SUMMARY OF HYDROLOGIC CONDITIONS
FOR THE
UPPER DELAWARE RIVER BASIN
July 2000


Prepared by the
Office of the Delaware River Master
Milford, Pennsylvania

Adjusted streamflow in the upper Delaware River basin during July was excessive. The maximum daily discharge of 8,690 cfs occurred on July 17. The minimum daily discharge was 1,980 cfs on July 10. 

On the basis of a multi-station average, precipitation during July was 4.24 inches, which was 104 percent of the 59-year average. The maximum daily-average precipitation during July was 1.52 inches on July 16. Precipitation in the upper Delaware River Basin during the past 12 months was 8.34 inches greater than the long-term average. Precipitation during July was 0.15 inches more than the long-term average for the month. 

The monthly mean streamflow of the Delaware River at Montague, N.J. during July was 3,586 cfs (observed), which was 144 percent of the median. The flow at Montague, adjusted for diversions from the basin and change in storage in the major reservoirs was 3,755 cfs, or 168 percent of median (water years 1961-90).

Storage August 1, 2000, in Pepacton, Cannonsville and Neversink Reservoirs was 98.4 percent of capacity above the point of maximum depletion. The combined storage of 267 billion gallons was 4.3 billion gallons less than that of one month ago and was 69 billion gallons more than that of one year ago. Median storage on the first day of August in 33 years of record is 230 billion gallons. Cannonsville Reservoir stopped spilling July 5 and spilled 84 million gallons during the month. Pepacton Reservoir stopped spilling on July 1. Neversink Reservoir spilled from July 15 to July 21 and spilled more than 3 billion gallons.

As part of a statewide network, the USGS operates 14 observation wells in the Pennsylvania part of the Delaware River Basin. Mean water levels during July were above average in 7 of the wells. Water levels in 13 of the wells were trending downward in comparison to June levels. Water levels in all 14 wells were above the July 1999 levels.

 

HYDROLOGIC CONDITIONS IN THE UPPER DELAWARE RIVER BASIN
Compiled by the Office of the Delaware River Master, Milford, Pa.
(Preliminary data - subject to revision)
PRECIPITATION, IN INCHES

 

 

 

Dec. 1940 to July 1999

August 1999 to July 2000

Average

Actual

Percent of average

Excess (+) or deficit (-)

Amount

Cumulative

Amount

Cumulative

By month

Cumulative

By month

Cumulative

Aug.

3.87 43.16 3.00 51.50 78 119 -.87 +8.34
Sept. 3.74 39.29 9.11 48.50 244 123 +5.37 +9.21
Oct. 3.40 35.55 2.72 39.39 80 111 -.68 +3.84
Nov. 3.87 32.15 2.75 36.67 71 114 -1.12 +4.52
Dec. 3.37 28.28 1.84 33.92 55 120 -1.53 +5.64
Jan. 3.02 24.91 3.44 32.08 114 129 +.42 +7.17
Feb. 2.64 21.89 3.26 28.64 123 131 +.62 +6.75
Mar. 3.32 19.25 *4.08 25.38 123 132 +.76 +6.13
Apr. 3.76 15.93 4.63 21.30 123 134 +.87 +5.37
May 4.17 12.17 5.76 16.67 138 137 +1.59 +4.50
June 3.91 8.00 6.67 10.91 171 136 +2.76 +2.91
July 4.09 4.09 4.24 4.24 104 104 +.15 +.15

Note: Amount shown in cumulative columns is total from month shown to present.

* Revised since previous month

STREAMFLOW, IN CFS

DELAWARE RIVER AT MONTAGUE, N.J.

Month

1940-98

 

Percent of

Maximum

Median

Minimum

Monthly mean

median

July (observed) 11,220 (1945) 2,486 864 (1954) 3,586 144
July (adjusted) 11,470 (1945) 2,193 391 (1965) 3,755 171
 
August (observed) 14,230 (1955) 2,105 715 (1954)    
August (adjusted) 17,410 (1955) 1,418 364 (1964)