2,499. Not Slaughtering Over Water, et al.
Hilchos Shechita 2:4
Let’s say that someone says that a (pregnant) animal is set aside for a peace offering but that its fetus is secular. If it’s slaughtered in the Temple courtyard, one may eat the offspring because it’s prohibited to slaughter that animal outside the courtyard.
Hilchos Shechita 2:5
One may not slaughter into rivers or seas out of concern that others might think he’s offering a sacrifice to the water. One may likewise not slaughter into a vessel of water out of concern that others might think he’s offering a sacrifice to the image that appears in the water. Similarly, one may not slaughter into utensils or a pit because this is the practice of idolators. If one does slaughter in such fashion, the slaughter is valid.