For 20 points, identify this river which flows through Georgetown, the chief river of Guyana.
The name of this river comes from an Arawak custom of using its stones for fireplaces, so its name means "hearth stones." In 1995, the mining company Cambior spilled cyanide into this river at the Omai Gold Mine, and cities on this river's banks include Tumatumari and Rockstone. This river joins with the Cuyuni and Mazaruni Rivers near the city of Bartica, and islands in this river's delta include Fort Island, Leguan, and Hog Island. This river's tributaries include the Rupununi, which has its source in the Kanuku Mountains, and the Potaro River which contains Kaietur Falls. It rises in the Acarai Mountains alongside the nearby Courantyne River, and was the subject of an 1899 boundary dispute between Britain and Venezuela. For 20 points, identify this river which flows through Georgetown, the chief river of Guyana.
The name of this river comes from an Arawak custom of using its stones for fireplaces, so its name means "hearth stones.
{Essequibo} River