Wikipedia
A borrow ditch, is a roadside channel dug for drainage purposes. Typically, the dirt is "borrowed" from the ditch, and used to crown the road. It is a variation of a Bar (borrow) Pit, in construction, when dirt is removed and used for construction purposes, and later left to fill with water, forming ponds or lakes. Also, adjacent to pasturage, confines cattle keeping livestock from straying onto road [cattle country, western USA][Possibly archaic] The term is most often used in the Southwestern United States.
Usage examples of "bar ditch".
Leonard made the right and Rex made it with them after taking a dip in a water-filled bar ditch.
They walked them along the bar ditch to the gate and led them through the gate and closed it.
A neighbor's complaint to the city resulted in my constructing a bar ditch to deal with a problem this had caused him.
The bar ditch created no problems that anyone has complained of, though it has benefited the growth of some plants by depriving others.