To find the rate at which the river is rising, we need to calculate the rise in water level per day.
The rise in water level over 10 days is 62 - 22 = 40 feet.
The rise in water level over 3 days is 34 - 22 = 12 feet.
So, the rise in water level over 7 days (10-3) is 40 - 12 = 28 feet.
Therefore, the rise in water level per day is 28 feet / 7 days = 4 feet/day.
Therefore, the river is rising at a rate of 4 feet per day.