Lake cleaning: destruction or help to the ecosystem?

Recently, on the page of Oleksandra Sladkova, the head of the Department of Ecology and Natural Resources in Lviv, a discussion broke out about "ecological betrayal" related to the cleaning of Lake Zelene Oko in Snopkivskyi Park. Oleksandra reported on this cleaning on December 19.

Activists began to insist that the lake had been destroyed. During the "Your City" stream, public activist Yuriy Plakhta thoroughly discussed the activities of communal workers:

"These lakes need maintenance, but it should be done according to the projects. There were no projects here; as far as I understand, people did everything according to their own logic. They removed silt masses from the center of the lakes, formed the geometry of the shoreline, and made slopes. After warming, the silty masses began to slide onto the road, which is a transit route and connects Kupalna and Zelena streets. As of now, it is destroyed," said the activist.

The case went all the way to the police, as a result of which, "based on the results of social networks monitoring," criminal proceedings were opened for improperly carrying out work on cleaning the lake in Snopkivskyi Park, under the article "Official Negligence."

Of course, everything did not end there; Oleksandra reacted both to the stream and the proceedings' opening. According to the government official, the banks were collapsing even before equipment intervention, and the works themselves had been carefully prepared for the last three years.

However, Sladkova understands the anger of eco-activists and even takes part of the blame: she says she did not communicate well with the public.

This situation showed us that we know too little about the cleaning of lakes, and when this process caused such a stir in Lviv, we should think about where and when such cleanings were carried out, how it can be done, and whether it is necessary at all. So, let's figure it out.

It is true that water bodies can exist by themselves. But nowadays, it is difficult to avoid anthropogenic intervention, so if the reservoir is in a city or near a settlement, it must be taken care of. Otherwise, the following factors can destroy the reservoir:

• Accumulation of silt. Over time, silt, which can reach 3 meters, forms at the bottom of the reservoir from the decay of mineral and organic substances. This can lead to the washing away of islands and, over time to the complete destruction of the reservoir.
• Branches and snags clog the bottom. If the pond is surrounded by old trees (forest, park, etc.), you should be prepared that parts of wood and fallen leaves will accumulate on the bottom.
• Accumulation of household and construction waste at the bottom is an urgent problem not only for urban but also for natural lakes, into which waste can be dumped.
• Aquatic vegetation. Its quantity increases due to the content of fertilizers in the water. When there are too many plants, they absorb excessive amounts of oxygen, killing fish and other biotas in the body of water. A large amount of aquatic vegetation also leads to water blooms.
• Pollution leads to the "swamping" of a water body, the appearance of a persistent unpleasant smell, and changes in the ecosystem. Therefore, it is necessary to regularly clean the reservoir from pollution, silt, algae, and other debris. If this is not done, the reservoir will become unsuitable for recreation, swimming, and fishing. And over time, it can completely become shallow and dry.

Lake cleaning is a rather complex procedure carried out with the help of specialized equipment or with the involvement of many people. The entire process is preceded by mandatory preparation with the study of the terrain and other features of the reservoir. The works are usually carried out in winter, at the end of December or January, when natural processes slow down, and the intervention does as little damage to the ecosystem as possible.

Zelene Oko Lake in Snopkiv Park was cleaned with the help of an excavator, mechanically. This method is used to deepen the bottom and clean coastal areas from construction debris, snags, parts of tree trunks, branches, and uprooted trees near the shore. In the case of Zelene Oko, in addition to cleaning the bottom of the lake, its shores were also prepared for landscaping.

But there are other ways of cleaning water bodies. In particular, mechanical, when the bottom is manually cleaned of large foreign objects, accumulation of algae. In this way, you can even independently clear a small area in shallow water and eliminate large objects and natural and household garbage. Often, such work precedes the use of a dredger, and such cleaning can be performed at any time of the year. For example, municipal services cleaned Lake Nyvky in Kyiv in April: several bags of garbage and even a car tire were removed from the bottom.

Another method is hydromechanical. It involves the use of a mini-dredger. It is equipped with pumping equipment and a pipeline, which makes it possible to wash away the silt and pump it to the shore. The dredge allows you to deepen the bottom, ridding it of silt.

If the whole process is done correctly, then the cleaning will not disturb the lake's natural ecosystem and will help it develop.

Recognizing the degree of water pollution is simple; the main indicators are the smell and color of the water, as well as the amount of algae.

1. A change in the color and transparency of the water is the first thing to pay attention to. Everything is simple here: if the water is cloudy and green, it needs cleaning.
2. The increase in algae can occur not only due to chemical pollution but also due to the accumulation of sediments at the bottom; this makes the reservoir shallow, which warms up well and blooms.
3. Unpleasant smell. This is usually due to the activity of bacteria or fungi, which begin to multiply actively.

Basically, these three points are quite enough to make a diagnosis — it's time to clean the reservoir of pollution, garbage, branches, silt, and algae.

It is important to say that not all lakes need cleaning. For example, the lakes of Snopkivskyi Park in Lviv are reservoirs of artificial origin, but their uniqueness lies in running water. Of all the park's seven lakes, only the Zelene Oko was planned for shoreline regulation work because there was a need for it.

Preparation for the process, according to Sladkova, lasted three years: hydrogeological studies were conducted, and passports of water bodies were developed, containing recommendations for cleaning. As for the destroyed path, which the activists were outraged by, Sladkova promises to fix everything: firstly, the landscaping near the lakes is planned, and secondly, the process of cleaning the lake itself has not yet been completed:

"Yes, cleaning the lakes is an "operation." We don't expect a person to get up, go to work, go for a run and eat everything on the second day after surgery. It's the same with lakes; it takes a certain amount of time to recover," the government official commented on her Facebook page.

But there is a problem with financing. In the conditions of martial law, the city is unlikely to be able to get additional funds from the budget for this process, Sladkova explains:

"Our legislation does not provide that project and estimate documentation is developed for the ongoing cleaning of lakes. Because this is not capital work, but current maintenance.

Difficulties can also arise with donors:

"Foreign funding, which we agreed with GIZ before the full-scale invasion, has become irrelevant because the donor's policy has changed. In addition, there is no legal requirement for this; it is the goodwill of management."

Ecologist Yurii Plakhta, who was outraged by the works carried out on the Zelene Oko, believes that the city is developing without regard to water bodies, and they need to be urgently restored and cared for:

"For this, it is necessary to create a concept of working with the water objects of the city; before that — carry out an inventory, analyze how many of them we have and how we will include them in the space of our city. It is also necessary to remember that a water body is also the surrounding territory," the ecologist explains.

That is, for the city to bring the lake into order, the balance keeper of the territories where the reservoirs are located must decide to take the following steps: 

1. Develop passports of water bodies if they do not exist yet.
2. Conducted relevant hydrological research.
3. Clean these objects.

You can also influence this process.

1. If you wish to improve the lake, please make an appropriate request to the local Department of Ecology and Natural Resources; contact details can be found at the link.
2. If you notice the lake's pollution: garbage, blooms, collapsing shores, drainage — leave a request on the SaveEcoBot portal.
3. Another way is to schedule a collective cleaning, during which you manually clean the shore and shallow water of debris. You can do this in the chat of the house, on the settlement's social network pages, etc.