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Most Recent Hydrologic Conditions Report
December 11, 2018
Precipitation

The average observed precipitation for the Delaware River Basin above Montague, New Jersey for the period January 1 to December 10, 2018 was 57.69 inches, or 14.69 inches above normal. Similarly, the average observed precipitation for the Delaware River Basin above Trenton, New Jersey was 63.10 inches, or 17.65 inches above normal for this period. Also, through December 10, the observed precipitation for Wilmington, Delaware was 55.24 inches, or 14.52 inches above normal.

The attached table summarizes precipitation for 2017 and 2018 for select stations in the Delaware River Basin (pdf 500 KB).

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 2018 was 17,431 cubic feet per second (CFS), or 383-percent of the long-term average for the month. The average observed streamflow of the Delaware River at Trenton, New Jersey in November was 36,413 CFS, or 363-percent of the long-term average for the month.

During December 1-10, the average observed streamflow of the Delaware River at Montague was 13,343 CFS, or 264-percent of the long-term average for the month. Similarly, the average streamflow at Trenton was 27,830 CFS, or 215-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 10, 2018 (pdf 350 KB).

Reservoirs

Lower Basin Reservoir Storage as of December 11, 2018:

Beltzville

13.52 BG usable, or 100.3% of usable storage

Blue Marsh

4.42 BG usable, or 99.6% of winter pool usable storage

Merrill Creek

15.57 BG usable, or 99.3% of usable storage

Upper Basin - New York City (NYC) Delaware Basin Reservoir Storage as of December 11, 2018:

Pepacton

138.7 BG usable, or 99.6% of usable storage

Cannonsville

91.2 BG usable, or 97.6% of usable storage

Neversink

34.8 BG usable, or 100.2% of usable storage

Total

264.7 BG usable, or 99% of usable storage

The long-term median storage for the NYC Delaware Basin Reservoirs for December 11 is 204.01 BG, or 76.3% percent of usable storage.

Click here for information on the NYC Delaware Basin reservoir storage levels from January 2017 to the present.

Groundwater

The table below displays the current status (as of December 11, 2018) 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 11, 2018

CURRENT INDICATOR STATUS AS OF DECEMBER 11, 2018

Sullivan

NY

USGS

Sv 535

2001

Above Normal

Above Normal

Wayne

PA

USGS

WN 64

1967

Above Normal

Above Normal

Monroe

PA

USGS

MO 190

1967

Above Normal

Above Normal

Carbon

PA

USGS

CB 104

1969

Above Normal

Above Normal

Schuylkill

PA

USGS

SC 296

1975

Above Normal

Above Normal

Lehigh

PA

USGS

LE 644

1971

Above Normal

Above Normal

Lebanon

PA

USGS

LB 372

1973

Above Normal

Above Normal

Bucks

PA

USGS

BK 1020

1975

Above Normal

Above Normal

Chester

PA

USGS

CH 10

1966

Above Normal

Above Normal

Delaware

PA

USGS

DE 723

1983

Above Normal

Above Normal

Burlington

NJ

USGS

050689

1955

Normal

Above Normal

Cumberland

NJ

USGS

110042

1972

Normal

Above Normal

New Castle

DE

Delaware GS

Db24-18

1993

Normal
(through August 2018; more recent data is currently unavailable)

Above Normal
(through Nov. 12, 2018; more recent data is currently unavailable)

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 from river mile 69 early in the month to downstream of river mile 54 as of November 30. Above-average precipitation increased freshwater inflow into the Delaware Estuary, resulting in the downstream movement of the salt front. 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 10, the salt front continues to be located downstream of river mile 54. The normal location of the salt front during December is river mile 69.


 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.