Answer:
Billie Jo's father decides to stay because he has a strong sense of loyalty and attachment to the land and the people who live there. He has a deep connection with the pond, which is part of his family’s history, and he also doesn’t want to leave Ma and Franklin behind. Additionally, he is aware of the potential consequences that leaving the pond unprotected could bring, so he decides to stay in order to protect his family and the land from any potential harm.