Lake Lanier Water Level Reading Error

Learn more about the water quantity issues facing Lake Lanier.

The LLA learned yesterday afternoon from the Corps that they had discovered on Friday, June 16 that the water level is actually lower (by 1.90 ft) than what was being reported: this was due to faulty readings from their water level monitoring equipment at the dam, caused by a callibration error which occurred during installation of the new monitoring equipment in early December 2005.

This error remained undetected from December 2005 until April 2006 as the lake level remained fairly constant. The low water observations reported directly to the Corps by the public and additionally by calls to the LLA led the Corps to perform traditional measurements when they discovered the problem.

The LLA will continue to work closely with the Corps to try to implement a 'fill up' strategy for the lake.

Following is the press release sent out by the Corps office in Mobile about the gauge error.

Mobile, Alabama Lake levels at Lake Sidney Lanier are actually lower than being reported due to a faulty gauge reading used to calculate inflows and outflows.  The lake level is being reported at 1067.62 when the actual level is 1065.72.

A calibration error led to additional releases totaling one half inch per day, or 650 cubic feet per second of outflow greater than was necessary over the past 52 days.This equates to an additional lowering of the lake by 1.9 feet during this 52 day period.

The lake level gauge is used in the process to determine inflow into the lake, said Robbins. With the error, we believed more water was entering the lake than was actually occurring. In the current drought conditions, we operate the system as a run of the river meaning whatever is entering the lake is released.

Since we were getting a faulty reading, we were passing more water than was necessary over the 52 day period.

The faulty gauge was off by four tenths of an inch per day, giving a reading that was higher than actual lake levels. Over the period of about a month, the cumulative affect of this error would equal nearly a foot.

We are now augmenting flows as necessary for water supply to metro Atlanta, water quality requirements throughout the basin and to protect endangered species in the Apalachicola River.  Hydropower needs are being met as part of the releases necessary to meet these other requirements, said Robbins. These augmented releases are necessary when basin inflows drop below 5,000 cubic feet per second at Jim Woodruff Dam.

The lake is now in operational zone 3, which means run of the river type operations will continue when flows warrant or augmented flows as necessary.

Lake levels are expected to continue to decline throughout the Apalachicola-Chattahoochee-Flint River basin throughout the summer if drought conditions persist. During previous historic drought periods the lake has been significantly lower. In 1981, the lake level dropped to 1052.66, 13-feet lower than the current level and as recent as 2001 the lake level was at 1055.61, 10-feet lower than the current reading. Given current conditions, the Corps does not project the lake levels will reach these previous historic lows during the summer.

The lake levels anticipated this summer will have critical impacts on recreation and hydropower production as levels decline.The gauge at Lake Lanier has been recalibrated so future levels will provide accurate readings. Mobile District will update its water management web pages to reflect actual readings over the time period. That site can be reached at www.sam.usace.army.mil under the heading Water Management.