Especially in the context of this sentence:
To my understanding, this sentence translates as "This lake was approximately twenty square kilometers in size, and resembled an inverted gourd, divided into an upper and lower lake." But I've seen a translation which said "This enormous lake had a radius of approximately twenty kilometers," which I don't particularly get. キロ四方 means 'square kilometer', right? Is "radius of 20 kilometers" a mistranslation?