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


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

 

Adjusted streamflow in the upper Delaware River basin during April was in the normal range. The maximum daily discharge of 18,100 cfs occurred on April 23. The minimum daily discharge was 7,190 cfs on April 3. 

On the basis of a 5-station average, precipitation during April was 4.63 inches, which was 123 percent of the 59-year average. The maximum daily-average precipitation during April was 0.92 inches on April 22. Precipitation in the upper Delaware River Basin during the past 12 months was 1.19 inches less than the long-term average. Precipitation during April was 0.87 inches more than the long-term average for the month. 

The monthly mean streamflow of the Delaware River at Montague, N.J. during April was 11,630 cfs (observed), which was 100 percent of the median. The flow at Montague, adjusted for diversions from the basin and change in storage in the major reservoirs was 13,370 cfs, or 96 percent of median (water years 1961-90).

Storage May 1, 2000, in Pepacton, Cannonsville and Neversink Reservoirs was 100.2 percent of capacity above the point of maximum depletion. The combined storage of 271 billion gallons was 15 billion gallons greater than that of one month ago and was 23 billion gallons more than that of one year ago. Median storage on the first day of May in 32 years of record is 271 billion gallons. Cannonsville Reservoir spilled continuously throughout the month and spilled more than 41 billion gallons. Pepacton Reservoir started spilling on April 15 and spilled more than 6 billion gallons through the end of the month.

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 April were above average in 9 of the wells. Water levels in most observation wells were trending upward in comparison to March 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 Apr. 1999

May 1999 to April  2000

 

Average

Actual

Percent of average

Excess (+) or deficit (-)

 

Amount

Cumulative

Amount

Cumulative

By month

Cumulative

By month

Cumulative

May

4.19 43.24 3.32 42.05 79 97 -.87 -1.19
June 3.94 39.05 2.28 38.73 58 99 -1.66 -.32
July 4.12 35.11 2.34 36.45 57 104 -1.78 +1.34
Aug. 3.87 30.99 3.00 34.11 78 110 -.87 +3.12
Sept. 3.74 27.12 9.11 31.11 244 115 +5.37 +3.99
Oct. 3.40 23.38 2.72 22.00 80 94 -.68 -1.38
Nov. 3.87 19.98 *2.75 19.28 71 96 -1.12 -.70
Dec. 3.37 16.11 1.63 16.53 48 103 -1.74 +.42
Jan. 3.02 12.74 3.22 14.90 107 117 +.20 +2.16
Feb. 2.64 9.72 3.07 11.68 116 120 +.43 +1.96
Mar. 3.32 7.08 3.98 8.61 120 122 +.66 +1.53
Apr. 3.76 3.76 4.63 4.63 123 123 +.87 +.87

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

April (observed 31,560 1940 11,670 3,322 1985 11,630 100
April (adjusted) 33,010 1940 13,900 3,847 1946 13,370 96
               
May (observed) 16,090 1943 7,019 2,215 1965    
May (adjusted) 18,970 1989 8,256 2,944 1941