by Paul R. Spitzzeri
In our arid Mediterranean climate, dry winters are quite common, though not as devoid of rain as we’re seeing this winter (even with today’s steady light rain, we look to be setting a record for lower precipitation ever recorded). In heavy rain years, however, flooding has historically been a significant problem.
For example, in 1825, the course of the Los Angeles River changed so that, instead of emptying into the Pacific Ocean where the Ballona Creek now does, the river shifted its bed to roughly the current route. Thirty-six years later, an estimated fifty inches fell in the winter of 1861-62 causing significant flooding through almost all of the basin. The winters of 1883-84, 1913-14 and 1915-16 were among other flood years.
After the latter, county officials stepped up efforts to develop better methods of flood control, including the building of dams. One location of concern was Big Tujunga Canyon and the prevention of flooding in the eastern San Fernando Valley as well as the Tujunga-Sunland area, where development was starting to become more common.
Today’s highlighted artifact from the Homestead’s collection is a map showing the area in the canyon slated for what became Big Tujunga Dam. It’s date of 10 March 1927 happened to follow another heavy rain year with major flooding, including at the Homestead, where water spilling over from San Jose Creek inundated the fields south of the Workman House and La Casa Nueva, which was approaching completion.
The Big Tujunga project was in the early planning stages a few years earlier and the passage of bonds in 1924 by county voters for flood control helped pave (!) the way for the work. The following year, California’s governor William Stephens signed a bill to amend the county flood control act so more funds could be raised by further bond issues. Although a November 1926 bond issue seeking to raise some $35 million for massive projects was defeated, there was enough in existing funds to continue with the Big Tujunga dam and reservoir.
The map was done as the planning process advanced, although there was a change in location from the mouth of the canyon to a spot two miles further up. It shows the plotting of section of federal land within the Angeles National Forest and along Big Tujunga Creek where the dam and reservoir were to be located.
The project was put out to bid and awarded in the last few months of 1929, just as the Great Depression erupted in New York, but with the funds dedicated, work pressed on. Construction began in January 1930 and was completed the following summer at a cost of about $1,000,000.
An unofficial dedication and luncheon was held at the end of May 1931 and a photo in the Los Angeles Times shows about two hundred guests eating on the fifteen-foot wide top of the dam some 240 feet above the creek. While contractor L.E. Dixon ceremonially presented the dam to county flood control chief engineer E.C. Eaton who then transferred it to Chairman Henry W. Wright of the Los Angeles County Board of Supervisors, it was not until mid-July that formal acceptance of the dam was made.
The dam’s reservoir collected natural runoff from a watershed of the San Gabriel Mountains and Angeles National Forest and had a spillway to allow the water out to spreading grounds for recharging water supply.
Yet, the flood risk in the area was not exactly mitigated as hoped. In 1938, another severe winter of floods throughout greater Los Angeles wreaked havoc, including in the area from La Cañada-Flintridge to San Fernando. The U.S. Army Corps of Engineers quickly built Hansen Dam, which opened in 1940, downstream from Big Tujunga, which certainly helped limit the damage of the floods two years prior.
While Hansen now serves as the primary flood control check for the area, Big Tujunga’s purpose has been to allow for both flood control and the recharging of groundwater supplies. After the Sylmar earthquake of 1971, however, the seismic stability of the dam was in question, so the amount of water in its reservoir was limited to a quarter of as-built capacity.
In recent years, though, seismic stregthening was conducted, thickening the face, cleaning up the foundation, replacing the crest, stabilizing the canyon walls and other measures. The 90-year old dam is now retrofitted so that it continue to do its important work for many years to come.