<p>16:4 <em>And the third poured out his bowl into the rivers and the fountains of the waters, and they became blood</em>- This is referring to judgments within the earth / land promised to Abraham; the surrounding sea has already been judged in :3. Again the allusion is to the judgments upon water sources which was part of the plagues upon Egypt in Ex. 7:19. That plague is alluded to in another judgment upon Egypt found in Ez. 32:6, where Egypt is told that she shall be covered with her own blood to the extent that her rivers will run with her own blood. And that prophecy goes on to state that her sun, moon and stars shall be extinguished, causing darkness (Ez. 32:7,8)- ideas to be developed here in :8,10. It is unclear when this prophecy of Ezekiel had its fulfilment. The initial context is of Israel trusting in Egypt for help against the Assyrian. And latter day Israel may likewise look to Egypt for help against the latter day Assyrian. But Egypt too, part of the &quot;sea&quot;, the territory immediately bordering the &quot;land&quot; promised to Abraham, is to be destroyed. Water turning in the blood of death may refer to some form of literal turning of water into the source of death- perhaps some form of biological warfare against Israel ends up affecting all within the land promised to Abraham. This is how God typically prefers to operate- allowing wicked men to be destroyed by the backfiring of their own devices, rather than by bolts of direct Divine judgment.</p>