Horses and people mixed up: who is polluting Lake Baikal
Scientists of the Limnological Institute of the Siberian Branch of the Russian Academy of Sciences published a study in which they pointed to the sources of traces of human and animal activity found in the waters of Lake Baikal. It turned out that fecal pollution of the lake may indicate not only imperfect sewage infrastructure, but also possible runoff from farms. The study says that this is part of the so-called diffuse runoff, which so far has not received much attention in federal projects to clean up various reservoirs in Russia. For more information, see the Izvestia article.
What is the essence of the study?
The results of the work of scientists from the LIN SB RAS have been published in the international scientific journal Journal of Great Lakes Research.
The annotation to the study notes that the coastal zone of the lake as a whole is susceptible to pollution from diffuse sources (i.e., for example, groundwater and meltwater), which has not yet been fully characterized. Therefore, it was decided to assess fecal pollution unrelated to known sewage facilities in coastal waters (near villages and beach areas) using molecular markers that make it possible to distinguish pollution from humans, ruminants and birds. In the end, the birds were justified — they do not contribute to the pollution of Lake Baikal, but traces of human and animal activity were found.
The researchers note that the work "highlights the impact of the underdeveloped sewage infrastructure of coastal settlements on water quality in the coastal zone of Lake Baikal."
At the same time, the document indicates that anthropogenic eutrophication of the waters of Lake Baikal (in other words, the intensification of processes that lead to blooming waters and waterlogging of reservoirs) is a relatively recent phenomenon for this lake and is most likely due to the growth of the tourism industry: approximately 110 thousand people live permanently on the shores, and the annual influx of tourists is 2.2 millions. Eutrophication is caused precisely by the intake of untreated wastewater from diffuse terrestrial sources, the text of the study says. However, researchers believe that it's not just human waste that is to blame.
Probably, the reason may be not only the imperfection of the sewage infrastructure, but also runoff from farms that reach the lake through groundwater.
"Human wastewater pollutes water bodies, introducing excess nutrients, pathogens, chemicals and other toxic substances. Long-term monitoring shows that the coastal waters of Lake Baikal near settlements have elevated levels of fecal indicator bacteria (FIB) compared to natural areas. As a result, zones with unfavorable sanitary and bacteriological conditions have formed in the coastal waters adjacent to populated areas. However, seemingly anthropogenic intestinal bacteria may in some cases be of non—human origin," the text of the document says.
How is the problem being solved now
Olga Belykh, head of the Laboratory of Aquatic Microbiology at the Limnological Institute of the Siberian Branch of the Russian Academy of Sciences, told Izvestia that the Baikal region has sewage systems and sewage treatment plants in large cities and towns located on the shores of Lake Baikal. There, the water is prepared, disinfected and drained into rivers.
"But there are also settlements where there is no centralized sewerage system — these are small towns, campuses, any kind of facilities, including some hotels," she said. — We are talking about local contamination, meaning that there is an unauthorized flow of faecal water, which is poorly disinfected.
Elena Sharoikina, Chairman of the Commission of the Public Chamber of the Russian Federation on Ecology and Sustainable Development and the National Committee of the United Nations Decade for Ecosystem Restoration, noted that it is not yet possible to accurately determine the sources of pollution based on the results of the study: large-scale monitoring measures are needed to identify the largest sources of pollution.
The Lake Baikal Foundation told Izvestia that the problem as a whole is in plain sight, and its solution requires a set of measures: from continuing the reconstruction and commissioning of new sewage treatment plants on the shore of Lake Baikal, which were carried out within the framework of the national project "Preservation of Lake Baikal", to developing cooperation with livestock farms, to prevent cattle from grazing in the immediate vicinity of the shore.
Dmitry Kobylkin, Chairman of the State Duma Committee on Ecology, Natural Resources and Environmental Protection, noted that the lack of life-supporting infrastructure in settlements around Lake Baikal has already caused amendments to the law "On the Protection of Lake Baikal", which make it possible to create such facilities.
— There are 160 settlements in the central ecological zone of the Baikal natural Territory, of which only 21 have sewage treatment plants. The task of the federal and regional executive authorities is to create sewage treatment plants, and there is such an opportunity today. The deputies are waiting for the government commission to start working, where proposals will be considered, including the creation of such facilities," he told Izvestia.
Elena Sharoikina notes that septic tanks and cesspools are inevitably leaking into ground networks, which is why it is so important to deal with centralized sewerage.
— As for animal waste, their source can be both farms that violate the requirements for the disposal of manure, and animals that belong to local residents and graze along the coast, — said the interlocutor of Izvestia.
The federal law "On by-products of animal Husbandry", adopted in 2022, is intended to work with farm waste, Dmitry Kobylkin noted. It also establishes responsibility for violations of the treatment of by-products.
At the same time, the Lake Baikal Foundation emphasizes that the lake remains one of the cleanest freshwater reservoirs in the world, and its transparency — the main indicator of cleanliness — has significantly improved in 2025: from 23 meters in 2023 to 28 meters in 2025. This indicates a decrease in the amount of suspended particles and microalgae in the upper layers of the water.
Why it is important to deal with diffuse runoff issues
According to Olga Belykh, scientists at the LIN SB RAS annually submit information about their research to the authorities, from where this data is included in the conclusions of the State Report on the state of Lake Baikal.The last such report published was for 2024. It mentions contamination with fecal indicator bacteria (FIB) in the coastal area and especially in recreational areas such as beaches and coves.
Tourist areas remain the most problematic. This includes the Small Sea and Olkhon, for example, the villages of Khuzhir, the bays of Mukhor-Khale, Kurkut, Shida, Zagli. FIBER concentrations are particularly high in interstitial water (i.e., contained in the sand of beaches).
In the sewage treatment plants of the city of Slyudyanka, it is said about the strongest exceedances — 2.5 thousand and 10 thousand. depending on the type of bacteria. This indicates that there is no actual disinfection of the water.
The Russian Ministry of Natural Resources and Environment stressed that the construction and modernization of wastewater treatment plants is currently underway under the national project "Environmental Well-being". There are three such facilities on Lake Baikal.
— The reconstruction of sewage treatment plants in Severobaikalsk (Republic of Buryatia) is underway, the project for the construction of sewage treatment plants for the Slyudyansky municipality (Irkutsk region) has been approved, the construction itself is scheduled to be completed in 2029. In addition, a project for the construction of sewage treatment plants in the Baikal Municipality is undergoing a state environmental assessment. Construction is scheduled to be completed by 2030, the ministry noted, adding that this is only a part of the facilities being built in this region for wastewater treatment.
However, a new study by LIN SB RAS shows that some of the pollution is not only of human origin, but also of agricultural origin — and penetrates through groundwater. These are diffuse sources. The construction of sewage treatment plants will not affect them in any way.
The Baikal Environmental Prosecutor's Office confirmed to Izvestia that they were facing the discharge of untreated wastewater both in settlements and from economic facilities, but could not promptly provide statistics on these cases.
Izvestia also sent requests to the governments of the Irkutsk Region and the Republic of Buryatia and Rosprirodnadzor, which did not respond at the time of publication.
Vladislav Polyanin, Director of the Institute of Water Problems of the Russian Academy of Sciences, emphasized in an interview with Izvestia that no one is systematically dealing with the problem of diffuse pollution in the country yet.
— In recent years, however, these issues have been discussed at various venues focused on water and environmental issues and organized at both the federal and regional levels, - said the scientist. — Moreover, the draft of the new "Water Strategy" recognizes the importance and necessity of reducing the risks of diffuse pollution. At the same time, such a concept still does not exist in the legislation, as there are no existing mechanisms for its direct regulation.
Define the concepts
According to Polyanin, a noticeable effect in protecting water bodies can be achieved only with long-term work, and not through individual short-term programs. And this is possible only with the official appearance of this concept in the basic legislation of the Russian Federation. Vladislav Polyanin is confident that this is a very important initiative, given "the scale of diffuse pollution, which largely determines the ecological state of water bodies throughout the country."
He also pointed out the actual absence of diffuse pollution in state environmental reports — there are only some of its manifestations: polluted wastewater from agricultural fields or stormwater from urban areas.
"Meanwhile, in the European Union, for example, it is recognized that sources of diffuse pollution have a negative impact on 38% of surface water bodies and 35% of groundwater in the EU," said the director of the IVP RAS, citing reports from the European Environment Agency. — Diffuse pollution is regulated in one way or another by several supranational European directives.
He believes that one of the approaches to regulating diffuse pollution is the development and implementation of industry—specific environmental standards that would cover every subject area of economic activity that forms the sources of this pollution. Many of the problems here are precisely related to the management system of organizations and business entities in the catchment areas, the expert noted.
— We have already proposed a concept for reducing diffuse pollution of the Volga River, which was sent to almost all environmental organizations and agencies, including all 38 regions of the Volga basin. But most of the provisions of this document are universal and thus applicable to the whole country," Vladislav Polyanin noted.
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