New Jersey Water Science Center
Summary of May 2011 Monthly Hydrologic Conditions
Compiled in cooperation with the New Jersey Department of Environmental Protection
Precipitation was above normal at the Newark index station and below normal at the Trenton and Atlantic City index stations. Newark reported 4.78 inches, which is 107.2 percent of normal. Atlantic City reported 3.33 inches, which is 98.52 percent of normal. Trenton reported 3.73 inches, which is 99.47 percent of normal. Total precipitation over the past 12 months was: 44.24 inches at Newark, which is -2.01 inches below normal; 37.07 inches at Atlantic City, which is -3.52 inches below normal; and 39.74 inches at Trenton, which is -1.65 inches below normal.
Combined storage in the thirteen major water supply reservoirs as of May 31 was 79.43 billion gallons (98.2 percent of capacity), which is higher than the average May contents for the reference period 1961-1990. The storage was -0.407 billion gallons less than one month ago and 3.211 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, Charlotteburg Reservoir, Echo Lake, Wanaque Reservoir and Spruce Run Reservoir.
Streamflow was above the long-term monthly-mean for the reference period 1971-2000 at the South Branch Raritan River near High Bridge and Delaware River at Trenton index stations, and below the long-term monthly-mean for the reference period 1971-2000 at the Great Egg Harbor River at Folsom index station. The monthly-mean discharge at South Branch Raritan River near High Bridge was 220 ft3/s, 129 percent of the long-term mean. The monthly-mean discharge of the Great Egg Harbor River at Folsom was 88.5 ft3/s, 86.8 percent of the long-term mean. The monthly mean discharge of the Delaware River at Trenton was 26,180 ft3/s, 170 percent of the long-term mean. The observed daily mean discharge of the Delaware River at Trenton on May 31 was 17,200 ft3/s.
Groundwater levels, as measured in water-table observation wells for the month of May, were above normal at the Readington School 11 index well and below normal at the Morrell 1 and Vocational School 2 index wells. Levels decreased from last month. Levels were higher than one year ago at the Readington School 11 and Morrell 1 index well, but were lower than one year ago at the Vocational School 2 index well.
Water-quality parameters collected from the Delaware River at Trenton were within recorded historical monthly extremes. Water temperature ranged from 12.3 to 23.7 degrees Celsius. Dissolved oxygen ranged from 8.3 to 10.9 milligrams per liter. Specific conductance ranged from 99 to 196 microsiemens per centimeter at 25°C.
Note: The preceding data is preliminary and subject to revision.
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