ᐅ Disposing of wastewater/sewage into lakes or rivers. Are there still options available?

Is it possible and legal to discharge the cooled water from a water-to-water heat pump into a lake or river?

You need to ask your local authority. They have to grant you the permit. This is usually issued for a few years and then needs to be renewed.
That’s how I understand it.

If the local authority eventually decides no longer to approve it, you will have to look for an alternative.

First of all, thanks for the reply... And one more thing...

Could this possibly also depend on the state / region? I unfortunately can't find anything about it online at all... So could the mayor simply tell me, yes, it can be initiated?