If you pull the school up on a maps app, you will see Winfield Creek running down from the north just behind the east end zone. It then takes an abrupt right hand turn and runs the entire length of the visitors side very close to the track. I'm guessing the creek was rerouted back in the sixties to make room for the field, which was no big deal at the time as most all of the land north of the school was farm fields.. Now its concrete and the creek becomes a river during heavy rains. Rivers do not like hard right angles. Thus, it overflows onto the field. Also, if you switch to satellite view, you will see to large swampy backwaters behind the creek, indicating lowland conditions.