Rain, rain, don’t go away...come back again as snow some day (soon!)
- Bill Moorhead
- 1 day ago
- 4 min read
Can California stay water-resilient without a healthy snow pack?
Southern California hasn't depended solely on local rainfall and snow for its water needs for quite some time now. In the early 1900s, Los Angeles began sourcing water from the Eastern Sierras by building the Los Angeles Aqueduct to transport water from the north to Southern California. The expansion of the Greater Los Angeles area demonstrated that the aqueduct alone wouldn't suffice for a long-term water supply, leading to the formation of the Metropolitan Water District of Southern California (MWD) in 1922 to seek additional water sources to meet increasing demands.
A feat of engineering...and foresight
MWD initially turned to the Colorado River, and the Colorado River Aqueduct emerged as one of the major public works initiatives of the Great Depression era. Completed by 1941, the 242-mile network of open canals, tunnels, and siphons delivered Southern California its first supply of fresh water from the Colorado River.
The ”Great Water Heist“
Well, you know us Southern Californians...we can never get enough of a good thing. So we wanted—and needed—more. Thus the State Water Project was built by the Metropolitan Water District and others, and started "delivering" (er...stealing? did I say that?) water in 1972 from our neighbors in Northern California.
One for all and all for one
OK, let’s back up: “Stealing” was meant as a joke that plays into the shameful politics that tries to tell us that Northern California and Southern California are two different states. We are all in this together, so let’s hold hands and come to the realization we all need each other in California. And, when it comes to “The West,” our common needs extend well beyond California to just about every state west of the mighty Mississippi.
Ok, sorry about that, let’s get back to the issue here.
You can't have one without the other
You can see where this is headed. Population and economic growth in California—and especially in Southern California—has grown exponentially, due in part to the fact that there were reliable sources of water to nourish this growth. To our credit, we realized our water resources had to sustain growth over the long-term, and we invested in water use efficiency measures like water recycling and water management infrastructure, most intensively since about 1990.
Didn't see that coming!
Previous projections for MWD water usage indicated an increase to over 3 million acre-feet annually, with total water demands in Southern California reaching approximately 5 million acre-feet.
An acre foot of water is an acre of water 1-foot deep, which supplies roughly three families of three water for a year (the OLD statistic was 1 acre-foot per family per year). Remember that—as we deal in acre-feet of water all the time in the “water business.”
Today the total demands in Southern California are hovering around 3 million acre-feet annually, with a demand for MWD water of about 1.2 million acre-feet of water—substantially less than the OLD projections. So if you've been diligent about your water use, pat yourself on the back! It's people like you who have contributed to the water success story in Southern California!
Snow wonder!
Herein lies the kicker. Statewide, the mountain snowpack acts as a natural "frozen reservoir," capturing winter precipitation and releasing it slowly during the dry spring and summer months. Local mountains in Southern California (like the San Gabriel or San Bernardino ranges) help to fill groundwater basins in Southern California, which produce about 1.2 million acre-feet of water (about 35% of the water demand in Southern California). Southern California meets its remaining demands through a combination of recycling and importing water from external snowmelt-driven systems—primarily the State Water Project (SWP) from Northern California and the Colorado River (whose basin is also fed by mountain snowpack).
In summary (I'll call this the punchline you've been waiting for): About 50% of Southern California's overall water needs are provided by imported water. This is the general statistic MWD uses. It varies considerably from year to year. But, because of climate change, the warmer weather will result in less snow in the mountains and more precipitation as rain compared to snow. This will mean higher volumes of runoff and more difficulty in capturing the water (compared to snow remaining as snow and melting slowly in the spring).
Did someone say "infrastructure"?
What does all this mean? Basically, more storage systems will have to be built to capture the water coming fast and furious so it doesn't all run away to the ocean—a problem that was more manageable when the snowmelt happened more gradually. And—guess what? The need for more storage will result in higher water costs for the long run.
So, there you go. The history and future of water in Southern California is a fascinating one. To read more, go to the Metropolitan Water District's website.
Please send me any questions you may have. If I don't know the answers, I can use my network of connections created through 50 years in the "water business" to get the right information for you.
William ”Bill” Moorhead, P.E.
Director, Moulton Niguel Water District
CANDIDATE FOR RE-ELECTION
On Nov. 3 I would appreciate your vote
References:
4. Discussions with MWD director Karl Seckel, P.E.
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