Many years ago the Eurondans constructed bunkers beneath the surface, pumping toxic gases into the planet's atmosphere in the hopes of exterminating the Breeder population. Once this was done, they would retake their planet. The Breeders retaliated, and for some time gained an upper hand over their enemy.
Breeders command the largest body of water on Euronda, where the Eurondans, and perhaps the Breeders themselves, extract deuterium (heavy water) from the sea to power their automated ships and defenses.
The Other Side - After learning the truth about the Eurondans, SG-1 destroys the bunker from the inside in the hopes of giving Breeders the upper hand, then returns to Earth through the Stargate.