0622lakeaudHear assistant state climatologist Pam Knox talks about the drought outlook for Lake Lanier.
The summer solstice arrived Friday evening, making Saturday the official first full day of summer.
From now on, the hours of daylight will start getting shorter. But the hottest temperatures of the year won’t hit Georgia until later.
This means Lake Lanier will soon enter a critical phase. Already 14 feet below full pool at the beginning of summer, the lake will begin losing water at a more rapid pace as air temperatures rise.Lisa Coghlan, spokeswoman for the U.S. Army Corps of Engineers, which manages Lanier, said the corps is monitoring the lake’s rate of "evapotranspiration." That’s a combination of the water that’s drawn up into the air by the sun’s radiant heat and water that is consumed by plants.
For example, Coghlan said, on Tuesday Lanier’s evapotranspiration was 0.42. That means the lake lost almost half an inch of water because of these natural factors, regardless of how much water the corps released from Buford Dam.
Coghlan said the corps is still releasing only the "minimum flow" at the dam, meaning enough water to maintain a flow of 750 cubic feet per second (cfs) in the Chattahoochee River at Peachtree Creek in Atlanta.
The corps recently adopted a revised interim operating plan for the Apalachicola-Chattahoochee-Flint river system, which allows slightly less water to be released at Woodruff Dam on the Apalachicola River near the Florida border.
Lake advocates, as well as the Georgia Environmental Protection Division, had requested the reduced flow in order to keep a bit more water in Georgia. But Coghlan said Wednesday that the revised plan "has no impact on Lake Lanier."
On Thursday, Patrick Robbins, spokesman for the corps’ Mobile, Ala., district, warned that the ACF system is still threatened by drought. Over the next five weeks, he predicted, West Point Lake could drop nearly 2.5 feet and Walter F. George could lose 1.25 feet.
Both lakes are downstream from Lanier, which is expected to lose about 1.3 feet over that same period.
If the other two lakes get too low, will more water be released from Lanier to help fill them up?
Coghlan declined to comment on that possibility.
"There’s too many variables involved," she said. "Anything I say at this time would be speculation."
One variable that neither the corps nor anyone else has control over is the weather. Assistant state climatologist Pam Knox said nobody knows how much precipitation will fall in the Lanier basin during the next three months.
"Predicting (rainfall) in the summer is hard," she said. "(But) we don’t really have any reason for optimism right now. Even if we get normal rainfall, we’re only in a holding pattern. We’re not improving."
Knox said the only thing that could pull Lanier up from its current abysmal level is a hurricane that sends massive amounts of moisture straight up through Georgia.
"While we think the number of tropical storms is going to be greater than usual (this year), we don’t really know where they’re going to go," she said. "And that’s a huge issue for Georgia, because in a typical summer, up to 40 percent of our rain comes from tropical storms."
Knox said the usual pop-up summer thunderstorms may be scarce, and the ones that do pass through the area may not be helpful.
"Right now, the soil is so dry that even when thunderstorms develop, there’s no moisture to keep them going and they die out," she said.
Knox explained that storm systems often form a feedback loop, so an area that is already wet can cause a thunderstorm to become stronger. That’s what’s happening in the Midwest, which has been pummeled by storms this year.
Knox said Lanier will need numerous days of heavy rainfall in order to start filling back up. And any tropical storms that develop right now are likely to be weaker than those that come in August or September.
The amount of water that Lanier could lose between now and the third week of September, when autumn officially begins, depends on two factors: how much water the corps releases, and how many storm systems move through Northeast Georgia.
A look at lake levels over the past decade shows that those amounts can vary wildly. In 2000, for example, Lanier lost almost 7.4 feet over the three-month period. But in 2001, it lost just 1.3 feet.
And in 2004, the lake actually gained almost a foot and a half, rising to 1,073.09, more than 2 feet above full pool.
How did that happen? You can thank Frances, Ivan and Jeanne — three hurricanes that spun through Georgia in rapid succession.