500
Groundwater seeps up from under rocks to the surface and runs into creeks, ponds, rivers and eventually to the ocean. Without groundwater, humans and animals would have to rely on only the rain for our water source, and that's not very predictable. Also, we need to keep the groundwater clean, for if it's contaminated, then that source may no longer be useable.
Explain the relationship between groundwater and human/animals.