The Urumea, arguably stemming from Basque "ur" 'water' + "me(he)a" 'thin') is a river in the Basque Country. It's one of a series of Basque rivers flowing into the Bay of Biscay (Atlantic basin) and best known for being the river flowing to the sea on the city of San Sebastian.The river is 59.4 km long from its source in the Navarrese municipality of Goizueta, 33 of them running through the province Gipuzkoa. The average temperature is 13.5 °C (56.3 °F) and the seasonal and year-to-year variation in water flow is less marked than in other basins of Gipuzkoa, the natural regulation of the basin proving very high. The quality of the water is fairly good, despite a slight deterioration downstream on nearing the mouth (moderate-good condition), where the city of Donostia lies. However, lately works have been done for the treatment and cleaning of water, resulting in an outstanding environmental recovery.