We already know that December brought Baltimore it's biggest December snowfall (Dec. 18-19), and it's snowiest and wettest December on record. Now the U.S. Geological Survey is adding to the most impressive statistics that piled up during 2009.

The year ended with 55.57 inches of precipitation at BWI, making it the 6th wettest year since record-keeping began there in 1871. The record is 62.66 inches, set in 2003.

December streamflow in Maryland was above normal in 90 percent of the USGS monitoring stations. Seven rivers and creeks struck new monthly mean streamflow records, including the Chicamacomico, Choptank, Nanticoke, Nassawango, Piscataway, St. Clements and St. Jones.

The new December record on the Nanticoke (graph above) broke one that had stood since 1948. And it marked the second straight month of record streamflow there after five months of increasingly high rates.

Groundwater levels have also been responding to the wet weather.  Levels in 81 percent of the USGS monitoring wells were above normal. Five set new records for December, all in Southern Maryland or on the Eastern Shore, including Kent County, Del., Somerset, Charles, Queen Anne's and Wicomico counties in Maryland.

The well in Kent County, Del. (graph below) topped records for the second-straight month, topping the 1967 record by four feet.

The reservoirs that serve Washington and Baltimore are in good shape, of course. But there is one curiosity: Liberty Reservoir stands at just 85 percent of capacity, according to the USGS. Not sure yet what's up with that, but we're trying to get an answer. Some sort of maintenance work, perhaps. Or maybe all these water main breaks have drained it. We'll see. Stay tuned.

UPDATE: Kurt Kocher, at the city Department of Public Works, says the USGS figure on Liberty Reservoir is incorrect. "The reservoir has been full since September." he said.