dams as to slow the river's sedimentation rate, causing geologic problems. The moist and fertile river bottom - large expanses of flat plain - is reserved mainly for agriculture and is subject to flash floods, even though the overall quantity of water is now in deficit relative to past quantities and to demand. The main products of the farms around the river are cereal
Cereal
Cereals are grasses cultivated for the edible components of their grain , composed of the endosperm, germ, and bran...

s including – unusually for Europe – rice
Rice
Rice is the seed of the monocot plants Oryza sativa or Oryza glaberrima . As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East Asia, Southeast Asia, South Asia, the Middle East, and the West Indies...

, which requires heavy irrigation
Irrigation
Irrigation may be defined as the science of artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall...

. The latter method is the chief consumer of surface water, while industrial and human consumption comes from underground water.

Protected areas

Po Delta wetlands have been protected by the institution of two regional parks in the regions
Regions of Italy
The regions of Italy are the first-level administrative divisions of the state, constituting its first NUTS administrative level. There are twenty regions, of which five are constitutionally given a broader amount of autonomy granted by special statutes....

 in which it is situated: Veneto
Veneto
Veneto is one of the 20 regions of Italy. Its population is about 5 million, ranking 5th in Italy.Veneto had been for more than a millennium an independent state, the Republic of Venice, until it was eventually annexed by Italy in 1866 after brief Austrian and French rule...

 and Emilia-Romagna
Emilia-Romagna
Emilia–Romagna is an administrative region of Northern Italy comprising the two historic regions of Emilia and Romagna. The capital is Bologna; it has an area of and about 4.4 million inhabitants....

. The Po Delta Regional Park in Emilia-Romagna, the largest, is characterized by four parcels of land on the right bank of the Po and to the south. Created by law in 1988, it is managed by a consortium, the Consorzio per la gestione de Parco, to which Ferrara
Ferrara
Ferrara is a city and comune in Emilia-Romagna, northern Italy, capital city of the Province of Ferrara. It is situated 50 km north-northeast of Bologna, on the Po di Volano, a branch channel of the main stream of the Po River, located 5 km north...

 and Ravenna
Ravenna
Ravenna is the capital city of the Province of Ravenna in the Emilia-Romagna region of Italy and the second largest comune in Italy by land area, although, at , it is little more than half the size of the largest comune, Rome...

 provinces belong as well as nine comuni
Comune
In Italy, the comune is the basic administrative division, and may be properly approximated in casual speech by the English word township or municipality.-Importance and function:...

: Comacchio
Comacchio
Comacchio is a town and comune of Emilia Romagna, Italy, in the province of Ferrara, 48 km from the provincial capital Ferrara.-Geography:...

, Argenta
Argenta
-Places:Canada* Argenta, British Columbia, a community in the Regional District of Central KootenayItaly* Argenta, Emilia–Romagna, a town in the Province of FerraraUnited States* Argenta, Illinois, a village in Macon County-Other uses:...

, Ostellato
Ostellato
Ostellato is a comune in the Province of Ferrara in the Italian region Emilia-Romagna, located about 50 km northeast of Bologna and about 25 km southeast of Ferrara...

, Goro, Mesola
Mesola
Mesola is a comune in the Province of Ferrara in the Italian region Emilia-Romagna, located about 80 km northeast of Bologna and about 50 km east of Ferrara. As of 31 December 2004, it had a population of 7,331 and an area of 84.2 km².Mesola borders the following municipalities:...

, Codigoro
Codigoro
Codigoro is a comune in the Province of Ferrara in the Italian region Emilia-Romagna, located about 70 km northeast of Bologna and about 40 km east of Ferrara.-Main sights:*Abbey of Pomposa...

, Ravenna
Ravenna
Ravenna is the capital city of the Province of Ravenna in the Emilia-Romagna region of Italy and the second largest comune in Italy by land area, although, at , it is little more than half the size of the largest comune, Rome...

, Alfonsine
Alfonsine
Alfonsine is a comune in the Province of Ravenna in the Italian region Emilia-Romagna, located about 60 km east of Bologna and about 15 km northwest of Ravenna....

, and Cervia
Cervia
Cervia is a town and comune in the province of Ravenna , central Italy.-History:Originally called Ficocle, it was probably of Greek origin and was located midway from current Cervia and Ravenna...

. The executive authority resides in an assembly of the presidents of the provinces, the mayors of the comuni and the board of directors. They employ a Technical-Scientific Committee and a Park Council to carry out directives. In 1999 the park was designated a World Heritage Site
World Heritage Site
A UNESCO World Heritage Site is a place that is listed by the UNESCO as of special cultural or physical significance...

 by UNESCO
UNESCO
The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations...

 and was added to "Ferrara, City of the Renaissance, and its Po Delta." The 53653 ha (132,579.3 acre) of the park contain wetlands, forest, dunes and salt pans. It has a high biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...

, with 1000-1100 plant species and 374 vertebrate species, of which 300 are birds.

The active delta

The most recent part of the delta, which projects into the Adriatic between Chioggia
Chioggia
Chioggia is a coastal town and comune of the province of Venice in the Veneto region of northern Italy.-Geography:...

 and Comacchio
Comacchio
Comacchio is a town and comune of Emilia Romagna, Italy, in the province of Ferrara, 48 km from the provincial capital Ferrara.-Geography:...

, contains channels that actually connect to the Adriatic and on that account is called the active delta by the park authorities, as opposed to the fossil delta, which contains channels that no longer connect the Po to the Adriatic (but once did). The active delta was created in 1604 when the city of Venice
Venice
Venice is a city in northern Italy which is renowned for the beauty of its setting, its architecture and its artworks. It is the capital of the Veneto region...

 diverted the main stream, the Po grande or Po di Venezia, from its channel north of Porto Viro
Porto Viro
Porto Viro, or Taglio di Porto is a comune in the Province of Rovigo in the Italian region Veneto, located about 45 km south of Venice and about 35 km east of Rovigo. It was first created during the Fascist era, but subsequently suppressed...

 to the south of Porto Viro in a channel then called the Taglio di Porto Viro, "Porto Viro cut-off." Their intent was to stop the gradual migration of the Po toward the lagoon of Venice, which would have filled up with sediment had contact been made. The subsequent town of Taglio di Po
Taglio di Po
Taglio di Po is a comune in the Province of Rovigo in the Italian region Veneto, located about 50 km south of Venice and about 35 km east of Rovigo...

 grew around the diversionary works. The lock of Volta Grimana blocked the old channel, now the Po di Levante, which flows to the Adriatic through Porto Levante.

Below Taglio di Po the Parco Regionale Veneto, one of the tracts under the authority of the Parco Delta del Po, contains the latest branches of the Po. The Po di Gnocca branches to the south followed by the Po di Maestra to the north at Porto Tolle
Porto Tolle
Porto Tolle is a town in the province of Rovigo, Veneto, Italy.The municipality of Porto Tolle contains the frazioni :Boccasette, Ca' Mello, Ca' Tiepolo , Ca' Venier, Ca' Zuliani, Donzella, Pila, Polesine Camerini, Santa Giulia, Scardovari and Tolle....

. At Tolle downstream the Po di Venezia divides into the Po delle Tolle to the south and the Po della Pila to the north. The former exits at Bonelli. The latter divides again at Pila into the Busa di Tramontana to the north and the Busa di Scirocco to the south, while the mainstream, the Busa Dritta, enters Punta Maistra and exits finally past Pila lighthouse.

Despite the park administration's definition of the active delta as beginning at Porto Viro, there is another active channel upstream from it at Santa Maria in Punta, where the Fiume Po divides into the Po di Goro and the Po di Venezia.

The fossil delta

The fossil Po is the region of no longer active channels from the Po to the sea. It begins upstream from Ferrara
Ferrara
Ferrara is a city and comune in Emilia-Romagna, northern Italy, capital city of the Province of Ferrara. It is situated 50 km north-northeast of Bologna, on the Po di Volano, a branch channel of the main stream of the Po River, located 5 km north...

. The Fiume Po currently flowing to the north of Ferrara is actually the result of a diversion at Ficarolo
Ficarolo
Ficarolo is a comune in the Province of Rovigo in the Italian region Veneto, located about 90 km southwest of Venice and about 30 km southwest of Rovigo...

 in 1152 made in the hope of relieving flooding in the vicinity of Ravenna
Ravenna
Ravenna is the capital city of the Province of Ravenna in the Emilia-Romagna region of Italy and the second largest comune in Italy by land area, although, at , it is little more than half the size of the largest comune, Rome...

. The diversion channel was at first called the Po di Ficarolo. The Fiume Po before then followed the Po di Volano, no longer connected to the Po, which ran to the south of Ferrara and exited near Volano
Volano
Volano is a comune in Trentino in the northern Italian region Trentino-Alto Adige/Südtirol, located about 15 km south of Trento. As of 31 December 2004, it had a population of 2,851 and an area of 10.8 km²....

. In Roman times it did not exit there but ran to the south as the Padus Vetus ("old Po") exiting near Comacchio
Comacchio
Comacchio is a town and comune of Emilia Romagna, Italy, in the province of Ferrara, 48 km from the provincial capital Ferrara.-Geography:...

, from which split the Po di Primaro exiting close to Ravenna
Ravenna
Ravenna is the capital city of the Province of Ravenna in the Emilia-Romagna region of Italy and the second largest comune in Italy by land area, although, at , it is little more than half the size of the largest comune, Rome...

.

Before 1152 the seaward extension of today's delta, about 12 km (7.5 mi), did not exist. The entire region from Ravenna to Chioggia was dense swamps, explaining why the Via Aemilia
Via Aemilia
The Via Aemilia was a trunk Roman road in the north Italian plain, running from Ariminum , on the Adriatic coast, to Placentia on the river Padus . It was completed in 187 BC...

 was constructed between Rimini
Rimini
Rimini is a medium-sized city of 142,579 inhabitants in the Emilia-Romagna region of Italy, and capital city of the Province of Rimini. It is located on the Adriatic Sea, on the coast between the rivers Marecchia and Ausa...

 and Piacenza
Piacenza
Piacenza is a city and comune in the Emilia-Romagna region of northern Italy. It is the capital of the province of Piacenza...

 and did not begin further north.

Geology

The Mediterranean Basin is a depression in the Earth's crust caused by the African Plate
African Plate
The African Plate is a tectonic plate which includes the continent of Africa, as well as oceanic crust which lies between the continent and various surrounding ocean ridges.-Boundaries:...

 slipping under the Eurasian Plate
Eurasian Plate
The Eurasian Plate is a tectonic plate which includes most of the continent of Eurasia , with the notable exceptions of the Indian subcontinent, the Arabian subcontinent, and the area east of the Chersky Range in East Siberia...

. Typically in geologic history the depression is filled with sea water under various geologic names such as Tethys Sea. In the last period of the Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...

 Epoch, the Messinian
Messinian
The Messinian is in the geologic timescale the last age or uppermost stage of the Miocene. It spans the time between 7.246 ± 0.005 Ma and 5.332 ± 0.005 Ma...

 (7-5 mya), the Messinian salinity crisis
Messinian salinity crisis
The Messinian Salinity Crisis, also referred to as the Messinian Event, and in its latest stage as the Lago Mare event, was a geological event during which the Mediterranean Sea went into a cycle of partly or nearly complete desiccation throughout the latter part of the Messinian age of the Miocene...

, a near drying of the Mediterranean, was caused by the sea level dropping below the sill at the Strait of Gibraltar
Strait of Gibraltar
The Strait of Gibraltar is a narrow strait that connects the Atlantic Ocean to the Mediterranean Sea and separates Spain in Europe from Morocco in Africa. The name comes from Gibraltar, which in turn originates from the Arabic Jebel Tariq , albeit the Arab name for the Strait is Bab el-Zakat or...

 and the equilibrium between evaporation and replenishment shifting in favor of evaporation. At that time the Po Valley and the Adriatic
Adriatic Sea
The Adriatic Sea is a body of water separating the Italian Peninsula from the Balkan peninsula, and the system of the Apennine Mountains from that of the Dinaric Alps and adjacent ranges...

 depression were a single canyon
Canyon
A canyon or gorge is a deep ravine between cliffs often carved from the landscape by a river. Rivers have a natural tendency to reach a baseline elevation, which is the same elevation as the body of water it will eventually drain into. This forms a canyon. Most canyons were formed by a process of...

 system thousands of feet deep. On the southwest the Apennine Mountains bordered a land mass termed Tyrrhenis geologically. Their orogeny
Orogeny
Orogeny refers to forces and events leading to a severe structural deformation of the Earth's crust due to the engagement of tectonic plates. Response to such engagement results in the formation of long tracts of highly deformed rock called orogens or orogenic belts...

 was just being completed in the Miocene. On the north the Alpine Orogeny
Alpine orogeny
The Alpine orogeny is an orogenic phase in the Late Mesozoic and Tertiary that formed the mountain ranges of the Alpide belt...

 had already created the Alps.

At the end of the Messinian the ocean broke through the sill and the Mediterranean refilled. The Adriatic transgressed into all of northern Italy. In the subsequent Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...

 sedimentary outwash primarily from the Apennines filled the valley and the central Adriatic generally to a depth of 1000 m (3,280.8 ft) to 2000 m (6,561.7 ft) but from 2000 m (6,561.7 ft) to 3000 m (9,842.5 ft) off the current mouth of the Po, with pockets as deep as 6000 m (19,685 ft). At the start of the Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....

 the valley was full. Cycles of transgression and regression are detectable in the valley and the Adriatic as far as its centre and in the southern Adriatic.

From the Pleistocene alternation of maritime and alluvial sediments occur as far west as Piacenza
Piacenza
Piacenza is a city and comune in the Emilia-Romagna region of northern Italy. It is the capital of the province of Piacenza...

. The exact sequences at various locations have been studied extensively. Apparently the sea advanced and receded over the valley in conformance to an equilibrium between sedimentation and glacial advance or recession at 100,000-year intervals and 100 m (328.1 ft) to 120 m (393.7 ft) fluctuation of sea level. An advance began after the Last Glacial Maximum
Last Glacial Maximum
The Last Glacial Maximum refers to a period in the Earth's climate history when ice sheets were at their maximum extension, between 26,500 and 19,000–20,000 years ago, marking the peak of the last glacial period. During this time, vast ice sheets covered much of North America, northern Europe and...

 around 20,000 years ago, which brought the Adriatic to a high point at about 5500 years ago.

Since then the Po delta had been prograding. The rate of coastal
zone progradation between 1000 BC and 1200 AD
was 4 m/yr. Human factors, however, brought about a change in the equilibrium in the mid-20th century with the result that the entire coastline of the northern Adriatic is now degrading. Venice
Venice
Venice is a city in northern Italy which is renowned for the beauty of its setting, its architecture and its artworks. It is the capital of the Veneto region...

, which was originally built on islands off the coast, is most at risk due to subsidence, but the effect is realized in the Po delta as well. The causes are first a decrease in the sedimentation rate due to the locking of sediment behind hydroelectric dams and the deliberate excavation of sand from rivers for industrial purposes. Second, agricultural use of the river is heavy; during peak consumption the flow in places nearly dries up, causing local contention. As a result of decreased flow salt water is intruding into the aquifer
Aquifer
An aquifer is a wet underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology...

s and coastal ground water. Eutrophication
Eutrophication
Eutrophication or more precisely hypertrophication, is the movement of a body of water′s trophic status in the direction of increasing plant biomass, by the addition of artificial or natural substances, such as nitrates and phosphates, through fertilizers or sewage, to an aquatic system...

 in standing waters and streams of low flow is on the increase. The valley is subsiding due to the removal of ground water.

Pollution

Always prone to fog, the valley is subject to heavy smog due to industrial atmospheric emissions, especially from Turin
Turin
Turin is a city and major business and cultural centre in northern Italy, capital of the Piedmont region, located mainly on the left bank of the Po River and surrounded by the Alpine arch. The population of the city proper is 909,193 while the population of the urban area is estimated by Eurostat...

.

In 2002, the city of Milan had no sewage treatment plant. The sewage went through channels directly into the Po, for which the European Environment Agency
European Environment Agency
European Environment Agency is an agency of the European Union. Its task is to provide sound, independent information on the environment. It is a major information source for those involved in developing, adopting, implementing and evaluating environmental policy, and also the general public...

 cited the city.

In 2005, water from the Po was found to contain "staggering" amounts of benzoylecgonine
Benzoylecgonine
Benzoylecgonine is a topical analgesic and the main metabolite of cocaine.-History:Benzoylecgonine is used as the main pharmaceutical ingredient in the prescription drug Esterom, a topical solution used for the relief of muscle pain....

, which is excreted
Excretion
Excretion is the process by which waste products of metabolism and other non-useful materials are eliminated from an organism. This is primarily carried out by the lungs, kidneys and skin. This is in contrast with secretion, where the substance may have specific tasks after leaving the cell...

 by cocaine
Cocaine
Cocaine is a crystalline tropane alkaloid that is obtained from the leaves of the coca plant. The name comes from "coca" in addition to the alkaloid suffix -ine, forming cocaine. It is a stimulant of the central nervous system, an appetite suppressant, and a topical anesthetic...

 users in urine
Urine
Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...

. Based on these figures, cocaine consumption was estimated to be about 4 kg daily, or 27 doses per day per thousand young adults in areas that feed into the river—a number nearly three times higher than previous estimates.

On February 24, 2010 the Po river was contaminated by an oil spill coming from a refinery in Villasanta
Villasanta
Villasanta is a comune in the Province of Monza and Brianza in the Italian region Lombardy, located about 20 km northeast of Milan.Villasanta borders the following municipalities: Arcore, Biassono, Monza, Concorezzo....

 through the Lambro
Lambro
For the river in Cilento, see Lambro . For the genus, see Lambro .The Lambro is a river of Lombardy, northern Italy, a left tributary of the Po....

, the Agenzia Nazionale Stampa Associata news agency has estimated that the spill is in the neighborhood of 600,000 liters.

Water resource management

Until 1989 water resources were administered regionally or locally. The major authority on the lower Po was the Magistrato alle Acque di Venezia, first formed in the 16th-century Republic of Venice
Republic of Venice
The Republic of Venice or Venetian Republic was a state originating from the city of Venice in Northeastern Italy. It existed for over a millennium, from the late 7th century until 1797. It was formally known as the Most Serene Republic of Venice and is often referred to as La Serenissima, in...

. It made all the decisions concerning the diversion of the lower river. Half the delta is still in Veneto
Veneto
Veneto is one of the 20 regions of Italy. Its population is about 5 million, ranking 5th in Italy.Veneto had been for more than a millennium an independent state, the Republic of Venice, until it was eventually annexed by Italy in 1866 after brief Austrian and French rule...

.

In 1907 unde the Kingdom of Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

 the agency became the Magistrato alle Acque and took responsibility for all the water resources in northeastern Italy. Currently it is a decentralized institution of the Ministry of Public Works, headed by a chairman appointed by the Head of State and the Council of Ministers. Its headquarters are in Venice. Its domain is the management and protection of the water system in Veneto
Veneto
Veneto is one of the 20 regions of Italy. Its population is about 5 million, ranking 5th in Italy.Veneto had been for more than a millennium an independent state, the Republic of Venice, until it was eventually annexed by Italy in 1866 after brief Austrian and French rule...

, Mantua
Mantua
Mantua is a city and comune in Lombardy, Italy and capital of the province of the same name. Mantua's historic power and influence under the Gonzaga family, made it one of the main artistic, cultural and notably musical hubs of Northern Italy and the country as a whole...

, Trento
Trento
Trento is an Italian city located in the Adige River valley in Trentino-Alto Adige/Südtirol. It is the capital of Trentino...

, Bolzano and Friuli-Venezia Giulia
Friuli-Venezia Giulia
Friuli–Venezia Giulia is one of the twenty regions of Italy, and one of five autonomous regions with special statute. The capital is Trieste. It has an area of 7,858 km² and about 1.2 million inhabitants. A natural opening to the sea for many Central European countries, the region is...

.

In 1989 in response to the major geologic problems that were developing along the river Law no. 183/89 was passed authorizing The Po Basin Water Board (Autorità di bacino del fiume Po), which would direct operations concerning all the water resources in the Po basin (see under Po Valley
Po Valley
The Po Valley, Po Plain, Plain of the Po, or Padan Plain is a major geographical feature of Italy. It extends approximately in an east-west direction, with an area of 46,000 km² including its Venetic extension not actually related to the Po River basin; it runs from the Western Alps to the...

). Its headquarters have been in Parma
Parma
Parma is a city in the Italian region of Emilia-Romagna famous for its ham, its cheese, its architecture and the fine countryside around it. This is the home of the University of Parma, one of the oldest universities in the world....

 since its inception in 1990. It considers itself a synergy among all the institutions concerned with the preservation and development of the Po basin. It is administered by officials chosen from the administrations of the constituent regions and provinces.

In the year 2009 the water board will initiate an Integrated River Basin Management Plan in compliance with the European Union
European Union
The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...

 (EU) Water Framework Directive
Water framework directive
The Water Framework Directive is a European Union directive which commits European Union member states to achieve good qualitative and quantitative status of all water bodies The Water Framework Directive (more formally the Directive 2000/60/EC of the European Parliament and of the Council of 23...

, 2000/60/EC. The plan includes many water management and flood risk plans already in place. Between 2009 and 2015 the Po Valley Project (the implementation of the plan) will carry out more than 60 measures to heighten and strengthen dikes, increase natural retention areas, recover sediment transport, recover hydromorphological characteristics, enlarge wetlands, afforest, renaturate, promote biodiversity and promote recreational use, among others.

Tributaries

The Po has 141 tributaries
Tributary
A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

. They include (R on the right bank, L on the left, looking downstream
Downstream
-Science:* In geography, away from the source of a stream or river* In meteorology, away from the source of an air parcel or mass, along the normal direction of water or air flow* Downstream , in computer or telecommunications networks...

):
  • Pellice
    Pellice
    The Pellice is a Italian torrent, which runs through the Province of Turin. It is a tributary of the Po River, into which it flows near Villafranca Piemonte....

     (L)
  • Varaita
    Varaita
    The Varaita is a 75 km river of the Province of Cuneo in north-west Italy. It is the first right tributary of the Po River....

     (R)
  • Maira
    Maira
    The Maira is an Italian river, a right tributary of the Po River, which runs through the province of Cuneo in eastern Piedmont. Its source is in the Cottian Alps near the Col de Mary on the French border...

     (R)
  • Dora Riparia
    Dora Riparia
    The Dora Riparia is an Italian river, a left-hand tributary of the Po. It is 125 km long, with a 1,231 km² drainage basin. It originates in the Cottian Alps, close to the Col de Montgenèvre in France, where it is called the Piccola Dora...

     (L)
  • Stura di Lanzo
    Stura di Lanzo
    Stura di Lanzo is a 65 km long river in north-western Italy . It is formed from several tributaries near Lanzo Torinese. It flows into the river Po in Turin.The name Stura has Celtic origin: stur, which means "to fall".-External links:...

     (L)
  • Orco
    Orco
    The Orco is an Italian river. It originates in the glaciers of the Piedmontese slopes of Gran Paradiso, and after about 90 km reaches the Po River near Chivasso...

     (L)
  • Dora Baltea
    Dora Baltea
    Dora Baltea or Doire Baltée , is a river in northern Italy. It is a left-hand tributary of the Po River, and is about 160 km long...

     (L)
  • Sesia
    Sesia River
    The Sesia is a river in north-western Italy, tributary to the Po. Its sources are the glaciers of Monte Rosa at the border with Switzerland. It flows through the Alpine valley Valsesia and the towns Varallo Sesia, Quarona, Borgosesia and Vercelli...

     (L)
  • Tanaro
    Tanaro River
    The Tanaro , known as Tanarus in ancient times, is a 276 km-long river in northwestern Italy. It rises in the Ligurian Alps, close to the border with France and is the most significant right-side tributary to the Po in terms of length, size of drainage basin and discharge.-Source:The Tanaro proper...

     (R)
  • Scrivia
    Scrivia
    The Scrivia is a right tributary of the Po River, in northern Italy. It runs through Liguria, Piedmont, and Lombardy....

     (R)
  • Agogna
    Agogna
    The Agogna is a narrow long river which runs through the Italian regions of Piedmont and Lombardy. It is a left side tributary of the river Po....

     (L)
  • Ticino
    Ticino River
    The river Ticino is a left-bank tributary of the Po River. It has given its name to the Swiss canton through which its upper portion flows.-The course:...

     (L)
  • Versa
    Versa (Po)
    The Versa is a tributary of the Po River which runs through the Province of Pavia in northern Italy.This river is not to be confused with the Versa that is a tributary of the Tanaro....

     (R)
  • Lambro
    Lambro
    For the river in Cilento, see Lambro . For the genus, see Lambro .The Lambro is a river of Lombardy, northern Italy, a left tributary of the Po....

     (L)
  • Trebbia
    Trebbia
    The Trebbia is a river predominantly of Liguria and Emilia Romagna in northern Italy. It is one of the four main right-bank tributaries of the river Po, the other three being the Tanaro, the Secchia and the Panaro...

     (R)
  • Nure
    Nure
    The Nure is a small river in northern Italy . It has its source on the northern slopes of Mt. Nero The Nure (Latin Nura) is a small river in northern Italy (province of Piacenza). It has its source on the northern slopes of Mt. Nero The Nure (Latin Nura) is a small river in northern Italy...

     (R)
  • Adda
    Adda River
    The Adda is a river in North Italy, a tributary of the Po. It rises in the Alps near the border with Switzerland and flows through Lake Como. The Adda joins the Po a few kilometres upstream of Cremona. It is 313 kilometres long...

     (L)
  • Arda
    Arda River (Italy)
    The Arda is a torrent of Emilia-Romagna, Italy, nearly all of its course being within the province of Piacenza. It is a right tributary of the Po River....

     (R)
  • Taro
    Taro River
    The Taro is a 126 km-long river in northern Italy, tributary to the Po River. It flows almost entirely in the province of Parma, west of the city Parma. The Taro flows into the Po River north of Parma....

     (R)
  • Parma
    Parma River
    The Parma River is a large stream of 92 km in length that begins in the Tuscan-Emilian Apennine mountains and flows in Parma valley.-Path:It begins from the lake Lago Santo parmense and small lakes Gemio and Scuro...

     (R)
  • Enza
    Enza
    The Enza is a river in northern Italy, a right affluence of the Po River. Its source is at the Alpe di Succiso, in the northern Apennines , at 1,406 m...

     (R)
  • Oglio
    Oglio
    The Oglio is a left-side tributary of the Po River in Lombardy, Italy. It is 280 km long....

     (L)
  • Mincio
    Mincio
    Mincio is a river in the Lombardy region of northern Italy.Called the Sarca River before entering Lake Garda, it flows from there about 65 km past Mantua into the Po River....

     (L)
  • Secchia (R)
  • Panaro
    Panaro
    The Panaro is an Italian river and the final right-hand tributary to the Po, discounting the Cavo Napoleonico canal. It runs right across Emilia-Romagna in a north-easterly direction: from its source close to the Apennine watershed, where Emilia-Romagna meets Tuscany, to its outlet where the Po...

     (R)


The Reno
Reno River
The Reno is a river of Emilia-Romagna, northern Italy. It is the tenth longest river in Italy and the most important of the region apart from the Po...

 (R) was a tributary of the Po River until the middle of the eighteenth century when the course was diverted to lessen the risk of devastating floods.

Isola Serafini

At the village of Isola Serafini in the comune
Comune
In Italy, the comune is the basic administrative division, and may be properly approximated in casual speech by the English word township or municipality.-Importance and function:...

 of Monticelli d'Ongina
Monticelli d'Ongina
Monticelli d'Ongina is a comune in the Province of Piacenza in the Italian region Emilia-Romagna, located about 130 km northwest of Bologna and about 20 km east of Piacenza....

, Piacenza Province, 40 km (24.9 mi) downstream from Piacenza, a 362 m (1,187.7 ft) long, 20 m (65.6 ft) high gate dam featuring eleven 30 m (98.4 ft) openings gated by vertical lift gates, crosses the Po. Nine gates are 6.5 m (21.3 ft) high and two are 8 m (26.2 ft) high for sediment-scouring purposes. A spillway to the right passes through a hydroelectric station of 4 generators of 76 MW each operated by a 3.5 m (11.5 ft) - 11 m (36.1 ft) head of water. The spillway connects to a diversionary canal subtending a 12 km (7.5 mi) loop of the Po. A ship lock 85 m (278.9 ft) long and 12 m (39.4 ft) wide next to the station passes some traffic through the canal, but above the dam traffic is mainly barges. The average flow at the dam is 854 m³/s, with a 12,800 m³/s maximum flood.

Mention by Polybius

The Po is first certainly identified in the Graeco-Roman historians and geographers of the late Roman Republic
Roman Republic
The Roman Republic was the period of the ancient Roman civilization where the government operated as a republic. It began with the overthrow of the Roman monarchy, traditionally dated around 508 BC, and its replacement by a government headed by two consuls, elected annually by the citizens and...

 and the early Roman Empire
Roman Empire
The Roman Empire was the post-Republican period of the ancient Roman civilization, characterised by an autocratic form of government and large territorial holdings in Europe and around the Mediterranean....

, long after the valley had been occupied successively by prehistoric and historic peoples: Ligures
Ligures
The Ligures were an ancient people who gave their name to Liguria, a region of north-western Italy.-Classical sources:...

, Etruscans, Celts, Veneti
Adriatic Veneti
The Veneti were an ancient people who inhabited north-eastern Italy, in an area corresponding to the modern-day region of the Veneto....

, Umbri
Umbri
The Umbri were an Italic people of ancient Italy. A region called Umbria still exists and is currently occupied by Italian speakers. It is somewhat smaller than the ancient Umbria....

, and Romans. At that late date the ancient authors were attempting to explain the provenance of the name. Perhaps the earliest of these, Polybius
Polybius
Polybius , Greek ) was a Greek historian of the Hellenistic Period noted for his work, The Histories, which covered the period of 220–146 BC in detail. The work describes in part the rise of the Roman Republic and its gradual domination over Greece...

 (2nd century BC), uses Pados (in Greek) and says that it was to be identified with the Eridanos of the poets. Moreover, the country people call it Bodencus.

This implies that a "country" population either remained from prehistoric times or adopted the name in use by that substrate. The name has been segmented as Bod-encus or Bod-incus, the suffix being characteristic of the ancient Ligurian language of northern Italy, southern France, Corsica and elsewhere.

Mention by Pliny the Elder

Pliny the Elder
Pliny the Elder
Gaius Plinius Secundus , better known as Pliny the Elder, was a Roman author, naturalist, and natural philosopher, as well as naval and army commander of the early Roman Empire, and personal friend of the emperor Vespasian...

 has the most to say about the Padus of his times. Herodotus
Herodotus
Herodotus was an ancient Greek historian who was born in Halicarnassus, Caria and lived in the 5th century BC . He has been called the "Father of History", and was the first historian known to collect his materials systematically, test their accuracy to a certain extent and arrange them in a...

 had expressed doubt concerning the existence of a river in Europe, Eridanos, which flowed into the northern sea, he said, from which amber
Amber
Amber is fossilized tree resin , which has been appreciated for its color and natural beauty since Neolithic times. Amber is used as an ingredient in perfumes, as a healing agent in folk medicine, and as jewelry. There are five classes of amber, defined on the basis of their chemical constituents...

 came. He believed it was a Greek name (there are other Eridanos rivers in Greece), "invented by some poet," but makes no conjectures as to where it might be. Pliny points out that in his own time the Eridanos had become wrongly identified with the Padus. He does not know when or how, but like Herodotus he blames the poets. Amber is supposed to have come from there. Phaëthon, son of the sun, struck by lightning changed into poplars and exuded tears every year, which is the source of amber (a myth of Pausanias
Pausanias (geographer)
Pausanias was a Greek traveler and geographer of the 2nd century AD, who lived in the times of Hadrian, Antoninus Pius and Marcus Aurelius. He is famous for his Description of Greece , a lengthy work that describes ancient Greece from firsthand observations, and is a crucial link between classical...

). Expressing surprise at the ignorance of the poets, Pliny says "There can be no doubt that amber is the product of the islands of the northern ocean (Baltic Sea
Baltic Sea
The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...

)" and attributes its introduction into the Po valley to the Veneti
Adriatic Veneti
The Veneti were an ancient people who inhabited north-eastern Italy, in an area corresponding to the modern-day region of the Veneto....

, the last link in a trade route to the north through Pannonia
Pannonia
Pannonia was an ancient province of the Roman Empire bounded north and east by the Danube, coterminous westward with Noricum and upper Italy, and southward with Dalmatia and upper Moesia....

 and Germany.

Pliny (Hist. Nat., iii. 122) also gives the Ligurian name of the Po river as Bodincus, which he translates as "bottomless". The root bod- has been generally analyzed as containing the PIE
Proto-Indo-European language
The Proto-Indo-European language is the reconstructed common ancestor of the Indo-European languages, spoken by the Proto-Indo-Europeans...

 base *bhu(n)d(h)- seen in Sanskrit
Sanskrit
Sanskrit , is a historical Indo-Aryan language and the primary liturgical language of Hinduism, Jainism and Buddhism.Buddhism: besides Pali, see Buddhist Hybrid Sanskrit Today, it is listed as one of the 22 scheduled languages of India and is an official language of the state of Uttarakhand...

 budhnah and Avestan
Avestan language
Avestan is an East Iranian language known only from its use as the language of Zoroastrian scripture, i.e. the Avesta, from which it derives its name...

 buna- "bottom", Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 pythmen "foundation", Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 fundus "bottom", Old Irish bond "sole of the foot". The word Bodincus appears in the place name Bodincomagus, a Ligurian
Ligures
The Ligures were an ancient people who gave their name to Liguria, a region of north-western Italy.-Classical sources:...

 town on the right bank of the Po downstream from today’s Turin.

See also

  • Piz Lunghin
    Piz Lunghin
    Piz Lunghin is a mountain in the Swiss canton of Graubünden, located in the Albula range, overlooking the Maloja Pass. It can be considered as the "roof of Europe" as the water running off the mountain can head towards the Atlantic, Mediterranean or Black Sea.-Geography and hydrography:Piz Lunghin...

     (triple watershed: Po-Rhine-Danube)
  • Witenwasserenstock
    Witenwasserenstock
    The Witenwasserenstock is a peak between the Swiss cantons of Valais and Uri, located in the Lepontine Alps. Close to the summit lies the tripoint border between the cantons of Valais, Uri and Ticino and the triple watershed of the Rhine, Po and Rhône basins.-Geography and hydrography:The...

    (triple watershed: Rhone-Rhine-Po)
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