If you were picking a material to make an artificial levee what major characteristic would you look for?

When selecting a material for an artificial levee, the major characteristic to consider is its impermeability to water. This quality helps prevent seepage and erosion, ensuring the levee effectively retains water and protects surrounding areas. Additionally, the material should have high compressive strength to withstand pressure from the soil and water, as well as durability to resist weathering and environmental degradation over time.