Definition - What does Natural Levee mean?
Natural levees are embankments formed naturally after a river floods and recedes. Friction with the floodplain during a flood causes a decrease in the velocity of the river leading to deposit of the material that the flood water is carrying. Pipelines can be installed thorough such natural formations without disturbing them by using trenchless construction methods like horizontal directional drilling (HDD) that don't disturb the embankments, slopes or vegetation surrounding the levee in any manner.
Trenchlesspedia explains Natural Levee
Natural levees are deposits containing mud, sand and stones and are formed to slope away from either side of the river or flood plain. Raised mounds are formed near the river bank where the larger material is deposited and the gently sloping sides are a result of the smaller particles deposited away from the river bank. Levees form an important part of the United States infrastructure. Breaching of a levee can cause economic and personal losses. It's estimated that every county has at least one levee with about 43 percent population living there, so it's essential that these levees are maintained and undisturbed.