Vehicle traffic of any kind of the levee creates ruts for rain water to cut a path, causing erosion. Persistent rainfall and rivers that have been staying high against the levees since the spring have saturated the levees, making them vulnerable to high water. Animal burrows are a major source of problems. A burrow gives water a direct route into the levee. The high water moves through the saturated levee, softening and weakeneing its foundation.
High water creates a tremendous force against the levee.
A boil is an area on the dry side that begins to slide away from the base. If left unchecked, the levee will collapse as the process continues. In order to slow the erosion process, sandbags are used to hold the boil in place. In extreme cases, the water is pooled with sandbags to equalize the pressure and slow the water down.