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Most Recent Hydrologic Conditions Report
December 12, 2017
Precipitation

The average observed precipitation for the Delaware River Basin above Montague, New Jersey for the period January 1, 2017 through December 11 was 44.78 inches, or 1.67 inches above normal. Similarly, the average observed precipitation for the Delaware River Basin above Trenton, New Jersey was 44.20 inches, or 1.37 inches below normal for this period. Also through December 11, the observed precipitation for Wilmington, Delaware was 39.19 inches, or 1.64 inches below normal.

The attached table (pdf 323 KB) summarizes precipitation for 2016 and 2017 for select stations in the Delaware River Basin.

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

Streamflow

The average observed streamflow of the Delaware River at Montague, New Jersey during November 2017 was 3,088 cubic feet per second (cfs), or 67.8-percent of the long-term average for the month. The average observed streamflow of the Delaware River at Trenton, New Jersey in November was 6,555 cfs, or 65.3-percent of the long-term average for the month.

During December 1-11, the average observed streamflow of the Delaware River at Montague was 1,934 cfs, or 38.3-percent of the long-term average for the month. Similarly, the average streamflow at Trenton was 3,970 cfs, or 30.7-percent of the long-term average for the month.

Attached are graphical presentations of daily mean streamflows at Montague and Trenton for the 365-day period ending December 11, 2017 (pdf 341 KB).

Reservoirs

Lower Basin

Lower Basin Reservoir Storage as of December 12, 2017:
Beltzville

13.5 bg usable, or 100.3% of usable storage

Blue Marsh

4.4 bg usable, or 100.0% of winter pool usable storage

Merrill Creek

13.5 bg usable, or 86.3% of usable storage (as of December 11)

Upper Basin

New York City (NYC) Delaware Basin Reservoir Storage as of December 12, 2017:
Pepacton

111.9 bg usable, or 79.8% of usable storage

Cannonsville

48.5 bg usable, or 50.7% of usable storage

Neversink

31.2 bg usable, or 89.2% of usable storage

Total

191.6 bg usable, or 70.7% of usable storage

The long-term median storage for the NYC Delaware basin reservoirs for December 12 is 208.2 bg, or 76.9% percent of usable storage.

Click here for information on the NYC Delaware Basin reservoir storage levels from January 2016 to the present.

Groundwater

The table below displays the current status (as of December 12, 2017) of groundwater levels for 13 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 SEPTEMBER 13, 2017

CURRENT INDICATOR STATUS AS OF DECEMBER 12, 2017

Sullivan

NY

USGS

Sv 535

2001

Normal

Below Normal

Wayne

PA

USGS

WN 64

1967

Above Normal

Normal

Monroe

PA

USGS

MO 190

1967

Normal

Drought Watch

Carbon

PA

USGS

CB 104

1969

Normal

Normal

Schuylkill

PA

USGS

SC 296

1975

Normal

Drought Watch

Lehigh

PA

USGS

LE 644

1971

Above Normal

Normal

Lebanon

PA

USGS

LB 372

1973

Above Normal

Normal

Bucks

PA

USGS

BK 1020

1975

Above Normal

Normal

Chester

PA

USGS

CH 10

1966

Drought Watch

Drought Warning

Delaware

PA

USGS

DE 723

1983

Normal

Drought Emergency

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 November, the seven-day average location of the salt front fluctuated between river miles 77 at the start of the month and 72 at the end of the month. The normal location of the salt front during November is river mile 70, a location that is eight miles downstream of the Delaware-Pennsylvania state line.

As of December 12, the salt front is estimated to be at river mile 74, which is five miles upstream of the normal location of the salt front during December.


 NOTES:

  • Report prepared by DRBC Staff.
  • Acknowledgments--Kimberly-Clark Corp.; NWS; NYC DEP; USACOE; USGS; Delaware Geological Survey (DGS).

  • Groundwater:
    • 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.
    • 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.