Arroyo Mocho means "cutoff creek". Erwin G. Gudde's California Place Names says it got the name because it historically had no outlet but dissipated into the ground after spreading out into many smaller streams between Livermore and Pleasanton. As early as 1852 it was also called Mocho Creek. Frank Latta, in his book on Joaquin Murrieta, says it got its name from the nickname of the man who ran the Murrietta gang's water stations and holding corrals in this area along La Vereda del Monte, the route of their drives of captured mustangs and stolen horses to the south. These stations were on the arroyo near Mud Springs and at Valle de Mocho, what is now known as Blackbird Valley, near the source of the arroyo, just south of Mount Mocho, which was also named for this man, known as "Mocho" (meaning lopped off or short) for his diminutive stature.Frank F. Latta, JOAQUIN MURRIETA AND HIS HORSE GANGS, Bear State Books, Santa Cruz, California. 1980.
