So lasting they are, the rivers !

Only think. Sources some­where in the mountains pulsate and springs seep from a rock, join in a stream, in the current of a river, and the river flows through centuries, millennia.
Tribes, nations pass, and the river is still there, and yet it is not, for water does not stay the same, only the place and the name persist, as a metaphor for a per­manent form and changing matter. The same rivers flowed in Europe when none of today’s countries existed and no lan­guages known to us were spoken. It is in the names of rivers that traces of lost tribes survive. They lived, though, so long ago that nothing is certain and scholars make guesses which to other scholars seem unfounded. It is not even known how many of these names come from before the Indo-European invasion, which is estimated to have taken place two thousand to three thousand years B.C.
Our civilisation poisoned river waters, and their contamination acquires a powerful emotional meaning. As the course of a river is a symbol of time, we are inclined to think of a poisoned time. And yet the sources continue to gush and we believe time will be purified one day. I am a worshipper of flowing and would like to entrust my sins to the waters, let them be carried to the sea.

Miłosz, Road-side Dog (1997)
translated by the author and Robert Hass

The hydroelectric plant is not built into the Rhine River as was the old wooden bridge that joined bank with bank for hundreds of years. Rather the river is dammed up into the power plant. What the river is now, namely, a water power supplier, derives from out of the essence of the power station.
In order that we may even remotely consider the monstrousness that reigns here, let us ponder for a moment the contrast that speaks out of the two titles, “The Rhine” as dammed up into the power works, and “The Rhine” as uttered out of the art work, in Hölderlin’s hymn by that name.
But, it will be replied, the Rhine is still a river in the landscape, is it not? Perhaps. But how?

In no other way than as an object on call for inspection by a tour group ordered there by the vacation industry.

Heidegger, The Question Concerning Technology (1949)
translated by William Lovitt

Das Wasserkraftwerk…
Das Wasserkraftwerk ist nicht in den Rheinstrom gebaut wie die alte Holzbrücke, die seit Jahrhunderten Ufer mit Ufer verbindet. Vielmehr ist der Strom in das Kraftwerk verbaut. Er ist, was er jetzt als Strom ist, nämlich Wasserdrucklieferant, aus dem Wesen des Kraftwerks.
Achten wir doch, um das Ungeheuere, das hier waltet, auch nur entfernt zu ermessen, für einen Augenblick auf den Gegensatz, der sich in den beiden Titeln ausspricht: »Der Rhein«, verbaut in das Kraftweih, und »Der Rhein«, gesagt aus dem Kunstwerk der gleichnamigen Hymne Hölderlins.
Aber der Rhein bleibt doch, wird man entgegnen, Strom der Landschaft. Mag sein, aber wie?

Nicht anders denn als bestellbares Objekt der Besichtigung durch eine Reisegesellschaft, die eine Urlaubsindustrie dorthin bestellt hat.

Heidegger, Die Frage nach der Technik (1949)