There are three outfall canals in New Orleans, Louisiana – the 17th Street, Orleans Avenue and London Avenue canals. These canals are a critical element of New Orleans’ flood control system, serving as drainage conduits for much of the city. There are 13 miles (21 km) of levees and floodwalls that line the sides of the canals. The 17th Street Canal is the largest and most important drainage canal and is capable of conveying more water than the Orleans Avenue and London Avenue Canals combined.