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| Open File Report |
by Bruce E. Krejmas, Gary N. Paulachok, and William J. Carswell, Jr.
U.S. Geological Survey Open File Report 2005-1204
Table of Contents
RIVER MASTER LETTER OF TRANSMITTAL AND SPECIAL REPORT
September 1, 2005
The Honorable
William H. Rehnquist
Chief Justice of the United States
The Honorable
Ruth Ann Minner
Governor of Delaware
The Honorable
Richard J. Codey
Acting Governor of New Jersey
The Honorable
George E. Pataki
Governor of New York
The Honorable
Edward G. Rendell
Governor of Pennsylvania
The Honorable
Michael R. Bloomberg
Mayor of the City of New York
No. 5, Original.—October Term, 1950
v.
State of New York and City of New York, Defendants,
Commonwealth of Pennsylvania and State of Delaware, Intervenors.
Dear Sirs and Madam:
For the record and in compliance with the provisions of the Amended Decree of the Supreme Court of the United States entered June 7, 1954, I am transmitting herewith the 48th Annual Report of the River Master of the Delaware River for the 12-month period from December 1, 2000, to November 30, 2001. In this report, this period is referred to as the River Master report year or the report year.
During the 2001 River Master report year, monthly precipitation in the upper Delaware River Basin ranged from 36 percent of the long-term average during April and November 2001 to 149 percent of the long-term average during March 2001. Total precipitation during the report year was 8.33 inches less than the long-term average. Precipitation during the December to May period, when reservoirs typically refill, was 2.80 inches less than the 60-year average. Precipitation during the report year was above normal in December, March, June, and September, and below normal in the other 8 months.
On December 1, 2000, when the report year began, combined storage in the New York City reservoirs in the upper Delaware River Basin was 220.805 billion gallons (Bgal) or 81.5 percent of combined storage capacity. Median combined storage on December 1, computed on the basis of 33 years of record, is 166.770 Bgal. Operations on December 1, 2000, were being conducted as prescribed by the Decree. Storage varied little during winter but, in early April, storage increased rapidly. The reservoirs were full in April and all the reservoirs spilled. Storage declined gradually from May to July, and then more rapidly from July to November. On the basis of combined storage, the basin entered drought watch on October 29, 2001, and drought warning on November 4, 2001. On November 30, 2001, combined storage in the New York City reservoirs was 66.406 Bgal, or 24.5 percent of combined capacity. Operations in the basin were conducted at reduced levels from October 29 to November 30, 2001.
The Delaware River Master Advisory Committee met at Matamoras, Pennsylvania, on April 25, 2001, to discuss hydrologic conditions in the basin and operational procedures for the 2001 reservoir-release season. During the report year, the following individuals served as members of the Advisory Committee:
| Delaware | Dr. Robert R. Jordan |
| New Jersey | Robert C. Shinn, Jr. |
| New York | N.G. Kaul |
| New York City | Joel A. Miele, Sr. |
| Pennsylvania | Irene B. Brooks |
The River Master informed the Committee that, on the basis of information provided by New York City, the excess-release quantity beginning June 15 was 7.381 Bgal. On the basis of modifications to reservoir release programs in Delaware River Basin Commission (DRBC) Docket No. D-77-20 CP (Revision No. 4), the excess-release quantity was to be used for various purposes. On the basis of hydrologic conditions in early June, the Parties to the Decree unanimously agreed to release that portion of the excess-release quantity that could be released starting June 15.
During the report year, the River Master and staff participated in a number of water-supply related meetings of the Delaware River Basin Commission. The Deputy Delaware River Master met periodically with representatives of the Parties to the Decree as a non-voting member of DRBC’s Flow Management Technical Advisory Committee. Issues of particular interest to the River Master involved management of reservoir releases and regulated streamflow in the upper Delaware River Basin.
The U.S. Geological Survey (USGS) continued the operation of its field office of the Delaware River Master at Milford, Pennsylvania. Gary N. Paulachok, Deputy Delaware River Master, continued in charge of the office, assisted by Bruce E. Krejmas, Hydrologist, and Heidi L. Soden, Secretary.
During the year, the USGS office at Milford continued the weekly distribution of a summary hydrologic report. These reports contain preliminary data on precipitation in the upper Delaware River Basin, releases and spills from New York City reservoirs to the Delaware River, diversions to the New York City water-supply system, reservoir contents, daily segregation of flow of the Delaware River at the Montague gaging station, and diversions by New Jersey. The reports were distributed to members of the Delaware River Master Advisory Committee and to other parties interested in Delaware River operations. A monthly summary of hydrologic conditions also was provided to Advisory Committee members.
The first section of this report documents Delaware River operations during the report year. During the year, the City of New York diverted 243.306 Bgal from the Delaware River Basin and released 125.440 Bgal from Pepacton, Cannonsville, and Neversink Reservoirs to the Delaware River. The River Master directed releases from these reservoirs to the Delaware River totaling 100.984 Bgal.
The second section of this report describes water quality at various monitor sites on the Delaware Estuary. The section includes basic data on chemical properties and physical characteristics of the water and presents summary statistics on the data.
Throughout the year, diversions to supply water to New York City and releases designed to maintain the flow of the Delaware River at Montague were made as directed by the River Master. Diversions by New York City from its reservoirs in the Delaware River Basin did not exceed the limit stipulated by the Decree. Diversions by New Jersey also were within mandated limits.
The River Master and staff are grateful for the continued cooperation and support of the Parties to the Decree. Also, the contributions of the PPL Corporation and Southern Company in informing the River Master of plans for power generation and furnishing data on reservoir releases are greatly appreciated.
A draft version of this report was furnished to the River Master Advisory Committee members for review and comment. These comments have been incorporated into this report.
| Sincerely yours, /Signed/ Stephen F. Blanchard Delaware River Master |
A Decree of the United States Supreme Court in 1954 established the position of Delaware River Master. In addition, the Decree authorizes diversions of water from the Delaware River Basin and requires compensating releases from certain reservoirs, owned by New York City, to be made under the supervision and direction of the River Master. The Decree stipulates that the River Master will furnish reports to the Court, not less frequently than annually. This report is the 48th Annual Report of the River Master of the Delaware River. It covers the 2001 River Master report year, that is, the period from December 1, 2000, to November 30, 2001.
During the report year, precipitation in the upper Delaware River Basin was 8.33 inches less than the long-term average. Combined storage in Pepacton, Cannonsville, and Neversink Reservoirs was above the long-term median on December 1, 2000. Reservoir storage increased rapidly in early April 2001 and all the reservoirs filled and spilled. Storage declined steadily from early July to November. Delaware River operations were conducted as prescribed by the Decree from December 1, 2000, to October 28, 2001, and at reduced levels from October 29, 2001, to November 30, 2001, when drought watch and warning conditions prevailed.
Diversions from the Delaware River Basin by New York City and New Jersey were in compliance with the terms of the Decree or with the reduced limits in effect during drought watch and warning conditions. Reservoir releases were made as directed by the River Master at rates designed to meet the flow objective for the Delaware River at Montague, N.J., on 155 days during the report year. Releases were made at experimental conservation rates—or rates designed to relieve thermal stress and protect the fishery in the tailwaters of the reservoirs—on all other days.
During the report year, New York City and New Jersey complied fully with the terms of the Decree, and during drought watch and warning conditions, complied fully with the terms of the “Interstate Water Management Recommendations of the Parties to the Decree” (DRBC Resolution 83-13), and directives and requests of the River Master.
As part of a long-term program, the quality of water in the Delaware Estuary between Trenton, N.J., and Reedy Island Jetty, Del., was monitored at various locations. Data on water temperature, specific conductance, dissolved oxygen, and pH were collected by electronic instruments at four sites. In addition, discrete water-quality data were collected at 3 sites on a monthly basis and at 19 sites on a semimonthly basis.
An Amended Decree of the United States Supreme Court, entered June 7, 1954, authorized diversions of water from the Delaware River Basin and provided for releases of water from certain New York City reservoirs to the Delaware River. The Decree stipulated that these diversions and releases were to be made under the supervision and direction of the Delaware River Master. The Decree also stipulated that reports on Delaware River operations be made to the Court not less frequently than annually. This report documents operations from December 1, 2000, to November 30, 2001, or the 2001 River Master report year. The report also presents information on water quality in the Delaware Estuary during the report year.
Some hydrologic data presented in this report include records of streamflow and water quality for U.S. Geological Survey (USGS) data-collection stations. These records were collected, computed, and furnished by the offices of the U.S. Geological Survey at Troy, New York; Malvern and New Cumberland, Pennsylvania; and West Trenton, New Jersey, in cooperation with the States of New York and New Jersey, the Commonwealth of Pennsylvania, and the City of New York. The locations of major streams and reservoirs, and selected streamflow-gaging stations in the Delaware River Basin are shown in figure 1.
Figure 1. Delaware River Basin above Wilmington, Delaware.
The River Master’s daily operation records were prepared from hydrologic data collected chiefly on a day-to-day basis. Data for these records were collected and computed by the Office of the Delaware River Master or were furnished by the following agencies and utilities: Data for Pepacton, Cannonsville, and Neversink Reservoirs by the New York City Department of Environmental Protection, Bureau of Water Supply; for Lake Wallenpaupack by the PPL Corporation; and for Rio Reservoir by Southern Company. Precipitation data and quantitative precipitation forecasts were provided by the National Weather Service.
The following definitions apply to various terms and procedures used in the operations documented in this report. A table for converting inch-pound units to the International System of Units (SI) is given on page vi.
Precipitation in the Delaware River Basin above Montague totaled 34.93 in. for the 2001 report year and was 8.33 in. less than the long-term average, December 1940-November 2000. Monthly precipitation ranged from 36 percent of the long-term average in April and November 2001 to 149 percent of average in March 2001. Data on monthly precipitation during the report year and long-term average precipitation are presented in table 1. These data were computed from records collected by the National Weather Service; the New York City Department of Environmental Protection, Bureau of Water Supply; and the River Master, at 10 geographically distributed stations.
The seasonal period from December to May typically is when surface-water and ground-water reservoirs fill. During this period in 2000-2001, total average precipitation at the 10 stations was 17.52 in., which is 86 percent of the 60-year average. During June to November, average precipitation at the 10 stations was 17.41 in., which is 76 percent of the long-term average. The maximum monthly precipitation was 7.24 in. in December 2000, measured at Liberty, New York; the minimum monthly precipitation was 0.65 in. in October 2001, measured at Rock Hill, New York (locations shown on Figure 1).
Operations on December 1, 2000, were conducted as prescribed by the Decree. The Montague flow objective was 1,810 ft3/s, and the allowable diversions to New York City and New Jersey were 800 Mgal/d and 100 Mgal/d, respectively. Conservation releases from New York City reservoirs were made at the experimental release rates shown in table 2.
From December 2000 to May 2001, the first half of the report year, total precipitation was 2.80 in. below average. Monthly precipitation ranged from 36 percent of the long-term average in April 2001 to 149 percent in March 2001 (table 1). Runoff in the upper basin was in the normal range during February; above normal during December and April; and below normal during January, March, and May.
On December 1, 2000, when the 2001 report year began, Pepacton Reservoir contained 109.916 Bgal of water in storage above the point of maximum depletion, or 78.4 percent of the 140.190 Bgal storstorage capacity. Cannonsville Reservoir contained 87.204 Bgal, or 91.1 percent of the 95.706 Bgal storage capacity. Neversink Reservoir contained 23.685 Bgal, or 67.8 percent of the 34.941 Bgal storage capacity. Combined storage in these reservoirs on December 1 was 220.805 Bgal, or 81.5 percent of combined capacity. Daily storage in Pepacton, Cannonsville, and Neversink Reservoirs is shown in tables 3, 4, and 5, respectively, and combined storage during the report year is illustrated in Figure 2.
Figure 2. Operation curves and actual contents for New York City reservoirs in the Delaware River Basin, Decembe 1, 2000 to November 30, 2001.
From December to May, inflow to the City’s reservoirs typically exceeds outflow and storage increases. The average inflow to Pepacton, Cannonsville, and Neversink Reservoirs for these 6 months during the 60-year period from December 1940 to May 2000 was 303.3 Bgal. During the corresponding 6 months of the current report year, inflow to the three reservoirs totaled 249.7 Bgal. Evaporation loss is not included in the computations.
Combined storage fluctuated moderately from December to March. Precipitation at the end of March, in combination with snow melt from an above-average snowpack, resulted in a storage increase to full capacity during mid-April. Combined storage decreased gradually through May. The combined storage of the reservoirs was about 93 percent of full capacity at the end of May.
Combined storage in the three New York City reservoirs was 220.704 Bgal on November 30, 2000 and 252.898 Bgal on May 31, 2001, a net increase of 32.194 Bgal or 11.9 percent of capacity. The maximum combined storage during the period from December to May was 276.596 Bgal on April 16. Typically, maximum storage in the individual reservoirs occurs on different days. Maximum storage in Pepacton Reservoir during the December to May period was 141.561 Bgal on April 17; maximum storage in Cannonsville Reservoir was 102.434 Bgal on April 11; and maximum storage in Neversink Reservoir was 35.553 Bgal on April 10, 2001. Pepacton Reservoir spilled April 14-26, Cannonsville Reservoir spilled from December 18 to January 10 and from March 21 to May 11, and Neversink Reservoir spilled April 8-28. A total of 73.033 Bgal of water spilled from these reservoirs during the December to May period.
During the December to May period, diversions to Rondout Reservoir by New York City totaled 118.178 Bgal (649 Mgal/d). The forecasted discharge at Montague, exclusive of water released from the City reservoirs, was greater than the flow objective on 10 days in May, and releases were directed. The observed daily mean discharge at Montague was less than the applicable flow objective on 5 days, but all observed flows were within 15 percent of the flow objective. Applicable design rates for the gaging station on the Delaware River at Montague, N.J. are presented in table 6.
Monthly precipitation from June to November was above average in June and September and below average in July, August, October and November. Total precipitation during the period was 17.41 in. or 5.53 in. less than the 60-year average (table 1).
Releases were directed to meet the Montague flow objective on 145 days between June 1 and November 30, 2001, when the forecasted discharge at Montague, exclusive of water released from the New York City reservoirs, was less than the flow objective. Releases at experimental conservation rates or at rates designed to protect the fishery were made at other times during the period. On the basis of River Master records, a total of 5,223 (ft3/s)-d or 3.384 Bgal was released from May 31 to July 25 for fisheries protection in the upper Delaware River Basin.
From June 1 to June 14, the Montague flow objective was 1,750 ft3/s (table 6). The forecasted flow, exclusive of releases from Pepacton, Cannonsville, and Neversink Reservoirs, did not fall below the flow objective and no releases were directed.
The New York City Department of Environmental Protection, Bureau of Water Supply, Quality, and Protection furnished the River Master with the following data for the 2001 calendar year, as stipulated by the Decree:
On the basis of the Decree and the above data, the aggregate quantity of excess-release water was 83 percent of (607.725 - 598.832), or 7.381 Bgal.
Data on water consumption by the City of New York for each calendar year since 1950, from all sources of supply, are presented in table 7.
On April 19, 2001, the reservoir release programs, described in DRBC Docket No. D-77-20 CP (Revision No. 4), were extended to April 30, 2002. A copy of the agreement extending the programs is included in this report as Appendix A. As part of these programs, 50 percent of the annual excess-release quantity was placed in a fishery-protection bank to augment releases during drought warning. The remainder of the excess-release quantity could be used to provide an increase in the Montague flow objective or could be banked in accordance with the procedures outlined in the Lower Basin Drought Management Plan.
On June 15, 2001, the beginning of the seasonal excess-release period, the Montague flow objective was increased to 1,800 ft3/s (table 6). Storage in the New York City reservoirs declined rapidly throughout summer and fall in response to below normal runoff and above normal releases required to meet the Montague flow objective (fig. 2). Combined storage declined below the drought watch level of the operation curves on October 24, 2001, and then remained below that level for 5 consecutive days. On October 29, 2001, the Montague flow objective was reduced to 1,655 ft3/s and the allowable diversions to New York City were reduced to 680 Mgal/d, as required by DRBC Docket No. D-77-20 CP (Revision No. 4). Combined storage continued to decline to the drought warning level on November 4, 2001, and consequently, the Montague flow objective was reduced to 1,550 ft3/s and allowable diversions to New York City and New Jersey were reduced to 560 Mgal/d and 70 Mgal/d, respectively. Storage continued to decline and reached an emergency level on November 26, 2001. The 5-consecutive days criterion for implementing drought-emergency operations was not met before the end of the River Master year.
Between June 15 and November 30, 2001, the forecasted flow at Montague, exclusive of releases from the New York City reservoirs, was less than the flow objective on 145 days and releases were directed. On 81 days during the June 15 to November 30 period, the observed flow was less than the flow objective. On 71 of these 81 days, observed flows were within 10 percent of the flow objective. Applicable design rates for the gaging station Delaware River at Montague, N.J. are presented in table 6.
The total discharge measured at Montague, the portion derived from uncontrolled runoff from the drainage area below the reservoirs, the portion contributed by power reservoirs, and the portion contributed by Pepacton, Cannonsville, and Neversink Reservoirs from July to November are shown in Figure 3. In developing the water budget for Montague, uncontrolled runoff was computed as the residual of observed flow minus releases and spill from all reservoirs, and, therefore, was subject to errors in observations, transit times, and routing of the various components of flow. The conservation release from Rio Reservoir is included in the uncontrolled-runoff component. The net effect of these uncertainties is incorporated in the derived hydrograph of uncontrolled runoff. Diversions to Rondout Reservoir from June 1 to November 30, 2001, totaled 125.128 Bgal.
Figure 3. Components of flow, Delaware River at Montague, N.J., July 1 to November 30, 2001.
From December 1, 2000, to November 30, 2001, diversions from three New York City reservoirs in the Delaware River Basin to Rondout Reservoir totaled 243.306 Bgal, and all releases from the three reservoirs to the Delaware River totaled 125.440 Bgal. River Master directed releases to the Delaware River from these reservoirs totaled 100.984 Bgal.
During the year, maximum storage in Pepacton Reservoir was 141.561 Bgal on April 17; 102.434 Bgal in Cannonsville Reservoir on April 11; and 35.553 Bgal in Neversink Reservoir on April 10. Maximum combined storage in the three reservoirs was 276.596 Bgal on April 16, 2001. The total combined spill for the year was 73.033 Bgal.
During the year, minimum storage in Pepacton Reservoir was 51.915 Bgal (37.0 percent of capacity) on November 30, 2001; 3.245 Bgal (3.4 percent of capacity) in Cannonsville Reservoir on November 26, 2001; and 11.019 Bgal (31.5 percent of capacity) in Neversink Reservoir on November 30, 2001. Minimum combined storage in the three reservoirs was 66.406 Bgal on November 30, 2001.
On November 30, 2001, the end of the report year, combined storage in the three reservoirs was 66.406 Bgal or 24.5 percent of combined capacity. From December 1, 2000, to November 30, 2001, the net change in combined storage was -154.298 Bgal, or a decrease in contents of 57.0 percent of combined capacity.
The distribution of combined storage for the three reservoirs on the first day of the month, for the reference period June 1967 to November 2000, and for the report year, is shown in Figure 4. Storage was above median from December to March and below median from April to November. Storage was above the 75th percentile in January and below the 25th percentile in June, October, and November.
Figure 4. Combined storage in Pepacton, Cannonsville, and Neversink Reservoirs on the first day of the month, December 2000 to November 2001 (this report year), and summary statistics for the period of record, June 1967 to November 2000.
An agreement between the PPL Corporation and New York City provides for supplemental releases from the Wallenpaupack hydroelectric powerplant if the Delaware River Basin Commission requests compensation for water consumed at the corporation’s Martins Creek steam-electric generating station. Releases may be requested if the flow of the Delaware River at Trenton, N.J., is expected to be less than 3,000 ft3/s for more than 3 consecutive days. No supplemental releases were requested during the report year.
The data and computations of the various components of flow form the basic operational records used by the River Master to carry out specific responsibilities related to the Montague formula. The operational record has two parts: forecasted flow at Montague, exclusive of controlled releases from New York City’s reservoirs (table 8), and segregation of components of daily mean flow at Montague (table 9).
The following components may be present in the flow of the Delaware River at Montague:
The releases from New York City’s reservoirs necessary to maintain the Montague objective were computed from the forecasted flow at Montague, exclusive of controlled releases from the reservoirs.
The following are average times for the effective travel of water from the various sources of controlled supply to Montague. These times were used for flow routing during the 2001 report year:
| Source | Hours |
|---|---|
| Pecpacton Reservoir Cannonsville Reservoir Neversink Reservoir Lake Wallenpaupack Rio Reservoir |
60 48 33 16 8 |
The travel times were computed from reservoir and powerplant operations data and historical gaging-station records. The travel times generally are suitable for use in the operations of the River Master. Occasionally, however, significant exceptions are observed. For example, when a large release from Cannonsville Reservoir follows a small release, a substantial portion of the water fills the channel en route, and the remainder may arrive at Montague as much as 18 hours later. During winter, the formation of ice cover, together with low streamflow, gradually increases the resistance to flow, resulting in increased travel times. Because ice-affected travel times increase gradually over several days, and releases were not being directed to meet the Montague objective during periods of ice cover, no adjustments were made to compensate for increased travel times during these periods.
The River Master daily operations record of reservoir releases and segregation of the various components contributing to the flow of the Delaware River at Montague are presented in table 9. The data are arranged to conform to the downstream movement of water from the various sources to Montague. Summation of data along individual lines in the table is equivalent to routing the various flow contributions to Montague, using the average travel times given previously. Uncontrolled runoff was computed as a residual by subtracting the flow contributions of all other sources from the observed discharge at Montague.
During the report year, the River Master used the following information for daily operations: (1) discharges computed from recorded or reported stream gage heights, for various 24-hour periods, without real-time information on any changes in stage-discharge relations; (2) daily discharge from New York City’s three reservoirs, measured with venturi meters; (3) rainfall reports for the previous 24 hours; (4) actual powerplant releases converted to daily discharge; (5) advance estimates of power demand converted to daily discharge; (6) advance estimates of uncontrolled runoff at Montague; and (7) average travel times for routing water from various sources. Although uncertainty is inherent in forecasts of future conditions, these data by necessity are used in the daily designs and direction of reservoir releases.
The 60-hour travel time of water from Pepacton Reservoir to Montague is greater than the travel time of water from any other reservoir in the upper Delaware River Basin. Releases from Cannonsville and Neversink Reservoirs were timed to arrive at Montague concurrently with releases from Pepacton Reservoir. To allow for differences in travel times, daily directed releases were scheduled to begin from Pepacton Reservoir at 1200 hours, from Cannonsville Reservoir at 2400 hours, and from Neversink Reservoir at 1500 hours the following day.
Releases from the City’s reservoirs required to maintain the specified flow at Montague were computed from forecasts of releases from Lake Wallenpaupack and Rio Reservoir and estimates of uncontrolled runoff at Montague. To account for the travel times from these sources to Montague, the computation requires that estimates of the following components of flow be made 2 or more days in advance: (1) release of water from Lake Wallenpaupack; (2) release of water from Rio Reservoir; and (3) uncontrolled runoff at Montague. The River Master daily operations record for computing daily directed release requirements during periods of low flow is given in table 8.
The electric utilities furnished forecasts of power generation and releases. Because the hydroelectric plants were used chiefly for meeting peak-power demands, the forecasts were subject to various modifying factors including the vagaries of weather on electricity demand. In addition, because the power companies are members of regional power pools, demand for power outside of the local service area unexpectedly may affect generation schedules. As a result, at times, the actual use of water for power generation differed considerably from the forecasts used in the design of reservoir releases.
For computational purposes during periods of low flow, estimates of uncontrolled runoff at Montague were treated as two components: (1) current runoff and (2) forecasted increase in runoff from precipitation. Estimates for these components are given in table 8.
During ice-free conditions, current runoff was computed using a routing and recession procedure based on discharges at 0800 hours at the following USGS gaging stations:
| Station Name | Drainage Area (mi2) |
|---|---|
| Beaver Kill at Cooks Falls, N.Y. Cadosia Creek at Cadosia, N.Y. Oquaga Creek at Deposit, N.Y. Equinunk Creek at Equinunk, Pa. Callicoon Creek at Callicoon, N.Y. Tenmile River at Tusten, N.Y. Lackawaxen River at Hawley, Pa. Shohola Creek near Shohola, Pa. Neversink River at Port Jervis, N.Y. |
241 17.9 67.6 56.3 110 45.6 290 83.6 336 |
During the winter period, the advance estimate of uncontrolled runoff (current conditions) was made on the basis of flows at a reduced network of gaging stations and the recession curve for computed uncontrolled flow at Montague.
The forecasted runoff from precipitation is shown in table 8 under the heading “Weather Adjustment.” Throughout the year, the National Weather Service office in Binghamton, N.Y., furnished quantitative forecasts of average precipitation and air temperatures for the drainage area above Montague, N.J. During winter, runoff was estimated on the basis of the current status of snow and ice, along with forecasted precipitation and temperature. During other periods, forecasted precipitation was used to estimate runoff.
The forecasted flow at Montague, exclusive of releases from New York City’s reservoirs (table 8), is computed as the sum of forecasted releases from power reservoirs, estimated uncontrolled runoff including conservation releases from Rio Reservoir, and weather adjustments. If the computed flow was less than the flow objective at Montague, then the deficiency was made up by directed releases from the City’s reservoirs.
When forecasts of precipitation or powerplant releases were revised appreciably, the releases required from the reservoirs were recomputed. Commonly, this procedure resulted in a reduced release requirement for New York City reservoirs for that day and, consequently, water was conserved. Only the final data for releases from New York City reservoirs are given in table 8.
Forecasts of streamflow at Montague, developed on the basis of anticipated contributions from the components described previously (excluding releases from New York City’s reservoirs), differed on most days from observed flow. Occasionally, variations in the components were partially compensating and observed flows were in good agreement with forecasted flows.
The forecasted flow of the Delaware River at Montague, exclusive of releases from New York City reservoirs, was less than the flow objective on most days from July 1 to November 30, 2001. The following tabulation compares estimates of three components of flow at Montague with actual operations during this period.
| Releases and Runoff | Forecasted flow [(ft3/s)-d] |
Actual flow [(ft3/s)-d] |
|---|---|---|
| Power releases Lake Wallenpaupack Rio Reservoir Runoff from uncontrolled area |
20,915 7,239 99,392 |
20,492 8,107 89,142 |
From July 1 to November 30, actual releases from Lake Wallenpaupack averaged 2 percent less than forecasted releases, and actual releases from Rio Reservoir averaged 12 percent more than forecasted releases. Observed runoff from the uncontrolled area was about 10 percent less than forecasted runoff.
On any given day, the forecasted releases and actual releases can differ considerably. The range of actual daily releases from July 1 to November 30 are as follows: daily releases at Lake Wallenpaupack differed by 198 ft3/s less to 315 ft3/s more than forecasted releases, and daily releases at Rio Reservoir differed by 128 ft3/s less to 624 ft3/s more than forecasted releases. On the basis of observed flows at Montague, total directed releases from New York City’s reservoirs during the report year were 0.6 percent less than that required for exact forecasting.
Comparison of hydrographs of forecasted daily runoff and observed daily runoff from the uncontrolled area (fig. 5) indicates that the forecasts generally were suitable for use in designing releases from New York City’s reservoirs. Numerical adjustments to the designs were made when needed to compensate for errors in the forecasts, but because of travel times, the effects of the adjustments on flows at Montague are not evident until several days after the design date.
Analysis of the precipitation forecasts shows that the total precipitation amount forecasted for the 3-day design periods is reasonably accurate, but often the timing of storms may be earlier or later than forecasted. The accuracy of the runoff forecasts is affected greatly by the timing of precipitation events. In addition, if the actual storm track differs from the forecasted track, the amount and timing of runoff can be substantially different than predicted.
Figure 5. Uncontrolled runoff component, Delaware River at Montague, N.J., July 1 to November 20, 2001.
The 1954 Amended Decree authorizes New York City to divert water from the Delaware River Basin at a rate not to exceed 800 Mgal/d. The Decree also specifies that the diversion rate shall be computed as the aggregate total diversion beginning June 1 of each year divided by the number of days elapsed since the preceding May 31.
Diversions during the report year from Pepacton, Cannonsville, and Neversink Reservoirs to the New York City water-supply system (Rondout Reservoir) are given in table 10. Included is a running account of the average rates of combined diversions from the three reservoirs, computed as prescribed by the Decree or the “Interstate Water Management Recommendations of the Parties to the Decree (DRBC Resolution 83-13).” The following tabulation shows allowable maximum diversion rates and average actual diversions for various periods during the report year.
| Effective dates | Allowable diversion (Mgal/d) |
Average actual diversion (Mgal/d) |
|---|---|---|
| June 1, 2000, to May 31, 2001 June 1, 2001, to October 28, 2001 October 29, 2001, to November 3, 2001 November 4-30, 2001 |
800 800 680 560 |
624 707 681 558 |
During the year, a total of 243.306 Bgal of water was diverted to the New York City water-supply system. The allowable diversion was 321.691 Bgal.
The following tabulation summarizes the “point of maximum depletion” and other pertinent levels and contents of Pepacton, Cannonsville, and Neversink Reservoirs. This information was provided by the New York City Board of Water Supply.
| Level | Pepacton Reservoir | Cannonsville Reservoir | Neversink Reservoir | |||
|---|---|---|---|---|---|---|
| Elevation (ft) | Contents (Bgal) |
Elevation (ft) | Contents (Bgal) |
Elevation (ft) | Contents (Bgal) | |
| Full pool or spillway crest Point of maximum depletion Sill of diversion tunnel Sill of river outlet tunnel Dead Storage |
1,280.00 1,152.00 1,143.00 1,126.50 |
*140.190 *3.511 *4.200 1.800 |
1,150.00 1,040.00 +1,035.00 1,020.50 |
*95.706 *1.020 *1.564 0.328 |
1,440.00 1,319.00 1,314.00 1,314.00 |
*34.941 *0.525 1.680 |
| *Contents shown are quantities stored between listed elevations. +Elevation of mouth of inlet channel of diversion works. | ||||||
Storage in Pepacton, Cannonsville, and Neversink Reservoirs, above the “point of maximum depletion,” or minimum full-operating level, is given in tables 3, 4, and 5.
On December 1, 2000, combined storage in the three reservoirs was 220.805 Bgal, or 81.5 percent of combined capacity. As noted previously, storage fluctuated moderately during the winter and then increased to full capacity in April. Pepacton Reservoir spilled a total of 3.863 Bgal from April 14-26, 2001. Cannonsville Reservoir spilled a total of 58.802 Bgal from December 18, 2000, to January 10, 2001, and from March 21 to May 11, 2001. Neversink Reservoir spilled a total of 10.368 Bgal from April 828, 2001. Combined storage reached a maximum for the year on April 16, 2001, when all three reservoirs were spilling. The seasonal decline in storage began in May, earlier than usual. Combined storage declined to 66.406 Bgal, or 24.5 percent of combined capacity, on November 30, 2001.
River Master operations essentially are day-to-day operations, which by necessity use preliminary data on streamflow. In this section, records used in River Master operations are compared to final data published for USGS gaging stations. Data on releases were reported in million gallons per day and converted to cubic feet per second for use in the comparisons.
River Master operations data on controlled releases from Pepacton, Cannonsville, and Neversink Reservoirs to the Delaware River were furnished by New York City. These data were obtained from calibrated instruments connected to venturi meters installed in the outlet conduits of the reservoirs.
The USGS gaging station on East Branch Delaware River at Downsville, N.Y., is 0.5 mi downstream from Downsville Dam (fig. 1). Discharge measured at this station includes releases from Pepacton Reservoir and a small amount of seepage and any runoff that enters the channel between the dam and the gaging station. The drainage area is 371 mi2 at the dam and 372 mi2 at the gaging station.
The following tabulation compares releases from Pepacton Reservoir (table 9), reported by New York City, to the final records for the USGS gaging station on East Branch Delaware River at Downsville, N.Y. (table 11), for the flow objectives shown.
|
Flow objective (ft3/s) N.Y.C.-measured flow (ft3/s) USGS-measured flow (ft3/s) Percent difference* |
45 45.0 46.8 -3.8 |
70 69.6 66.0 +5.5 |
95 94.4 85.5 +10.4 |
356-360 358 250 +2.3 |
619-645 631 635 -0.6 |
| *Computed as (N.Y.C.-measured flow minus USGS-measured flow) | x100 |
| (USGS-measured flow) |
The differences at all flow rates except 95 ft3/s are less than 6 percent. The River Master’s office made one discharge measurement during the year. This measurement yielded a difference similar to that shown in the tabulation at the 70 ft3/s flow rate. The calibration of instruments connected to the venturi meters was adjusted periodically by New York City to improve the accuracy of the recorded data.
The USGS gaging station on West Branch Delaware River at Stilesville, N.Y., is 1.4 mi downstream from Cannonsville Dam (fig. 1). Discharge measured at this station includes releases from Cannonsville Reservoir and runoff from 2 mi2 of drainage area between the dam and the gaging station. The drainage area is 454 mi2 at the dam and 456 mi2 at the gaging station.
The following tabulation compares releases from Cannonsville Reservoir (table 9), reported by New York City, to the final records for the USGS gaging station on West Branch Delaware River at Stilesville, N.Y. (table 12), for the flow objectives shown.
|
Flow objective (ft3/s) N.Y.C.-measured flow (ft3/s) USGS-measured flow (ft3/s) Percent difference* |
45 45.0 55.3 -18.6 |
160 160 162 -1.2 |
300-900 566 537 +5.4 |
900-1400 1,190 1,180 +0.8 |
|
| *Computed as (N.Y.C.-measured flow minus USGS-measured flow) | x100 |
| (USGS-measured flow) |
The gaging-station records are considered fair at flows greater than 100 ft3/s and poor at flows less than 100 ft3/s. The records include substantial runoff from precipitation on the area between the dam and the gaging station and seepage near the base of the dam. On January 21, 1998, the seepage was measured at 3.9 ft3/s, which was greater than rates estimated in prior years. The differences in flow between reservoir-release records and USGS gaging-station records continue to be monitored by the River Master’s office, in cooperation with New York City and the USGS Water Science Center in Troy, N.Y. To further investigate the differences, one discharge measurement was made during the report year, just below the Cannonsville release outlet. By measuring flow at this location, most of the runoff contribution from the intervening area between the outlet and the gaging station is eliminated, although seepage near the base of the dam is included. The measurement differed from New York City release records by +4.6 percent (unadjusted) and +6.9 percent (adjusted) for the 160 ft3/s flow objective.
The USGS gaging station on Neversink River at Neversink, N.Y., is 1,650 ft downstream from Neversink Dam (fig. 1). Discharge measured at this station includes releases from Neversink Reservoir and, during storms, a small amount of runoff that originates between the dam and the gaging station. The drainage area is 92.5 mi2 at the dam and is 92.6 mi2 at the gaging station.
The following tabulation compares releases from Neversink Reservoir (table 9), reported by New York City, to the final records for the USGS gaging station on Neversink River at Neversink, N.Y. (table 13), for the flow objectives shown.
|
Flow objective (ft3/s) N.Y.C.-measured flow (ft3/s) USGS-measured flow (ft3/s) Percent difference* |
25 24.8 25.4 -2.4 |
53 52.5 50.1 +4.8 |
74 74.3 66.3 +12.1 |
90-95 92.4 89.4 +3.4 |
|
| *Computed as (N.Y.C.-measured flow minus USGS-measured flow) | x100 |
| (USGS-measured flow) |
The River Master’s office made one discharge measurement during the year to further investigate the differences between reservoir-release records and USGS gaging-station records. This measurement yielded differences similar to those in the tabulation at the 53 ft3/s flow rate.
Records of daily discharge through the Wallenpaupack powerplant were furnished by the PPL Corporation and published by the U.S. Geological Survey as Wallenpaupack Creek at Wilsonville, Pa. (table 14). These discharges represent the flow through the turbines of the powerplant and were computed on a midnight-to-midnight basis. For River Master operations, flows were computed on a 24-hour basis beginning at 0800 hours to compensate for the 16-hour travel time to Montague (table 9).
From December 2000 to November 2001, the River Master’s record agrees with the published U.S. Geological Survey record except for some very small differences that result mainly from differences in time frame and rounding of computations. Overall, the records agree to within 0.2 percent for the year.
Records of diversions through the East Delaware, West Delaware, and Neversink Tunnels (fig. 1) were furnished by the City of New York. These records were obtained from the City’s calibrated instruments connected to venturi meters installed in the tunnel conduits. The measured flows were transmitted electronically, on a 15-second interval, to the New York City Department of Environmental Protection computer at the Rondout Effluent Chamber. On 5-minute intervals, release and diversion quantities for the preceding 5-minute period were computed on the basis of the instantaneous rate-of-flow data from each instrument. These 5-minute quantities were summed to compute daily total flows, which were reported to the River Master’s office on a daily basis. On a weekly basis, the diversion values were checked against the flow meter totalizer readings and were corrected when necessary. Periodic current-meter measurements were made by the River Master’s office to verify the reported diversions. The measurements were made in the outlet channels below the tunnels.
The East Delaware Tunnel is used to divert water from Pepacton Reservoir to Rondout Reservoir. Conditions in the outlet channel of the East Delaware Tunnel were unfavorable for flow measurements during the report year because of high water levels in Rondout Reservoir. Comparison of diversion data provided by New York City with gage height record for the outlet channel of the East Delaware Tunnel did not indicate any large discrepancies in diversions reported by the City.
The generating plant at the downstream end of the East Delaware Tunnel operated most days of the report year. When the powerplant was not in operation, some water leaked through the wicket gates and was not recorded on the totalizer. A current-meter measurement made in 1989 shows that the rate of leakage (assumed constant) is about 8.0 Mgal/d. Because the powerplant was not in operation for the equivalent of 54 days during the 2001 report year, the unmeasured leakage totaled about 0.4 Bgal. The record of diversions through the East Delaware Tunnel is considered essentially correct.
The West Delaware Tunnel is used to divert water from Cannonsville Reservoir to Rondout Reservoir. One current-meter measurement of flow in the West Delaware Tunnel outlet channel was made during the year. This measurement shows that the venturi instrument gave a larger result, specifically, +0.7 percent for the totalizer and +0.9 percent for the rate-of-flow indicator, when compared to the current-meter measurement. Inspections of the channel below the outlet, when valves were closed, revealed only negligible leakage.
A hydroelectric powerplant uses water diverted through the West Delaware Tunnel, but the plant operates only when diversions are less than 300 Mgal/d. When the powerplant is not operating, the valves on the pipelines to the plant are closed, and there is no leakage through the system. The results of the measurements and inspections made during the report year and previous years indicate that the reported record of diversions through the West Delaware Tunnel is essentially correct.
The Neversink Tunnel is used to divert water from Neversink Reservoir to Rondout Reservoir. One current-meter measurement of flow from Neversink Tunnel was made during the report year. This measurement shows that the venturi instrument gave a larger result, specifically, +6.1 percent for the totalizer and +7.1 percent for the rate-of-flow indicator, when compared to the current-meter measurement. The record of diversions through the Neversink Tunnel is considered essentially correct.
A hydroelectric plant uses water diverted through the Neversink Tunnel. When the powerplant is not operating and the main valve on the diversion tunnel is open, leakage develops that is not recorded on the venturi instruments. One measurement made in 1999 showed a leakage rate of 16.2 ft3/s (10.5 Mgal/d). When the powerplant was operating, the leakage was included in the recorded flow. No leakage occurs when the main valve on the tunnel is closed.
During the 2001 report year, the powerplant operated part of the day on most days and was not operated the equivalent of 254 days. Using the leakage rate noted above and records of power-plant operation, about 2.7 Bgal of water was diverted but not recorded.
The Amended Decree authorizes New Jersey to divert water from the Delaware River or its tributaries in New Jersey to areas outside the Delaware River Basin, without compensating releases. These diversions may not exceed 100 Mgal/d as a monthly average, and the daily mean diversion may not exceed 120 Mgal/d. The USGS gaging station on Delaware and Raritan Canal at Port Mercer, N.J. (fig. 1), is used as the official control point for measuring diversions by New Jersey (table 16).
The following tabulation gives the allowable diversion by New Jersey, the period in which the diversion was in effect, and the maximum monthly diversion during the report year:
| Effective dates | Allowable monthly average diversion (Mgal/d) |
Maximum monthly average diversion (Mgal/d) |
Month of maximum average diversion |
|---|---|---|---|
| Dec. 1, 2000, to Nov. 3, 2001 Nov. 4-30, 2001 |
100 70 |
101 61.0 |
August 2001 November 2001 |
The maximum daily mean diversion was 114 Mgal on August 5, 2001. Diversions by New Jersey were within the allowable limits prescribed by the Decree except during August, when the monthly mean diversion was slightly elevated, but within the accuracy of the recorded discharge.
From December 1, 2000, to October 28, 2001, operations of the Delaware River Master were conducted as stipulated by the Decree. From October 29, 2001, to November 30, 2001, operations were conducted as prescribed by the “Interstate Water Management Recommendations of the Parties to the Decree (DRBC Resolution 83-13 and DRBC Docket No. D-77-20 CP (Revision No. 4), which were designed to alleviate impending or actual drought conditions in the basin.
Diversions from the Delaware River Basin to the New York City water-supply system were less than those authorized by the Decree and the “Interstate Water Management Recommendations of the Parties to the Decree.” Under compensating releases of the Montague Formula, New York City released water from its reservoirs at rates designed by the River Master to maintain the applicable flow objectives at Montague. During the report year, New York City complied fully with the directives of the River Master.
Diversions from the Delaware River Basin by New Jersey were in compliance with applicable limits. New Jersey complied fully with the requests of the River Master.
Table 1. Precipitation in the Delaware River Basin above Montague, N.J.
Table 2. Conservation release rates for New York City reservoirs in the Delaware River Basin
Table 3. Storage in Pepacton Reservoir, N.Y., for year ending November 30, 2001
Table 4. Storage in Cannonsville Reservoir, N.Y., for year ending November 30, 2001
Table 5. Storage in Neversink Reservoir, N.Y., for year ending November 30, 2001
Table 6. Design rates for Delaware River at Montague, N.J. gaging station, December 1, 2000 to November 30, 2001
Table 7. Consumption of water by New York City, 1950 to 2001
Table 8. New York City reservoir release design data
Table 9. Controlled releases from reservoirs in the upper Delaware River Basin and segregation of flow of Delaware River at Montague, N.J.
Table 10. Diversions to New York City water supply
Table 11. Daily mean discharge, East Branch Delaware River at Downsville, N.Y. (station number 01417000), for year ending November 30, 2001
Table 12. Daily mean discharge, West Branch Delaware River at Stilesville, N.Y. (station number 01425000), for year ending November 30, 2001
Table 13. Daily mean discharge, Neversink River at Neversink, N.Y. (station number 01436000), for year ending November 30, 2001
Table 14. Daily mean discharge, Wallenpaupack Creek at Wilsonville, Pa. (station number 01432000), for year ending November 30, 2001
Table 15. Daily mean discharge, Delaware River at Montague, N.J. (station number 01438500), for year ending November 30, 2001
Table 16. Diversions by New Jersey; daily mean discharge, Delaware and Raritan Canal at Port Mercer, N.J. (station number 01460440), for year ending November 30, 2001
This section describes the water-quality monitoring program for the Delaware Estuary during the River Master 2001 report year, December 1, 2000, to November 30, 2001. This program is conducted by the U.S. Geological Survey, in cooperation with the Delaware River Basin Commission (DRBC). Selected data collected for this program are presented and water-quality conditions are summarized. The DRBC and others use these data to assess water-quality conditions and track the movement of the “salt front” in the Delaware Estuary.
As part of a long-term program, the quality of water in the Delaware Estuary between Trenton, N.J., and Reedy Island Jetty, Del., is monitored at various locations (fig. 6). Data on temperature, specific conductance, dissolved oxygen, and pH were collected by electronic instruments at four sites -- Trenton, Benjamin Franklin Bridge (Philadelphia), Chester, and Reedy Island Jetty. Data on temperature and specific conductance were collected in the same manner at Fort Mifflin. Water-quality monitors at Benjamin Franklin Bridge and Chester were not operated from December 2000 to March 2001. Monitors at Trenton and Reedy Island Jetty were operated continuously throughout the report year. The monitor at Fort Mifflin was operated only from November 7-30, 2001.
Water-quality data were obtained on a monthly basis in March, June, July, September, October, and November and on a semimonthly basis in April, May, and August 2001 at 19 sites between Biles Channel and Mahon River (sample sites A-T on fig. 6). These data were collected by the State of Delaware for the DRBC. At each of these sites, water samples were collected near the center of the channel and analyzed for selected physical properties and chemical constituents. These analyses consist of field measurements and laboratory determinations.
From March to November, water-quality data were obtained on a monthly basis at three additional sites in lower Delaware Bay (sites U-W on fig. 6). Water samples were analyzed for selected physical properties and chemical constituents.
Data obtained from the water-quality monitors are processed and stored in the USGS National Water Information System database. These data are published annually by the USGS in water resources data reports for New Jersey and Pennsylvania. Data for the other sampling sites are not presented in this report but are available from the DRBC and STORET, an environmental-quality database operated by the U.S. Environmental Protection Agency.
Figure 6. Location of water-quality monitoring sites on the Delaware Estuary.
Streamflow has a major effect on the quality of water in the Delaware Estuary. High freshwater flows commonly result in improved water quality by limiting the upstream movement of seawater and reducing the concentration of dissolved substances. High flows also aid in maintaining lower water temperatures during warm weather and in supporting higher concentrations of dissolved oxygen. Under certain conditions, however, high streamflows can transport large quantities of nutrients to the estuary, which may result in noxious algal blooms.
Streamflow from the Delaware River Basin above Trenton, N.J., is the major source of freshwater inflow to the Delaware Estuary. During the report year, monthly mean streamflow measured at the USGS gaging station Delaware River at Trenton, N.J., was highest during April 2001 (24,960 ft3/s) and lowest during November (2,849 ft3/s; table 17). Monthly mean streamflows were greater than long-term mean monthly flows in December, April, and June, and were less than the long-term flows in the other months. The greatest flow deficiency was in November 2001, when monthly mean streamflow was about 27 percent of the long-term mean monthly flow. Long-term monthly mean streamflow was computed on the basis of data for the period from 1913 to 2000. The highest daily mean streamflow during the report year was 64,400 ft3/s on December 19, 2000. The lowest daily mean streamflow was 2,520 ft3/s on November 23, 2001.
Water temperature has an important influence on water quality, because it affects various physical, chemical, and biological properties of water. Generally, increases in water temperature have detrimental effects on water quality by decreasing the saturation level of dissolved oxygen and increasing the biological activity of aquatic organisms. Although the primary factors that affect water temperature in the Delaware Estuary are climatic, various kinds of water use, especially powerplant cooling, also can have significant effects.
Water-temperature records for the monitor site at Benjamin Franklin Bridge, Philadelphia, Pa., show that monthly mean temperatures during the report year were less than the long-term mean monthly temperatures in April, June, and July, and were greater than the long-term mean monthly temperatures in May, August, September, and November. In October, the monthly mean water temperature was equal to the long-term mean water temperature. Long-term mean water temperatures were computed using data for the period from 1964 to 2000 (fig. 7). The maximum daily mean water temperature of 27.6°C was recorded on August 10, 11, and 16, 2001.
Figure 7. Water temperature in the Delaware Estuary at Benjamin Franklin Bridge at Philadelphia, Pa., April to November.
Specific conductance is a measure of the capacity of water to conduct an electrical current and is a function of the types and quantities of dissolved substances in water. As concentrations of dissolved ions increase, specific conductance of the water increases. Specific conductance measurements are good indicators of dissolved solids content and total ion concentrations. Seawater and some man-made contaminants can cause the specific conductance of estuary water to increase substantially. Dilution associated with high streamflows results in decreased levels of dissolved solids and reduced specific conductance whereas low streamflows have the opposite effect.
The upstream movement of seawater and the accompanying increase in chloride concentrations is an important concern for water supplies obtained from the Delaware Estuary. Water with chloride concentrations greater than 250 mg/L (milligrams per liter) is considered undesirable for domestic use, and water with concentrations exceeding 50 mg/L is unsatisfactory for some industrial processes. Chloride concentrations in the estuary increase in a downstream direction, with proximity to the Atlantic Ocean.
Chloride concentration was not measured directly at the Reedy Island Jetty, Del., monitor site. Instead, a mathematical relation between specific conductance and chloride concentration has been developed on the basis of long-term field measurements of specific conductance and laboratory analyses of chloride; this relation can be used to estimate chloride concentrations from specific conductance values. Chloride concentrations estimated from the relation are presented in table 18. The specific conductance-chloride relation is less reliable when chloride concentrations are less than 30 mg/L, because other dissolved ions may be present in amounts large enough to affect the relation. Therefore, chloride concentrations estimated from specific conductance data are not presented when concentrations of less than 30 mg/L would result from the relation. Instead, estimated values less than 30 mg/L are reported as < 30 mg/L. Chloride concentrations at Chester, Pa. (table 19), were measured directly by Kimberly Clark Chester Operations and are not derived from specific conductance data.
At Fort Mifflin, the water-quality monitor was operated only on 24 days of the 2001 report year. The data set is not large enough to form the basis for meaningful descriptive statistics on chloride concentrations.
At Reedy Island Jetty, the highest daily maximum chloride concentration was 8,200 mg/L on December 7, 2000 (table 18) and October 2, 2001. Daily maximum chloride concentrations during the report year exceeded 1,000 mg/L on 96 percent of the days. The lowest daily minimum chloride concentrations for the report year were less than 30 mg/L on April 12-16, 2001. Daily minimum chloride concentrations exceeded 1,000 mg/L on 68 percent of the days. From December to April, a period of generally higher freshwater inflow, daily maximum chloride concentrations at Reedy Island Jetty ranged from 39 to 8,200 mg/L. From May to November, freshwater inflow was lower and daily maximum chloride concentrations ranged from 2,100 to 8,200 mg/L.
At Chester, the highest daily maximum chloride concentration was 800 mg/L on November 15, 2001 (table 19). During the report year, daily maximum concentrations exceeded 50 mg/L on 77 percent of the days. The lowest daily minimum chloride concentration was 27 mg/L on June 17, 2001. Daily minimum concentrations exceeded 50 mg/L on 60 percent of the days. Chloride concentrations were persistently high from August to November, when daily minimum concentrations exceeded 50 mg/L on all days of each month except 2 days in August.
Dissolved oxygen in water is necessary for the respiratory processes of aquatic organisms and in chemical reactions in aquatic environments. Fish and many other clean-water species require relatively high dissolved oxygen concentrations at all times. The major source of dissolved oxygen in the Delaware Estuary is diffusion from the atmosphere, and to a lesser extent, photosynthetic activity of aquatic plants. The principal factors that affect dissolved oxygen concentrations in the Estuary are water temperature, biochemical oxygen demand, freshwater inflow, phytoplankton, turbidity, salinity, and tidal and wind-driven mixing.
Concentrations of dissolved oxygen at several sites on the Delaware Estuary have been measured since 1962 by the U.S. Geological Survey. Two of these sites, Delaware River at Benjamin Franklin Bridge at Philadelphia, Pa., and Delaware River at Chester, Pa., have nearly continuous records and are in the reach of the estuary most affected by effluent discharges. The mean and minimum daily mean dissolved oxygen concentrations from July to September at these stations during the 1965-2001 report years is shown in figure 8. An increasing trend in concentration is evident. Although concentrations have increased considerably over this 37-year period, mean concentrations can vary substantially from year to year.
Concentrations of dissolved oxygen in the Delaware Estuary generally are greatest near Trenton and decrease in a downstream direction. In an area just below the Benjamin Franklin Bridge, concentrations usually reach minimum levels. During the report year, daily mean concentrations of dissolved oxygen at the Benjamin Franklin Bridge monitor site were lowest in late June and mid-August, and the lowest recorded daily mean concentration was 3.5 mg/L on August 13 and 14 (table 20). Daily mean concentrations of dissolved oxygen were consistently 6.0 mg/L or greater from April 1 to May 17, May 29 to June 14, and from October 8 to November 30, 2001. At Chester, daily mean dissolved oxygen concentrations were lowest during late-June and mid-August, and the lowest recorded daily mean concentration was 3.5 mg/L on June 26-28 (table 21).
Histograms of hourly dissolved oxygen concentrations at the Benjamin Franklin Bridge and Chester monitor sites during the critical summer period – July to September 2001 – are presented in figure 9. Hourly concentrations at the Benjamin Franklin Bridge were 4 mg/L or less during 6 percent of this period. In comparison, in 2000, hourly concentrations decreased to levels of of 4 mg/L or less during 12 percent of the critical period. At Chester, hourly dissolved oxygen concentrations were 4 mg/L or less during 6 percent of the 2001 critical summer period. In 2000, hourly concentrations decreased to levels of 4 mg/L or less during 13 percent of the critical period. Dissolved oxygen concentrations of less than 4 mg/L can have adverse, and possibly lethal, effects on fish and other aquatic organisms.
Figure 8. Mean and minimum daily mean dissolved oxygen concentrations from July to September at two monitor sites on the Delaware Estuary, 1965-2001.
Figure 9. Distribution of hourly dissolved oxygen concentrations at two monitor sites on the Delaware Estuary, July to September 2001.
The pH of a solution is a measure of the effective concentration (activity) of dissolved hydrogen ions. Solutions having a pH less than 7 are characterized as acidic whereas solutions with a pH greater than 7 are considered basic or alkaline. The pH of uncontaminated surface water generally ranges from 6.5 to 8.5. Major factors affecting the pH of surface water include the geologic composition of the drainage basin and human inputs including wastewater discharges. In addition, photosynthetic activity, and dissolved gases including carbon dioxide, hydrogen sulfide, and ammonia can have a considerable effect on pH. During the report year, pH was measured seasonally at the Benjamin Franklin Bridge and Chester monitor sites, and continuously at the Reedy Island Jetty site. The range of median pH for these stations is as follows: Benjamin Franklin Bridge, 6.7 to 7.5; Chester, 6.8 to 7.5; and Reedy Island Jetty, 7.0 to 8.0. Generally, the pH of water in the Delaware Estuary is lowest near Trenton, N.J. and increases (that is, becomes more alkaline) in a downstream direction.
Table 17. Daily mean discharge, Delaware River at Trenton, N.J. (station number 01463500), for year ending November 30, 2001
Table 18. Daily maximum and minimum chloride concentrations estimated from values of specific conductance, Delaware River at Reedy Island Jetty, Del. (station number 01482800), for year ending November 30, 2001
Table 19. Daily maximum and minimum chloride concentrations, Delaware River at Chester, Pa. (station number 01477050), for year ending November 30, 2001
Table 20. Daily mean dissolved oxygen concentration, Delaware River at Benjamin Franklin Bridge at Philadelphia, Pa. (station number 01467200), for year ending November 30, 2001
Table 21. Daily mean dissolved oxygen concentration, Delaware River at Chester, Pa. (station number 01477050), for year ending November 30, 2001
NO. 2001-5
EXTENSION OF DOCKET NO. 77-20 CP (Revision 4)
DELAWARE RIVER BASIN COMMISSION
A RESOLUTION extending Docket No. D-77-20 CP (Revision 4) for one year to continue the experimental augmented conservation release program for the New York City Delaware Basin Reservoirs.
WHEREAS, Document No. 77-20 CP (Revision 4) specified the current augmented experimental release program and instituted a drought watch and a revised drought warning level for the three New York City Delaware Basin reservoirs beginning in May 1999 and ending on April 30, 2001; and
WHEREAS, Docket No. 77-20 CP (Revision 4) condition h. provides for an extension of the provisions of this Docket upon agreement of all parties to the 1954 supreme Court Decree; and
WHEREAS, the State of New York and New York City are in the process of negotiating to revised experimental release program to develop conservation releases more responsive to the water conditions downstream of the dams; and
WHEREAS, it is anticipated that the development and agreement of a revised experimental augmented conservation release program will not be completed until after April 30, 2001, the date at which the current program will automatically terminate; and
WHEREAS, the State of New York requested the Commission on February 27, 2001 to extend Docket No. 77-20 CP (Revision 4) for one calendar year until April 30, 2002;now therefore
BE IT RESOLVED by the undersigned Commissioners and Parties to the Decree
Docket No. 77-20 CP (Revision 4) is hereby extended for one year to April 30, 2002.
| /S/ Kevin C. Donnely | |
| Kevin C. Donnelly, Chairman pro tem | |
| /S/ Pamela M. Bush | |
| Pamela M. Bush, Commission Secretaryand Assistant General Counsel |
ADOPTED: April 19, 2001