The Challenges in Building Rindge Dam
Design drawing for Rindge Dam by Wayne Loel who was a prominent geologist at that time, working with many petroleum companies in Southern California during the oil boom. (From the California Division of Dam Safety archive.)
In the early part of the 20th century, concrete dam construction became the technological darling of reliable water storage, particularly in drought prone Southern California. Most large dam projects were built with public funding, but Malibu mogul May Rindge took on the challenge of building her own private dam to support her 13,316-acre cattle ranch. The challenges she faced were both geological and financial.
Although the State of California didn’t require permits for dams back then, Rindge retained a prominent engineering team of noted geologist Wayne Loel and civil engineer A.M. Strong to design and construct Rindge Dam. Loel oversaw the planning and construction of the 100-foot tall, 120-foot wide at top and 60-foot wide at streamline concrete barrier that could store over 500 acre-feet of water on Malibu Creek. Within a month of their permit inquiries to the State Engineer in March 1924, dam construction was underway.
An example bill sent by the state to the Malibu Ranch Company for traveling from Sacramento to inspect the dam during construction. (From the California Division of Dam Safety archive.)
Decades before Malibu Canyon Road broke ground in the early 1950s, Rindge’s ranch hands blazed a two-mile road up the rocky canyon from Malibu, hauling in 30,000 sacks of imported, slow-drying cement to the dam site. To help cut costs, dismantled railroad ties from the Rindge rail line were also hauled up and repurposed into the dam’s framing.
The Division of Dam Safety’s archives include letters between the project leads and State Engineers regarding the dam’s design, placement of rails, concrete materials, etc. Inspectors traveled from Sacramento to the dam site during construction and billed Rindge’s Malibu Ranch Company for expenses. They watched the crews make and pour wet cement into the forms from buckets suspended by two cables spanning the narrow canyon. As there are no construction joints in the dam, a continuous-pour method of new concrete over the previous pour was made within 24 hours. They completed the dam by December 1924.
Rindge Dam in February 1925 before the addition of the spillway. (From the California Division of Dam Safety archive.)
The Santa Monica Mountains are young in geological years. This caused problems after the first heavy storm. Loel didn't anticipate the erosion of the marine sedimentary soil. Severe storms in the years after construction quickly created the potential for failure issues within a decade. In addition, before Rindge Dam was completely finished, May Rindge had started to run out of money from years of lawsuits over a coastal highway easement through her property. She eventually lost this lawsuit.
The State of California, becoming concerned with dam safety, required an adequate spillway for Rindge Dam. As the dam began to fill, leakage was noted at the left abutment. Loel responded to the state with an alternative plan on cutting a notch through the bedrock for the spillway feature citing his client’s lawsuit costs. The state insisted on their spillway requirements and ultimately Rindge agreed to perform the work. Later inspections proved the spillway was still insufficient and required concrete reinforcement.
This drawing was submitted by Wayne Loel in 1928 to the state's Division of Dam Safety after years of not responding to their request for the official dam blueprints. (From the California Division of Dam Safety archive.)
Correspondence starting in 1925 in the State’s Division of Engineering archive indicates ongoing requests of Loel to submit the dam’s final plans. Additional letters indicated that H. Hawgood had taken over as the project engineer for the spillway construction with flow control gates at the top. He wrote that he was reluctant to ask Loel for the drawings to assist in the construction. In June 1928, Loel finally responded with only a sketch “from memory” in a letter notifying the State he was in a lawsuit with Rindge’s Malibu Ranch Company for final payment.
During the winter storms of 1925/26, additional improvements to the spillway design were needed. Although a final state inspection of the dam was performed in September 1926, the following May during a heavy storm, the spillway gates didn’t work automatically as intended. An on-site dam keeper was hired to ensure the gates operated when needed. Rindge Dam continued to need repairs and have work done on the dam, spillway and reservoir.
A photo taken in 1930 of the caretaker's house to operate the spillway gates when needed.
Many of the local dams built in that era had failure issues and topping the list was aqueduct engineer William Mulholland's St. Francis Dam catastrophe of 1928. Located ten miles north of Santa Clarita, the dam’s sudden and unexpected collapse killed over 430 people downstream and is considered the worst American civil engineering disaster of that century.
Since the last century, we've gained a better understanding of how development can harm our natural resources and ecosystems. River restoration in Southern California is an important step toward correcting past mistakes that have endangered both public safety and wildlife. While we can remove dams, we cannot reverse the permanent loss of such species as the endangered Southern steelhead.