pH of the Mississippi River: Slightly Alkaline and Variable

The Mississippi River typically has a pH between 7.5 and 8.5, making it slightly alkaline. However, this value fluctuates along its 2,340‑mile course due to several influences:

• Geology: Limestone bedrock in the upper basin contributes carbonate ions that raise pH.
• Pollution: Industrial discharges and agricultural runoff (fertilizers, pesticides) can alter acidity.
• Seasonal Flow: High water dilutes contaminants; low water concentrates them.

Monitoring programs track these changes to assess ecosystem health and drinking‑water safety for the millions who rely on the river.