What killed the fish

Results:

Scenario 1:
In May, June, July of every year there is an increase in the amount of rainfall. However, this year in August there was a sudden change in the amount of water that appeared. There was much higher water flow due to the abnormal amounts of rainfall. The fish died in scenario 1 because of the excess in pesticides. The reason this is weird is because there was no un usual amount of rainfall, water flow, or dissolved oxygen in the month of August. The pesticides were present in September and it too a week to kill the fish in August. This is because it took a week for the dangerous amount of pesticides to flow into the water.

Scenario 2:
In May, June, and July there is still excessive amounts of rainfall appearing in these months. Because of these huge amounts of water, this caused much of the nitrate to flow into the water.  What killed the fish in scenario 2 was the extreme amount of nitrate. This could have causes the fish kill because nitrate could prevent oxygen from being carried throughout the fish's body causing bubbles to occur in their blood.