Water-The Third Rail Part XXIV-Conserving our way out of this drought

“Most Council Members Water Usage Has Risen” is the headline in the UT San
Diego article August 9, 2014. While this blog agrees that public officials
should “walk the walk” if they are going to do the “talk”, we cannot
conserve out way out of this drought. Doing the same thing over and over
again, expecting a different result is an accepted form of insanity.

Let’s assume the drought goes on for another three years, that the El Nino
does not arrive. A few numbers might help. See footnote 1.

For this hypothetical scenario, assume we ignore the weakening status of
imported water sources and just focus on conservation, as the County water
leaders are doing. And also assume we look westward, but to no avail, for
the anxiously awaited El Nino. What then?

On the plus side if it goes on line, we will have the long-awaited Carlsbad
desalination plant providing 50,000,000 gallons per day. Wow, sounds like a
big number. We’re saved! Wrong. It’s interesting every time officials want
to spin water statistics they use millions of gallons per day, so let’s
un-spin it. The output of the Carlsbad plant, in round numbers is fifty-six
thousand acre-feet. Or conservatively ten percent of San Diego County’s
needs. Where do we get the other 90%? We import it.

So, in this hypothetical, four hundred-fifty thousand acre-feet, or
450,000,000 gallons per day have to be imported or drawn from storage. If we
divide the population of San Diego County by the amount of water used equals
about 150 gallons per day per person. However in the article above for the
City of San Diego Jeff McDonald reports 84 HCF’s per month for the last six
month average. That is an astounding figure, if It is correct. Converting
that to gallons per day per person, using an average household of four
persons, computes to 524 gallons per person per day.

Mentioned earlier in the blog is an assumption that the three year drought
becomes a six year drought. We have had that many dry years in the past in
San Diego’s history. The average HCF’s of the council members water use
published in the referenced article is 65, or converting to gallons per day,
1620. Dividing by four family members, that’s over 400 gallons per day per
person, assuming an average of four in each household. Next year and the
years following, will that average of 400 gallons per day drop to 320
gallons per day? Will average San Diego County per capita drop from 150 to
120 gallons per day? Maybe.

Totally confused by now? You are not alone. It’s really not rocket science,
unless we develop new water sources like potable recycling, we cannot
conserve our way out of this drought.

Will the average of the City Council’s use drop from 65 HCF’s to the
county’s average of 24 HCF’s? Yes, and the Israeli/Hamas conflict will also
be solved. Not!

Footnote 1 But first we need to examine the figure put into every water article
published, that an acre-foot is the amount of water used by two families of
four in a year, or 325,900 gallons. Good round number, but it’s wrong. San
Diego County water use is 150 gallons for every person in its 3.1 million
population. It is true that an acre foot is an acre covered by one foot of
water. What isn’t true is that if we multiply 150 gallons average daily use
times four people, times two households we get a much larger number. The
result is 438,000 gallons, not 325,900.

We can still use the latter number
for converting from acre feet to gallons, but the statement that 325,900 is
the amount of water used by two families of four in a year in San Diego is
short by 112,000 gallons or 35%. For the City of San Diego, per the article
cited above, the average monthly usage is 84 HCF’s or an astounding 524
gallons per day per person compared to the county’s 24 HCF’s month usage.