In 1769, Spanish explorer Captain Gaspar de Portola was in search of Monterey Bay. He found his way to the ocean shore of beautiful San Pedro Valley, which now is a part of the city of Pacifica. San Pedro Valley soon became an important link in the Spanish Mission System, for it offered valuable resources, which could not be produced in San Francisco at Mission Dolores. The valley became a Mission Outpost, which offered good soil, cattle-grazing land, sunshine, and Indians as a work force. Important crops such as wheat, fruits, and vegetables could be grown without problems.

More recently, the Middle Valley was used for grazing on its hillsides and commercial farming in the meadows, with crops of pumpkins and artichokes. The south fork of San Pedro Creek became a trout farm, operated by John Gay, until 1962, when storm rains washed out the entire operation. The south fork is a seasonal water source for the City of Pacifica.