Question

Why do excess nitrates and phosphates from fertilizers often end up as runoff in natural bodies of water and groundwater? Why is this problematic?

Answer 1

Excess nitrogen can harm water bodies. Excess nitrogen can cause over-stimulation of growth of aquatic plants and algae. Excessive growth of these organisms, in turn, can clog water intakes, use up dissolved oxygen as they decompose, and block light to deeper waters.  They also can cause 1 plant to overgrow choking out other types of plants.