The Engine 311/Ladder 158 firehouse stands at the northeast corner of Springfield Park (map), a lovely green space with a stream running through it and a pond in the middle. This building brings to mind the nearby Engine 314 firehouse located at the northeast corner of Brookville Park, another streamy/pondy park (map). In fact, the locations of the firehouses relative to their respective parks are so similar that I initially thought I was looking at the same firehouse we saw earlier, even though I remembered there was a different mural painted on the door.
I can't find anything to confirm this, but I'd guess the proximity of these firehouses to the parks is not a coincidence. Until fairly recently, southeastern Queens relied on local wells for its water supply, so perhaps it seemed like a wise idea back in the 1920s (when this firehouse was put up) to build firehouses near bodies of surface water that could be used as backup, or maybe even primary, sources of water for the fire engine tanks. (At that time, I believe these ponds were still being used to feed the Ridgewood Reservoir, which supplied water to Brooklyn until 1959.) A third similar park in the area, Baisley Pond Park, does not appear to have a firehouse located particularly close to it, however, so maybe I'm just full of crap.
And I suppose it's also possible that the firehouses were built on city land simply as a cost-saving measure, with the nearby water playing no role in the decision.