Arnica ecological organization alarmsthat the state-owned company Povodí Odry has started work on a protected section of the Olza River. Modification of the river course may cause ecological damage among others destruction of habitats of protected species. Works take place between the state border with Poland and the Czech town of Jabłonków.
“Completely wrong idea.” The Czechs are interfering with the Olza River
The river bed is deepened and the banks reinforced with gravel and stone. Olza was one of the rivers that flooded during the September flood. This is one of the reasons why the river was taken care of. However, ecologists warn that the actions taken do not increase the flow of the stream in any way and cause ecological damage. Moreover, they are supposed to increase risk of serious damage in the event of further floods. By removing natural sandy hills, the speed and destructiveness of the flow increase.
Jan Hradecký, head of the Department of Physical Geography and Geoecology at the Faculty of Natural Sciences of the University of Ostrava, considers work on the river to be a “completely wrong idea”.
One of the positives of flooding is the possibility of renaturalizing river ecosystems
– he explains.
The river returned to its natural dynamics. Some water levels that previously constituted migration barriers for protected fish species have become clear, and the coast, which is crucial for the ecosystem, has been restored without threatening nearby buildings.
– Not only was the potential for restoration trampled into the ground, but the riverbed received another impetus for degradation. The phenomenon of “starved water”, resulting in a lack of sediments, will lead, along with the reduction of the erosion base, to the deepening of the river. For Carpathian rivers, this is often a path to complete devastation. Proper river management should combine flood protection and supporting the ecological functions of river ecosystems. Here almost everything that modern science knows about rivers has been contradicted – explains Jan Hradecký.
Endangered animals. Including the Polish grass snake
Due to works on the river, the following are at risk: populations of lamprey, mountain toad and common viper. We learned from ecologists from the Arnika organization that there is a lot of confusion Polish nature may also suffer. They warn that the work may have a negative impact on the population osprey grass snake (Natrix tessellata).
– The destruction of the canal has disastrous consequences for it, because in order to bask on the shore it needs heated pools in bends of slower flowing water, with a varied morphology of the canal. It prefers coastal vegetation for shelter. It is also endangered because it needs natural, “weedy” flows with plenty of fish, which constitute the basis of its prey. It needs coastal vegetation because basks near the water and likes to be protected – Lubosz Pawłowic explains to us.
However, it is reassuring that with informationwhich the organization has, does not indicate that the Polish side is deepening or modifying the river in an invasive way. The Czech side is different. Arnica even folded request to initiate an investigationin which it demands an immediate cessation of this activity, a reassessment of the activities of the Odra basin and the introduction of corrective measures. “In some places, irreversible damage has already occurred, but in other sections it is still possible to stop the destructive interventions,” they warn.
We also asked Povodí Odry for a comment, but we did not receive a response before the article was published. We asked, among others: about why work was undertaken on the river and whether it actually poses a threat to nature.