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Global warming: Reservoir drawdowns a factor in atmospheric methane levels

Reservoir drawdowns appear to have the potential to increase heat-trapping methane in the atmosphere.

Study measures increased methane emissions as reservoir levels drop

By Summit Voice

Lowering water levels in reservoirs may significantly increase emissions of heat-trapping methane gas, according to Washington State University researchers who measured dissolved gases in the water column of Lacamas Lake.

Graduate student Bridget Deemer found methane emissions jumped 20-fold when the water level was drawn down. A fellow WSU-Vancouver student, Maria Glavin, sampled bubbles rising from the lake mud and measured a 36-fold increase in methane during a drawdown.

Methane is 25 times more effective than carbon dioxide at trapping heat in the atmosphere. And while dams and the water behind them cover only a small portion of the earth’s surface, they harbor biological activity that can produce large amounts of greenhouse gases. There are also some 80,000 dams in the United States alone, according to the U.S. Army Corps of Engineers National Inventory of Dams.

“Reservoirs have typically been looked at as a green energy source,” Deemer said. “But their role in greenhouse gas emissions has been overlooked.” Continue reading

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Morning photo: Lakes!

(or reservoirs … )

Clinton Gulch Reservoir at twilight. Summit County, Colorado.

By Bob Berwyn

SUMMIT COUNTY — For the purposes of my environmental reporting, I’m often careful to make a clear distinction between lakes and reservoirs — for good reason here in Colorado, where the majority of the population depends on stored water to drink, shower and for watering lawns.

Lakes follow a natural life cycle and rhythm, driven by precipitation, temperatures, inflows and other natural factors. But reservoirs are completely controlled by human actions and their levels rise and fall depending on human needs.

It’s an interesting distinction, and a lot of people still don’t get it, as evidenced by the fact that Dillon Reservoir, near my home in Frisco, Colorado, is still called Lake Dillon by many locals and visitors, and some still appear surprised when the water level falls by several feet within a few short weeks during dry years (like now).

But for the sake of the popular #FriFotos Twitter chat, I’ve included pictures of both lakes and reservoirs, focusing on their aesthetic qualities rather than technical definitions. Join the fun by posting your own photos, tagged with #FriFotos and enjoy lake pictures from around the world. Continue reading

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