 The Tsna and the Lonnitsa are technically inflows of the Vyshny Volochyok Reservoir, which has two outflows, one into Lake Mstino and the Msta, and another one into the Tvertsa River.The Tvertsa, a left tributary of the Volga River, is also the biggest river in the central part of the district.Some areas in the southwestern part of the district belong to the drainage basin of the Poved River, a right tributary of the Tvertsa.