New Jersey Water Science Center
Summary of September 2006 Monthly Hydrologic Conditions
Compiled in cooperation with the New Jersey Department of Environmental Protection
Precipitation was below normal at the Newark index station, and above normal at the Atlantic City and Trenton index stations. Newark reported 3.38 inches, which is 84.3 percent of normal. Atlantic City reported 6.32 inches, which is 201 percent of normal. Trenton reported 4.49 inches, which is 131 percent of normal. Total precipitation over the past 12 months was: 54.88 inches at Newark, which is 8.63 inches above normal; 51.92 inches at Atlantic City, which is 11.33 inches above normal; and 49.70 inches at Trenton, which is 8.31 inches above normal.
On September 15, several townships in Ocean County experienced localized flooding after an isolated storm brought an average of 6 to 8 inches of rain in 12 hours or less, according to local newspapers. Several roads were closed and/or damaged due to the flooding, including the Garden State Parkway. Area homes, businesses, and a high school also reported flood damage.
The greatest recorded rainfall amount was in Bayville, with a total of 8.82 inches. As a result of the storm, Cedar Creek at Lanoka Harbor, a USGS stream gage approximately 3 miles south of Bayville, had a peak discharge 850 ft3/s, which ranks as 3rd highest on record. The gage has 33 years of peak record dating back to 1933. The September peak discharge is associated with a 20-year recurrence interval. The Lanoka Harbor gage can be affected by high tides, and although its peak coincided with the recorded high tides at Barnegat Bay at Seaside Heights and East Thorofare at Shipbottom, it does not appear that the tide was high enough to influence the peak at Lanoka Harbor. Instead the peak was the result of the heavy precipitation only.
Another notable peak occurred at the stream gage on Westecunk Creek at Stafford Forge, which is approximately 19 miles southwest of Bayville. The peak discharge of 150 ft3/s ranks as the 2nd highest in 21 years of record, dating back to 1974. This peak is associated with a 5-year recurrence interval.
Streamflow was above normal at all three index stations. The monthly-mean discharge at South Branch Raritan River near High Bridge was 100 ft3/s, 121 percent of normal. The monthly-mean discharge of the Great Egg Harbor River at Folsom was 86.3 ft3/s, 154 percent of normal. The monthly mean discharge of the Delaware River at Trenton was 12,310 ft3/s, 191 percent of normal. The observed daily mean discharge of the Delaware River at Trenton on September 31 was 11,300 ft3/s.
Combined storage in the thirteen major water supply reservoirs as of September 30 was 69.0 billion gallons (85.8 percent of capacity), which is greater than the average September contents for the reference period 1961-1990. The storage was 2.94 billion gallons more than one month ago and 30.2 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.
Groundwater levels, as measured in water-table observation wells for the month of September, were above normal at all three index wells. Levels decreased from last month at the Readington School 11 and Vocational School 2 wells, and increased from last month at the Morrell 1 well. Compared to last year, levels were higher at all three index wells.
Water quality parameters collected from the Delaware River at Trenton were within recorded historical monthly extremes. Water temperature ranged from 16.8 to 22.5 degrees Celsius. Dissolved oxygen ranged from 8.2 to 10.1 milligrams per liter. Specific conductance ranged from 127 to 215 microsiemens per centimeter at 25°C.
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