Shallowing of Oskol Reservoir, Ukraine

Problems

• The Oskil Reservoir was an artificial lake on the Oskil River in Kharkiv Oblast, Ukraine.
  
  Before it was drained, the reservoir's area was 130 km², with a maximal length of 125 km, a maximal width of 4 km, an average depth of 4 m and a volume of approximately 474 hm³. The purpose of the reservoir was to regulate water levels, serve as a source of electricity, and help the fishing industry.
  
  During the Russian invasion of Ukraine, the reservoir was noted for its strategic importance, as causing downstream flooding would be one way to slow Russian advances in the Donbas.
  
  When the dam broke, the gardens were flooded, and the water reached the houses. But it did not reach a critical situation - it looked like spring floods. However, it was no longer possible to cross to the other side, the current was very swift, and the boatman did not risk transporting people.
  
  People were evacuated on boats to the territory controlled by Ukraine: this was the only opportunity to leave. They also sent medicines and food to each other.
  
  After the destruction of the hydroelectric complex, the reservoir quickly became shallow: about 9 thousand hectares of the bottom were exposed. The water level has dropped six times: there are about 80 million cubic meters left. Almost 2 million fish - catfish, pike perch, carp, perch - died.
  
  The Oskol reservoir in the Kharkiv region is turning into a desert: due to mines, and it is still impossible to restore it. And the settlement of Oskol, where the dam of the reservoir is located, survived the Russian occupation.
  
  The Oskol reservoir, which in some places reached a depth of ten meters, now looks more like a desert. Bushes are sprouting from the bottom, the water has become almost six times less, and small lakes look like oases.
  
  The region is shallow, the reservoir was a reserve of drinking water. In addition, 4 thousand hectares of the reservoir are a regional landscape park. The state environmental inspectorate calculated the damage in the billions.
  
  The ichthyofauna and aquatic vegetation were destroyed. And, given the lack of water in the region, this hurt the situation in the region. Preliminary assessments are not yet possible to ascertain, because this area remains uncleared. However, for those areas that were part of the regional landscape park, the damage is estimated and amounts to about UAH 3.5 billion,” said Andriy Nereta, director of the environmental protection department of the Kharkiv Regional Military Administration.
  
  According to environmentalists, almost 2 million fish died, and 9,000 hectares of the bottom became shallow. The country suffered damage worth billions of hryvnias.

• Can the reservoir be restored?

  Eco-activist Artem Prikhodko became interested in the restoration of the reservoir. He became known throughout the country when, together with like-minded people, he installed the country's first garbage catcher Trash Killer on the polluted Kharkiv river Udy, which had already caught 30 tons of trash.
  The Oskol reservoir, after being filled with water, will have to be stocked with fish, but the activist is convinced that the destroyed flora and fauna cannot be quickly restored.
  
  - To restore the flora that was there, and those types of fish, it takes 10-15 years, and then it will not be possible to restore everything. We can say that some plants that were on the banks of the river, the reservoir, disappeared forever, - explained Prikhodko.
  
  Activists are ready to clear the forest, restore the hydraulic structure and do everything to make the Oskol reservoir the way it was before the war.

• Should the Oskil Reservoir be rebuilt after the war?

  The practice of getting rid of old and small / non-functional dams has long been accepted in the EU and the US and is actively spreading today. 
  
  If, after the examination, the further operation of the reservoir and hydroelectric power station is found to be inappropriate, the dam will be dismantled.
  
  The restoration of the natural runoff of Oskol will give them a chance to return to their habitat for many species of fish, the existence of which requires running water and an unblocked riverbed. They will be a good forage base for birds that nested in the reed thickets of the former reservoir, or those that will return to the restored floodplain landscapes. Among the species protected by the Red Book of Ukraine and in need of a flowing riverbed.
  
  After the return of water flow, its quality will increase – the number of phosphates will be regulated naturally. This will eliminate the problem of eutrophication because such organic impurities as phosphates (the amount of which in the samples from the reservoir was much higher than normal) served as a kind of fertilizer for the growth of photosynthetic algae.
  
  The decision to dismantle the dam will help speed up decisions on the modernization of water supply systems in Donbas. But in addition to the undoubtedly important communication and economic functions, getting rid of the dam, first of all, means returning dozens of representatives of flora and fauna to their natural habitat. This is a step of man toward nature.