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Summary of December 2011 Monthly Hydrologic Conditions

Compiled in cooperation with the New Jersey Department of Environmental Protection
Provisional assessment of hydrologic conditions in New Jersey

December 2011

Map of New Jersey showing sites where hydrologic conditions are reported.

Precipitation was above normal at the Newark and Trenton index stations, and below normal at the Atlantic City index station for the reference period 1981-2010. Newark reported 4.51 inches, which is ­­­­118 percent of normal.  Atlantic City reported 3.65 inches, which is 98.9 percent of normal.  Trenton reported 4.42 inches, which is 119 percent of normal. Total precipitation over the past 12 months was: 69.91 inches at Newark, which is 23.66 inches above normal; 48.53 inches at Atlantic City, which is 6.78 inches above normal; and 59.78 inches at Trenton, which is 13.34 inches above normal.

Combined storage in the thirteen major water supply reservoirs as of December 31 was 78.795 billion gallons (97.4 percent of capacity), which is higher than the average December contents for the reference period 1961-1990.  The storage was -0.728 billion gallons less than one month ago and 15.039 billion gallons more than one year ago.  The thirteen major water supply reservoirs are as follows: Lake Tappan, Woodcliff Lake, Oradell Reservoir, DeForest Lake, Splitrock Reservoir, Boonton Reservoir, Canistear Reservoir, Oak Ridge Reservoir, Clinton Reservoir, Charlotteburg Reservoir, Echo Lake, Wanaque Reservoir and Spruce Run Reservoir.

Streamflow was above the long-term monthly-mean for the reference period 1981-2010 at all three index stations. The monthly-mean discharge at South Branch Raritan River near High Bridge was 265 ft3/s, 174 percent of the long-term mean.  The monthly-mean discharge of the Great Egg Harbor River at Folsom was 159 ft3/s, 162 percent of the long-term mean.  The monthly mean discharge of the Delaware River at Trenton was 26,510 ft3/s, 175 percent of the long-term mean. The observed daily mean discharge of the Delaware River at Trenton on December 31 was 23,900 ft3/s.

Groundwater levels, as measured in water-table observation wells for the month of December, were above normal at all three index wells. Levels increased from last month at the Vocational School 2 index well, but decreased from last month at the Readington School 11 and Morrell 1 index wells. Levels were higher than one year ago at all three index wells.

Water-quality parameters collected from the Delaware River at Trenton were within recorded historical monthly extremes. Water temperature ranged from 3.0 to 9.1 degrees Celsius. Dissolved oxygen ranged from 11.3 to 13.8 milligrams per liter. Specific conductance ranged from 111 to 177 microsiemens per centimeter at 25°C.

Note: The preceding data is preliminary and subject to revision.

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