Florida says it’s not just about the mussels
11Alive has a nice story today about some of the other issues facing Florida if the water continues to dwindle. Among other things, they say:
Branch said recreational fishing businesses in his county rely on the Apalachicola River, but boats are running aground in the middle of it. He said the lower flows have affected groundwater levels to the point where area farmers are having a harder time irrigating crops.
I’m rather torn about all of this. While human lives are obviously more important, things don’t appear to be getting critical — at least not yet. Do we throw away jobs in Florida just in case things keep getting worse up here, or do we wait until things are in a more critical state? What do you think?
July 23rd, 2008 at 9:44 am
it seems like the effects described there are perfectly normal for a drought. We’re experiencing the same thing here. The reservoir was created to supply water to the Atlanta area, not to prevent symptoms of drought in Florida. Its clear from the amount of water flowing into the lake that the river flow downstream would be severely diminished if the lake didn’t exist. “Farmers having a harder time irrigating crops” just doesn’t sound like a terribly tragedy to me.
July 23rd, 2008 at 10:53 am
When will someone notice that we are in a drought and droughts mean less water being sent down stream? When the lake is empty will they still complain and want more? We suffer you suffer it’s that simple.
July 23rd, 2008 at 11:52 am
The resevoir was created for hydroelectric power, actually, as well as flood prevention. I think most of the modern uses of the water in the reservoir and the Chatahoochie are above and beyond the original scope of the project both in GA and in FL.
July 24th, 2008 at 7:39 am
Prootwadl has it right, according to the February 2008 appellate court decision:
Since the dam and the lake belong to congress, barring an act of congress Atlanta will not get an increased share of that water.
Here’s another quote that gives an interesting perspective (source):
That was written in 2002. It’s still true now: I haven’t seen any more reasonable proposals by the political leaders of the state of Georgia. It’s easy to say that people’s lives are at stake and so Georgia should get the water, but until Georgia can demonstrate that it is taking meaningful strides to permanently reduce its water usage I guess that these claims will fall on deaf ears until the people here are facing an imminent danger.
July 25th, 2008 at 3:27 pm
That Jeremy Branch is a real a-hole. He says “the issue is Atlanta’s greed and gluttony versus Floridians’ necessity and survival.” Then in his next sentence he is complaining about boats running aground. He doesn’t think we have boats running aground on Lanier???
He is the embodiment of the reason the states can’t come to an agreement. Boats running aground in his state are about “necessity and survival”. Boats running aground in Georgia are “greed and gluttony”.
What a jerk.
July 26th, 2008 at 12:03 am
The 11Alive cut off half of the article by AP news. For the full story see http://www.naplesnews.com/news/2008/jul/21/fla-ga-water-war-not-just-about-mussels . It adds “Oyster beds are being reduced and shrimp are disappearing, and if the problems continue, tourism will decline along with the seafood industry. Even honey production is affected because the river’s flood plains are drying up, which hurts tupelo blooms.”
An article appeared in the Jacksonville, FL newspaper (http://www.jacksonville.com/tu-online/stories/071908/met_306184980.shtml) about the city council inacting a permenant water restriction law and the NE Florida area is not under drought conditions like Atlanta is.
“The irrigation bill limits lawn-watering to two days a week most of the year, and once a week during late fall and winter. It gives city employees authority to write tickets for violations - a warning the first time, $50 the second time, $250 after that.”
What water restrictions are currently in place for the metro Atlanta? I seem to recall most restrictions have been lifted, yet the drought continues. Go figure. To the Atlanta mayors’ credit I saw a news segment on the national news about the billions of dollars being spent to fix most of the leaking municipal pipes.
July 26th, 2008 at 6:37 pm
You recall wrong. Restrictions are in place statewide. Some restrictions have been eased in some counties. Restrictions in the Metro Atlanta counties that draw water from Lanier have not been eased. Those restrictions are: No sprinklers. Watering is allowed three days per week for 25 minutes only, and only between midnight and 10 a.m. Use a hand-held garden hose with an automatic shut-off and use only one hose at a time.
– DSO –
July 27th, 2008 at 12:33 am
Not about the mussels? No surprise there. In truth, it has never been about the mussels. Florida’s noisy concern over “endangered” mussels is and always has been just a convenient ploy, a ruse to muster the power of the Endangered Species Act to bolster the case for 5000 cfs minimum flows in the Apalachicola River.
Alas, the “endangered” mussels gig was busted earlier this year so crying about endangered mussels can longer guarantee 5000 cfs minimum flows in the Apalachicola River. Now a new reason must be invented, and so it was. That new reason is, “recreational fishing, exposed sandbars, and the plight of farmers in the counties surrounding the Apalachicola River.”
Fact: The Herbert Scholz power plant is in located on the Apalachicola River in Jackson County, FL, and requires 5000 cfs flows.
Fact: Jeremy Branch, the loudest windbag at that hastily arranged forum, is a Jackson County Commissioner.
It is both ironic and telling that Commissioner Branch’s comments about the Apalachicola River and the plight of Florida farmers in surrounding counties could have equally applied, word for word, to Lake Lanier and the plight of Georgia farmers in the counties surrounding Lanier.
A word to Jeremy Branch, your silly over-the-top rhetoric has been duly noted and duly dismissed. It is the height of hypocrisy to rant, as you did, about Atlanta’s “greed and gluttony” while simultaneously trying to secure continued access to more than 10 times the amount water from the ACF than Atlanta consumes. If Atlanta’s use is “gluttony” then what is ten times Atlanta’s use? Do keep it up, though, because the louder and more frequently politicians like you rant about Atlanta’s “greed and gluttony” the sooner Congress will step in and apportion 1/3 to 1/2 of Lanier capacity to Georgia.
In my next post I will detail the reasons why the Herbert Scholz plant should be shut down.
– DSO –
July 27th, 2008 at 2:23 am
The Herbert Scholz power plant is located a few miles south of the Florida-Georgia boarder on the Apalachicola River. It is a coal-fired plant that produces 92 MW of power. For that 92 MW of power, the plant requires a flow of 5000 cfs in the Apalachicola River. That is a rate of 54 cfs of water flow per MW of power. Remember that number because it will soon be compared to a modern power plant’s water usage.
The modern example will be the Farley Nuclear Power Plant in Dothan, Alabama. That plant produces 1820 MW of power which is almost 20 times the power of the Herbert Scholz plant. For that 1820 MW, the Farley plant requires a mere 2000 cfs of flow. That is a rate of 1.1 cfs of water flow per MW of power.
With this data the water use efficiency of the two plants can now be compared. On a per MW basis, the Herbert Scholz power plant requires almost 50 times the water flow of the Farley plant. In other words, the Herbert Scholz plant is operating at 2% of the water use efficiency of the Farley plant. To look at it another way, if the Herbert Scholz plant were as water efficient as the Farley plant, the Herbert Scholz plant would require a mere 101 cfs of water flow for its full 92 MW output.
How does this pertain to Lake Lanier? Well, in periods of drought Lanier has been historically called upon to supplement flows in the Apalachicola River to maintain a minimum flow of 5000 cfs for the Herbert Scholz power plant. So let’s run some numbers. Holding inflow at zero, if Lanier were at full pool of 1070 ft, how long would it take to drop 5 feet to 1065 ft at a discharge rate of 5000 cfs? Answer, 18.5 days.
Now let’s hypothetically give the Herbert Scholz plant the water use efficiency of a modern power plant such as the Farley plant and run the numbers again. Holding inflow at zero, if Lanier were at full pool of 1070 ft, how long would it take to drop 5 feet to 1065 ft at a discharge rate of 101 cfs? Answer, 2.5 years.
These examples are illustrative only. Because other lakes in the ACF have also contributed to the 5000 cfs flow, Lanier has never been tapped at a full 5000 cfs to supplement Apalachicola flows during times of drought. Nevertheless, Lanier has been significantly tapped to supplement Apalachicola flows during times of drought. One example is the year 2000 when the Lanier dropped from a springtime high of 1068.4 ft to a wintertime low of 1055.6 ft. Another example is 2007, when Lanier dropped from a springtime high of 1068.5 ft to a wintertime low of 1050.8 ft.
The point is this; Florida has over 1000 miles of ocean coastline affording an abundant source of cooling water for power plants. In this era of recurring droughts and dwindling fresh water resources in the southeast USA, it is beyond absurd that an aging, grossly inefficient coal-fired power plant 3 miles south of the GA-FL boarder, producing a paltry 92 MW of power, should be apportioned 5000 cfs of vital fresh water flow from Georgia’s reservoirs in times of drought. The plant should be shut down.
In my next post will address the purported need to maintain 5000 cfs flows in the Apalachicola River for environmental reasons.
– DSO –
July 27th, 2008 at 3:22 am
If the Herbert Scholz power plant were to be shut down, as it should be, then questions about minimum flows in the Apalachicola River would necessarily be limited issues about the environmental and recreational impact of low flows. Does the Apalachicola River require a minimum flow of 5000 cfs to remain healthy? The short answer is this: extended periods of 5000 cfs flows are simply not sufficient to maintain a healthy Apalachicola River and Bay.
Now here’s the long answer. Prior to the mid 1980s, the Apalachicola River enjoyed, with very few exceptions, annual flushing flows from the ACF of over 40,000 cfs lasting several months. These annual flushings had nothing to do with Atlanta’s water usage or USACE retention policy and everything to do with the fact that the ACF drainage basins were receiving copious quantities of rain.
Starting in 1986, however, there began a succession of multiyear droughts and, accordingly, a succession of multiyear periods in which these large annual Apalachicola River flushings simply did not occur. This, again, had nothing to do with Atlanta’s water usage or USACE retention policy and everything to do with a nasty climatic phenomenon called a drought. The water was simply not there. Atlanta didn’t consume it. Nobody consumed it. It just never fell from the sky, pure and simple. Yes, a minimum of 5000 cfs was maintained in the Apalachicola River for the Herbert Scholz power plant. However, it is becoming increasingly clear that that 5000 cfs flows are just not sufficient to sustain the kind of productive fishery environments in the Apalachicola River and Bay that were routinely enjoyed prior to 1986.
Like it or not, the climate has shifted and, like it or not, water for healthy large annual Apalachicola flushings has simply not been there during the multi-year droughts of the last few decades. Blame it on global warming if you wish, or blame it on the stars, but the fact remains that the southeast USA has shifted towards a drier climate.
So let’s run some numbers and see what a healthy pre-1986 flushing of the Apalachicola River would require of Lake Lanier if that burden were placed solely upon Lake Lanier. Holding inflow at zero, how long would it take to drain Lanier of its entire capacity from 1071 ft down to 1030 ft at a discharge rate of 40,000 cfs? Answer, 15 days.
Again, that example is for illustrative purposes. Such a discharge rate from Lanier is not feasible for a number of reasons. Nevertheless, it remains that the fishery problems in the Apalachicola River and Bay have nothing to do with Atlanta’s relatively meager water consumption and everything to do with this one simple fact: the water for a healthy multi-month 40,000 cfs flushing of the Apalachicola River is nowhere to be found within the ACF and will not be there until the current drought is over. No amount of ranting from Florida politicians will change that fact.
– DSO –
July 28th, 2008 at 10:54 am
Good posts as usual DSO. Particularly your comment -
“It is both ironic and telling that Commissioner Branch’s comments about the Apalachicola River and the plight of Florida farmers in surrounding counties could have equally applied, word for word, to Lake Lanier and the plight of Georgia farmers in the counties surrounding Lanier. ”
I will add to your statement that while the effects are similar in both areas, the main difference is the number of people affected and dollars lost. Where in Florida, thousands of people are feeling the effects and losing millions of dollars, in Georgia, millions of people are feeling the effects and losing billions of dollars. If I were a totally impartial bystander I would have to weigh that heavily.
July 28th, 2008 at 12:53 pm
Why aren’t we all in a panic?
Lake Lanier Water Level - 1064.27 on 7/28/07
Lake Lanier Water Level - 1055.28 on 7/28/08
Am I missing something?
July 28th, 2008 at 1:11 pm
Because we know that, despite the drought, we still will have enough water in Lake Lanier to meet drinking water requirements. No need to panic while there are stuff sufficient resources.
Now, if this situation continues on for anothers several years, I would be a lot more concerned. I’m quite concerned now. Just not “panicking”.
July 28th, 2008 at 1:11 pm
I mean “still sufficient resources.”
My fingers went off typing again without editing properly.
July 28th, 2008 at 2:16 pm
MarkB - To further address your questions. Yes as DSO pointed out we are still under strict watering restrictions. They have just been somewhat relaxed from the extreme restrictions of last year.
Also I will point out that Jacksonville is on a totally seperate water system than Atlanta. I have no idea what their concerns are, but they have nothing to do with Atlanta because they do not get their water from the ACF.
You say “city council inacting a permenant water restriction law and the NE Florida area is not under drought conditions like Atlanta is.”
Couldn’t you also just as easily say “Florida is demanding water from North Georgia even though North Georgia is in a drought condition and Florida isn’t”?
July 28th, 2008 at 5:24 pm
Again though, let’s keep in mind that right now at this moment, Lanier is only being tapped for enough water to meet the needs of Atlanta - both in intake, and in diluting the treated return water. This amount would be required whether or not Florida or Alabama existed.
Lanier is not, right at this moment, being tapped to refill other reseveroirs. Or keep mussels alive, or cool a coal fired plant, or feed fresh water to oysters and fish.
What I find more telling is that were Lanier and the other reseveriors not to exist, Florida would get about half the water it is getting right now, due to the drought. Check me on this, but I don’t think any of Georgia’s reseveroirs states as a reason for it’s existance, to serve the downstream needs of Florida.
That’s not to say the water should or shouldn’t be released. Just that some arguements being made don’t hold water at the present moment. So to speak.
July 28th, 2008 at 8:11 pm
Rkolter - theoretically you are right that Lanier isn’t being tapped “at this moment” to feed Florida. But the words “at this moment are key”. Also, I would be interested to know why outflow rates are as high as they are when as you say, Lanier should be outflowing at a minimum rate to support Atlanta’s needs right now.
If you look at the data here http://water.sam.usace.army.mil/gage/acf/prob2.txt
you can see that outflow has varied widely. If you look at April numbers, it is clear that approx 500 cf/s can take care of Atlanta’s needs. Even if you adjust that up by half to compensate for summer needs, you get a figure of 750 cf/s. On June 27th for instance, outflow was 1919 CF/s. I’m not sure who that is supporting, but it isn’t Atlanta.
Also while you may be right about what Florida is getting, remember there are two issues - what they are getting and what they are asking for. Because they are asking for / demanding flows to increase above the current level. That has to come from somewhere and that somewhere will be Lanier sooner or later.
July 29th, 2008 at 1:37 pm
RichS - the current flow is not just for Atlanta’s needs, but also to dilute the water that returns from Atlanta to the river downstream. I hate to not provide a link, but it came from an AJC article that itself provided a link to the USACE, that confirmed it. I’m not sure on the variation though; you would think they could pretty accurately set how much water comes from the dam. Why does it vary by even 100CF/s, let alone several hundred? There must be more to the equation they use to determine what amount of water will flow each day.
You’re right of course that the issue is twofold with Florida. My point is that people are harping on issues that are not current (or at least, not as significant in my mind) while not bringing up what I consider a very key arguement - that Florida is already getting double or more the water they would get without Georgia’s reseveroir system.
It seems far more rational to explain, “Thanks to Georgia, the oyster fishing has not died out entirely from these past droughts, let alone this one. Far from being the big bully on the block, USACE, Georgia, and the reseveroir system has kept your business running without gaining a benefit from doing so.”
July 29th, 2008 at 2:24 pm
Here is one link:
http://www.ajc.com/metro/content/metro/stories/2008/02/14/water_0215.html
The amount of water needed to dilute the discharge increases in the summer “when the river’s temperature rises and the level of dissolved oxygen plummets.”
July 30th, 2008 at 1:53 pm
I don’t think we have any big disagreements here, but I would love to know why 600 CF/s is enough some days and other days it’s 1900 CF/s. Obviously the 500 CF/s that we were seeing late in the winter isn’t going to support Atlanta’s needs in the summer, but variations from day to day of threefold or more can’t be explained by Atlanta’s needs. It would be nice if the COE was a little more forthcoming about it’s decision process.
July 30th, 2008 at 3:26 pm
RichS, here’s a link to a PDF file that should give you more information:
http://www.sam.usace.army.mil/ACF%20Water%20Resources%20Management/BufordTempDeviation/GAEPD_ACF%20Call%20Talking%20Points%2005-07-08.pdf
It says: “Georgia’s Rules for Water Quality Control require a minimum daily average instream concentration of 5 mg/l for dissolved oxygen in the Chattahoochee River below Peachtree Creek.”
About 5 mg/l of dissolved Oxygen (DO) is necessary to maintain the quality of the water. ACE has to release sufficient water to maintain the required amount of dissolved oxygen (DO). The amount of DO varies with the temperature of the water. A graph on http://www.lenntech.com/why_the_oxygen_dissolved_is_important.htm shows how the amount of DO in water varies according to temperature. I think maintaining sufficient DO is the main reason why 1900 CF/s is required now when 600 CF/s was sufficient in May.
July 30th, 2008 at 3:40 pm
RichS, let me try this again.
As I understand it, the waste water released by Atlanta contains little or no dissolved oxygen (DO), so it has to be diluted by water from Lake Lanier to raise the DO to the minimum level. More water is required to dilute the waste water when temperatures are higher than is required when temperatures are lower, because the higher the temperature, the lower the amount of DO in the water.
July 30th, 2008 at 8:23 pm
GThierry - I am not talking about the variation between May and July. I am talking about the variation from day to day during June and July. For instance, June 27th, they released 1919 cf/s. The next day, they released 617 CF/s. July 10 and 11 they released around 620 CF/s but most days in July have been just over 1000 but July 6, it spiked up to 1528. I don’t see any way to reconcile those wild swings with Atlanta usage / sewage dilution.
July 30th, 2008 at 10:17 pm
richs - Now I see what you’re asking.
We have had some widely scattered showers recently, some of which were heavy. Don’t they base the releases on the flow at various gauges - especially the one at Peachtree Creek? Heavy rain in one spot might not show in the official records, but the runoff would eventually reach the river and reduce the need for water from the lake.
July 31st, 2008 at 8:13 am
The figures I am looking at are at the dam. So the effects of rainfall would be negligible unless the COE is releasing more water for some reason when it rains. I hope they aren’t doing that. If we get rainfall, we really need to retain it here in Lanier - not send it downstream where they don’t need it as badly.
July 31st, 2008 at 9:10 am
July could well require far more water than May to achieve the same effect - Atlanta uses more water in July, which means more oxygen poor water to dilute in July.
As far as day to day within a month goes… remember that statistically most of those numbers fall within some “reasonable” range around the mean. I haven’t done the analysis, but just from a glance, it looks like most of the numbers are fairly close, with just a few that might be outliers. It all depends on how exactly they can control the flow out of the dam - which will affect how big the standard deviation is - numbers within three standard deviations of the mean are “good”.
If there were only a few outliers, those might be days that they are deliberately releasing water for reasons other than to dilute the treated water from Atlanta. And, we don’t know what all those reasons are.
July 31st, 2008 at 10:18 am
RichS - I think that is exactly what they are doing. I’ve been looking at the lake level pretty consistently over the last month. A couple of times we’ve had close to an inch of rain at the lake, and the level of the lake goes up by less than the amount of rain. It ought to be more given that the Chatahoochee inflow to the lake ought to increase in addition to the rain that goes directly in, not to mention the expectation of releasing less water from the dam given the additional rain downstream. July 13 for example, we get over an inch of rain, and the lake goes up by less than half an inch.
July 31st, 2008 at 10:57 am
pardon me for interrupting your absolutely brilliant discussion, but weren’t watering restrictions supposed to tighten again this month?
LITTLE HAS COME BACK TO ROOST
BGAAAAAAWWWKKKKKKKKKKKKK
July 31st, 2008 at 11:44 am
The larger releases are clearly purposeful. The biggest question is how much needs to be released to support Atlanta and a healthy dilution of sewage at this time of year? The number appears to be somewhere in the range of 600 - 1000 cf/s based on release rates.
The second question is why they release more than that amount from time to time. I think it would be fairly easy for the COE to answer those questions. It seems like something the public should have a right to know.
July 31st, 2008 at 2:47 pm
Yeah, but they may be wary of telling the public. Good grief. They’re stuck with following the law, but it often sounds like people want to drag the COE out into the streets and tar and feather them. Even here last year there was funny but not-so-funny talk about people taking the dam by force.
If I were the COE, I’d probably be hesitant to say anything that I didn’t have CYA prior to saying and that includes specific authorization to say anything at all.
At a guess… and it’s purely a guess… the extra releases may be because they do sometimes have to release water to the downstream reseveroirs. Or Lanier may occasionally be called on to supplement the water flow downstream (they release downstream, then release from Lanier to refill). Or, there could be a policy we don’t know about - like to maintain a certain flow at a certain gauge, or the puple-spotted Musk-Moth requires a bi-weekly flow of water.
I can say that it is far, far more likely that they have a legitimate reason, and don’t want the furor that results from saying, than it is that they simply decided to release extra water (or someone periodically falls asleep at the gauge, or whatever).
July 31st, 2008 at 5:29 pm
Not bad guesses, but while I am sure the reason is legitimate, it doesn’t mean that I would have to agree with it nor does it mean that it is a good reason or well thought out.
The decision making process should be something that they could be held to account for. That’s the way the government is supposed to work in this country - sunshine laws, freedom of information, etc. Problem is that the COE isn’t really accountable to the public in the same way as most government agencies.
August 1st, 2008 at 8:04 am
The COE is a federal agency, not a state agency. Why woudl the COE be held accountable by the whims of Atlanta? Lake Lanier is not (as far as I know) Georgia’s property. Nor was it designed to feed water to Atlanta. Surely, that is what it does now. And equally surely it would make common, if not HUMAN sense for the COE to listen to Georgia.
But, you talk as if they’re obligated to Georgia. They’re no more obligated to Georgia than they are to Missouri - they put three million sandbags out for our flooding problem - and now refuse to devote any time or money to move them - entire towns are cut in half by 10′ tall walls of sandbags and a massive volunteer effort to move saturated, stinky, slime covered sandbags is underway.
I don’t know if you want individual states to have the authority to direct the COE, or to hold the COE directly accountable. Alabama and Florida outweigh Georgia both in political clout and in sheer population. What if they adopted the same attitude and decided to make their case in the same way?
No. I’m more heartened by what the COE has actually done - gone up to the government bodies that give them their marching orders and said, “Look, we need to conserve some of this water - change the rulings.” They certainly had no obligation to do that; it was done because it was the right thing to do.
I believe that at their core the COE is a good organization. Even if they left us buried in wet sand, and you without regulation over the lake that sits next door to your city.
August 1st, 2008 at 11:11 am
Accountable to the whims of Atlanta? No.
Accountable to me as a citizen and taxpayer? Yes
August 1st, 2008 at 11:13 am
And by the way, accountability doesn’t mean control. I don’t expect to be able to issue orders to the COE. I just don’t think they should have autonomous authorityl.
August 2nd, 2008 at 12:50 pm
But they don’t. They’re regulated by other agencies - they have authority but must meet goals given to them by entities outside their control. For example, they must meet the 5000 cf/s (4750 right now?) goal for the mussels. That’s given to them by the Fish and Wildlife commission.
They’ve chosen to meet it by utilizing as little water as possible from Lanier. Which in the end, is exactly what you would want to have happen (barring a removal of that requirement at all).
August 2nd, 2008 at 10:03 pm
Folks, there is no mystery here, and, no, the US Army Corps of Engineers is not currently releasing more water from Lanier when it rains. In fact, USACE is releasing less water from Lanier when the Chattahoochee receives additional inflow from rains in Atlanta. Rains falling directly into Lanier or over the Lanier drainage basin currently play no role in determining USACE’s daily Lanier discharges. This has been the case for months now.
Current Lanier outflow is a continuous 600 cfs supplemented by a burst of 5200 cfs each day at 3 PM. The length of each daily burst is a function of the Chattahoochee flow just downstream of Atlanta’s water intake pipes (just downstream from the Paces Ferry Road Bridge). The current target flow just downstream from Atlanta’s intake pipes is a daily average of 750 cfs. This target flow is designed to meet minimum summertime dissolved oxygen requirements for a healthy river.
When no rain falls in Atlanta, USACE releases a daily volume of about 1050 dsf* from Lanier to meet this downstream goal. Holding Lanier inflow at zero, a 1050 dsf daily outflow volume represents a daily drop of 0.8 inches in Lanier’s level**.
Now let’s look at the specific numbers for July 13 and 14, because, as dreidson noted, both Atlanta and Lanier got a shot of rain during that period. Lanier inflow for the two days was 2228 dsf. Lanier outflow for the two days was 1603 dsf (which USACE was able to reduce from the usual 2100 dsf two-day outflow because of the additional Chattahoochee inflow from the Atlanta rains). Now let’s do the math, 2228 minus 1603 equals 625. So Lanier had a net gain in volume of 625 dsf during that two day period. At Lanier’s current level, a 625 dsf volume gain represents an increase of 0.48 inches in Lanier’s level.
Lastly, it should be noted that just because the rain gauge at the Buford dam measured 1” it doesn’t necessarily follow that 1” fell across the entire lake. Indeed, looking at just at a couple of rain gauges (Buford, Gainesville) is a poor way indeed to gauge a rain’s effect on the Lake. Instead, look to the Lanier inflow data.
– DSO –
* dsf = Day Second Feet. One dsf is the volume of water represented by a flow of 1 cfs for one day.
** Lanier’s current surface area is about 49 sq mi.
August 2nd, 2008 at 11:52 pm
Rich,
I generally enjoy your posts but I must correct you on this one. The 500 cfs April outflows you cite are just the flows out of Lanier into the Chattahoochee. In April, however, the Chattahoochee was receiving significant additional inflows. For example, from 4/1/08 to 4/14/08, while Lanier outflow averaged 511 cfs, the Chattahoochee flow at the Paces Ferry Road Bridge (USGS Gauge 02336000) averaged 1053 cfs. So, while it is true that the 511 cfs flows from Lanier “took care of Atlanta’s needs”, they did so with the help of an additional 542 cfs of average daily inflow directly into the Chattahoochee River between the Buford dam and Atlanta’s intake pipes.
Alas, those were the happy days of April. Things are different now. Inflows in Lanier as well as the Chattahoochee (exclusive of Lanier outflow) are way down from April’s inflows.
The current target Chattahoochee flow is 750 cfs just downstream of Atlanta’s intake pipes. USACE measures that flow by measuring the flow at the Paces Ferry Road Bridge and then subtracting the flows in the intake pipes just downstream of the bridge. USACE is currently idling Lanier outflow at about 620 cfs and then opening the big gates just long enough each day to make the downstream measurement average out to 750 cfs daily.
Look at July’s daily Lanier outflow. Most of the daily outflows are in the 1025 cfs range but sometimes the daily outflows drop down to the 600-800 cfs range. Those lower outflows are the days that the Chattahoochee received inflows from Atlanta rains and, therefore, the USACE didn’t have to hold the big Lanier gates open as long (or at all) to achieve the aforementioned downstream target flow of 750 cfs.
As for the occasional higher daily outflows – you mentioned the June 27 outflow of 1919 – you must admit that these are rather rare. I’m sure there is a very good local reason for those occasional larger outflows. Indeed, I’ll offer this: Urgent call from Cobb County water plant operator to USACE operators at Buford, “Hey guys my intake pipe has 6” of water covering it and the Chattahoochee is down 2” from this morning. I’ll be sucking air by midnight if you guys don’t dump a ton-o-water in the stream PRONTO!”
– DSO –