May 2008

Precipitation was above normal at the Newark and Atlantic City index stations, but below normal at the Trenton index station. Newark reported 3.95 inches, which is 88.57 percent of normal.  Atlantic City reported 4.59 inches, which is 135.8 percent of normal.  Trenton reported 4.83 inches, which is 128.8 percent of normal. Total precipitation over the past 12 months was: 50.29 inches at Newark, which is 4.04 inches above normal; 43.57 inches at Atlantic City, which is 2.98 inches above normal; and 39.93 inches at Trenton, which is -1.46 inches below normal.

Combined storage in the thirteen major water supply reservoirs as of May 31 was 77.50 billion gallons (96.4 percent of capacity), which is higher than the average May contents for the reference period 1961-1990.  The storage was -1.053 billion gallons lower than one month ago and 0.896 billion gallons higher 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, Charlottesburg Reservoir, Echo Lake, Wanaque Reservoir and Spruce Run Reservoir.                   

Streamflow was below normal at all three index stations. The monthly-mean discharge at South Branch Raritan River near High Bridge was 127 ft3/s, 74.3 percent of normal.  The monthly-mean discharge of the Great Egg Harbor River at Folsom was 85.8 ft3/s, 84.1 percent of normal.  The monthly mean discharge of the Delaware River at Trenton was 10290 ft3/s, 66.8 percent of normal. The observed daily mean discharge of the Delaware River at Trenton on May 31 was 6320 ft3/s.   

Ground-water levels, as measured in water-table observation wells for the month of May, were below normal at Vocational School index wells, and above normal at the Readington School and the Morrell 1 index well. Levels increased from last month at both the Readington School and Vocational School index wells, but decreased from last month at the Morrell 1 index well. Levels were higher than one year ago at the Readington School and Morrell 1 index wells, but lower than one year ago at the Vocational School index station.  

Water quality parameters collected from the Delaware River at Trenton were within recorded historical monthly extremes. Water temperature ranged from 21.5 to 12.5 degrees Celsius. Dissolved oxygen ranged from 12.4 to 8.6 milligrams per liter. Specific conductance ranged from 221 to 174 microsiemens per centimeter at 25°C.

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

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Combined Storage in the 13 Major Water Supply Reservoirs

Monthly precipitation at three selected sites

Ground-water levels in selected Water-table observation wells

Streamflow at selected sites

Water quality for the Delaware River at Trenton