In 1869, gold was discovered near Julian attracting hordes of miners from the Mother Lode and swelling the town to a population greater than that of San Diego. Also, during this period, zinc, lead, and silver mines were booming in the western canyons of the Santa Anas (hence, Silverado Canyon). Nearby, in Trabuco Canyon, stands the remains of the large (and unproductive) tin mine, once owned (about 1900) by Gail Borden of the Eagle Milk Co. He had hoped to use its yield to produce cans for his milk.

The influx of miners left its mark on the land. Trees were cut for mine timbers, heat and cooking fuel. Great expanses of brush were burned so miners could penetrate new areas to search for minerals.

As the mines petered out, so did many of the early ranches which had been overgrazed and had lost their chief labor force as the Indian population died off due to hardship and disease.

The principal end results was steadily growing threats to the watersheds, which by now were of critical importance to southern California communities.

Early reports from the 1870's - 1880's refer to fires that burned uncontrolled for weeks at a time. Lack of protection from fire was causing serious damage to irrigation works, the water supplies of rural areas, the small metropolitan area of San Diego, and other coastal towns of the late 1800's. The need for a forest reserve was evident to the first California Forestry Commission, appointed by Governor Stone in 1886. The commission recorded in its findings the necessity for special protection of the watershed cover to prevent the occurrence of major fires and subsequent erosion which were injuring the climate, agriculture and future prospects of southern California.

The widespread support for better resource management found a few opposing voices. Among these were timber and ranching interests who viewed the movement as leading to greater restriction on their activities.

Regardless, the Forest Reserve Act was passed in 1891. Although the Act was meant to slow wasteful and illegal timber cutting, the problem was different in southern California. It was to protect their watersheds that Californians immediately began demanding Forest Reserves.

Cleveland National Forest became one of the first in the new system and had its basis in the 50,000 acre Trabuco Canon Forest Reserve (in the Santa Ana Mountains), created by President Harrison in February 1893. In February 1897 President Cleveland created San Jacinto Forest Reserve, a 700,000 acre area which included the desert lands southeast of Palomar Mountain. In 1899, the Trabuco Reserve was more than doubled, in response to a petition sent to the General Land Office by residents near Trabuco Canyon.

These early Forest Reserves had been administered by the General Land Office (GLO) in the U.S. Department of Interior. However, the GLO lacked any trained foresters to aggressively take charge. As a result in 1905 the reserves were transferred to a new Bureau of Forestry (now the Forest Service) in the U.S. Department of Agriculture. In 1907 their designation as Forest Reserves was changed to National Forests.

In 1907 President Roosevelt made extensive additions to both the Trabuco Canyon and San Jacinto Forest Reserves, to include Palomar and Laguna Mountains and those farther south to the Mexican Border. A year later (1908) President Roosevelt combined the two Reserves to form the new 1,904,826 acre Cleveland National Forest.

During the next seventeen years there were several deletions to the Cleveland. A major one in 1915 when 749,730 acres of non-forest value lands were returned to public entry, and another in 1925 when the San Jacinto unit was transferred to the San Bernardino National Forest. Today the Cleveland National Forest consists of approximately 424,000 acres of forest land.