The observed precipitation for the Delaware River Basin above Montague, New Jersey for the period January 1, 2013 through May 6, 2013 was 8.86 inches, or 4.72 inches below normal. The observed precipitation for the Delaware River Basin above Trenton, New Jersey for the same period was 9.70 inches, or 4.73 inches below normal. Also for the same period, the observed precipitation for Wilmington, Delaware was 11.24 inches, or 3.16 inches below normal.

The attached table summarizes precipitation for 2012 and thus far in 2013 for select stations in the Delaware River Basin.

Precipitation Departure Maps (National Weather Service Middle Atlantic River Forecast Center's Web Site)

The average observed streamflow of the Delaware River at Montague, New Jersey in April 2013 was 5,297 cubic feet per second (cfs), or 46.5-percent of the long-term average for the month. The average observed streamflow of the Delaware River at Trenton, New Jersey in April 2013 was 11,197 cfs, or 55.7-percent of the long-term average for the month.

During May 1-6, the average observed streamflow of the Delaware River at Montague was 3,167 cfs, or 46.2-percent of the long-term average for the month. Similarly, the average streamflow at Trenton was 7,618 cfs, or 55.8-percent of the long-term average for the month.

Below are graphical presentations of daily mean streamflows at Montague and Trenton for the period from January 2012 through May 6, 2013.

Lower Basin

Lower Basin Reservoir Storage as of May 7, 2013:
Beltzville	13.94 billion gallons (bg) usable, or 100.1% of usable storage
Blue Marsh	5.64 bg usable, or 100.6% of summer pool usable storage
Merrill Creek	14.88 bg usable, or 94.9% of usable storage (as of May 5, 2013)

Upper Basin

New York City (NYC) Delaware Basin Reservoir Storage as of May 7, 2013:
Pepacton	137.145 bg usable, or 97.9% of usable storage
Cannonsville	94.200 bg usable, or 98.4% of usable storage
Neversink	33.441 bg usable, or 95.7% of usable storage
Total	264.786 bg usable, or 97.8% of usable storage

The long-term median storage for the NYC Delaware basin reservoirs for May 7 is 270.961 bg, or 100% percent of usable storage.

Attached is a graphical presentation of the reservoir storage levels from January 2012 to the present.

The table below displays the current status (May 7, 2013) of groundwater levels for 14 monitoring wells in the Delaware River Basin and compares them to levels reported at the last DRBC commission meeting. Refer to Groundwater Notes at the end of this report for more details about the wells. Water levels within the 25- to 75- percentile range are defined as “normal”.

During April 2013, the location of the seven-day average of the 250-ppm isochlor (salt front) ranged from river mile 70 to river mile 72. The normal location of the salt front during April is river mile 61, a location which is 17 miles downstream of the Delaware-Pennsylvania state line.

As of May 6 (the most recent date for available data), the salt front was located at river mile 70, which is six miles upstream of the normal location of the salt front during May. 

Prepared by DRBC Staff.
Acknowledgments: Kimberly-Clark Corp.; National Weather Service; New York City Department of Environmental Protection; U.S. Army Corps of Engineers; U.S. Geological Survey; and Delaware Geological Survey.

Groundwater Notes:

• Counties are ordered from North to South and East to West
• Indicator status for PA wells is based on 30-day moving average of daily measurements and 30-day moving average statistics.
• Indicator status for NY and NJ wells is based on a daily measurement and monthly-averaged statistics.
• Indicator status for the DE well is based on a monthly, instantaneous measurement and monthly-averaged statistics.
• The historical record for the NY well is too short to define a “normal” zone.  A graph of daily water levels is available on-line.
• Records of groundwater levels (depth to water) at each well can be statistically analyzed to determine the percent of time that a given value is not exceeded. For example, the 25-percentile groundwater level is the level that is not exceeded 25 percent of the time in the existing record. Such percentiles are useful to compare to current groundwater levels; the three most commonly reported are the 25-, 50- and 75-percentiles (the 50-percentile is also called the median value). In this report we follow the customary practice of referring to the range of values defined by the 25- and 75-percentile as the “normal” range.
• USGS uses the following definitions for water-level statistics: Normal (25- to 75- percentile flows); Drought Watch (10- to 25- percentile flows); Drought Warning (5- to 10- percentile flows); and Drought Emergency (0- to 5- percentile flows). Note: The categories labeled Drought Watch, Drought Warning, and Drought Emergency reflect only the relative range of the indicator values and are used for hydrological assessment purposes. Such category labels areindependent of official drought status which is declared only by the Governor of the respective state. Official declarations of drought stage are based upon a review of multiple ground and surface water conditions, soil moisture, precipitation, weather forecasts, purveyor reports, and other considerations.