4PLANET MAGAZINE
How a dead mine became a wetland
A disused mine in Portugal filled with water after extraction stopped. Instead of erasing the scars, rewilding teams are using them as the bones of a new wetland — a test of whether restoration can sometimes work better when design knows when to stop.
A mine is designed to remove things. Rock comes out. Water is pushed away. Slopes, channels and pits are engineered around extraction. At Paul de Toirões in Portugal’s Greater Côa Valley, that logic left behind a landscape so heavily altered that its scars eventually became the raw material for something else.
Tin, tungsten and sand were extracted from the site for decades before mining ended in the early 2010s. The abandoned ground was a rough geometry of deep pits, steep banks and drainage systems. Then water began collecting in the hollows. What had been industrial damage started behaving like habitat.
Rewilding Portugal began managing the roughly 300-hectare site in late 2022. According to Rewilding Europe, the approach has combined targeted interventions with natural regeneration: retain more water, improve wildlife access, address non-native plantations and then allow ecological processes to take over where they can.
Do not erase the scar too quickly
Conventional restoration can be tempted by the image of a clean reset — remove the damage, recreate the landscape that should have been there, plant the right things and declare the site repaired. Paul de Toirões suggests a different design instinct. The excavations themselves created variation: deep and shallow water, wet margins, ditches, islands of vegetation, dry ground and regenerating woodland.
That heterogeneity matters because living systems respond to conditions, not intentions. Different depths and moisture regimes create niches. Temporary ponds can become breeding habitat. Regenerating forest changes shade and shelter. A badly altered landscape can still contain physical structure that recovery is able to reuse.
Restoration can be an act of design restraint: change the conditions, then allow the living system to answer.
What has actually been measured
Rewilding Europe reports that surveys in 2023 and 2024 recorded 94 aquatic plant species across the site. Environmental DNA analysis detected more than 200 species, while bird and amphibian monitoring has documented use of the new wetlands by species including black storks, marsh harriers and spoonbills. The organisation also highlights the southern bladderwort, an insectivorous plant sensitive to water quality and rare inland in Portugal.
These are strong signs of ecological use, but they are not the same thing as proof of a completed restoration outcome. Rewilding Portugal field officer André Couto describes the surveys as baselines. That is important. A baseline tells you where you are. The harder question — what changed because of which intervention, and whether that change lasts — requires repeated monitoring over years.
A stepping stone, not an island
Paul de Toirões also matters because habitats are rarely useful in isolation. Rewilding Europe describes the site as part of a wider effort to improve ecological connectivity through the Greater Côa Valley. Wetlands and regenerating forest can function as stepping stones for species moving through a broader landscape that is typically much drier.
This is where the story becomes bigger than an unusual wetland. Industrial landscapes are everywhere. Quarries, mines, canals, reservoirs, rail corridors and brownfield sites contain engineered forms that nature may be able to reuse. The question is not whether every scar should be celebrated. It is whether restoration teams can learn to see latent ecological structure before bulldozing it away.
The design lesson
The most useful thing about Paul de Toirões may be the shift in posture. Restoration does not always mean manufacturing a finished picture of nature. Sometimes it means identifying the pressures that still prevent recovery, removing enough of them, keeping the system under observation and resisting the urge to control every next step. The site is not evidence that nature heals automatically. It is evidence that recovery can become surprisingly inventive when design leaves room for life to participate.
Sources
- A landscape reborn: rewilding is transforming an old mine in the Greater Côa Valley
- Paul de Toirões — restoration actions and landscape context
- Aquatic plant survey — methods, water chemistry and rare species