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Most Recent Hydrologic Conditions Report
September 13, 2016
Precipitation

The average observed precipitation for the Delaware River Basin above Montague, New Jersey[1] for the period January 1, 2016 through September 12, 2016 was 27.85 inches, or 3.54 inches below normal. Similarly, the average observed precipitation for the Delaware River Basin above Trenton, New Jersey[2] was 28.00 inches, or 5.17 inches below normal for this period. Also through September 12, the observed precipitation for Wilmington, Delaware was 29.48 inches, or 1.01 inches below normal.

The attached table summarizes precipitation for 2015 and 2016 for select stations in the Delaware River Basin.

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

 

[1]Average observed precipitation is based on the weighted average of 9 stations.

[2] Average observed precipitation is based on the weighted average of 99 stations.

Streamflow

The average observed streamflow of the Delaware River at Montague, New Jersey in August 2016 was 3,216 cubic feet per second (cfs), or 148.3-percent of the long-term average for the month. The average observed streamflow of the Delaware River at Trenton, New Jersey in August 2016 was 5,862 cfs, or 132-percent of the long-term average for the month.

During September 1-12, the average observed streamflow of the Delaware River at Montague was 1,822 cfs, or 90.4-percent of the long-term average for the month. Similarly, the average streamflow at Trenton was 2,905 cfs, or 65.4-percent of the long-term average for the month.

Below are graphical presentations of daily mean streamflows at Montague and Trenton for the 365-day period ending September 12, 2016.

Reservoirs

Lower Basin: DRBC began directing releases from Beltzville Reservoir on September 5 and Blue Marsh Reservoir on September 9 to meet the Trenton Flow Objective.

Lower Basin Reservoir Storage as of September 13, 2016:
Beltzville

12.88 billion gallons (bg) usable, or 95.5% of usable storage

Blue Marsh

5.43 bg usable, or 94.3% of summer pool usable storage

Merrill Creek

13.91 bg usable, or 88.7% of usable storage (as of Sept. 12)

Upper Basin

New York City (NYC) Delaware Basin Reservoir Storage as of September 13, 2016:
Pepacton

109.154 bg usable, or 77.9% of usable storage

Cannonsville

56.825 bg usable, or 59.4% of usable storage

Neversink

26.261 bg usable, or 75.2% of usable storage

Total

192.240 bg usable, or 71.0% of usable storage

The long-term median storage for the NYC Delaware basin reservoirs for September 13 is 194.3 bg, or 71.7% percent of usable storage.

Attached is a graphical presentation of the reservoir storage levels from January 2015 to the present.

Groundwater

The table below displays the current status (September 13, 2016) 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”.

COUNTY

STATE

AGENCY
DATA

WELL ID

YEAR RECORD BEGINS

INDICATOR STATUS AS OF JUNE 14, 2016

CURRENT INDICATOR STATUS AS OF
SEPT. 13, 2016

Sullivan

NY

USGS

Sv 535

2001

Normal

Below Normal

Wayne

PA

USGS

WN 64

1967

Drought Watch

Normal

Monroe

PA

USGS

MO 190

1967

Drought Watch

Drought Watch

Carbon

PA

USGS

CB 104

1969

Normal

Drought Watch

Schuylkill

PA

USGS

SC 296

1975

Drought Watch

Normal

Lehigh

PA

USGS

LE 644

1971

Drought Watch

Drought Watch

Berks

PA

USGS

BE 623

1975

Below Drought Emergency

Drought Emergency

Lebanon

PA

USGS

LB 372

1973

Normal

Drought Watch

Bucks

PA

USGS

BK 1020

1975

Normal

Normal

Chester

PA

USGS

CH 10

1966

Normal

Drought Watch

Delaware

PA

USGS

DE 723

1983

Drought Watch

Drought Watch

Burlington

NJ

USGS

050689

1955

Below Normal

Below Normal

Cumberland

NJ

USGS

110042

1972

Normal

Normal

New Castle

DE

Delaware GS

Db24-18

1993

Normal

Normal

Chlorides (Salt Front)

The salt front is defined as the 250 parts-per-million isochlor. The seven-day average location of the salt front is used by DRBC as an indicator of salinity intrusion in the Delaware Estuary. The salt front’s location fluctuates along the main stem Delaware River as streamflow increases or decreases in response to changing inflows, diluting or concentrating chlorides in the river.

During August, the location of the seven-day average of the 250-ppm isochlor (salt front) fluctuated between river mile 72 and river mile 73. The normal location of the salt front during August is river mile 74, a location which is four miles downstream of the Delaware-Pennsylvania state line.

As of September 12 (the most recent date for available data), the salt front was estimated to be at river mile 78, which is two miles upstream of the normal location of the salt front during September.

 


 

Report prepared by DRBC Staff.

Acknowledgments: Kimberly-Clark Corp.; NWS; NYC DEP; USACOE; USGS; Delaware Geological Survey (DGS).

NOTES:

  1. The groundwater 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. Drought Watch represents values in the 10-25 percentile depth, Drought Warning represents values in the 5-10 percentile depth, and Drought Emergency represents values in the 0-5 percentile depth. Such category labels are independent 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.
  2. Counties are ordered from North to South and East to West.
  3. Indicator status for PA wells is based on USGS 30-day moving average of daily measurements and 30-day moving average statistics.
  4. Indicator status for the NY and NJ wells is based on USGS daily measurements and monthly-averaged statistics.
  5. The indicator status for the DE well is based on Delaware Geological Survey (DGS) instantaneous measurements and monthly-averaged statistics, as available. The Average, 75-percentile, and 25-percentile curves used to determine status were calculated by DRBC staff using the period of record up to December 2000.
  6. 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.