"Board agreed to increase the flow rate over the Moses-Saunders Power Dam near Cornwall, Ont. – from 10,200 to 10,400 cubic metres a second. That’s the equivalent of four Olympic-sized swimming pools draining into the river every second."
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Increase from 3.92 to 4.00 Olympic pools per second.
Or  - 2% increase.
How concise and less dramatic when Math is used.