re: is it true that the river will wash away sediment when it....

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so for the month or so that the water has been covering the levee that dirt is getting very saturated. So when the water begins to recede the force of the receding water could break off small parts of the levee

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Pretty close. Two things happen. The weight of saturated soil is a lot heavier than dry soil. If the river recedes too quickly the soil will slide because there is no more pressure from the river to hold it in place. The corps will use the same things it did to drop the water levels in reverse to keep the levels high and try and force a slow decrease in water levels. The other thing is as the river rose with those high volumes it may have scoured the bottom of the levee and again when pressure is removed the soil could slide off the side.