 The Mono Debris Dam, an Ambursen-type structure, was built in 1936 and had completely filled with 1 million yd3 (770,000 m3) of sediment by 1938.The concrete-arch Agua Caliente Debris Dam was completed in late 1937 and by 1941 had filled with 750,000 yd3 (570,000 m3) of sediment.Despite the scale of these conservation projects, they only extended Gibraltar's useful life by a few years.