Rain and snowmelt flow down 63 tributaries into Lake Tahoe, but just one river runs out of the alpine lake — the Truckee River. But many visitors to the famed lake may not realize that 400 feet downstream sits the Tahoe Dam, a 110-year old concrete structure in Tahoe City controlling the top six feet of water stored in Big Blue. 

Spanning roughly 192 square miles across California and Nevada and with a maximum depth of 1,645 feet, Lake Tahoe’s massive size makes it an important water source for the region. The water flowing through the Truckee River is vital for the communities downstream, provides invaluable habitat for wildlife and fish, and irrigates thousands of acres of cropland in western Nevada. 

But how the water was going to be used wasn’t always so clear. The first dam on the Truckee River was reportedly constructed in the early 1870s, according to the California Department of Water Resources. At the time, an increase in the river’s flow was needed to help transport logs for construction of the transcontinental railroad and burgeoning mining industry. Though a San Francisco engineer bought the land surrounding the river outlet and attempted to get approval to construct an aqueduct for transporting Tahoe’s water back to his home city, the plans were eventually nixed. 

Ultimately, California awarded the rights to the dam to the Donner Lumber and Boom Company, owned by influential executives of the Central Pacific Railroad. Later on, the Truckee River General Electric Company became owners of the dam, and hydroelectric power plants dotted the riverbank supporting other manufacturers in the region. 

In 1902, Congress passed the Newlands Reclamation Act, creating what is now the United States Bureau of Reclamation (USBR). The goal was to increase agricultural irrigation out west thanks in large part to advocacy by Nevada House of Representatives member Francis G. Newlands. The first project created by the act focused on the Truckee River. In 1905, construction of the Derby Dam was completed 20 miles east of Reno, ultimately diverting water into the Carson River watershed for agricultural irrigation. 

In 1909, the Newland Project began negotiations upstream to obtain the rights to the Tahoe Dam from the Truckee River General Electric Company. Though an agreement wasn’t reached until 1915, during that time both the USBR and the electric company contributed funds to replace the original dam with an 18-foot-tall concrete slab and buttress structure. In 1981, the dam was placed on the National Register of Historic Places. 

In 1987, the dam underwent some structural upgrades to improve its earthquake resistance. Today, that same dam controls outflows by a gated spillway with 17 bays. A federal watermaster dictates the flows out of the Tahoe Dam to ensure that the proper volume of water — measured in cubic feet per second (CFS) — is running to meet minimum requirements for downstream users. 

The Tahoe Dam controls the top 6.1 feet of Lake Tahoe’s water, so when the water goes below the lake’s natural rim — which sits at an elevation of 6,223 feet — water doesn’t reach the dam. However, there is water in the Truckee River further downstream due to groundwater underflow and seepage. While the amount of water released each year from the dam is usually anywhere from a foot to a foot and a half, it’s not the largest contributor to water loss. In fact, Tahoe loses roughly 39 inches of water every year from evaporation. 

To experience the Tahoe Dam firsthand, walk along the Fanny Bridge in Tahoe City, which is aptly named for the number of rears on display as people peer over to look at the dam. Afterwaters, head to the Gatekeeper’s Museum State Park — the dam gatekeeper used to live on-site — to see the reconstructed log cabin and exhibits on natural history, Indigenous basket weaving, and Tahoe maritime artifacts, to name a few.

Editor’s note: This article originally appeared in the Winter 2023 edition of Tahoe Magazine.