Greetings family, friends and history buffs!  Today's brief local history chronicle is about Mission Valley's direct connections with Yosemite National Park. Who would have guessed?

Perched on the steep hillside near Mission San Jose and overlooking the South Bay is the “Irvington Portal”, the end of a 3-1/2 mile section of the pipeline that has transported water 167 miles from the Sierra Nevada Mountains to the Bay Area since the 1930’s and connects Mission Valley with Yosemite National Park and Crystal Springs Reservoir on the San Francisco Peninsula.

The battle for local water resources has been raging since the early 1900’s when the pioneer farmers and nurserymen of our region began fighting the diversion of the abundant water resources of the Niles Aquifer, Alameda Creek and Alvarado’s artesian wells by the politically powerful cities of San Francisco and Oakland. In order to secure a permanent water source beyond Washington Township, San Francisco began a decades long effort, battles with the Sierra Club and an act of congress to secure the water rights of the Tuolumne River in Yosemite National Parks pristine Hetch Hetchy Valley. 

The project required the scouring of all vegetation from the mile long and two thirds of a mile wide valley, excavating the dam site down to bedrock, building several construction material plants and a temporary 68 mile long railroad, and the construction of California’s largest cement dam at the time. In order to get the precious drinking water from the 7 mile long reservoir behind O’ Shaughnessy Dam to millions of thirsty Bay Area residents a series of pipelines, tunnels and bridges were required to cross the Central Valley, pass under the coast ranges and over the southern end of San Francisco Bay to reach the San Francisco Peninsula. 

The tunnel between Sunol Valley and Irvington passes near the Calaveras and over the Hayward earthquake faults was enlarged and seismic upgraded in 2014. The Irvington Portal is visible above Mission Blvd. and the pipeline and valve control buildings are evident on Driscoll Road and on Paseo Padre near Central Park. Hetch Hetchy electricity generated in the Sierra foothills at the Moccasin power plant crosses over the foothills parallel to the pipeline through Mission San Jose and passes along Auto Mall Parkway to the distribution yard near Pacific Commons. Mission Valley and Yosemite are truly connected!

A complete history is available in Hetch Hetchy and It’s Dam Railroad by Ted Worm. Howell North Books 1973