In an earlier
SWFWMDmatters blog post, I wrote about the dilemma surrounding the status
of an ailing, iconic Silver Springs and a water use permit being sought by a
proposed 10,000 acre, 30,000 cattle, feeding operation that would take another
13.2 million gallons every day (annual daily average) from the same aquifer
“springshed” that feeds the main spring.
The status of the
spring system at that time was historic.
In the many years records have been kept of the spring’s flow, there is
no record that documents the spring flow as ever to have fallen to the level it
was at that time, approximately 50% of its historic long term average. It seemed sharply plain to most that taking
more water from its source, especially an amount that is even greater than that
which City of Ocala now takes, would surely have an undesirable impact upon the
springs’ already dangerously low flow.
Since then, the
St. Johns River Water Management District has scrambled to put together a
position that would legally, scientifically and politically justify the
issuance or denial of the requested permit.
Wanting to avoid being accused of thinking only inside that proverbial
box, the staff came upon a theory that at best can only be described as novel
because it flies in the face of what most would consider reasonable thinking.
Hal Wilkening, P. E. |
Rather than me trying
to explain just how bizarre this concept is, you will likely have greater
interest reading the thoughts of Charles Lee. As most of you know Charles is the widely known
and a highly respected voice on many issues for Florida Audubon, especially on
legislative matters. He’s the
organization’s Director of
Advocacy/Regional Director. With his
permission, here’s what he wrote recently in an email:
Interestingly,
this (concept) was presented in much more tentative terms to the board,
but is trumpeted here in SJRWMD propaganda as the “Ah, Ha” answer to the decrease in flow
at Silver Springs.
Wilkening
advanced the theory that vegetation growing in Silver Springs Run and the
Ocklawaha River have created a backwater effect, raising water levels in the spring
run and therefore creating a hydrostatic head that they claim is suppressing
the amount of water coming out of the spring. The amount of water level
increase they claim is about .9 foot. The amount of decline in springflow
claimed because of this is 100 to 120 CFS. (Note, even if a 100 to 120 CFS
decline resulted from increased water levels, Silver Springs is still flowing
about 300 CFS less than what would be expected after this summer of
extraordinary rains. Flow figures from the 1960s and 1970s would have this
spring producing over 1000 CFS after the rainfall we have had recently, and it
is only flowing around 600 CFS).
The theory
is not without some scientific basis. However, to have publically advanced it
at the board meeting, and then trumpeting it here without some peer review and
more detailed analysis is, frankly, irresponsible. Had some environmental group
presented conclusions like this, Ed de la
Parte would have been screaming “JUNK
SCIENCE”! Instead, he was sitting in the audience smiling. For example,
one of the tests that they could have performed would have been a statistical
analysis of variance in flows from historic norms at times when the water
levels in the Silver Run and the Ocklawaha have been distinctly BELOW normal
during the past 12 years. That data is readily available, but (conveniently) is
not provided.
The
observations about aquatic vegetation growth in Silver Run and the Ocklawaha
were tied to drought conditions and not attributed to nitrates. The story
according to Wilkening is that lower flows from the chain of lakes down the
Ocklawaha produced less brown colored water moving downstream and that in turn
allowed greater aquatic vegetation growth because of increased light
penetration. The weeds hold water back in his view, raising the water level
therefore pressing down on the spring and reducing flow.
Along with
that analysis, Wilkening produced a chart with three monitoring wells near
Silver Springs. Two of the wells showed about a .5 foot average decline over
the last 12 years, and one showed a water level that did not change. From that,
Wilkening told the board that there had been no decline in aquifer levels,
therefore a decline in aquifer levels could not have caused spring reductions
over the past 12 years…HMM two wells show a distinct decline, one does
not, and that means no change…. Interesting way of looking at math.
I was able
to take the graph that other members of the SJRWMD staff had used during the
morning session to give the aquifer level readings in the monthly hydrological
report to show that even with the huge rainfall amounts since June, the aquifer
levels throughout the Silver Springs springshed and in N.E. Florida generally
remain at distinctly abnormal low levels. I also questioned picking out just
three wells and drawing broad conclusions from them rather than looking at a
much bigger data set about aquifer levels which was readily available.
Finally, Guy Marwick of the Felburn Foundation pointed out to the board that the high water
levels claimed by Wilkening were really not historically high. The gift shop
and walkways at Silver Springs flooded on numerous occasions when springflow at
its peak produced very high water levels in decades gone by.
I
characterized Wilkening’s presentation, with an old medical adage, as a “zebra
diagnosis”. ("When you hear hoofbeats behind you, expect to
see a horse, not a zebra).
Charles
Well said,
Charles. Thanks.
It’ll be
interesting to see where the district technical staff go with this. As mentioned, they have a task that will
require them to make the science legally defensible in the face of an ill
political wind that is saying, “Issue a permit or you may find your job in
jeopardy.”
Not likely? Ask Connie
Bersok.
That is definitely an interesting idea. Do you think some people will think that means water flow could be increased if we just cut down the vegetation forming this blockage? I am not well versed in these matters but it seems like this wouldnt be enough to keep the permit from being issued.
ReplyDeleteTaylor Beardsley