3 more materials “We can confirm a generally high ability of the examined microbiological system for self-cleaning from organic contaminations,” the report reads. “The research showed reduction of organic load between the site where the fuel leaked into the water and the source of the Pyasina River due to physical, chemical and biological processes associated with the water’s self-cleaning.” Experts say that in the examined areas downstream of the accident site, in the Daldykan and Ambarnaya Rivers, the oil contamination had affected the phytoplankton. Contrastingly, in Lake Pyasino and the Pyasina River they discovered the species that used to live there before the accident, which proves that there was no damage from the oil products to the water bodies' ecosystem.