A group of genízaro colonists from Abiquiú, New Mexico, arrived in the area in the early 1840s. Don Juan Bandini donated a portion of Rancho Jurupa to them on the condition that they would assist in protecting his livestock from Indian raids. Lorenzo Trujillo led ten of the colonist families to 2,000 acres on the "Bandini Donation" on the southeast bank of the Santa Ana River and formed the village of La Placita while others went to the northwest bank of the river and created the town of Agua Mansa. Farms, orchards, and vineyards were planted and developed after an extensive irrigation system was incorporated. Livestock were tended on the mesa pasture area to the southeast in what is now Riverside. Formal establishment of the area as a political unit occurred in 1852 when the Board of Supervisors of Los Angeles County established a town called "San Salvador" encompassing Jurupa, Agua Mansa, and other adjacent settlements; Lorenzo Trujillo's house was established as the official location for elections. The region now resides in Riverside and San Bernardino Counties. After the Great Flood of 1862 and a second flood in 1886, most residents moved to other locations including what is now south Colton.