The terrace of a beach that has formed on the backshore, above the sea level during high tide, is known as Berm. A berm several metres wide may be put down on some beaches each summer, only to be obliterated by heavy storm waves the following winter. This natural protection against erosion is called a "winter berm." Winter berm construction starts in early fall when the high water mark is reached. Material such as sand or gravel is placed on the beach to create a barrier against wave action and further erosion. The size of the berm depends on the severity of the weather conditions and the frequency of high tides. At some locations, it may be necessary to rebuild the berm each year because it is constantly being destroyed. Winter berm maintenance involves replacing any material that was used for its initial construction with fresh material each year. This prevents any permanent changes to the character of the beach caused by the berm. For example, if coarse rock is used for the berm, then it should be replaced with finer material each year so that the berm does not become smooth like a rock terrace. Winter berm construction can be done by anyone who has access to the beach. However, if you are going to use heavy equipment such as a tractor-trailer, then you should get permission from your local government first.