What kind of dirt should be used to fill in a pond?

When filling in a pond, it's best to use clean, compactable fill dirt, such as clay or sandy soil, as these materials help prevent water from seeping through and promote stability. Avoid using organic materials or topsoil, as they can decompose over time and lead to settling or future erosion. Additionally, layering the fill and compacting it thoroughly will help maintain the integrity of the filled area. Always check local regulations and guidelines before proceeding with such projects.