Water-The Third Rail Part XII

When confronted with a page of water numbers and stats, unless you are an
engineer or math major, the eye takes it all in and goes immediately to the
glaze setting. Especially if there is no graphic break to the numbers up.
This blog has tried to steer away from such a mind-numbing experience, but
sometimes it can be helpful. Stay with us on this one because it will affect
your daily life in a major way.

If you are a resident of San Diego and intend to be around in 2035 and are
eighty years old, you will be one hundred and two. Unlikely you need to read
this. However if you are in your forties and fifties, then in twenty two
years you will be in your sixties and seventies.

So here goes. First some facts:
1991 San Diego’s population was 2.5 million, give or take a few migrants. By
2013 it had jumped to 3.2 million, or an increase of 30,000 a year over the
twenty-two year span. That in round numbers is a net increase of one percent
a year (births, deaths, newcomers, outgoers, etc.)

Currently San Diego needs about 545,000 acre-feet of water a year. Don’t try
to picture how much water that is. It’s a lot. That figure is actually down
from a higher number in 1991 mostly due to the changes in plumbing fixtures
and other devices that have mandated flow rates now. But, the bad news is
that we have reached the bottom of the barrel.

Little thought was given to what happens when there is less water in the sewer systems, and that is currently a big deal.

The City of San Diego is a defendant in many lawsuitsdue to the stinky sewers from low water flow, but we’ll save that story for another time. The point is the odds are slim and none having the population increase and at the same time see our water usage go down in the coming years.

Getting back to 2035 when, we are told, there is some hope on the horizon
that San Diego won’t be as dependent on imported water as it is now, let’s
do some calcs. Stay with me. It makes sense does it not, that if our
population increases at the rate of one percent a year, then our water needs
will go up about the same, especially if we have squeezed the efficiencies
down as tight as we can? That means in 2035, our water needs will be in the
range of almost 700,000 acre-feet a year, which incidentally was what it was
in the early 1990’s.

“Some hope”… what is that hope? For starters there is a plan to make
around 100 million gallons per day of new water by recycling sewage, and
then there is the Carlsbad Desalination plant coming on line now that will
be two decades old in 2035. It will provide fifty million gallons per day.
To compare oranges and apricots, how many acre-feet of water is there in a
million gallons? Three.

The two “new” sources of water will provide 150 mgd (millions of gallons per
day). So 150 mgd times 3 acre-feet per million is 450 acre-feet per day, or
164,250 acre-feet per year. Look a couple of paragraphs back and you will
see our needs in 2035 will be near 700,000 acre-feet per year.

With all of the intended hoopla, we will just about keep up with the population growth,
still dependent on the same amount of imported water as we need this year.
And the poor, old Colorado River that doesn’t even reach its delta any
longer may be called the Big Muddy Creek instead of the Colorado.

If you have read this far, congratulations for hanging there. When officials
want water quantities to sound like a lot they use millions of gallons per
day. Don’t be fooled.

Milt Burgess