Question

one problem that arises with monitoring freshwater supplies is that it can take years to detect pollution in underground water. there is no federal regulation of groundwater. the world is mostly covered with water. most freshwater supplies are found on the surface of earth.

Explanation:

Underground water pollution is hard to detect promptly due to its hidden nature and slow - moving characteristics in the aquifer system. This makes monitoring freshwater supplies difficult. Other options are not directly related to the problem of monitoring freshwater supplies.

Answer:

It can take years to detect pollution in underground water.