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Summary of April 2013 Monthly Hydrologic Conditions

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

April 2013

Precipitation was below normal at all three index stations for the reference period 1981-2010. Newark reported 1.47 inches, which is ­­­­35.00 percent of normal.  Atlantic City reported 2.74 inches, which is 75.48 percent of normal.  Trenton reported 2.27 inches, which is 64.12 percent of normal. Total precipitation over the past 12 months was: 38.44 inches at Newark, which is 7.81 inches below normal; 53.50 inches at Atlantic City, which is 11.75 inches above normal; and 38.11 inches at Trenton, which is 8.33 inches below normal.

Combined storage in the thirteen major water supply reservoirs as of April 30 was 76.620 billion gallons (94.7 percent of capacity), which is higher than the average April contents for the reference period 1961-1990.  The storage was 1.371 billion gallons less than one month ago and 3.943 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 below 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 98.3 ft³/s, 48.7 percent of the long-term mean.  The monthly-mean discharge of the Great Egg Harbor River at Folsom was 94.9 ft³/s, 79.1 percent of the long-term mean.  The monthly mean discharge of the Delaware River at Trenton was 11,190 ft³/s, 52.7 percent of the long-term mean. The observed daily mean discharge of the Delaware River at Trenton on April 30  was 8,850 ft³/s.

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

Water-quality parameters collected from the Delaware River at Trenton were within the range of historical monthly values. Water temperature ranged from 6.9 to 16.4 degrees Celsius. Dissolved oxygen ranged from 9.3 to 14.2 milligrams per liter. Specific conductance ranged from 155 to 208 microsiemens per centimeter at 25°C.

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

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