After a Series of Heavy Rains, the Nurse in the Local

After a series of heavy rains, the nurse in the local health department increases the water monitoring of the local beach because several upstream creeks flow into it. Why did the nurse increase the water monitoring?

A) Monitor the water purity of the creek flow.
B) Make sure that no debris is swept into the water.
C) Make sure that tidal currents are safe for swimming.
D) Monitor the water for potential microorganisms that could prevent safe swimming.