There is definitely a nice watershed area the spillway could feed into;
Not water leaving the pond via the spillway.
By watershed I meant where does the fill water come from to fill the pond? Does water drain off sloping land to fill the pond after rains?. Some northern dug ponds have no basic watershed and stay full from rainfall and building roof drains. Some ponds receive water from ground water seeping into the pond. Some ponds are spring fed where streams enter the pond.
