After California was ceded to the United States in the Treaty of Guadalupe Hidalgo, the Berreyesas filed the claim with the American Public Land Commission in their wives' names in 1852, and the grant was patented to them in 1863.

[4][5] By 1853, José de Jesus and Sisto Berelleza had sold minor parcels of Rancho Las Putas, referred to as Berryessa Ranch by the American settlers,[5] to pay gambling debts.

In 1866, the developers holding the majority of land in the valley divided Rancho Las Putas into smaller parcels to sell to farmers, and platted a town called Monticello.

A four- and six-horse stagecoach ran from the 300 men[6] working at the remote quicksilver mining town of Knoxville south through rocky hills to Monticello, where the horses were changed, then west to Napa.

The large adobe estate house belonging to Sisto Berreyesa was left to ruin, but a second, smaller one, was held by a settler named Abraham Clark.

[2] Residents of Monticello protested, but California Governor Earl Warren and Solano County promoted the dam as necessary for the economic and agricultural growth of the surrounding area.

[8] Dorothea Lange and Pirkle Jones were commissioned to shoot a photographic documentary of the death of the town, and of the displacement of its residents, for Life, but the magazine did not run the piece.