The swamp lake is not only very large but also very deep, although no one knows exactly how deep it is. The local elders say they have lived for decades and have never seen the water of the swamp lake dry up. Even during the great drought thirty or forty years ago, the lake's water did not reach the bottom.
Because the swamp lake is somewhat far from Swamp Prefecture, although the people know the lake's water is good, they are too lazy to go fetch it. Only during droughts do they go to the swamp lake to get water.
The health issues of the people in Swamp Prefecture partially stem from drinking saline water for years. Zhao Yao had been in Swamp Prefecture for a while and hadn't noticed this until a few days ago when he was inspecting the people's farmland and drank their water, realizing it was salty.
