Comment by aljp

It could also be akin to the guardian of a minor, whilst a minor may have a mind, they wouldn't necessarily be in charge of making decisions regarding legal recourse, or in some cases personal health. If we pursue this train of thought, there could be some expectations for the "legal guardians of rivers" to justify what course of action they should take on behalf of such a thing, in that they may be expected to ensure the health and longevity of the river, and hopefully improve the quality of life for all living things in and around rivers.