Year after the restoration of the Jemielnica. WWF summarizes the results

It took just over a year for the Jemielnica – a small river in the Opole region – to begin regaining its natural balance. Thanks to clearing the concrete weir that dammed the water, fish once again gained the ability to migrate freely upstream. Along with them, many other species of fish and invertebrates have returned to the Jemielnica. A minor intervention brought surprisingly large effects.

The reborn Jemielnica is a river teeming with life

The restoration carried out in 2024 became an impulse for the recovery of the local ecosystem. Only a dozen or so months were enough for the river to once again show the presence of several fish species, including burbots and gudgeons. Removing human-made obstacles allowed them to migrate freely upstream.

However, this is not the only change. The Nature and Culture Association POD PRĄD published a report from an inventory of a 12-kilometre section of the Jemielnica. Preliminary studies revealed high diversity of aquatic vegetation: 33 macrophyte species were identified, including the partially protected thread-leaved water-crowfoot (Ranunculus trichophyllus) and species rare in the Opole region, such as the winged figwort (Scrophularia umbrosa) and fennel pondweed (Stuckenia pectinata).

The appearance of fish in the Jemielnica also created favourable conditions for mussels, as well as mayflies, stoneflies and dragonflies. Invertebrates now constitute nearly 40 percent of the entire benthic fauna. This is evidence that the river is regaining ecological stability.

What did the restoration of the Jemielnica involve?

Bringing life back to the Jemielnica became possible thanks to an apparently minor change consisting in clearing the concrete weir. The initiative was carried out by the Nature and Culture Association POD PRĄD with the support of WWF Poland.

The weir was built in the 1970s to dam water, probably for irrigating nearby fields. Over time it stopped fulfilling its function. Water did flow over the concrete structure, but for fish it was an impassable barrier. Clearing the weir – rather than removing it, which would have been far more expensive and formally difficult – took just two days.

Stones, the quiet heroes of change

It is worth pausing over elements that at first glance may seem completely ordinary – the stones that today form a chain of natural riffles on the Jemielnica. Their presence is not only an aesthetic addition to the riverbed. The stones disperse the current, stir the water and make it better oxygenated. For gill-breathing organisms this is a difference that becomes visible very quickly. In the zones between stones, microhabitats form with varied flow speeds, temperatures and light conditions. In these small spaces, bottom-dwelling fish and numerous invertebrates find shelter – including mayflies, stoneflies and caddisflies, species whose presence usually indicates an improvement in the ecological quality of a river.

WWF writes more about the restoration of the Jemielnica – here.

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main photo: Fidzios/Wikimedia