Paper short abstract:

Algal blooms haunt the former clear-water Lake Stechlin, Germany. The blooms are caused by legacy nutrients, sedimented over decades of pollution from a nuclear power plant and reactivated under climate warming. After years of denial and amnesia locals demand action to restore its pristine past.

Paper long abstract:

Lake Stechlin, Germany, was known for its fabulous transparency. Until the late 1960s transparencies of more than 15 m were not uncommon. Summer guests admired its crystal-clear water and its lush underwater meadows of stonewort, rich in perch and pike. The lake, to this date is home of its own endemic cisco (Coregonus fontanae). But the extinction of the Fontane cisco is imminent, and the extensive underwater meadows are long gone. Today transparencies of more than 5 m are rare. The lake has transformed. It served as a cooling-water reservoir for a nuclear power plant (NPP) from 1966-1990. During this time its waters not only absorbed the excessive heat from the plants reactor but ingested a soup of dead algae, produced during the passage through the heat-exchangers, and the sewage of the NPP-personnel. Over decades the waste sedimented silently on its bottom.

Today, under climate warming, the NPP-legacy comes to light again, causing year after year colorful mass blooms of green and red cyanobacteria. After decades of denial and amnesia the locals now demand for a lake restauration. That ambition, if realized, would require a long-term management, not much different from the treatment of the plants nuclear waste. The lake would transform into a landscape-machine with the promise to be an immortal, primordial lake of tomorrow. Yet, in this sad story subtle signs of accepting the irretrievable are visible, signs of a search to attune with the lakes transformations and to develop better, less violent relations with its non-human inhabitants.