GRAND RAPIDS, Mich. (WOOD) — In the last two weeks — not including Thursday — most of us in West Michigan have all picked up about 2 inches of rain.
That is a lot of water when you think about how much square mileage is involved, and that the 2 inches we’ve seen is about 0.5 inches to 1 inches more than usual for the two-week time span.
To help visualize just how much water that is, I looked up the square mileage for each West Michigan county to see how many gallons of water has fallen.
Here’s the square mileage of each county:
- Oceana: 512.07
- Muskegon: 499.25
- Newaygo: 813.20
- Montcalm: 705.40
- Ionia: 571.30
- Kent: 846.95
- Ottawa: 563.47
- Allegan: 825.23
- Barry: 553.09
- Van Buren: 607.47
- Kalamazoo: 561.66
- Calhoun: 706.23
- Berrien: 567.75
- Cass: 490.06
- St Joseph: 500.59
- Branch: 506.37
That is a total area of 9,830.9 square miles.
According to the U.S. Geological Survey, an inch of rain water over a square mile adds up to 17,380,000 gallons of water. That helps put our 2 inches of rain into perspective. That means roughly 341.6 billion gallons of water has rained on us in just the last two weeks (if we include only the counties listed above).
That’s a whole 85.4 billion to 170.8 billion gallons more than usual, again, just in the last two weeks.
It is not fair to assume all of this water has run straight into Lake Michigan. Multiple factors are at play when determining where rainwater goes. Plants absorb it, the sun or wind evaporate it and many gallons become groundwater.
Lake Michigan is spans an area of 22,394 square miles. That means an inch of water on its surface adds up to about 389.2 billion gallons of water.
Even if all the water that’s fallen over the last two weeks doesn’t go straight to our big lake, it is still a substantial enough amount that it is keeping our lake very high and making it difficult for water levels to drop. It is forecast continue to rise 2 inches, or roughly 778.4 billion gallons, over the next month.