Summary of Flows in the Delaware River at Trenton and Montague with Major Upstream Diversions, 1913-2002

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USER'S GUIDE

1. IDENTIFICATION INFORMATION

1.1 CITATION

Hoffman, J.L., 2004, Summary of Flows in the Delaware River at Trenton and Montague with Major Upstream Diversions, 1913-2002: Excel workbook, N.J. Geological Survey Digital Geodata Series DGS04-8, Trenton.

1.2 DESCRIPTION

1.2.1 ABSTRACT

This product is an Excel workbook (called 'DelQ.xls') which documents annual, seasonal, and monthly flows in the Delaware River at the Trenton and Montague streamflow gages, along with annual and monthly withdrawals by major upstream intakes. Only surface-water intakes that export water from the Delaware River watershed upstream of the Trenton gage are included. This is defined as 'depletive' water use. Surface-water and ground-water withdrawals for use in the basin upstream of Trenton are not included. Changes in storage in reservoirs may also affect streamflows but these changes are not documented here.

There are four major depletive users upstream of the Trenton gage. They are, in order from upstream to downstream:

1) New York City has been diverting water from the Delaware watershed to the Hudson watershed since 1954. Diversions are made from the Cannonsville Reservoir on the West Branch Delaware River, the Pepacton Reservoir on the East Branch Delaware River, and the Neversink Reservoir on the Neversink River.

2) The Delaware and Raritan Canal withdraws water from the Delaware River near Raven Rock in Hunterdon County, New Jersey. The canal was completed in 1834. It has been utilized as a water supply since 1948. Water is diverted primarily to the Raritan watershed.

3) The Point Pleasant pump station removes water from the Delaware River near Point Pleasant in Bucks County, Pennsylvania. It has supplied water to the Philadelphia Electric Company, the North Wales Water Authority, and the North Penn Water Authority since 1989. The water is returned to the Delaware River via the Schuylkill River, after some consumptive loss, below the streamflow gage at Trenton..

4) Trenton City has withdrawn water from the Delaware River in Mercer County, New Jersey, since at least 1925. The water is withdrawn upstream of the Trenton streamflow gage and returned to the Delaware River, after some consumptive loss, below the gage.

In 2002 New York City exported 182 billion gallons of water out of the Delaware basin and the Delaware and Raritan Canal 29 billion gallons. Withdrawals in 2002 by the Point Pleasant pump station (13 billion gallons) and Trenton City (7.6 billion gallons) were returned to the Delaware River, after some consumptive loss, below the Trenton streamflow gage.

'Consumptive' water use is defined as evaporative use in the watershed. Water that is withdrawn, used, and then returned to the same watershed is subject to some consumptive loss. The percentage consumptive loss depends on the specific use the water is put to and the season. In the New Jersey portion of the watershed above the Trenton gage the consumptive water loss is estimated to have been 4.4 billion gallons in 1999 based on unpublished data on file with the N.J. Geological Survey. Based on relative estimates of population, consumptive water use in the Pennsylvania and New York portions of the watershed above the Trenton gage may have been about twice as much. Total consumptive water loss in the Delaware watershed upstream of Trenton is thus roughly estimated to have been on the order of 15 billion gallons in 1999.

This workbook (DelQ.xls) includes a number of data tables, analysis tables, and graphs. The purpose of this workbook is to provide these data in a consistent and usable format to interested parties.

1.2.2. LIST OF FILES AND BRIEF DESCRIPTION

DelQ.xls is a Microsoft Excel workbook which contains information on flow in the Delaware River at Trenton and major upstream surface-water withdrawals. This workbook contains 12 worksheets:

S1. Metadata - This metadata worksheet. It is a description of how the data were generated, analyzed, and presented.

S2. Monthly Data - A worksheet which contains reported monthly flows, in millions of gallons. This contains the basic data on flow in the Delaware River at Trenton and four major upstream withdrawals - the Delaware and Raritan Canal, New York City, Point Pleasant pumping station, and Trenton City Water Works. This worksheet also contains graphics displaying flow and withdrawals. All volumes are in millions of gallons.

S3. Annual Data - A worksheet which contains reported annual flows, in millions of gallons. This contains the basic data on flow in the Delaware River at Trenton and four major upstream withdrawals - the Delaware and Raritan Canal, New York City, Point Pleasant pumping station, and Trenton City Water Works. This worksheet also contains graphics displaying flow and withdrawals. All volumes are in millions of gallons.

S4. Trenton Monthly Deviations - A worksheet which contains information on the amount by which reported monthly flow in the Delaware River at Trenton deviated from average monthly flow (for that month). The data are present in tabular and graphical form.

S5. Trenton Annual Deviations - A worksheet which contains information on the amount by which reported annual flow in the Delaware River at Trenton deviated from the long-term average annual flow. The data are present in tabular and graphical form.

S6. Trenton Monthly Analysis - A worksheet which presents a statistical analysis of monthly flows in the Delaware River at Trenton for 3 different time periods. Eight different statistics are calculated for each month for the 3 different time periods. The time periods are 1913-2002 (the entire period of record), 1913-1954 (before major diversions began occurring), and 1960-2002 (after major diversions were well established). The eight statistics for each month are average, minimum, 10% exceedence frequency, 25% exceedence frequency, median (which is equivalent to the 50% exceedence frequency), 75% exceedence frequency, 90% exceedence frequency, and maximum. In this context the n% exceedence frequency is defined by that value which is greater than n% of the reported streamflows. Thus the 10% exceedence frequency monthly flow represents a low flow value - it is greater than only 10% of reported monthly flows while the remaining 90% of the months had greater flows. The 90% exceedence value is greater than 90% of reported streamflows. Thus this represents a wet time period as 90% of flows were less and only 10% of flows were greater. The results are presented in tabular form. The average, 10% exceedence values, and 90% exceedence values are also presented in graphical form.

S7. Trenton Seasonal Analysis - A worksheet which presents a statistical analysis of seasonal flows in the Delaware River at Trenton for 3 different time periods. Eight different statistics are calculated for each season for the 3 different time periods. The time periods are 1913-2002 (the entire period of record), 1913-1954 (before major diversions began occurring), and 1960-2002 (after major diversions were well established). The eight statistics for each season are average, minimum, 10% exceedence frequency, 25% exceedence frequency, median (which is equivalent to the 50% exceedence frequency), 75% exceedence frequency, 90% exceedence frequency, and maximum. In this context the n% exceedence frequency is defined by that value which is greater than n% of the reported streamflows. Thus the 10% exceedence frequency seasonal flow represents a low flow value - it is greater than only 10% of reported flows for that season, and the remaining 90% of the reported values for that season were wetter. The 90% exceedence value is greater than 90% of reported streamflows. Thus this represents a wet time period as 90% were drier and only 10% were wetter. For this analysis winter is defined as the months January, February and March; spring is April, May and June; summer is July, August and September; and fall is October, November and December.

S8. Montague Monthly Deviations - Equivalent to the analysis in worksheet S4 except for Delaware River flows at Montague.

S9. Montague Annual Deviations - Equivalent to the analysis in worksheet S5 except for the Delaware River at Montague.

S10. Montague Monthly Analysis - Equivalent to the analysis in worksheet S6 except for Delaware River flows at Montague.

S11. Montague Seasonal Analysis - Equivalent to the analysis in worksheet S7 except for Delaware River flows at Montague.

S12. Map - Map of the Delaware River Basin

1.2.3. LIST OF KEYWORDS

Delaware River, streamflow, withdrawals, Delaware and Raritan canal, Trenton, Montague, New Jersey, Pennsylvania, New York, diversions

1.3. GEOGRAPHIC EXTENT

Delaware River Basin, New Jersey, Pennsylvania, New York, New York City

1.4. CONTACT INFORMATION

Jeffrey L. Hoffman, Research Scientist I
New Jersey Geological Survey
Land Use Management
New Jersey Department of Environmental Protection
PO Box 427
Trenton, NJ 08625

phone: (609) 984-6587
email: Jeffrey.L.Hoffman@dep.nj.gov

Website: www.state.nj.us/dep/njgs/

1.5. ACKNOWLEDGEMENTS

David Sayers and Judith Strong of the Delaware River Basin Commission were very helpful in supplying information on file with the DRBC. Robert A. Mayer of the Bureau of Water Supply, NYC Department of Environmental Protection also supplied useful information on New York City diversions. David Sayers also provided a much needed technical review of the data.

2. DATA CREATION INFORMATION

2.1 NAME OF DATA

DelQ.xls is a Microsoft Excel workbook which contains data on flow in the Delaware River at Trenton and Montague and major upstream surface-water withdrawals that affect the flow.

2.2. Delaware River flows at Trenton

Flow in the Delaware River at Trenton is monitored by the United States Geological Survey at gage # 01463500. This gage became operational in October 1912. The total watershed area above this gage is 6,780 square miles. The USGS reports flow on its web page: http://waterdata.usgs.gov/. All Delaware River flows in this workbook were obtained from the USGS streamflow web site.

The USGS reports flows in terms of cubic feet per second (cfs). Water-supply volumes tend to be reported in terms of millions of gallons per a defined time period. For this report all flow rates have been converted into million of gallons per month or million of gallons per season or million of gallons per year, depending on the analysis time period. A constant flow rate of 1 cfs is equivalent to 0.6463 million gallons per day (mgd)

2.3. Delaware River flows at Montague

Flow in the Delaware River at Montague is monitored by the United States Geological Survey at gage # 014638500. This gage became operational in October 1939. The total watershed area above this gage is 3,480 square miles. The USGS reports flow on its web page: http://waterdata.usgs.gov/. All Delaware River flows in this workbook were obtained from the USGS streamflow web site.

2.4. Delaware and Raritan Canal withdrawals

The Delaware and Rartian Canal withdraws water from the Delaware River at Raven Rock in Hunterdon County, New Jersey. This canal supplies potable water to purveyors in the Raritan River watershed. Reported withdrawals are available from 1948. From January 1948 to July 1990 flow values are from the Kingston streamflow gage (# 01460500). From August 1990 to December 2002 flow values are from the Port Mercer streamflow gage (# 01460440). All values were obtained from the USGS streamflow web site and converted into millions of gallons.

The Delaware and Raritan Canal was finished in 1834 and was used for commercial transport purposes until 1923 (National Canal Museum website). The volume of water withdrawn from the Delaware River to support this commericial use is unknown.

2.5. New York City withdrawals

The City of New York has withdrawn water since 1954 from the Cannonsville Reservoir on the West Branch Delaware River, the Pepacton Reservoir on the East Branch Delaware River, and the Neversink Reservoir on the Neversink River (fig. 33). Withdrawal volumes for 1954-1981 are from published annual reports of the Delaware River Master on file with the Delaware River Basin Commission.. Withdrawals for 1982 to 2002 were supplied in digital form by the NYC Department of Environmental Protection.

2.6. Point Pleasant withdrawals

The Delaware Canal takes water from the Delaware River via the Point Pleasant pump station in Bucks County, Pennsylvania. It was completed in 1834 and was used for commercial transport purposes until 1931 (from the website of the National Canal Museum). The volume of water withdrawn from the Delaware River to support this commercial use is unknown.

The Delaware Canal currently supplies water to the Philadelphia Electric Company, the North Wales Water Authority, and the North Penn Water Authority. These withdrawals began in 1989. The withdrawal volumes reported here were supplied by staff of the Delaware River Basin Commission with a few data gaps filled in by consulting the USGS series of annual water resources reports. The withdrawn water is returned to the Delaware River, after some consumptive loss, downstream of the gage at Trenton.

2.7. Trenton City Water Works withdrawals

The Trenton City Water Works withdrawals water from the Delaware River upstream of the gage at Trenton in Mercer County, New Jersey, for potable supply. This water is returned, after some loss to consumption, to the Delaware River downstream of the gage. The USGS reports monthly withdrawals in its series of annual water resources reports. This series of reports contains values of Trenton withdrawals since October 1968 and these data are repeated here.

The USGS annual water resources reports prior to 1968 do not contain information on Trenton City withdrawals. Trenton began withdrawing Delaware water at least as early as 1925 but the start date is uncertain. The average monthly withdrawal based on reported data is for 1968 - 2002 is 987 million gallons. This value was assigned to all months between January 1925 and September 1967. This is probably a reasonable assumption because Trenton's population hasn't fluctuated dramatically over this time period. Additionally, the volumes involved are a very small percentage of total flow in the Delaware River at Trenton so errors are not as significant.

3. DESCRIPTION OF TABLES

3.1 Table 1. Delaware River monthly flows at Trenton and Montague with major upstream diversions (millions of gallons)

This table is in worksheet S2. It is the basic data sheet. All other tables in this workbook pull data (directly or indirectly) from this table.

Table 1 shows monthly flows (in millions of gallons) for the Delaware River at Trenton, as well as reported and estimated monthly diversions for the Delaware and Raritan Canal, New York City, Point Pleasant pumping station, and Trenton City Water Works.

3.2. Table 2. Delaware River annual flows at Trenton and Montague with major upstream diversions

This table is in worksheet S3. It shows annual flows (in millions of gallons) for the Delaware River at Trenton, as well as reported and estimated monthly diversions for the Delaware and Raritan Canal, New York City, Point Pleasant pumping station, and Trenton City Water Works.

3.3. Table 3. Deviations of Delaware River monthly flows at Trenton from long-term monthly averages

This table is in worksheet S4. Monthly average flows were calculated for each calendar month (table 5). Table 3 shows, for each month in the data record, the result of flow in that month minus the monthly average flow. This is called the monthly deviation of flow. A positive number indicates more flow that month than average, a negative number less flow.

3.4. Table 4. Deviations of Delaware River annual flows at Trenton from long-term average annual flow

This table is in worksheet S5. The long-term average annual flow for the Delaware River at Trenton, based on reported annual flows for 1913-2002, is 2,739,688 million gallons per year. This number was subtracted from the reported total flow volume for each year and results in the deviation of annual flow from the long-term average. A positive number indicates more flow that year than average, a negative number less flow.

3.5. Table 5. Statistical Analysis of Delaware River at Trenton monthly flows, 1913-2002

This table is worksheet S6. It presents eight statistics for reported flow in the Delaware River at Trenton in each calendar month. The eight statistics for each month are average, minimum, 10% exceedence frequency, 25% exceedence frequency, median (which is equivalent to the 50% exceedence frequency), 75% exceedence frequency, 90% exceedence frequency, and maximum. In this context the n% exceedence frequency is that value which is greater than n% of reported flows. Thus the 10% exceedence frequency monthly flow is that flow which is greater than only 10% of reported flows for that month; 90% of the reported monthly flows values for that calendar month were greater than this value. The 10% exceedence frequency monthly flow represents flow in a dry month. The 90% exceedence frequency monthly flow represents flow in a wet month.

3.6. Table 6. Statistical Analysis of Delaware River at Trenton monthly flows, 1913-1954

This table is in worksheet S6. It is the same as table 5 except that the time period analyzed is 1913-1954. This represents a time when the only major diversion upstream of the gage at Trenton was for Trenton City.

3.7. Table 7. Statistical Analysis of Delaware River at Trenton monthly flows, 1960-2002

This table is in worksheet S6. It is the same as table 5 except that the time period analyzed is 1960-2002. This represents a time period when all four of the diversions reported here were active.

3.8. Table 8. Statistical Analysis of Delaware River at Trenton seasonal flows, 1913-2002

This table is worksheet S7. It presents eight statistics for reported flow in the Delaware River at Trenton in each season. For this analysis winter is defined as the months January, February and March; spring is April, May and June; summer is July, August and September; and fall is October, November and December.

The eight statistics for each season are average, minimum, 10% exceedence frequency, 25% exceedence frequency, median (which is equivalent to the 50% exceedence frequency), 75% exceedence frequency, 90% exceedence frequency, and maximum. In this context the n% exceedence frequency is that value which is greater than n% of reported flows. Thus the 10% exceedence frequency seasonal flow is that flow which is greater than only 10% of reported flows for that season; 90% of the reported seasonal flows values for that season were greater than this value. The 10% exceedence frequency seasonal flow represents flow in a dry season. The 90% exceedence frequency seasonal flow represents flow in a wet season.

3.9. Table 9. Statistical Analysis of Delaware River at Trenton seasonal flows, 1913-1954

This table is in worksheet S7. It is the as table 5 except that the time period analyzed is 1913-1954. This represents a time period when the only major upstream diversion was by Trenton City.

3.10. Table 10. Statistical Analysis of Delaware River at Trenton seasonal flows, 1960-2002

This table is in worksheet S7. It is the same as table 5 except that the time period analyzed is 1960-2002. This represents a time period when all four of the diversions reported here were active.

3.11. Table 11. Deviations of Delaware River monthly flows at Montague from long-term monthly averages

This table is in worksheet S8. Monthly average flows were calculated for each calendar month (table 13). Table 11 shows, for each month in the data record, the result of flow in that month minus the monthly average flow. This is called the monthly deviation of flow. A positive number indicates more flow that month than average, a negative number less flow.

3.12. Table 12. Deviations of Delaware River annual flows at Montague from long-term average annual flow

This table is in worksheet S9. The long-term average annual flow for the Delaware River at Montague based on reported annual flows for 1940-2002, is 1,334,441 million gallons per year. This number was subtracted from the reported total flow volume for each year and results in the deviation of annual flow from the long-term average. A positive number indicates more flow that year than average, a negative number less flow.

3.13. Table 13. Statistical Analysis of Delaware River at Montague monthly flows, 1940-2002

This table is worksheet S10. It presents eight statistics for reported flow in the Delaware River at Montague in each calendar month. The eight statistics for each month are average, minimum, 10% exceedence frequency, 25% exceedence frequency, median (which is equivalent to the 50% exceedence frequency), 75% exceedence frequency, 90% exceedence frequency, and maximum. In this context the n% exceedence frequency is that value which is greater than n% of reported flows. Thus the 10% exceedence frequency monthly flow is that flow which is greater than only 10% of reported flows for that month; 90% of the reported monthly flows values for that calendar month were greater than this value. The 10% exceedence frequency monthly flow represents flow in a dry month. The 90% exceedence frequency monthly flow represents flow in a wet month.

3.14. Table 14. Statistical Analysis of Delaware River at Montague monthly flows, 1940-1954

This table is in worksheet S10. It is the same as table 13 except that the time period analyzed is 1940-1954. This represents a time when there were no major diversions upstream of the gage.

3.15. Table 15. Statistical Analysis of Delaware River at Montague monthly flows, 1960-2002

This table is in worksheet S10. It is the same as table 13 except that the time period analyzed is 1960-2002. This represents a time period when the diversion for New York city was active.

3.16. Table 16. Statistical Analysis of Delaware River at Montague seasonal flows, 1940-2002

This table is worksheet S11. It presents eight statistics for reported flow in the Delaware River at Montague in each season. For this analysis winter is defined as the months January, February and March; spring is April, May and June; summer is July, August and September; and fall is October, November and December.

The eight statistics for each season are average, minimum, 10% exceedence frequency, 25% exceedence frequency, median (which is equivalent to the 50% exceedence frequency), 75% exceedence frequency, 90% exceedence frequency, and maximum. In this context the n% exceedence frequency is that value which is greater than n% of reported flows. Thus the 10% exceedence frequency seasonal flow is that flow which is greater than only 10% of reported flows for that season; 90% of the reported seasonal flows values for that season were greater than this value. The 10% exceedence frequency seasonal flow represents flow in a dry season. The 90% exceedence frequency seasonal flow represents flow in a wet season.

3.17. Table 17. Statistical Analysis of Delaware River at Montague seasonal flows, 1940-1954

This table is in worksheet S11. It is the same as table 16 except that the time period analyzed is 1940-1954. This represents a time period when there were no major diversions upstream.

3.18. Table 18. Statistical Analysis of Delaware River at Montague seasonal flows, 1960-2002

This table is in worksheet S18. It is the same as table 16 except that the time period analyzed is 1960-2002. This represents a time period when the diversion for New York city was active.

4. DESCRIPTION OF FIGURES

4.1. Figure 1. Monthly flows, Del. R. gage @ Trenton, and major upstream withdrawals 1913-2002

This figure is in worksheet S2. It shows reported and estimated monthly flows (in millions of gallons) for the Delaware River at Trenton, as well as reported and estimated monthly diversions for the Delaware and Raritan Canal, New York City, Point Pleasant pumping station, and Trenton City Water Works for the time period 1913-2002. The data that are plotted here are from Table 1.

4.2. Figure 2. Monthly flows, Del. R. gage @ Trenton, and major upstream withdrawals 1980-2002

This figure is in worksheet S2. It is the same as figure 1 except that the time period is only 1980-2002. This allows for a better viewing of more recent conditions.

4.3. Figure 3. Monthly flows, Del. R. gage @ Montague, and New York City withdrawals 1940-2002

This figure is in worksheet S2. It shows reported and estimated monthly flows (in millions of gallons) for the Delaware River at Montague, as well as reported and estimated monthly diversions for New York City for the time period 1940-2002. The data that are plotted here are from Table 1.

4.4. Figure 4. Monthly flows, Del. R. gage @ Montague, and New York City withdrawals 1980-2002

This figure is in worksheet S2. It is the same as figure 3 except that the time period is only 1980-2002. This allows for a better viewing of more recent conditions.

4.5. Figure 5. Major monthly withdrawals upstream of Del. R. gage @ Trenton, 1913-2002

This figure is in worksheet S3. It shows reported and estimated monthly diversions for the Delaware and Raritan Canal, New York City, Point Pleasant pumping station, and Trenton City Water Works for the time period 1913-2002. It shows the same data as figure 1 except for the exclusion of Delaware River flows. It allows for a better viewing of just the diversions. The data that are plotted here are from Table 1.

4.6. Figure 6. Major monthly withdrawals upstream of Del. R. gage @ Trenton, 1980-2002

This figure is in worksheet S2. It is the same as figure 5 except that the time period is only 1980-2002. This allows for a better viewing of more recent conditions

4.7. Figure 7. Annual flows, Del. R. gage @ Trenton, and major upstream withdrawals 1913-2002

This figure is in worksheet S3. It shows reported and estimated annual flows (in millions of gallons) for the Delaware River at Trenton, as well as reported and estimated monthly diversions for the Delaware and Raritan Canal, New York City, Point Pleasant pumping station, and Trenton City Water Works for the time period 1913-2002. The data that are plotted here are from Table 2.

4.8. Figure 8. Annual flows, Del. R. gage @ Trenton, and major upstream withdrawals 1980-2002

This figure is in worksheet S3. It is the same as figure 7 except that the time period is only 1980-2002. This allows for a better viewing of more recent conditions.

4.9. Figure 9. Annual flows, Del. R. gage @ Montague, and New York City withdrawals 1940-2002

This figure is in worksheet S3. It shows reported and estimated annual flows (in millions of gallons) for the Delaware River at Montague, as well as reported and estimated monthly diversions for New York City for the time period 1940-2002. The data plotted here are from Table 2.

4.10. Figure 10. Annual flows, Del. R. gage @ Montague, and New York City withdrawals 1980-2002

This figure is in worksheet S3. It is the same as figure 9 except that the time period is only 1980-2002. This allows for a better viewing of more recent conditions.

4.11. Figure 11. Major annual withdrawals upstream of Delaware River gage @ Trenton, 1913-2002

This figure is in worksheet S3. It shows reported and estimated annual diversions for the Delaware and Raritan Canal, New York City, Point Pleasant pumping station, and Trenton City Water Works for the time period 1913-2002. It shows the same data as figure 1 except for the exclusion of Delaware River flows. It allows for a better viewing of just the diversions. The data plotted here are from Table 1.

4.12. Figure 12. Major annual withdrawals upstream of Delaware River gage @ Trenton, 1980-2002

This figure is in worksheet S3. It is the same as figure 9 except that the time period is only 1980-2002. This allows for a better viewing of more recent conditions

4.13. Figure 13. Monthly deviations from long-term average monthly flows, Del. R. @ Trenton, 1913-2002

This figure is in worksheet S4. It plots the monthly deviation from average. Months with more flow than average are shown by positive numbers, drier months are negative. The data plotted here are from table 3.

4.14. Figure 14. Monthly deviations from long-term average monthly flows, Del. R. @ Trenton, 1980-2002

This figure is in worksheet S4. It is the same as figure 5 except that the time period is only 1980-2002. This allows for a better viewing of more recent conditions.

4.15. Figure 15. Annual deviations from long-term average annual flows, Delaware River @ Trenton, 1913-2002

This figure is in worksheet S5. It plots the annual flow deviation from average. Years with more flow than average are shown by positive numbers, drier years are negative. The data plotted here are from table 4.

4.16. Figure 16. Annual deviations from long-term average annual flows, Delaware River @ Trenton, 1980-2002

This figure is in worksheet S5. It is the same as figure 12 except that the time period is only 1980-2002. This allows for a better viewing of more recent conditions.

4.17. Figure 17. Average Monthly Flows, Delaware River at Trenton

This figure is in worksheet S6. It plots monthly average flows calculated for three different time periods, 1913-2002 (the entire period of record), 1913-1954 (before major diversions began occurring), and 1960-2002 (after major diversions were well established). The data plotted here are from tables 5, 6 and 7.

4.18. Figure 18. Low Monthly Flows, (10% exceedence frequency) Delaware River at Trenton

This figure is in worksheet S6. It plots monthly 10% exceedence frequency flows calculated for three different time periods, 1913-2002 (the entire period of record), 1913-1954 (before major diversions began occurring), and 1960-2002 (after major diversions were well established). This represents a low-flow month, only 10% of months reported less flow than this volume during the reported analysis time period. The data plotted here are from tables 5, 6 and 7.

4.19. Figure 19. High Monthly Flows (90% exceedence frequency) Delaware River at Trenton

This figure is in worksheet S6. It plots monthly 90% exceedence frequency flows calculated for three different time periods, 1913-2002 (the entire period of record), 1913-1954 (before major diversions began occurring), and 1960-2002 (after major diversions were well established). This represents a high-flow month, 90% of months reported less flow than this volume during the reported analysis time period. The data plotted here are from tables 5, 6 and 7.

4.20. Figure 20. Average Seasonal Flows, Delaware River at Trenton

This figure is in worksheet S7. It plots seasonal average flows calculated for three different time periods, 1913-2002 (the entire period of record), 1913-1954 (before major diversions began occurring), and 1960-2002 (after major diversions were well established). The data plotted here are from tables 8, 9 and 10.

4.21. Figure 21. Low Seasonal Flows, (10% exceedence frequency) Delaware River at Trenton

This figure is in worksheet S7. It plots seasonal 10% exceedence frequency flows calculated for three different time periods, 1913-2002 (the entire period of record), 1913-1954 (before major diversions began occurring), and 1960-2002 (after major diversions were well established). This represents a low-flow season, only 10% of seasons reported less flow than this volume during the reported analysis time period. The data plotted here are from tables 8, 9 and 10.

4.22. Figure 22. High Seasonal Flows (90% exceedence frequency) Delaware River at Trenton

This figure is in worksheet S7. It plots seasonal 90% exceedence frequency flows calculated for three different time periods, 1913-2002 (the entire period of record), 1913-1954 (before major diversions began occurring), and 1960-2002 (after major diversions were well established). This represents a high-flow season, 90% of seasons reported less flow than this volume during the reported analysis time period. The data plotted here are from tables 8, 9 and 10.

4.23. Figure 23. Monthly deviations from long-term average monthly flows, Del. R. @ Montague, 1940-2002

This figure is in worksheet S8. It plots the monthly deviation from average. Months with more flow than average are shown by positive numbers, drier months are negative. The data plotted here are from table 11.

4.24. Figure 24. Monthly deviations from long-term average monthly flows, Del. R. @ Montague, 1980-2002

This figure is in worksheet S8. It is the same as figure 23 except that the time period is only 1980-2002. This allows for a better viewing of more recent conditions.

4.25. Figure 25. Annual deviations from long-term average annual flows, Delaware River @ Montague, 1940-2002

This figure is in worksheet S9. It plots the annual flow deviation from average. Years with more flow than average are shown by positive numbers, drier years are negative. The data plotted here are from table 12.

4.16. Figure 26. Annual deviations from long-term average annual flows, Delaware River @ Montague, 1980-2002

This figure is in worksheet S9. It is the same as figure 25 except that the time period is only 1980-2002. This allows for a better viewing of more recent conditions.

4.27. Figure 27. Average Monthly Flows, Delaware River at Montague

This figure is in worksheet S10. It plots monthly average flows calculated for three different time periods, 1940-2002 (the entire period of record), 1940-1954 (before major diversions began occurring), and 1960-2002 (after major diversions were well established). The data plotted here are from tables 13, 14 and 15.

4.28. Figure 28. Low Monthly Flows, (10% exceedence frequency) Delaware River at Montague

This figure is in worksheet S10. It plots monthly 10% exceedence frequency flows calculated for three different time periods, 1940-2002 (the entire period of record), 1940-1954 (before major diversions began occurring), and 1960-2002 (after major diversions were well established). This represents a low-flow month, only 10% of months reported less flow than this volume during the reported analysis time period. The data plotted here are from tables 13, 14 and 15

4.29. Figure 29. High Monthly Flows (90% exceedence frequency) Delaware River at Montague

This figure is in worksheet S10. It plots monthly 90% exceedence frequency flows calculated for three different time periods, 1940-2002 (the entire period of record), 1940-1954 (before major diversions began occurring), and 1960-2002 (after major diversions were well established). This represents a high-flow month, 90% of months reported less flow than this volume during the reported analysis time period. The data plotted here are from tables 13, 14 and 15

4.30. Figure 30. Average Seasonal Flows, Delaware River at Montague

This figure is in worksheet S11. It plots seasonal average flows calculated for three different time periods, 1940-2002 (the entire period of record), 1940-1954 (before major diversions began occurring), and 1960-2002 (after major diversions were well established). The data plotted here are from tables 16, 17 and 18.

4.31. Figure 31. Low Seasonal Flows, (10% exceedence frequency) Delaware River at Montague

This figure is in worksheet S11. It plots seasonal 10% exceedence frequency flows calculated for three different time periods, 1940-2002 (the entire period of record), 1940-1954 (before major diversions began occurring), and 1960-2002 (after major diversions were well established). This represents a low-flow season, only 10% of seasons reported less flow than this volume during the reported analysis time period. The data plotted here are from tables 16, 17 and 18.

4.32. Figure 32. High Seasonal Flows (90% exceedence frequency) Delaware River at Montague

This figure is in worksheet S11. It plots seasonal 90% exceedence frequency flows calculated for three different time periods, 1940-2002 (the entire period of record), 1940-1954 (before major diversions began occurring), and 1960-2002 (after major diversions were well established). This represents a high-flow season, 90% of seasons reported less flow than this volume during the reported analysis time period. The data plotted here are from tables 16, 17 and 18.

4.33. Figure 33. Delaware River Basin

This figure is in worksheet S12. It shows the Delaware River Basin in New Jersey, Pennsylvania, New York and Delaware. This figure was taken from the web site of the Delaware River Basin Commission: http://www.state.nj.us/drbc/drbc.htm

5. DISTRIBUTION INFORMATION

This file consists of one Excel workbook. This product may be distributed with proper attributation and if it is unchanged.

6. AUTHOR NOTES

Please report any errors in this workbook to the authors.

Check the NJGS website for possible additional information: www.state.nj.us/dep/njgs/

Use of brand, commercial, or trade names is for identification purposes only and does not constitute endorsement by the New Jersey Geological Survey or New Jersey Department of Environmental Protection.

7. ABBREVIATIONS

DRBC - Delaware River Basin Commission

NJDEP - New Jersey Department of Environmental Protection

NYC - New York City

USGS - United States Geological Survey

8. PREVIOUS VERSIONS

Version 1 (and various modifications) were distributed internally in the DEP and the DRBC starting in March 2004 to report on preliminary results and for error checking. Version 2.0 is the first version to be released to the public. It was released in August 2004.

Later versions may be released if significant errors in data input or processing are found or additional analyses are added.

9. INTERNET RESOURCES

New Jersey Geological Survey: www.state.nj.us/dep/njgs/

Delaware River Basin Commission: www.state.nj.us/drbc/drbc.htm

New York City Department of Environmental Protection: www.nyc.gov/html/dep/

New Jersey Department of Environmental Protection:www.state.nj.us/dep/

National Canal Museum: www.canals.org

10. EPIGRAM

In order to meet the large demands of agriculture and industry and the small but imperative demand of domestic consumption, water must be collected, stored, allocated and distributed. The water itself falls from the heavens, but it is not free. Human intervention in the natural water cycle always entails some cost, and occasionally the cost is high.

--- Ambroggi, R.P., 1980, Water: Scientific American, v. 243, no. 3, p. 100-116.