If the Hebrew text is correct as it stands, the meaning is “Nineveh has been like a (placid) pool of water from earliest times. Now they flee” (New Jerusalem Bible). The words here translated “from earliest times” are probably the result of a copying error. The majority of modern translations change them in accordance with the ancient Greek translation, the Septuagint. Revised Standard Version, for instance, translates Nineveh is like a pool whose waters run away (compare Jerusalem Bible, New American Bible, New International Version, Bible en français courant, Die Bibel im heutigen Deutsch). Since this is the first mention of Nineveh in the Hebrew text since 1.1, it will be helpful in many languages to say “The city of Nineveh.”
Good News Translation follows this wording but makes the point of the comparison explicit: “Like water from a broken dam the people rush from Nineveh!” This refers of course to the people trying to escape when the city is captured. In some languages the second line needs to be placed first: “The people rush from the city of Nineveh just as water pours out of a broken dam.”
The second half of the verse gives a vivid picture of the officers trying in vain to stop the defending troops from fleeing with everyone else. They call out “Halt! Halt!” … but none turns back. The words they cry are not in the Hebrew but are inserted in several modern versions (Revised Standard Version, New English Bible, New International Version; compare Bible en français courant, Die Bibel im heutigen Deutsch) to make clear that the previous words “Halt! Halt!” are direct speech. Good News Translation uses the idiomatic English expression “the cry rings out” to make the effect more vivid and dramatic. In many languages it will be necessary to state explicitly who is crying out; for example, “The officers shout, ‘Stop! Stop!’ But no one turns around and comes back.”
Quoted with permission from Clark, David J. & Hatton, Howard A . A Handbook on the Book of Nahum. (UBS Helps for Translators). New York: UBS, 1989. For this and other handbooks for translators see here .