On the Angara, entire broods of river terns died because of a sharp rise in water. Tiny islets where the birds had nested were flooded in hours. Ecologists warn that such water level swings can kill thousands of waterbird chicks, while power engineers blame an emergency in the power system. The story again raises the question of how hydropower plants affect the coastal ecosystem and why ecologists and power engineers need a common approach.

As Irkutsk ecologist and ornithologist Vitaly Ryabtsev writes in his LiveJournal, on June 20 an entire brood of river terns died on tiny islets in the middle of the Angara just below the Irkutsk Hydroelectric Power Station. The reason was a sharp rise in water level.
-As early as June 19, I watched through binoculars as tiny chicks, about three days old, were bustling around in the nests. There were 12-14 pairs living on those exposed islets. Over the past few years, the water level in the Angara has fallen, so the birds nested there in the spring, the ecologist says. - The next day my wife and I were walking near that same place again. I looked—and those islets were all flooded. The chicks died… And it was already too late to lay new eggs this year.
According to Vitaly’s estimates, thousands of tern, duck, and sandpiper chicks could have died this way in the Angara floodplain. The saddest thing is that literally a couple of hours after the flooding, the water receded.
-Of course, it never occurs to anyone to take nature into account, to calculate the damage such actions do to the river ecosystem. Supposedly it’s nothing, - the ecologist laments. – Hydroelectric power stations are extremely dangerous for everything that is still alive in the Angara.
Specialists at the Irkutsk RDU, who are responsible for the water level in the reservoir, explained that it was precisely on June 20 that an emergency situation occurred.
At a power unit in Buryatia, which is connected to the power supply line in the Irkutsk district, the generator failed for several hours, and to make up the deficit, additional hydroelectric power station capacity had to be brought into use. That is why the water level rose, by energy workers’ estimates, by 1 meter.
As Igor Fefelov, an ornithologist at the Institute of Biology of ISU, says, a low water level is of course dangerous because, on the one hand, it provides many good places for water birds, but on the other, there is always a risk of flooding. And since the Angara’s water level has dropped sharply in recent years, birds unfortunately often die. The picture Vitaly describes is something we observe often. We understand that the hydroelectric power station operating regime is a complicated thing, but it always has a serious impact on the coastal ecosystem. But ecologists and energy workers need to be able to reach agreements so that there are fewer such cases.