Translation
Then the third one poured his bowl
into the rivers and springs of the waters
Go to footnote numberand they became blood.
Paraphrase
Then the third one set in motion the consequences demanded by the evidence, directing them at the physical sources of abundance which revive and refresh (i.e. that make life easy) and
they became a source of death instead.
Footnotes
1
Here again we have a layering of three images working together. “Rivers and waters” both refer to abundance, while the word “springs” refers to something that refreshes and revives.