About frosts in the summer period

Causes of summer fish kills:
- high air and water temperatures, including at night;
- low water levels in reservoirs.

Summer fish kills occur as a result of a critical deficit of dissolved oxygen in the water, leading to the death of fish and aquatic animals.

The main reasons for the decrease in dissolved oxygen content are water "blooming" (reproduction and death of blue-green algae), rotting of flooded vegetation in river floodplains due to a sharp increase in water levels after heavy rains, inflow of swamp waters with high content of humic acids and iron into reservoirs, and active consumption of oxygen by algae and aquatic plants at night at high night temperatures.

Signs of pre-fish kill phenomena:
- accumulation of fish near the water surface, their concentration near tributaries, mouths of inflowing watercourses where the water is colder and richer in oxygen;
- intense water "blooming";
- high turbidity;
- appearance of an oily film and gas bubbles from the bottom of the reservoir.

In case of detecting facts of fish kills or pre-fish kill phenomena, citizens visiting water bodies are strongly urged to inform the territorial bodies of the Ministry of Natural Resources and Environmental Protection, and local authorities about these cases.