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Harnessing the Mountain Waters of San Diego, County -- Creating What Was Then California's Second Largest Artificial Lake 

Colossal topographical map of Warner's Ranch, San Diego County, California, prepared in 1916, prepared in connection with the project to dam the San Luis Rey River and create Lake Henshaw.

While the scale of the map is impressive, its purpose is well-hidden at the lower left, where the words "Warner Dam" appears at the narrowing of the valley, where the San Luis Rey River begins a northwesterly course through the mountains toward the Pacific Ocean.

The map was prepared by Volcan Water & Land Company, as part of an attempt by William Griffith Henshaw and Colonel Edward Fletcher to impound the waters flowing through the ranch into the San Luis Rey River, a plan that was first hatched by Henry Huntington.  At the time of the map's creation, the project to build a dam to create Lake Henshaw and harness a reliable water source to develop coastal the lands of North San Diego, which had begun in 1911 had stalled during World War I (1914-1918).

The present map was prepared during the period shortly after Henshaw and Fletcher had contracted with John Eastwood to design what would become the Lake Henshaw dam in 1914. Eastwood, had come to prominence as an engineer for his work designing flumes and irrigation works in the Sierra Nevada mountains in the 1870s, followed by important hydroelectricity projects in the San Joaquin Valley in the 1890s and by the early 20th Century was designing a number of California's largest dams, including the 92 foot high Big Bear Valley Dam.  Between 1917 and 1918, Fletcher and Eastwood would successfully build 4 major dams in San Diego County, although the Lake Henshaw dam project would be delayed until the 1920s.

The present map illustrates Warner Ranch and the area which would become Lake Henshaw and environs, shortly before construction on the dam would recommence, and is likely one of the last surviving large scale maps to provide a topographical overview of the region before the recommencement of construction.  Moreover, it is almost certain that this map was prepared specifically for the purpose of studying the project and promoting it to prospective investors and in connection with the approval processes required to construct the dam.

The present map was made 7 years before the Henshaw Dam was finally completed in 1923. Unsurprisingly, the hydrography of the area has changed considerably since the map was made in 1916; Big Lake, Lost Lake, and Chimney Lake are no longer regularly visible, with Swan Lake being the only remaining consistent body of water that is depicted on the map.  

Warner Ranch, Lake Henshaw and Water Development in San Diego County 

The history of Warner's Ranch dates the the 1830.  In 1830 an American-born citizen called John Trumbull Warner left Connecticut and headed to California, passing through this valley. He worked as a fur trader and merchant in Los Angeles.  By 1844, he had become a naturalized Mexican citizen and changed his name to Juan Jose Warner. He received the Rancho San Jose del Valle Mexican land grant. Warner established a successful cattle ranch there in the San Jose Valley.

On December 2, 1846, Stephen Watts Kearney, with a small command from New Mexico, reached the ranch on what proved to be his way to the Battle of San Pasqual. He was later followed by the Mormon Battalion, that was establishing the route of Cooke's Wagon Road from New Mexico to California

Warner's Ranch was a stop on the San Antonio-San Diego Mail Line in 1857 and the Butterfield Overland Mail stagecoach line between 1858 and 1860. It was linked to San Diego by the San Diego - Fort Yuma mail route via the road through Santa Isabel to San Diego. Travelers rested here along their journey, after the trip through the desert.

During the American Civil War, Union troops established Camp Wright on the grounds of Warner's Ranch on October 18, 1861. The installation was designed to protect California from attack along the route of the emigrant travel route between Arizona and California, although high winds forced relocation of the camp within less than a year.

The ranch passed through several hands until in 1880, John G. Downey, former governor of California, became sole owner of Warner's Ranch. He started legal efforts in 1892 to evict the Cupeño Indians. They challenged his actions under provisions of Mexican and United States law, but lost their case in the U.S. Supreme Court in 1901. The court ruled they were correct in their assessment of rights to the land, but had waited too long to press their claim.  The case was followed closely by many citizens who had sympathy for the Cupeño. They tried to purchase their own land but were unable to raise sufficient funds. The local tribe was relocated to Pala Indian Reservation on May 12, 1903. 

Warner Ranch would become of interest to California developers when Henry Huntington purchased the land hoping to harness the waters of the San Luis Rey River. In 1901, Colonel Ed Fletcher (1872-1955) — who was interested in water, roads and development — became an agent for Huntington and represented his interests in the San Luis Rey water project.

As note by Donald Jackson:

In 1911, (Ed) Fletcher became associated with William G. Henshaw, a San Francisco-based businessman who owned the Riverside Cement Company and who had recently purchased the Warner Ranch at the headwaters of the San Luis Rey River. Development of the Lake Henshaw project (as it later came to be known) had begun in 1905, when Fletcher served as an agent for Henry Huntington's South Coast Land Company.

When Huntington abandoned his own plans for this scheme, Fletcher arranged for Henshaw to buy Warner Ranch; in turn, Fletcher assumed management of the newly formed Volcan Land and Water Company to develop water rights along the San Luis Rey River that were tied to the ranch. The Lake Henshaw project proved more complicated than originally envisaged and remained incomplete for more than a decade. In 1914, however, Fletcher and Henshaw approached John S. Eastwood for a dam design. This initiative foundered, but it was soon followed by plans for another multiple arch dam along the nearby San Dieguito River."

In 1900 a U.S. Supreme Court ruling had authorized "the eviction of the Cupa people from their ancestral homeland at Warner Springs, leading to a forced removal two years later. May 27, 1902 Congress appropriates $100,000 to purchase land in Southern California for Mission Indians and to relocate them to the new land holdings. In 1903, the Cupenos are forcibly transported to the Pala reservation by Indian agents in a three-day "Trail of Tears" and settled among the distinctly different Luiseno people with whom they eventually become integrated." (San Diego University website: Chronology of the Indigenous Peoples of San Diego County). 

In 1911, William G. Henshaw purchased the Warner Ranch from the heirs of John G. Downey. Henshaw and his partner, Colonel Ed Fletcher, set plans in motion to construct a dam at the headwaters of the San Luis Rey River. The dam would create California’s second largest artificial lake to date. A tunnel and the head gates were constructed within a few years, but then the dam project halted at the start of World War I.

The project stalled until the early 1920s, when construction recommenced and the dam was completed.

Yale University has the Clifton Ewing Hickok papers, which document the Volcan Land & Water Company's attempts to sell land and water to the city of San Diego. William S. Post, the creator of this map, was a business partner of Hickok. OCLC shows material prepared by the company between 1910 and 1919, giving a sense of the extent of their operations.

San Diego History gives the following account of Ed Fletcher's importance for San Diego water development:

Ed Fletcher was instrumental in developing the majority of San Diego County’s water systems, including the Cuyamaca Water System on the San Diego River (supplying the La Mesa Irrigation District and City of San Diego), the Volcan Water System (including Lake Henshaw Dam), the San Dieguito Water System, and the Lake Hodges and San Dieguito Dams (supplying San Dieguito and Santa Fe Irrigation District plus part of the City of San Diego).


The map is unrecorded, but OCLC locates a smaller map related through its connection with the Volcan Land & Water Company, entitled, "Map of San Luis Rey Valley in vicinity of Foss Lake and San Luis Rey Mission : showing ground water contours".

Condition Description
Very large folding cyanotype map. Minor wear at some of the folds.
Donald Jackson, Building the Ultimate Dam: John S. Eastwood and the Control of Water in the West.