Beginning in 1851, Mormon colonists began emigrating to the San Bernardino Valley. The Mormons bought and subsequently split up Rancho San Bernardino, and greatly improved the area's agricultural production by bringing in thousands of head of livestock and overhauling the local irrigation network. In order to obtain lumber for their settlements, they also began the first large-scale logging operations in the San Bernardino Mountains, starting in the Mill Creek valley. Luis Vignes built the first sawmill in the range sometime between 1851 and 1853. By 1854, six lumber mills were in operation in the mountains, some as high as the crest of the range three-quarters of a mile above San Bernardino, accessed by a twisting road through Waterman Canyon. Some of these mills were driven by waterwheels, although most were steam powered.