The Agency is working to prevent flooding, for example by reducing run-off.
According to the South Ostrobothnia Environment Centre, there is already water in the rapids and the water level above them has risen in some places.
The Agency is working to prevent the formation of silt by reducing water run-off, for example from Lake Evijärvi, and by installing silt ropes at six locations.
The Agency has also reduced the flow from Lappajärvi.
The situation on the river is monitored with game cameras and terrain inspections.
The large flow of water prevents the formation of an ice cover, so the rapids can be filled with hypocooled ice slush, or jelly. It can generate floods above the rapids.
The Ähtävänjoki has flash floods almost every year in the vicinity of the settlements of Ähtävä, Lappfors and Kolpi.
The ice problem has also occurred in Lestijoki, Lapuanjoki and Lapvärtin-isojoki.
The risk of ice dams is greatest during the frosts of early winter, when there is no ice cover in the river yet.