Early settlers grazed cattle and sheep, but soon farming became the dominant activity in the valley. In 1968, the Nature Conservancy of California acquired the first parcel, often called the Paine Preserve, of the Semitropic Ridge Preserve-complex. In the following years other parcels were added to the Preserve and, during the summer of 1997, the lands were transferred to the Center for Natural Lands Management. Acquisition of some of the recently added parcels was provided by the California Energy Commission funds and money from different mitigation projects. The valley's climate is typically Mediterranean, with hot, dry summers and cool, moist winters.
Rainfall is scant during normal years, averaging only six inches per year.
The topography of the Preserve consists mostly of flat areas, although areas with numerous gently sloping mounds and intervening depressions are also present. In the winter, the depressions fill with water, forming vernal pools. Patches of non-native grassland are also present in the Preserve. The animals include the San Joaquin kit fox, blunt-nosed leopard lizard, San Joaquin antelope ground squirrel, and Tipton kangaroo rats. Other species of interest include horned lizard, golden eagle, burrowing owl, weasel and coyote.