Chris Smith emerged from the mist along the banks of the Chattahoochee River on a recent morning with the verdict on USGS 02334430, otherwise known as the river gauge measuring the flow of water out of Lake Lanier's Buford Dam.

"We're measuring 590, and we're showing 583 on the Web," Smith said, referring to the U.S. Geological Survey's real-time data posted on its Web site. His partner, Tim Pojunas, used a hand-held velocity meter and a rope strung across the water to measure the water's speed and depth.

Todd R. McQueen (ENLARGE)

Hydrologist Tim Pojunas measures the outflow from Buford Dam on the Chattahoochee River. Many depend on the measures. For example, kayakers use them to look for the best place to paddle.

"That's almost a bull's eye," said Brian McCallum, assistant director of the USGS Georgia Water Science Center. The pair are in the river less than half a mile downstream from Buford Dam.

The numbers referred to the volume of water flowing out of the dam in cubic feet per second. In this case, it was the equivalent of 381.3 million gallons — enough to fill about 575 Olympic-size swimming pools.

If that doesn't sound like critical information, ask a homeowner on Lanier whose dock is dry. Or an oyster man downstream in Apalachicola Bay, where the amount of water released from Lanier can make or break the ecosystem in a drought.

After the U.S. Army Corps of Engineers mistakenly released nearly 2 feet of water from Lanier in 2006, the U.S. Geological Survey took over operation of a gauge at the dam that measures the lake's elevation.

Together, the river and dam gauges work like a car's speedometer, telling the corps exactly how much water is being released into the Chattahoochee in real-time data every 15 minutes.

What the gauges don't do is track water quality. The USGS has only one gauge in the 65 river miles between metro Atlanta's sewage treatment plants and West Point Lake that measures the dissolved oxygen and acidity of the water, indicators of the water's health.

Monitoring plan

Sally Bethea, executive director of the Upper Chattahoochee Riverkeeper, a river advocate, said when people ask her about the health of the state's most important river, she has to hedge.

"I find myself explaining that there is so little monitoring done that we really don't know for sure," she said.

"I don't think a robust, comprehensive state water plan can possibly be put together without a much improved water monitoring and assessment program."

The state Environmental Protection Division, which is just beginning a three-year statewide water plan that will rely heavily on USGS monitoring data, said in a statement that the USGS monitoring program is a "vital asset that safeguards lives, protects property and ensures adequate water supplies."

To protect water supplies, the corps limits releases from the dam to the minimum necessary to meet metro Atlanta's water needs. Even so, the lake is 14 feet below full and lower than it has ever been at this time of year.

The rest of the state's 260 or so stream monitors tell a similar story.

"What's scary is we set the historic low last year, and [now] we're worse than last year on many of the gauges," McCallum said.

The gauges are used by kayakers looking for the best place to paddle and local water managers trying to decide whether there's enough water in a stream to pump out drinking water for their communities. Departments of transportation use them to determine how high to build bridges.

State's help

Georgia this year will pay about $1.6 million for the state's stream and groundwater monitoring program, including some water quality monitoring. The USGS, which runs the program, matches the state contribution. In past years, the state Legislature has threatened to ax part of the state's contribution, threatening maintenance of dozens of gauges.

Some of those have been operating for more than 100 years and are gold mines of scientific information.

To learn more about what the USGS does in Georgia, and to view the real-time data, go to http://ga.water.usgs.gov/.