HYDROLOGIC CONDITIONS REPORT October 21, 2009

The observed precipitation for the Delaware River Basin above Montague, New Jersey for the period January 1 through October 20, 2009 was 36.17 inches or 2.13 inches above-normal. The observed precipitation for the Delaware River Basin above Trenton, New Jersey for the same period was 35.83 inches or .68 inches above-normal. Also for the same period, the observed precipitation for Wilmington, Delaware was 36.62 inches or 2.27 inches above-normal.

The attached table summarizes precipitation for 2008 and thus far in 2009 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 September 2009 was 2,718 cubic feet per second (cfs), or 126-percent of the long-term average for the month. The average observed streamflow of the Delaware River at Trenton, New Jersey in September was 6,922 cfs, or 139-percent of the long-term average for the month.

For the period of October 1-20, the average observed streamflow of the Delaware River at Montague was 1,803 cfs, or 75-percent of the long-term average for the month.  Similarly, the average streamflow at Trenton was 5,247 cfs, or 99-percent of the long-term average for the month.

Attached are graphical presentations of daily mean streamflows at Montague and Trenton for the period from January 2008 through October 20, 2009.

Lower Basin

Lower Basin Reservoir Storage as of October 21, 2009:
Beltzville	12.98 billion gallons (bg) usable, or 99.8% of usable storage
Blue Marsh	6.04 bg usable, or 126.9% of winter pool usable storage This reservoir is currently being drawn-down from summer pool storage of 6.5 bg to winter pool storage of 4.76 bg.
Merrill Creek	14.961 bg usable, or 95.4% of usable storage (as of October 19, 2009)

Upper Basin

New York City (NYC) Delaware Basin Reservoir Storage as of October 21, 2009:
Pepacton	115.393 bg usable, or 82.3% of usable storage
Cannonsville	82.839 bg usable, or 86.6% of usable storage
Neversink	28.049 bg usable, or 80.3% of usable storage
Total	226.281 bg usable, or 83.5% of usable storage

Attached is a graphical presentation of the reservoir storage levels from January 2008 to the present.

The table below displays the current status (October 21, 2009) 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 September, the location of the seven-day average of the 250-ppm isochlor (salt line) ranged from river mile 67 to river mile 72.  The normal location of the salt line during September is river mile 79, a location which is one mile upstream of the Delaware-Pennsylvania state line.

As of October 20 (the most recent date for available data), the salt line was located at river mile 74. This location is seven miles downstream of the normal location for October.

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.

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