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Summary of April 2009 Monthly Hydrologic Conditions

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

April 2009

Precipitation was above normal at the Atlantic City and Newark index stations, but below normal at the Trenton index station. Newark reported 4.61 inches, which is 117.6 percent of normal.  Atlantic City reported 6.23 inches, which is 180.6 percent of normal.  Trenton reported 3.08 inches, which is 85.56 percent of normal. Total precipitation over the past 12 months was: 44.06 inches at Newark, which is 2.19 inches below normal; 44.98 inches at Atlantic City, which is 4.39 inches above normal; and 40.15 inches at Trenton, which is 1.24 inches below normal.

Combined storage in the thirteen major water supply reservoirs as of April 30 was 72.484 billion gallons (90.1 percent of capacity), which is lower than the average April contents for the reference period 1961-1990.  The storage was 0.662 billion gallons more than one month ago and -6.073 billion gallons less 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 105 ft3/s, 50.0 percent of normal.  The monthly-mean discharge of the Great Egg Harbor River at Folsom was 104 ft3/s, 85.0 percent of normal.  The monthly mean discharge of the Delaware River at Trenton was 11670 ft3/s, 54.0 percent of normal. The observed daily mean discharge of the Delaware River at Trenton on April 30 was 6830 ft3/s.

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

Water quality parameters collected from the Delaware River at Trenton were within recorded historical monthly extremes. Water temperature ranged from 21.1 to 7.6 degrees Celsius. Dissolved oxygen ranged from 14.1 to 8.4 milligrams per liter. Specific conductance ranged from 209 to 152 microsiemens per centimeter at 25°C.

All of the files listed below are in Portable Document Format (PDF) which can be viewed/printed with the Adobe Acrobat® Reader, freely available for most computer platforms.

• Combined Storage in the 13 Major Water Supply Reservoirs
• Monthly precipitation at three selected sites
• Groundwater levels in selected Water-table observation wells
• Streamflow at selected sites
• Water quality for the Delaware River at Trenton