Thursday, July 27, 2017

Water views

When I was visiting family in San Diego last winter, we went for daily walks around this reservoir. I overheard some other walkers discuss why this reservoir was so low, if they had been getting so much rain lately. It took a great deal of effort for me not to run up to them and explain at that time. ;-)

Most of the water in the reservoirs near where people live in coastal California is imported!  They are really just decorative water storage tanks.

You can see more land along the shores of Lake Murray in this photo than you do during dryer times precisely because people in the reservoir's service area need to use less piped-in water during rainy periods.

Moreover, they want to leave some room in the reservoir to catch the runoff from the storms in the local area.  Local rain augments the imported water supply (and not the other way around.)

Remember during the drought and last winter when the newspapers showed this weekly reservoir status map?  You can download it from the CA Data Exchange.  Click on Selected Reservoirs Daily Graphs PDF.

This well-designed graphic shows the relative sizes of reservoirs. The scale breaks down for the smallest reservoirs in the southern end of CA but you get the overall idea.

It doesn't matter if some area gets 200% of normal precipitation if that normal is 3". It's not as significant as another place getting 120% of normal (PON) when their normal is 65".

Check out the wide normal rainfall variation at the California-Nevada River Forecast Center.

It also matters where that rain falls.  Is it over a wide area?  Did it fall in a drainage basin connected to dry areas by our plumbing (rivers and aqueducts)?

The plumbing that brings water from where it falls to where it is used is a complex system of aqueducts, ditches, rivers and pumps.  About 20-25% of the electricity consumed in California is used to move water around.  (Water is heavy.)

Read the in-depth, California's Water Supply, A 700 Mile Journey to learn more about the CA aqueduct. I'll write about the Colorado River later.

Los Angeles is a semi-arid place surrounded by tall mountain ranges and the ocean.  Bringing enough water to it is a challenge.  That is why it had to become a leader in water recycling.  There is really no choice.

The takeaway is that your water travels farther than you think.  It isn't just the total distance, but the number of (vertical) lifts required to get it to you.  Lifting water uphill is energy intensive and we can not cut our carbon footprint without lowering our water footprint.

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