CER paragraph

Claim: In this stream dataset, dissolved oxygen is lowest on the warmest days.\nEvidence: My graph shows dissolved oxygen held between 8.5 and 9.2 milligrams per liter on days when the water was 12 to 16 degrees Celsius, then dropped to 5.1 milligrams per liter on the day the water reached 26 degrees Celsius.\nReasoning: The warmest-day oxygen reading is about 40 percent lower than the cool-day readings, so the data supports the claim that oxygen falls as this stream warms up.\nCorrelation or causation: This is correlation. The graph shows warm water and low oxygen appearing together, but the numbers alone do not prove the warmth caused the drop.\nAlternative explanation: The warmest day was also the day after a heavy rain that washed fertilizer into the stream, and that runoff can feed bacteria that use up oxygen. Until I rule out the runoff, I can only claim that temperature and low oxygen are correlated, not that heat caused it.