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Summary of July 2009 Monthly Hydrologic Conditions

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

July 2009

Precipitation was above normal at all three index stations. Newark reported 6.60 inches, which is 141 percent of normal.  Atlantic City reported 3.86 inches, which is 100 percent of normal.  Trenton reported 5.93 inches, which is 139 percent of normal. Total precipitation over the past 12 months was: 49.98 inches at Newark, which is 3.73 inches above normal; 49.05 inches at Atlantic City, which is 8.46 inches above normal; and 45.23 inches at Trenton, which is 3.84 inches above normal.

Combined storage in the thirteen major water supply reservoirs as of July 31 was 77.65 billion gallons (96.58 percent of capacity), which is higher than the average July contents for the reference period 1961-1990.  The storage was 0.73 billion gallons less than one month ago and 13.06 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, Charlottesburg Reservoir, Echo Lake, Wanaque Reservoir and Spruce Run Reservoir.

Streamflow was above normal at the South Branch Raritan River near High Bridge and  Delaware River at Trenton index stations, but was below normal at the Great Egg Harbor River at Folsom index Station. The monthly-mean discharge at South Branch Raritan River near High Bridge was 120 ft3/s, 131 percent of normal.  The monthly-mean discharge of the Great Egg Harbor River at Folsom was 56.7 ft3/s, 86.4 percent of normal.  The monthly mean discharge of the Delaware River at Trenton was 9894 ft3/s, 136 percent of normal. The observed daily mean discharge of the Delaware River at Trenton on July 31 was 18200 ft3/s.

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

Water quality parameters collected from the Delaware River at Trenton were within recorded historical monthly extremes. Water temperature ranged from 27.0 to 20.9 degrees Celsius. Dissolved oxygen ranged from 12.8 to 6.8 milligrams per liter. Specific conductance ranged from 243 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