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©Etang Prele Secheresse|Claire Curt
Why Do the Ponds

Seem Empty ?

In the summer, when walking in the Dombes, many ponds seem empty.
This phenomenon, increasingly common, is mainly due to climate change and increasingly hot summers.

Here’s why.

Water, an Essential Resource for the Ponds

The Dombes has natural characteristics ideal for the creation of ponds. These are artificial water reserves created by humans in the early 11th century to produce fish. They are fed only by runoff, rainwater, and water from surrounding ponds. Indeed, the waters from the upper ponds fill the lower ponds through a network of ditches.
Their exploitation system is unique and organized in cycles. Two periods alternate: assec (drying and cultivation) and évolage (flooding).

Thanks to a traditional and well-managed process, water, a precious resource, was until recently perfectly utilized. 1,200 ponds were thus maintained and exploited in accordance with centuries-old traditions.

Drought, a Real Plague for the Ponds

Unfortunately, in recent years, many ponds have suffered from a lack of water…
Unlike lakes, ponds are very shallow (1.5m at the deepest point and 30cm on the edges). In case of high temperatures, the water temperature can quickly rise to over 35°C. The heat, sometimes combined with wind, causes evaporation, and the pond’s water level can drop significantly (up to 3cm per day). The ponds then appear empty or in assec.

As of June 1, 2023, about 40% of the ponds in the Dombes were dry. Also, two out of three ponds are filled to less than 25%.

Despite thunderstorms, the rains are insufficient to fill the ponds and the already very low groundwater due to a recurring rainfall deficit in recent years. The Dombes is regularly placed on heightened alert.

Saving Fish Production

The ponds are private properties. They are a tool for fish farmers who use them to produce fish (carp, pike, tench, whitefish).
Fish farmers are now worried about the recurring drought episodes. The high temperature of the pond water and its low quantity lead to a lack of oxygen for the fish. Aerators installed in some ponds can help limit the consequences, but this is not always the case.

Some ponds must therefore be fished “urgently” without waiting for autumn, the usual fishing season.

Protecting to Preserve

As frustrating as it may be for Dombes hikers, private property is part of the pond, which leads to the richness of vegetation and bird species present. If we fully open the ponds, the birds will no longer nest, there will be too much disturbance, and we will no longer have this variety of bird and plant life.

Many ponds are visible from the paths, where one can already observe a very rich life. But caution is needed. The nesting period for Dombes birds such as the whiskered tern or the duck spans from mid-March to mid-August.

Théo, chargé d'études Natura 2000

the Ponds

The most curious can turn to one of the five “Sensitive Natural Areas” (ENS) equipped with observatories.
However, even on these ponds accessible to the public, it will not be possible to make a complete tour! There is intentionally a preserved area so that humans are not too close to the birds.

The Tourist Office and France Nature Environnement also offer guided tours around the ponds.
Finally, since spring 2023, the Parc des Oiseaux has been organizing tours of the ornithological reserve.