As cool as it may sound, probably not.
First of all, I'm not sure where so much gallium would come from.
Secondly, there can't be a "gallium cycle" in the way that there is a water cycle, because gallium boils at 2400 C (despite its low melting point of 30 C). If you don't have a gallium cycle, what replenishes the gallium in the lake? It will seep away, get carried away by weather, leaks, animals, plants... It could be on some impermeable layer of granite in the middle of a barren wasteland as @Tigt suggests. It could remain fairly intact if underground.
There are gallium alloys with different melting/boiling points. Galinstan, an alloy of gallium, indium, and tin, melts at -19 C and boils at over 1300 C.
There are also similar substances - an alloy of sodium and potassium is liquid between -12.6 C and 785 C, but will react violently with many things.
Caesium melts at 28.5 C and boils at 671 C, but is extremely reactive.
If you want lakes of any liquid metal, your best bet is mercury, which melts at -39 C and boils at 357 C, enough to give off (very toxic) vapours at room temperature. This is quite close to water's 100 C, so I can imagine the water cycle being replaced by a mercury cycle on a not-so-Earthlike planet.