Answer;
Agriculture
Agriculture is the major source of both nitrogen and phosphorus entering most estuaries, such as chesapeake bay.
Step-by-step explanation;
The largest source of pollution to the Bay comes from agricultural runoff, which contributes roughly 40 percent of the nitrogen and 50 percent of the phosphorus entering the Chesapeake Bay.
-Agricultural practices including over-irrigating farmland, over-tilling soil and over-applying fertilizers and pesticides, can push pollution into the Bay and its local waterways. Agriculture is the single largest source of nutrient and sediment pollution entering the Chesapeake Bay. The fastest growing source of nitrogen pollution to the Bay is polluted runoff.