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November 30, 2010

Thirsty? Plenty of water in the reservoirs

Loch Raven ReservoirWith December arriving tonight along with what is expected to be a heavy rain, you could say we're entering the recharge season for the region's reservoirs.

Despite a summer of hot, dry weather, the city's reservoir system stands at 86 percent of capacity, according to the Department of Public Works. There are some 65 billion gallons in storage, about 10 billion short of capacity.

Liberty Reservoir is at 83 percent; Loch Raven is at 90 percent, and Prettyboy stands at 87 percent.

That's probably pretty good for this time of year, said Kurt L. Kocher, spokesman for the DPW:

"There have been so many fluctuations over the years that what is typical is hard to pinpoint.  In the mid 80s percent range is solid to a bit above average. We started out the year and went through most of last year with full or close to full reservoirs. We hit a dry spell in the summer with very hot temperatures which increases water usage. Higher temperatures meant high evaporation as well, then we had that one tropical event. Usually we would see a couple tropical storms replenish summer losses, but this is still quite good for late fall."

And with most vegetation now dormant for the winter, whatever falls in the watershed from now on will mostly seep into groundwater or flow into the surface system, recharging it for next year.

(SUN PHOTO: Barbara Haddock Taylor, Loch Raven Reservoir, November 2007)

Posted by Frank Roylance at 3:32 PM | | Comments (2)
Categories: By the numbers


Liberty Reservoir is at 83%?? The northern branch of it, which 140 crosses over looks like a mud flat. Must be the shallow end.

FR: The high end. It drains to the south.

Indeed; I've taken to calling this Carroll/Baltimore County end of the reservoir "Liberty Meadow." Got to say, that soil out there sure grows a nice bed of grass when it's not under water.

One thing that always had me wondering: We hear of "lake-effect snows" up around the Great Lakes, which, I surmise, are a consequence of cold air interacting with a large body of water (to put it simply). Is there a noticeable "lake-effect" on local weather from the reservoirs and the Bay? I guess a better question would be, "How big does the water feature have to be to have an effect?"

FR: Our reservoirs are not big enough for that. You need a pretty long "fetch" of wind across the water to produce the phenomenon. But there have been instances of "lake effect" snows off the Delaware Bay, Cape Cod Bay and similar-sized bodies of water. The Chesapeake Bay-effect snow I recall reading about involved northwest winds blowing down the bay, picking up moisture and dumping it as snow on the Norfolk area. I posted something here about it in 2007. Here's the link, though a few of the links within the post have expired.

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About Frank Roylance
This site is the Maryland Weather archive. The current Maryland Weather blog can be found here.
Frank Roylance is a reporter for The Baltimore Sun. He came to Baltimore from New Bedford, Mass. in 1980 to join the old Evening Sun. He moved to the morning Sun when the papers merged in 1992, and has spent most of his time since covering science, including astronomy and the weather. One of The Baltimore Sun's first online Web logs, the Weather Blog debuted in October 2004. In June 2006 Frank also began writing comments on local weather and stargazing for The Baltimore Sun's print Weather Page. Frank also answers readers’ weather queries for the newspaper and the blog. Frank Roylance retired in October 2011. Maryland Weather is now being updated by members of The Baltimore Sun staff

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