Previously contaminated areas within the affected area include the Techa river, which had previously received 2.75 MCi (100 PBq) of deliberately dumped waste, and Lake Karachay, which had received 120 MCi (4,000 PBq).
Daerah yang sebelumnya terkontaminasi di daerah yang terkena bencana termasuk sungai Techa, yang sebelumnya telah menerima 2,75 MCi (100 PBq) limbah yang dibuang dengan sengaja, dan Danau Karachay, yang telah menerima 120 MCi (4.000 PBq).