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GARONNE

French: Garonne, Spanish: Garona.

Length (km): 525
Drainage Area (km2): 57 000
Discharge (m3/s): 200
Countries: 2
Population: 2 500 000
Sea at Mouth: Atlantic
Ramsar Sites: 0

Flowing for a distance of 525 km, the Garonne is the most important river of Southwestern France. Its watershed covers 57 000 km2. It originates in Spain at 1 900 m altitude in the Val d’Aran in the Pyrénées. Its main tributaries are the Lot, the Tarn and the Aveyron. After the city of Toulouse, the Garonne becomes navigable. It goes through Bordeaux and joins the Dordogne to form the Gironde estuary. The Gironde estuary is the largest estuary in Europe: 75 km long, up to 12 km wide, covering an area of 635 km².

The Garonne traverses 217 French municipalities including five main cities: Saint-Gaudens, Toulouse, Agen, Marmande, and Bordeaux. The Bordeaux industrial region extends along the Gironde’s southern coast. The estuary region is well known for the quality of its vineyards.

An accompanying canal was built in the XIX century connecting Bordeaux and the canal du Midi at Toulouse. The Garonne frequently leaves its bed; the most catastrophic floods were recorded in 1770, 1856 and 1930.

The Garonne is an important breeding area for sturgeon and also for the migration of Atlantic salmon. The Gironde estuary in particular is a very important site for fish and bird migrations. The water quality varies with the tide, with wastewater from Bordeaux causing important nitrogen and phosphorous concentrations downstream of Bordeaux. One tributary of the Garonne, the Dropt, is particularly sensitive to eutrophication, but globally the water quality of the Garonne is between good to very good.

2003 Heat-wave

The Garonne was the French river which most suffered from the 2003 summer heatwave. During the month of August, its runoff fell to 41 m3/s at Lamagistère, and 14 m3/s at Valentine, reaching the critical runoff limit at this station. The 27 million m3 of water released by EDF (Electricite de France) and the restrictive measures for consumers only limited the impacts.

AZF Factory Explosion

The explosion which destroyed the “AZF“ factory in Toulouse on 21 September 2001 is one of the most severe industrial accidents of the last decades in terms of magnitude and consequences.

Among its environmental impacts, the explosion released a cloud of atmospheric pollution essentially made up of nitrogenous compounds which then spread over the South-Western part of the urban centre. The accident also caused the release of nitrogenous compounds into the branch of the Garonne river bordering the plant. Finally, the blast sprayed fragments of soil and particles from this old industrial site over the neighbouring districts.

Agence de l'Eau Adour-Garonne: www.eau-adour-garonne.fr
Garonne Portal: www.lagaronne.com