It is obvious that our current drought plans do not provide
true balance for the Savannah River Basin. Simple logic says the act of
sending more water downstream than nature provides in rain is unbalanced.
And recent history shows repeated destruction to the recreational
infrastructure around the lakes (marinas, campgrounds, houses built for
recreation at the lake, dock builders, restaurants along the lake, etc.; not
whether you can fish a given spot) with no similar destruction to downstream
interests.
Right now before the lakes begin to drop is a crucial time
for achieving true balance of all the needs of the Savannah River Basin.
If you wait until the lakes begin to drop before you start corrections
you lose balance. First and foremost true balance requires that you
factor in all the engineering knowledge you have about the system.
Following is a list of what we know from operations in past droughts:
·
The amount of rain over a year in the droughts
between the year 2000 and 2010 was equivalent to 3600cfs inflow to Lake
Thurmond. Hence, in a drought matching those, you have to decrease
releases to 3600cfs or you will lose continuity of lake levels.
·
Surveys of downstream interests in the drought
of 2008 (all stakeholders were asked to comment on whether they could survive
releases as low as 3100cfs) showed no significant impact from 3600cfs.
The only derogatory comments about 3600cfs came from NOAA and those comments
were simply statements of concern over what might happen. Since flows can
be increased immediately if any of the possible concerns become real, there is
no need to destroy recreation over something that might happen.
·
Recreation infrastructure is severely impacted
when lake levels drop more than 10’. Based on the droughts between 2000
and 2010, reducing releases to 3600cfs at the onset of a drought will prevent
lake level drops of more than 10’.
·
The Army Corps of Engineers can control lake
levels to within a fraction of a foot on a month to month basis using their
hydrology models and knowledge and data on rain inputs.
·
Fears of low river flows impacting dissolved
oxygen levels in the Savannah Harbor are unfounded. Both measurements of
dissolved oxygen at Clyo and the fact that ocean tides are 10x the input from
the river say that dropping releases to 3600cfs is not harmful.
·
The critters in the river survived for thousands
of years before the dams were built with river flows in severe droughts as low
as 500cfs. Additionally there are no endangered species threatened by
releases of 3600cfs.
·
The most important criteria for power production
from our dams is peaking power. As long as the lakes have plenty of water
to permit power production during peak demand the other power needs for SEPA
can be satisfied by purchases which are insignificant in cost compared to the
cost to the recreational infrastructure when lake levels drop drastically.
·
Instrumentation at the dams shows the status of
downstream flows permitting the Corps to safely stop releases when the river is
flooded from rains.
·
Concern about unnecessary reduction in flows
when we are not truly in a drought is unfounded. Such reduction in flows
will cause the lakes to refill quickly if we are not in a drought.
·
The time the river is at reduced flows will be minimized
if we drop release rates at the beginning of a drought. This is because
it takes less time to refill the lakes when they contain more water at the end
of the drought.
Factoring all these together yields a good engineering basis
for developing a drought plan to protect all the various needs of the Savannah
River Basin. This plan is different from the one currently in use by the Corps
of Engineers because it corrects for low lake levels on day 1 of a drought
rather than waiting until the lakes have already dropped several feet. It
should protect all aspects of the Savannah River Basin including the vast
recreational infrastructure around the lakes.
1)
Maintain lake levels at full pool as long as
this can be done without dropping release rates below 3600cfs. In other
words balance input and output in such a fashion that the lakes stay full
rather than allowing the lakes to drop several feet before becoming concerned
about lake levels.
2)
Once the lakes drop more than 2’ with a release
rate of 3600cfs, maintain 3600cfs (3100 in winter months) until the lakes
return to full pool.
3)
Anytime the lakes are down more than 2’ and the
river is swollen from heavy rains, shut off flows from the dams until the river
flows return to normal. This will help minimize the amount of time
reduced release rates are needed.
There is one further concern that needs to be
addressed. In the past the lakes were dropped 4’ after labor day. The
reasoning is to provide better flood protection with heavy rains. This
was set up when Lake Thurmond was the only lake catching the runoff from the
Savannah River Basin. We now also have Lake Hartwell and Russell.
With the combination of all 3 lakes, 2’ drop should give the same protection as
the 4’ drop used originally for Lake Thurmond. Hence we recommend the
Corps change the drop used after Labor Day to 2’ instead of
4’. During the months when the lakes are deliberately down 2’, releases
should be 3600 anytime the level drops any significant amount.
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