In eastern Germany, enormous pits carved into the landscape by decades of lignite mining are being transformed into a vast network of lakes, wetlands and restored land. The Lusatian Lakeland, spread across Brandenburg and Saxony between Berlin and Dresden, is being created by flooding former open-cast mines and reshaping their surroundings.
Important to note: These are old open-pit mines from the era of German division. Back then, the GDR didn’t waste any resources on reclamation; instead, it simply shut off the pumps that had kept the pits dry. As a result, they filled with groundwater, and the pyrite contained in the coal seams weathered into sulfuric acid. Long story short: The lakes had to, and still have to in many cases, be heavily limed for renaturation or to make them usable again, since the pH level naturally hovers around pH 4.
According to the “Bundesanstalt für Gewässerkunde” at least for some of the bigger (and older ones) the water quality is “excellent”.
For example Senftenberger See and Geierswalder See. Unfortunately for many of them no data about water quality is publicly available. Probably because they are not open to swimming. Source: https://geoportal.bafg.de/karten/badegewaesser/?page=Seite#zoom_to_selection=true
Yes, but that is due to continues liming of many of those lakes. That is likely to keep happening for the next century or two at least in those lakes, which do not have a river running through them. Even that has issues, as the pollution from those lakes can kill the entire river. There are ways to deal with that too, but it is not a perfect situation.
https://web.archive.org/web/20190404101757/http://www.klimaretter.info/energie/hintergrund/23814-der-feind-des-bergmanns-kehrt-zurueck
Thanks for linking this article. It was very interesting to read! Especially the part with rising Groundwater levels and the negative impact on existing buildings that did not plan for rising groundwater levels after the end of the mining in the area.
The building problem might actually be less of a problem long term, as Lusatia is experiencing population decline. One of the towns mentioned Hoyerswerda went from 71k in 1981 to 31k today. So giving up some buildings is probably going to happen anyway. Might as well go for the ones with ground water problems.
Even for empty buildings this can be a problem. Because nobody takes care of them the city will need to take care of it to prevent the Building to negatively impact adjacent Buildings (e.g. structural hazard due to instability).
And if it affects public buildings (schools, City Council, etc.) they are directly affected. So yeah… quite messy.
The buildings are usually demolished. Google Maps has some issues in that area, because roads have been removed, as they would only lead to demolished commie blocks. Housing is super cheap though.
That’s correct.
In the case of Lake Geierswalde, liming was carried out to raise the pH level. Lake Senftenberg is unique among post-open-pit-mining lakes in the area in that it was already operated as a reservoir during the GDR era and was therefore flooded with water from the Schwarze Elster River. As a result, less groundwater containing ~~oxalic ~~ sulfuric acid has flowed into it.
What I meant to say with my comment wasn’t that the lakes are bad or have poor water quality… just that their renaturation and restoration to a usable state is an ongoing, active process.
Ah ok. Thanks for clarification!