From the Guidebook:
Don Juan Bandini, owner of
the Jurupa Rancho, donated parts of his rancho to a group
of New Mexican colonists in 1845 on the understanding
that they would aid in repelling Indian raids on his stock.
The community was named Agua Mansa-Gentle Water-and was
prosperous until 1862, when a great flood suddenly swept
down the Santa Ana, carrying away the village of adobe
buildings and covering the fields with sand and gravel.
The village was rebuilt on higher ground, but never regained
its former prosperity.