But Lake Teletskoye is more than a large, deep lake. It is located within the 9,000 km2 Altaisky Zapovednik nature reserve, which helps protect its unspoiled waters. The main flow into the lake is the Tchulyshman River, but approximately 70 rivers and hundreds of seasonal streams also flow into the lake. The lake water drains and ultimately flows north to become one of Siberia's great rivers, the Ob. Surrounding the lake are ancient taiga forests. Large lakes such as Teletskoye serve as repositories of regional paleoclimate data including sediment records and atmospheric pollutants. Teletskoye is included as one of Russia's long-term ecological monitoring sites.