[citation needed] In 1861, the family moved again to Carson City, Nevada, where Harriet met her future husband, Charles Lyman Strong.

She was married in Virginia City, Nevada at the age of nineteen, and at thirty-nine was left a widow with four daughters when her husband committed suicide after a series of business failures.

She then devoted her attention to the management and development of this estate, which was known as Ranchito del Fuerte in San Gabriel Valley, California.

In 1897 she drilled a number of artesian wells, and to utilize the water thus obtained purchased 1,000 acres (4.0 km2) of land five miles (8 km) away, installed a pumping plant, and incorporated the property under the name of the Paso de Bartolo Water Company, of which she was president, and her two daughters, respectively, treasurer and secretary, and issued bonds amounting to $110,000 to carry on the enterprise, selling the property four years later at a handsome profit.

In 1918 she appeared before the congressional committee on water power and urged the government to store the floodwaters of the Colorado River by constructing a series of dams by her method in the Grand Canyon, (which in its full capacity is 150 miles (240 km) long), and thus control floods and increase irrigation water, making available thousands of acres of land and unlimited power for generating electricity.

Harriet Strong was a dedicated student of Christian Science and was a founding member of First Church of Christ, Scientist, Whittier, California.