How we’re reviving a poisoned river

The Oder river brings water all the way from the Czech Republic down to the Baltic Sea. Over its last 200 kilometers it marks the border between Poland and Germany.  Last year it became the focal point of international attention after a mysterious disaster killed millions of Oder fish in a matter of days. At the time, experts and officials couldn’t agree on the cause nor the remedy of this mass extinction.

We went to the Oder Delta to understand what actually happened – and to help bring back life to the death-stricken river ecosystem.

Watch here how we helped create a lifeline for a struggling river: 

The mystery of the mass fish extinction

Let’s start by piecing together what actually happened. On July 28th 2022, there were already indications of toxic substances further upstream at Opole, but nobody sounded the alarm yet. 

On August 2nd, a local newspaper in southern Poland reported a sighting of dead fish in one of the Oder’s contributing canals. But still, few people took notice.

Only 5 days later, the water monitoring system for the Oder in Frankfurt, Germany went crazy. Measurements spiked and went literally off the charts, across all kinds of water health indicators, showing a wave of organic material heading downstream, indicating what then would become evident for all to see. 

Over the next weeks, thousands of fish died and washed up all along the Oder shores, together with countless small invertebrates. Even beavers, ducks and other birds living along the riverbanks had been found dead. 

For the months following the disaster, experts and officials could not agree on what had actually caused it. Was it chemical waste illegally dumped into the water? High salt concentration? The water was tested for 300 substances. Was it a crime? A bounty of over 200.000 Euros was announced to find the perpetrator. An investigation by the Polish police discovered a total of 282 illegal drain pipes leading into the river. But which one was the culprit? And who was responsible? It seemed like everybody was trying to shift the blame. But without a clear understanding of the problem, there couldn’t be a plan to fix it or prevent it from happening again. 

What was actually the cause?  

Now, a year later, the picture is becoming clearer. A conference on the health of the Oder river, held earlier this year in Frankfurt, concluded that the extinction was caused by the convergence of two man-made problems:

Number 1: A discharge of industrial pollution into the river, which raised its salt concentration and according to a Greenpeace report can largely be traced back to the mining industry.

Number 2: The increasing effects of climate change, which caused higher than normal water temperatures and extremely low water levels.

This combination led to the blooming of the golden algae, an organism that normally only exists in salty water and does not belong in the Oder. This algae creates neurotoxins that are poisonous to the fishes nervous systems and can destroy their blood cells.

And it gets worse: Now that the algae has spread in the river, it will likely stay, ready to bloom again as soon as the same conditions arise.

And indeed, reports are already coming in this year that fish are dying again. The numbers will be lower, and might not make the headlines. But that’s only because there aren’t many fish left with only one year to recover. So ironically lower numbers mean an overall larger problem.

It is clear that political regulation is needed to stop this. But with two countries involved, different economic interests, and strong industrial lobbies, there is complete diplomatic gridlock on the topic. Which means no meaningful regulation in sight. Poland's right wing government is obfuscating the facts, to protect its mining industry, while Germany holds back for diplomatic and geo-strategic reasons. Which means no meaningful regulation anywhere in sight.

So is there anything we can do right now to help the ecosystem - something pragmatic, actionable and outside of politics that can boost the river’s resilience? 

So what can we do?

We have found a way to do just that and we partnered with Arthur Furdyna from Rewilding Oder Delta to make it happen. Artur has worked there over 20 years to restore nature along the Oder’s tributaries. 

While often overlooked, these tributaries have always been crucial to the health of any river ecosystem. But since the disaster in 2022, Artur’s work has gained a new dimension as the contributory streams are now becoming a lifeline for the struggling Oder. During the disaster the tributaries were full of fish, fleeing there to take rescue from certain death. And healthy tributaries can be vital breeding grounds for all kinds of fish and aquatic life that can then repopulate the wider river ecosystem.

The method

A big part of Arthur’s work is undoing the harm humans have done to the tributary streams at a time when they didn’t know better. The Ina was one of the first rivers in Europe to be channelized as part of the Hanseatic trading routes in the 16th century.

What seemed like indisputable progress at the time, is now understood to cause a whole range of ecological problems: Channelization means straightening and deepening the stream. The result is a loss of breeding ground for fish that need diverse riverbed structures and even destroys the surrounding meadow habitats that depend on natural overflow.

After WW2, commercial use of the Ina stopped. The river has started to self restore through natural meandering. But nature alone won't be able to undo the effects of human intervention. Because the original ground material that the riverbed needs, was created during long-gone glacial times. Luckily we can help.

Arthur has been pioneering an effective method to rewild the river and restore its original habitat. It simply relies on giving back to nature what humans have taken from it: Gravel. 

20 years ago Arthur started doing something very simple: replenishing the riverbeds with the gravel stones that canalization had depleted them of. 

The impact

By filling up the river bed with a specific kind of gravel, multiple things happen at once: 

Number 1 - new breeding grounds: It’s the perfect breeding ground for many fish species, including Trout, Greyling, and Salmon, as it provides shelter for spawned eggs, as well as for baby fish through their larvae and early juvenile stages.

Number 2 - water cleansing: It cleans the water by drastically increasing the surface area for bacteria to live, which then feed on dead organic matter. While not visible to the naked eye, bacteria are one of the most important, albeit overlooked, aspects of biodiversity on earth. 

Number 3 - oxygenation: By creating countless little turbulence in the water, the stream can absorb more oxygen. Different from the air we breathe, oxygen levels in the water can vary tremendously, and if there’s too little, life can’t flourish.

Number 4 - natural overflow: The shallower riverbed increases natural overflow during heavy rains or snow melt, which protects the river itself from destructive currents and erosion. 

Number 5 - new habitats: The overflowing meadows and forests form habitats for new plant and animal species like marsh marigold, aquatic insects, frogs, salamanders and so on.

Number 6 - feeding grounds: Those wetlands then serve as feeding grounds for birds, like Kingfisher, Bee Eater, and Saint Martin bird, who have all come back here.

Number 7 - passageways:  The shallower riverbeds provide passage for large mammals that couldn’t cross over before, including the European bison that was completely extinct in the wild 100 years ago, but has been reintroduced to the region by our friends at ZTP. We did a whole video on this topic, that you can watch right here. 

Arthur and his team have been doing this for 20 years and it’s amazing to see how quickly nature can regenerate with a little help. Even after one year, the effects are already clearly visible and will only increase with time.

Most importantly, rivers like the Ina that begin to thrive again and reach their full potential for spawning new life, create a constant downstream effect to add biodiversity to the larger river ecosystem of the Oder Delta.

Our support

That’s where our support comes in. The Planet Wild community is funding the creation of new breeding grounds in two of the Oder’s Tributaries: the Ina river, and the Gowienica river a bit further north.

The method is already proven as we’ve seen, so now we just need to scale it up. By rebuilding the lost breeding grounds, we can help to massively increase the possibility of natural reproduction of many species. 

What makes this rewilding method so successful is how simple and straightforward it is: it’s very cost efficient, requires no heavy construction work, creates low bureaucratic hurdles (which can be a crucial aspect for success), and it requires zero maintenance after implementation. It just gives back to nature and then lets nature take over.

This way, even while political regulation is lagging, we can do something to actively strengthen the river ecosystem, by creating crucial spaces for distressed fish to find refuge, and from where they can always repopulate and as a result make the Oder Delta ecosystem more resilient as a whole.

A personal note 

This is not the first mission where nature get’s in the crossfire of politics and I won’t deny that this can be a frustrating observation to make especially when it’s recurring. In these moments I remind myself of the stoic principle: we can't always control what happens to us, but we can always decide how we react to it. With Planet Wild we chose to focus on those areas where we have the power to act rather than those where we are powerless. It’s that pragmatic approach that keeps me sane in light of all the things I could decide to get disheartened by. Our community is an open invitation for everyone who wants to follow that same principle.

Markus Gilles

Co-Founder, Planet Wild

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