Question: What is the name of the reservoir fed by the river that the Vyatka connects to?

full_context: Document 1: Vyatka River: The Vyatka River (; ; ; , "Viče", , "Vatka") is a river in Kirov Oblast and the Republic of Tatarstan in Russia, a right tributary of the Kama River. It is long, and its drainage basin covers .
Document 2: Kazakhstan: It shares borders of 6,846 kilometres (4,254 mi) with Russia, 2,203 kilometres (1,369 mi) with Uzbekistan, 1,533 kilometres (953 mi) with China, 1,051 kilometres (653 mi) with Kyrgyzstan, and 379 kilometres (235 mi) with Turkmenistan. Major cities include Nur-Sultan, Almaty, Karagandy, Shymkent, Atyrau, and Oskemen. It lies between latitudes 40° and 56° N, and longitudes 46° and 88° E. While located primarily in Asia, a small portion of Kazakhstan is also located west of the Urals in Eastern Europe.Kazakhstan's terrain extends west to east from the Caspian Sea to the Altay Mountains and north to south from the plains of Western Siberia to the oases and deserts of Central Asia. The Kazakh Steppe (plain), with an area of around 804,500 square kilometres (310,600 sq mi), occupies one-third of the country and is the world's largest dry steppe region. The steppe is characterised by large areas of grasslands and sandy regions. Major seas, lakes and rivers include the Aral Sea, Lake Balkhash and Lake Zaysan, the Charyn River and gorge and the Ili, Irtysh, Ishim, Ural and Syr Darya rivers.
Document 3: Volga Delta: The Volga Delta is the largest river delta in Europe, and occurs where Europe's largest river system, the Volga River, drains into the Caspian Sea in Russia's Astrakhan Oblast, north-east of the republic of Kalmykia. The delta is located in the Caspian Depression—the far eastern part of the delta lies in Kazakhstan. The delta drains into the Caspian approximately 60 km downstream from the city of Astrakhan.
Document 4: Akosombo Dam: The Akosombo Dam, also known as the Volta Dam, is a hydroelectric dam on the Volta River in southeastern Ghana in the Akosombo gorge and part of the Volta River Authority. The construction of the dam flooded part of the Volta River Basin, and led to the subsequent creation of Lake Volta. The flooding that created the Lake Volta reservoir displaced many people and had a significant impact on the local environment. Lake Volta is the largest man-made lake in the world by surface area. It covers , which is 3.6% of Ghana's land area. With a volume of 148 cubic kilometers, Lake Volta is the world's third largest man-made lake by volume, the largest being Lake Kariba which is located between Zimbabwe and Zambia in Southern Africa and contains 185 cubic kilometers of water.
Document 5: Yug River: The Yug () is a river in Kichmengsko-Gorodetsky, Nikolsky, and Velikoustyugsky Districts of Vologda Oblast and in Podosinovsky District of Kirov Oblast in Russia. It is long, and the area of its basin is . The Yug joins the Sukhona near the town of Veliky Ustyug, forming the Northern Dvina, one of the biggest rivers of European Russia.
Document 6: Chelyabinsk: Chelyabinsk () is a city and the administrative center of Chelyabinsk Oblast, Russia, located in the northeast of the oblast, south of Yekaterinburg, just to the east of the Ural Mountains, on the Miass River, on the border of Europe and Asia. Population:
Document 7: Geography of Russia: Truly alpine terrain appears in the southern mountain ranges. Between the Black and Caspian seas, the Caucasus Mountains rise to impressive heights, forming a boundary between Europe and Asia. One of the peaks, Mount Elbrus, is the highest point in Europe, at 5,642 meters. The geological structure of the Caucasus extends to the northwest as the Crimean and Carpathian Mountains and southeastward into Central Asia as the Tian Shan and Pamirs. The Caucasus Mountains create an imposing natural barrier between Russia and its neighbors to the southwest, Georgia and Azerbaijan.
Document 8: Russia: Russia (/ ˈrʌʃə / (listen); Russian: Росси́я, tr. Rossiya; IPA: (rɐˈsjijə)), also officially known as the Russian Federation (Russian: Российская Федерация, tr. Rossiyskaya Federatsiya; IPA: (rɐˈsijskəjə fjɪdjɪˈratsɨjə)), is a country in Eurasia. At 17,125,200 square kilometres (6,612,100 sq mi), Russia is the largest country in the world by surface area, covering more than one - eighth of the Earth's inhabited land area, and the ninth most populous, with over 144 million people at the end of March 2016. The European western part of the country is much more populated and urbanised than the eastern; about 77% of the population live in European Russia. Russia's capital Moscow is one of the largest cities in the world; other major urban centers include Saint Petersburg, Novosibirsk, Yekaterinburg, Chelyabinsk, Nizhny Novgorod, Ufa, and Kazan.
Document 9: Kuta River: The Kuta River is a Siberian river north of Lake Baikal in Irkutsk Oblast, Russia, that flows into the Lena River at Ust-Kut. With its right tributary, the Kupa River, it forms a ‘T’ shape with the flat head pointing west and the point at Ust-Kut.
Document 10: Letka River: Letka River () is a river in the Komi Republic and Kirov Oblast in Russia, an arm of the Vyatka River. The river is long, and its drainage basin covers . The Letka is navigable along its lower reaches.
Document 11: Kilmez River: Kilmez River (; ) is a river in Udmurtia and Kirov Oblast in Russia, a left tributary of the Vyatka River. The river is long, and the area of its drainage basin is . The Kilmez freezes up in November and remains icebound until the second half of April. Its main tributaries are the Lumpun, Loban, and Vala rivers.
Document 12: Kuybyshev Reservoir: Kuybyshev Reservoir or Kuybyshevskoye Reservoir (, "Kuybyshevskoye Vodokhranilishche", ), sometimes called Samara Reservoir and informally called Kuybyshev Sea, is a reservoir of the middle Volga and lower Kama in the Chuvash Republic, Mari El Republic, Republic of Tatarstan, Samara Oblast and Ulyanovsk Oblast, Russia. The Kuybyshev Reservoir has a surface area of 6,450 km² and a volume of 58 billion cubic meters. It is the largest reservoir in Europe and third in the world by surface area. The major cities of Kazan, Ulyanovsk, and Tolyatti are adjacent to the reservoir.
Document 13: Ay River: Ay River (, ) is a river in Bashkortostan and Chelyabinsk Oblast in Russia, a left tributary of the Ufa River. The river is long, and its drainage basin covers . The Ay freezes up in late October or early November and remains icebound until mid-April. The cities of Zlatoust and Kusa are along the Ay River. Along the banks of the river, there are many steep cliff sides and caves. The current of the river has been used for hydroelectric power. It is also possible to fish for pike, bleak, and carp, to name a few species.
Document 14: Vyoksa River: The Vyoksa River () is a river running in the western part of the Kostroma Oblast in the Central Russia. The river originates at the outflow of Lake Galichskoye. The Vyoksa River runs 84 kilometres (52 mi) and drains into the Kostroma River in the town of Buy.
Document 15: Caspian Sea: The Volga River, the largest in Europe, drains 20% of the European land area and is the source of 80% of the Caspian's inflow. Its lower reaches are heavily developed with numerous unregulated releases of chemical and biological pollutants. The UN Environment Programme warns that the Caspian "suffers from an enormous burden of pollution from oil extraction and refining, offshore oil fields, radioactive wastes from nuclear power plants and huge volumes of untreated sewage and industrial waste introduced mainly by the Volga River".The magnitude of fossil fuel extraction and transport activity in the Caspian also poses a risk to the environment. The island of Vulf off Baku, for example, has suffered ecological damage as a result of the petrochemical industry; this has significantly decreased the number of species of marine birds in the area. Existing and planned oil and gas pipelines under the sea further increase the potential threat to the environment.
ground_truth: Kuybyshev Reservoir
sub_queries: What river does Vyatka River connect to? Answer: Kama River
Kama River >> mouth of the watercourse Answer: Kuybyshev Reservoir