The Anadyr River watershed is the largest in the Russian Far East. It is formed by three main rivers - Anadyr, Velikaya and Kanchalan - which flow into the Anadyr estuary in the western part of Anadyr Bay, on the Bering Sea. The biota of the Anadyr watershed is unique and diverse, featuring:
- more than 600 species of vascular plants;
- about 800 species of mosses and lichens;
- more than 700 species, varieties, and forms of diatoms;
- over 400 species and subspecies of fresh water invertebrates.
There are ten species of salmon that inhabit the river system, including the Russian Far East's largest stock of chum salmon, out of 31 species of fish. Among 145 species of birds, 34 are listed in the Red Book of the Russian North East. Terrestrial mammals include 36 species, of which seven species and one subspecies are registered in the Red Book. Five of the 15 species of sea mammals are listed in the Red Book.