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Low-Flow Statistics for Selected Streams in New York, Excluding Long Island

Timothy J. Stagnitta, Alexander P. Graziano, Joshua C. Woda, Robin L. Glas, Christopher L. Gazoorian, S.J. Bhatti · U.S. Geological Survey

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Prepared in cooperation with the New York State Department of Environmental Conservation

Low-Flow Statistics for Selected Streams in New York, Excluding Long Island

Scientific Investigations Report 2024–5055

U.S. Department of the Interior U.S. Geological Survey

Cover. Photograph of the confluence of the upper Esopus Creek and Birch Creek in the Catskill Mountains of New York, October 2022. Photograph by Don Bonville, U.S. Geological Survey.

Low-Flow Statistics for Selected Streams in New York, Excluding Long Island By Timothy J. Stagnitta, Alexander P. Graziano, Joshua C. Woda, Robin L. Glas, and Christopher L. Gazoorian

Prepared in cooperation with the New York State Department of Environmental Conservation

Scientific Investigations Report 2024–5055

U.S. Department of the Interior U.S. Geological Survey

U.S. Geological Survey, Reston, Virginia: 2024

For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment—visit https://www.usgs.gov or call 1–888–392–8545. For an overview of USGS information products, including maps, imagery, and publications, visit https://store.usgs.gov/ or contact the store at 1–888–275–8747. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. Suggested citation: Stagnitta, T.J., Graziano, A.P., Woda, J.C., Glas, R.L., and Gazoorian, C.L., 2024, Low-flow statistics for selected streams in New York, excluding Long Island: U.S. Geological Survey Scientific Investigations Report 2024–5055, 39 p., https://doi.org/10.3133/sir20245055. Associated data for this publication: Stagnitta, T.J., Graziano, A.P., Woda, J.C., Glas, R.L., and Gazoorian, C.L., 2024, Low-flow statistics for New York State, excluding Long Island, computed through March 2022: U.S. Geological Survey data release, https://doi.org/10.5066/P9NOM6FR. ISSN 2328-0328 (online)

iii

Acknowledgments The authors would like to thank the New York State Department of Environmental Conservation for providing funding for this work. In addition, we would like to thank Rob Dudley, John Hammond, and Neil Terry of the U.S. Geological Survey for their detailed reviews of this manuscript and data release.

Contents Acknowledgments��iii Abstract��1 Introduction��1 Study Area and Gage Selection��2 Methods for Calculating At-Site Low-Streamflow Statistics��4 Data Handling for Missing and Irregular Streamflow Values��4 Trend Analysis��5 Low-Streamflow Frequency Analysis��6 Low-Streamflow Nonexceedance Frequency Analysis��6 Results��6 Trend Analysis��6 Low-Streamflow Frequency Analysis��8 Discussion��8 Summary��9 References Cited��9 Appendix 1. Low-Streamflow Statistics for 213 Unaltered and 79 Altered Gages��13

Figures 1.

Map showing the 213 unaltered and 181 altered gages with daily streamflow evaluated for this study in New York and adjacent States��3 2. Graph showing the total number of occurrences of the annual minimum 7-day values within each month for all available data across unaltered gages in New York, excluding Long Island, that were included in this study��5 3. Map showing a comparison of 7Q10 values for 91 long-record unaltered gages with data available pre- and post-1972��7

Conversion Factors U.S. customary units to International System of Units

Multiply

To obtain

square mile (mi2)

2.590

square kilometer (km2)

cubic foot per second (ft3/s)

0.02832

cubic meter per second (m3/s)

Datum Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Abbreviations α

statistical significance level

30Q10

the lowest annual 30-day average streamflow that occurs (on average) once every 10 years

7Q10

the lowest annual 7-day average streamflow that occurs (on average) once every 10 years

NWIS

National Water Information System

NYSDEC

New York State Department of Environmental Conservation

USGS

U.S. Geological Survey

Low-Flow Statistics for Selected Streams in New York, Excluding Long Island By Timothy J. Stagnitta, Alexander P. Graziano, Joshua C. Woda, Robin L. Glas, and Christopher L. Gazoorian

Abstract The U.S. Geological Survey, in cooperation with the New York State Department of Environmental Conservation, updated low-streamflow statistics for New York, excluding Long Island and including hydrologically connected watersheds in bordering States, for the first time since 1972. Historical daily streamflow data for active and inactive gages were considered for this study with periods of record as recent as March 31, 2022, adding 50 years of data to the last published low-streamflow statistics report for New York and including 119 new gages where low-streamflow statistics are calculated for the first time. Gages were evaluated across several criteria to identify gages that were not suitable for lowstreamflow frequency analysis. In addition, gages were evaluated for the presence of alteration within the streamflow period of record based on previous studies and U.S. Geological Survey National Water Information System site metadata including peak flow codes. A trend analysis was performed using the Wilcoxon rank-sum hypothesis test comparing data from the most recent 30 years of record to data from 30 years and earlier for each long-record gage (30 years or more of available data). Results from the trend analysis indicated that 45 unaltered and 32 altered long-record sites had a statistically significant trend for the annual minimum n-day time series; most gages showed increasing trends in the annual minimum n-day time series. Low-streamflow statistics were calculated using the most recent 30 years of record for gages with a statistically significant trend. Before and after 1972, the lowest annual 7-day and 30-day average streamflow that occurs (on average) once every 10 years (7Q10 and 30Q10 statistics respectively) increased significantly at 41 unaltered gages and decreased significantly at 3 unaltered gages where data were available.

Introduction Reliable information about the magnitude, frequency, and duration of low streamflow is critical for water-supply management; reservoir design; waste-load allocation; and the

preservation of water quality and quantity for irrigation, recreation, and ecological conservation purposes. Low-streamflow frequency and duration information are particularly important in regions and States that are periodically affected by drought, including New York. As part of their mission to protect public health and aquatic ecosystems, State agencies such as the New York State Department of Environmental Conservation (NYSDEC) need accurate and representative low-streamflow statistics to establish realistic and applicable criteria for both water quality and water quantity (NYSDEC, [1998]). For example, low-streamflow statistics, such as the lowest annual 7-day or 30-day average streamflow that occurs (on average) once every 10 years (7Q10 or 30Q10, respectively), have been used by NYSDEC water-resource managers and planners as a threshold criterion for applying for regulatory measures affecting chronic aquatic life (for which 7Q10 data are used) or chronic human health (for which 30Q10 data are used). These statistics are further used by NYSDEC to regulate waste-load allocations for point sources and total maximum daily loads for streams (NYSDEC, [1998]). To that end, the U.S. Geological Survey calculated low-streamflow statistics of New York with the NYSDEC. Given the importance of these applications, it is critical to effectively measure and document low-streamflow data for characterizing low-streamflow frequency relations on a regular basis, preferably every 10 years, and especially after periods of extremely low streamflow (Feaster and Lee, 2017; Farmer and others, 2019). Recent droughts (2016, 2020, and 2022) in New York (U.S. Drought Monitor, 2023) have heightened the need for pertinent low-streamflow information for State and local agencies to make critical water-resources decisions. Low-streamflow statistics in New York have not been updated statewide since 1972 (Eissler, 1978), and low-streamflow characteristics in New York may have been changing since that time (Suro and Gazoorian, 2011; Dudley and others, 2020). The objective of this study was to compute new 7Q10 and 30Q10 low-streamflow statistics for New York (excluding Long Island) and hydrologically connected watersheds in bordering States.

2 Low-Flow Statistics for Selected Streams in New York, Excluding Long Island

Study Area and Gage Selection The study area consists of the State of New York and hydrologically connected streams from bordering States of Pennsylvania, New Jersey, Connecticut, Massachusetts, and Vermont (fig. 1). Site-specific metadata and daily average streamflow data were accessed using the R package dataRetrieval (R Core Team, 2020; De Cicco and others, [2014]) from the U.S. Geological Survey (USGS) National Water Information System (NWIS) database (USGS, 2016) for 684 active or discontinued gages across New York, and an additional 79 gages from bordering States. A total of 763 gages with daily average streamflow data were available in the study area. Based on the gage-selection criteria described throughout this section, 394 gages met all gage-selection criteria. First, 29 Long Island gages were removed from this study because Long Island has unique hydrologic characteristics and those gages are affected by varying degrees of urbanization and regulation (Glas and others, 2023). Accurate lowstreamflow statistics for Long Island would require additional analysis beyond the scope of this study. Second, 270 gages with less than 10 years, or 3,652 days, of available daily streamflow records were removed from the study. Typically, low-streamflow statistics are computed for streams when at least 10 years of continuous daily record are available (Lukasz, 2021; Williams-Sether, 2021; Hammond and others, 2022a). However, statistics computed from longerterm records (typically 30 years or more of available data) are preferred because they are likely to be more representative of a broader range of hydrologic conditions. Thus, long-term streamflow data are better suited for trend assessments, but to be more inclusive of available data, gages with at least 10 years of data were included in this study. Third, 29 gages had more than 20 percent of the period of record missing. Missing data is a common problem in hydrologic data analysis and there are several existing methods and guidance frameworks established for filling in or developing procedures to remove missing data (Gustard and Demuth, 2008). However, this study took a conservative approach in not estimating missing daily streamflow records. Based on Gustard and Demuth (2008), a threshold of 20 percent of missing days in the streamflow record was used to consider the record incomplete and exclude gages from the study. Fourth, 94 gages had records with days of zero streamflow and would therefore not be suitable to calculate lowstreamflow statistics because log transformations are required to calculate 7Q10 and 30Q10. An exception was made for the Housatonic River at Stevenson, Conn. (station 01205500) gage which has a long period of record that includes one day with a recorded zero streamflow near the beginning of the period of record. The zero-streamflow observation for this gage was considered an outlier in magnitude when compared with the entire period of record, so to avoid disqualifying this record entirely, the time series was truncated to remove the zero-streamflow observation. Although including gages with observed zero-streamflow measurements is outside the scope

of this study, an avenue for potential further study would include performing a logistic regression to better understand the probability of zero-streamflow observations occurring within these basins. Fifth, nine gages were discontinued, where all recorded data were transferred to a nearby new gage. Novak (1985) indicated that two discharge records could be considered equivalent if they are on the same stream and there is less than a 5 percent difference in drainage area between the gages or differences in monthly discharge between the two gages could be expected to be less than 5 percent. These nine gages were not included in the study to avoid double counting their record. Sixth, 16 gages were removed due to having less than 10 recorded climatic years. Low-streamflow metrics were computed on a climatic-year basis. A climatic year is a continuous 12-month period selected for the presentation of data relative to a hydrological or meteorological phenomenon of interest and is usually designated by the year of the first month in the 12-month period (Langbein and Iseri, 1960). In the Northeast, streamflow is typically lowest during the late summer months and highest during the earlier spring months, thus the climatic year from April 1 to March 31 was used for low-streamflow frequency analysis to increase the likelihood that the lowest streamflow values were captured within each climatic year. In total, 369 gages were removed from this study given the gage-selection criteria (numerous gages met multiple removal criteria), and 394 gages remain for further analysis; this reflects an additional 119 gages analyzed since low-streamflow statistics were last calculated in 1972 (Eissler, 1978). Developing models to estimate low-streamflow statistics for ungaged locations is difficult where streamflow has been altered by human influence and not reflected by natural basin characteristics, which are the primary predictors used to create a model. Therefore, the gages meeting selection criteria for this study were classified into two groups: 181 altered and 213 unaltered gages (fig. 1), where all historical data available were obtained up to March 31, 2022. Altered gages have documented alterations of observed daily streamflow due to human-related water use and management such as reservoir operations, surface water or groundwater withdrawals, diversions, engineered drainage systems, and impervious areas from urban development. For this analysis, altered gages were determined from previous work by Suro and Gazoorian (2011), and analysis of remark comments in the water-year summaries of individual gages on the USGS Water Data for the Nation website (U.S. Geological Survey, 2016) by flagging words associated with alteration (for example, “regulation,” “pumping,” and “diversion”). All gages classified as unaltered were compared with gage lists and regulation designations from statewide flood-frequency studies (Wall and others, 2014; Lumia and others, 2006) to determine whether peak streamflow values at the gage have been affected by some degree of regulation or diversion (specifically, peak streamflow

80°W

78°W

76°W

74°W

72°W

EXPLANATION Type of daily streamflow site

CANADA

Unaltered Altered

CANADA

Map area

ME VT NH

NY MA CT

44°N PA

NEW HAMPSHIRE

ATLANTIC OCEA

LAKE ONTARIO VERMONT

NEW YORK RIE

LAK

MASSACHUSETTS 42°N

CONNECTICUT

100 MILES

100 KILOMETERS

PENNSYLVANIA NEW JERSEY

Long

Island

Sound

Base map from U.S Geological Survey, scale 1:3,000,000 Universal Transverse Mercator, zone 18 north North American Datum of 1983

Figure 1. Map showing the 213 unaltered and 181 altered gages with daily streamflow evaluated for this study in New York and adjacent States.

Study Area and Gage Selection 3

4 Low-Flow Statistics for Selected Streams in New York, Excluding Long Island codes 5 and 6; https://nwis.waterdata.usgs.gov/nwis/peak? help). In addition, all gages were evaluated for alteration by analyzing satellite imagery for the presence of upstream dams or other visible signs of alteration (for example, power plants or wastewater facilities) and by considering site information provided in databases including the Geospatial Attributes of Gages for Evaluating Streamflow, version II (GAGES-II; Falcone, 2011).

Methods for Calculating At-Site Low-Streamflow Statistics The most common low-streamflow statistics used by organizations across the United States to inform decisions during low-streamflow periods are calculated using a moving average across a standard interval (typically a 7-day or 30-day period) of the daily average streamflow values (U.S. Environmental Protection Agency, 1986; Smakhtin, 2001). Low-streamflow statistics calculated using the moving average n-day values are representative of persistent low-streamflow periods within the daily streamflow record. The moving average 7-day and 30-day streamflow time series were calculated using daily average streamflow data available across all gages for this study, and the annual minimum 7-day and 30-day values were determined for each climatic year across the period of record.

Data Handling for Missing and Irregular Streamflow Values Missing data within a daily streamflow time series are a persistent problem for hydrologic frequency analysis (Gustard and Demuth, 2008). Missing data can be present within a USGS daily streamflow time series for multiple reasons. For example, the gage may have only operated on a seasonal basis, the intention of the gage may have only been to measure a limited range of streamflow, or the gage may have been temporarily discontinued due to equipment failure, lost funding, or other related issues (Novak, 1985). For this study, missing daily streamflow data were classified as not available directly within the raw data time series obtained from NWIS. In addition, a streamflow value was classified as not available if a date or multiple dates were missing from the raw data time series obtained from NWIS, and the missing dates were added to the time series to create a set of continuous dates for all gages. Missing daily data and irregular timing of low streamflow (for example, lowest streamflow values occur during typical high-streamflow months) were flagged to determine if an individual climatic year should be removed if the data met any of the following criteria:

• The low-streamflow months of July, August, September, and October included any missing daily values. • The annual minimum n-day value included missing daily values within the moving average n-day period. • The annual minimum n-day value was within the first 7 or 30 days of April (the beginning of the climatic year), and the moving average window included daily data from the previous climatic year. The annual minimum 7-day and 30-day time series for unaltered gages did not include any gages with missing daily data within any annual minimum n-day moving average values across all climatic years. The altered gages included 12 gages where at least one annual minimum 7-day (5 gages) or 30-day (7 gages) value for a climatic year includes at least one missing value within the moving average window; a climatic year meeting this criterion was removed from the period of record. Figure 2 is a histogram of the month that the annual minimum 7-day values occurred for each climatic year across the period of record for all unaltered gages. The unaltered gages were used to determine the low-streamflow months because they are the most representative of natural climatic conditions within the study area. As expected, the annual minimum 7-day values occurred most often during July, August, September, and October. At least 1 climatic year was removed for 13 unaltered and 22 altered gages that had missing daily data during the low-streamflow months. Any annual minimum n-day time series that spanned the end of one climatic year and the start of the next (March 31 to April 1) were not included in the annual minimum time series for a gage. The unaltered gages included 12 where at least 1 climatic year was removed for annual minimum 7-day (3 gages) or 30-day (9 gages) values near the start of a climatic year. Unaltered gages typically would not have annual minimum n-day values during the high-streamflow months. These gages were further evaluated, and it was determined that these values were high outliers when compared with the annual minimum values across the period of record. The altered gages included 82 where at least 1 climatic year was removed for annual minimum 7-day (31 gages) and 30-day (51 gages) values near the start of a climatic year. Altered or minimally altered gages are more likely to include annual minimum streamflow values near the start of the climatic year during typically high-streamflow months because the observed streamflow may be consistent with the alteration patterns of a specific gage where the lowest streamflow values occur during the high-streamflow months (for example, station 01357499 is a diversion channel for the Erie Canal, where the locks are closed during the winter; the streamflow of station 01325000 is regulated by the Conklingville Dam, where the lowest streamflow values typically occur during the winter months).

Methods for Calculating At-Site Low-Streamflow Statistics 5

Total number of occurrences of the annual minimum 7-day values within each month

3,500

3,000

2,500

2,000

1,500

1,000

500

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sep.

Oct.

Nov.

Dec.

Month

Figure 2. Graph showing the total number of occurrences of the annual minimum 7-day values within each month for all available data across unaltered gages in New York, excluding Long Island, that were included in this study.

The same climatic years were removed for the annual minimum 7-day and 30-day time series to ensure that the same years were used to calculate the 7Q10 and 30Q10 statistics for any gage to avoid a mismatch in the climatic years used to calculate each low-streamflow statistic. In total, 20 unaltered and 69 altered gages have at least 1 climatic year removed from the annual minimum 7-day and 30-day time series because of missing data during the low-streamflow months, missing daily data within the annual minimum n-day moving average window, or annual minimum n-day values near the start of the climatic year. Across all 213 unaltered and 181 altered gages, a total of 32 and 363 climatic years, respectively, were removed given the criteria listed in this section.

Trend Analysis Recent studies have documented changes in precipitation patterns across the Northeast, and the need to account for trends in hydrologic frequency analysis to calculate accurate low-streamflow statistics (Dethier and others, 2020; Dudley and others, 2020; Hammond and others, 2022b). McCabe and Wolock (2021) investigated drought and pluvial periods using a simple water balance model across the conterminous United States from 1900 through 2014. Across most of the conterminous United States and in the Northeast, most severe drought events occurred before 1970 and the region has been

in a sustained pluvial period for the last 50 years (McCabe and Wolock, 2021). In addition, Seager and others (2012) study precipitation patterns in the Catskill Mountains region and determined that a severe drought occurred during the mid-1960s, followed by a wet period that continues through the end of their study period (2007). Affecting most of the Northeast, the severe 1960s drought created long-lasting water supply issues and shaped future water policy across the region (Barksdale, 1968). Blum and others (2019) and Vogel and Kroll (2020) find that using a recent subset of the period of record for frequency analysis improves the accuracy of low-streamflow frequency statistics when nonstationary conditions are observed. Blum and others (2019) use Monte Carlo simulation experiments with monotonic trends observed at gages in the Chesapeake Bay watershed and observe that, when a statistically significant trend in low streamflow was present, the best estimate of the 7Q10 statistic was more accurately computed using the most recent 30 years of historical record. Blum and others (2019) suggest a simple adaptive framework for computing 7Q10: use the most recent 30 years of the record when a statistically significant (α) trend was detected (at α≤0.1) or use the full historical record. Similar to the adaptive method developed by Blum and others (2019), this study used the Wilcoxon rank-sum hypothesis test to determine whether data from the most recent

6 Low-Flow Statistics for Selected Streams in New York, Excluding Long Island 30 years of record are statistically different from data from 30 years ago and earlier. The Mann-Kendall trend test was explored for this study but was ultimately not used because data gaps are included within the annual minimum n-day (7-day or 30-day values) datasets and this trend test requires little to no missing data to provide an accurate test result (Helsel and others, 2020). In addition, the two-sample t-test was explored for this study, but the log-transformed annual minimum n-day time series for each group appeared abnormal for most gages. The nonparametric two-sample Wilcoxon rank-sum hypothesis test compares two groups without any prior knowledge that either group would be higher or lower than one another (Helsel and others, 2020). The null hypothesis for this study states that the annual minimum n-day streamflow values from the most recent 30 years of available data come from the same distributions as data from 30 years and earlier within the period of record. A less stringent α=0.1 was used for this study to determine statistical significance of the hypothesis test.

Low-Streamflow Frequency Analysis The low-streamflow statistics for 7Q10 and 30Q10 were calculated using the annual minimum 7-day and 30-day moving average of the daily average values for each climatic year across the available period of record for each gage. The Wilcoxon rank-sum hypothesis test results were used to determine which set of years were used to calculate the statistics, and then the annual minimum 7-day and 30-day time series were fit to a probability distribution to calculate the streamflow value associated with a specific probability of nonexceedance. The log-Pearson type III probability distribution was used to fit the n-day low-streamflow values for the low-streamflow frequency analysis (Bhatti and others, 2019). The log-Pearson type III distribution has been widely used to model low- and peak-streamflow statistics throughout the country (England and others, 2019; Helsel and others, 2020). The log-Pearson type III distribution of the n-day time series to determine the streamflow of the 10-year recurrence interval (Q10) is defined as: ln(Q10   ) = µ  y + K10   σy  ,

(1)

is the log-space mean, and

σy

is the log-space standard deviation of the n-day time series.

K10 is a frequency factor approximated by the WilsonHilferty transformation, which is a function of the nominal skew G (Kirby, 1972) defined as:

n∑ ni=1 ( Yi  − µy  )   3 ______________ G =       , ( n − 1)( n − 2) σy    3

G Z10   G  2 2 2 K 10(G) = _ (1 + _   − _ )  − _ 6 36 G G 3

(3)

where n

is the number of climatic years,

is the log-transformed annual minimum n-day value for a specific climatic year (i), and

Z10

is the 10th percentile from the standard normal distribution.

Low-Streamflow Nonexceedance Frequency Analysis The nonexceedance probability tables were determined for the daily moving average 7-day and 30-day values for the 102 altered gages determined not to be suitable for lowstreamflow frequency analysis (Stagnitta and others, 2024). The nonexceedance probabilities of the n-day average time series were determined using Weibull’s plotting position to rank the daily n-day average streamflow values constructing an empirical cumulative distribution (Langbein and Iseri, 1960). These nonexceedance percentiles should not be construed to be a representation of a low-streamflow frequency, but as an empirical representation of recorded n-day average streamflow values.

Results Low-streamflow frequency analysis requires detailed methods to account for missing data or trends to ensure that low-streamflow statistics are accurately calculated to represent current conditions. Results from the trend analysis are detailed in the following section, including a comparison of 7Q10 values calculated pre- and post-1972.

Trend Analysis

where µy

and

(2)

Low-streamflow statistics for New York State were last calculated using data from 1972 and earlier (Eissler, 1978). The comparison of the 7Q10 values for 91 long-record (30 years or more of available data) unaltered gages where data were available pre- and post-1972 is shown in figure 3. Across 83 of the 91 gages, 7Q10 values have increased since 1972, with the largest changes occurring in the western, Catskill, and Adirondack regions of the State. Of the 83 unaltered sites with an increase, 41 of the increases were statistically significant (α≤0.1) and averaged 46 and 48 percent for

80°W

78°W

CANADA

Map area

76°W

74°W

72°W

CANADA

ME VT NH

NY 44°N

MA CT NJ

EXPLANATION Change with significant trend Increase Decrease

NEW HAMPSHIRE

ATLANTIC OCEA

Change without significant trend Increase Decrease Magnitude of 7Q10 change, in percent <25

LAKE ONTARIO

25–50

VERMONT

50–75 75–100

NEW YORK

>100

RIE

LAK

MASSACHUSETTS 42°N

CONNECTICUT

0 0

25 25

50 75

100 MILES

100 KILOMETERS

PENNSYLVANIA NEW JERSEY

Long

Island

Sound

Base map from U.S Geological Survey, scale 1:3,000,000 Universal Transverse Mercator, zone 18 north North American Datum of 1983

Results 7

Figure 3. Map showing a comparison of the lowest annual 7-day average streamflow that occurs (on average) once every 10 years (7Q10) values for 91 long-record (30 years or more of available data) unaltered gages with data available pre- and post-1972. 7Q10 values were calculated with data from before 1972 and data available from the entirety or a subset of the period of record depending on results from Wilcoxon rank-sum hypothesis test. Gages where 7Q10 increased from pre-1972 data are marked with an upward blue triangle. Gages where 7Q10 decreased from pre-1972 data are marked with a downward red triangle. The size of the triangle corresponds to the positive or negative percent change from pre-1972 7Q10 versus 7Q10 calculated for this study. Gages marked with a filled triangle indicate that no significant trend (α>0.1) was found at the gage. >, Greater than; <, less than.

8 Low-Flow Statistics for Selected Streams in New York, Excluding Long Island the 7Q10 and 30Q10 values, respectively. Of the 8 unaltered sites with a decrease, 3 of the decreases were statistically significant (α≤0.1) and averaged 9 and 8 percent for the 7Q10 and 30Q10 values, respectively. Of the 213 unaltered gages, 121 gages had at least 30 years of available data and were evaluated for nonstationarity. The null hypothesis was rejected for 45 unaltered gages at α=0.1 significance level and the most recent 30 years of available data were used to calculate low-streamflow statistics for these gages. The remaining 76 unaltered gages failed to reject the null hypothesis, and the entire period of record was used to calculate low-streamflow statistics. In addition, for the remaining 92 unaltered gages where no hypothesis testing was performed, the entire period of record was used to calculate low-streamflow statistics because these gages had less than 30 years of available data. The annual minimum 7-day time series for all altered gages were visually inspected to determine whether there was an irregular change in the annual minimum values and whether the overall trend displayed was inconsistent with the underlying natural condition of increasing low-streamflow values in the study area (fig. 3; for example, the annual minimum values showed an irregular pattern due to inconsistent surface water withdrawals near the gage). Of the 181 altered gages inspected, 79 displayed consistent trends of the annual minimum 7-day time series and were suitable for low-streamflow frequency analysis. Of the 79, 73 had at least 30 years of available data and were evaluated for nonstationarity. The null hypothesis was rejected for 32 altered gages at α=0.1 and the most recent 30 years of available data were used to calculate low-streamflow statistics. The remaining 41 altered gages failed to reject the null hypothesis, and the entire period of record was used to calculate low-streamflow statistics. In addition, for the remaining six altered gages where no trend analysis was performed, the entire period of record was used to calculate low-streamflow statistics because these gages had fewer than 30 years of available data. For gages that exhibited different hypothesis test results for trends in the annual minimum 7-day and 30-day time series, the entire period of record was used to calculate lowstreamflow statistics and the same set of years were used for each n-day time series.

Low-Streamflow Frequency Analysis Stagnitta and others (2024) and table 1.1, located in appendix 1, include the 7Q10 and 30Q10 values calculated for all 213 unaltered and 79 altered gages.

Discussion Methods for handling missing and irregular data ensure accurate and consistent streamflow values are included to calculate low-streamflow statistics that best represent lowstreamflow conditions observed within the study area. This analysis provides methods to flag and remove outlier annual minimum n-day values from the low-streamflow time series. Most climatic years were included across all gages for this study, where only 20 unaltered and 69 altered gages were flagged to remove at least 1 climatic year from the period of record. A trend analysis of the annual minimum n-day values ensures that the low-streamflow frequency analysis using historical annual values represents current conditions observed within the stream. Performing a low-streamflow frequency analysis may not yield the most accurate and least biased estimate of current n-day low streamflow when there are statistically significant trends in the data. More than half of the gages had long records (30 years or more of available data), where 45 unaltered and 32 altered gages had a statistically significant trend in the data, and the most recent 30 years of available data were used to calculate low-streamflow statistics. The rise in values of low-streamflow statistics statewide is consistent with findings from other studies across the Northeast and may be attributed to increased precipitation across the region for much of the last 50 years (McCabe and Wolock, 2021; Seager and others, 2012). Further analysis is needed to understand the drivers and covariates of trends in low streamflow across New York. A trend analysis of lowstreamflow statistics along with precipitation, groundwater storage, anthropogenic variables, and other variables of interest is needed to better understand the causes of changes to low streamflow at both unaltered and altered gages across the State and is beyond the scope of this study. Such work would help better define the selection of period of record for computing low-streamflow statistics. For example, selecting a period of record that begins with the advent of a dam, diversion, or step change in precipitation may present different results. Record extension for unaltered gages was initially explored for this study but was not pursued to permit the potential for further research using the low-streamflow statistics.

References Cited 9

Summary The U.S. Geological Survey updated low-streamflow statistics in New York with the cooperation of the New York Department of Environmental Conservation. Low-streamflow statistics are used for several applications including wastewater permitting, withdrawal permitting, determining total maximum daily loads, setting in-stream flow criteria to protect aquatic life, and drought monitoring. Using streamflow data available through the U.S. Geological Survey National Water Information System, the low-streamflow statistics, such as the lowest annual 7-day average streamflow that occurs (on average) once every 10 years (7Q10 and 30Q10, respectively), were calculated for 213 unaltered and 79 altered gages. Nonexceedance probabilities for the daily moving average 7-day and 30-day values were calculated for the remaining 102 altered gages that were not suitable for low-streamflow frequency analysis. Three categories of situations resulted in missing or irregular daily data and the removal of a climatic year from the period of record for selected gages: missing daily data within the low-streamflow months of July, August, September, and October; missing daily data within the moving average window for an annual minimum 7-day or 30-day value; and an annual minimum 7-day or 30-day value, where the moving average spans the end of one and start of the next climatic year. A trend analysis was performed to account for nonstationarity present within the period of record for longrecord sites. A hypothesis test using the Wilcoxon rank-sum hypothesis test was used to compare data from the most recent 30 years of record to data from 30 years ago and earlier to determine whether there was a statistically significant trend. Statistically significant trends (α≤0.1) were observed for 45 unaltered and 32 altered gages; data from the most recent 30 years of record were used to calculate low-streamflow statistics for these gages. The remaining unaltered and altered gages used the entire period of record to calculate lowstreamflow statistics.

References Cited Barksdale, H.C., 1968, The Northeast water supply crisis of the 1960s: U.S. Geological Survey monograph, 14 p., accessed August 15, 2023, at https://doi.org/10.3133/ 70039594. Bhatti, S.J., Kroll, C.N., and Vogel, R.M., 2019, Revisiting the probability distribution of low streamflow series in the United States: Journal of Hydrologic Engineering, v. 24, no. 10, article no. 04019043, 11 p., accessed February 21, 2024, at https://doi.org/10.1061/(ASCE)HE.1943- 5584.0001844.

Blum, A.G., Archfield, S.A., Hirsch, R.M., Vogel, R.M., Kiang, J.E., and Dudley, R.W., 2019, Updating estimates of low-streamflow statistics to account for possible trends: Hydrological Sciences Journal, v. 64, no. 12, p. 1404–1414, accessed February 21, 2024, at https://doi.org/10.1080/ 02626667.2019.1655148. De Cicco, L.A., Hirsch, R.M., Lorenz, D., Watkins, W.D., and Johnson, M., [2014], dataRetrieval—Retrieval functions for USGS and EPA hydrologic and water quality data (v. 2.7.13, 2023): U.S. Geological Survey software release, accessed November 1, 2023, at https://doi.org/10.5066/P9X4L3GE. Dethier, E.N., Sartain, S.L., Renshaw, C.E., and Magilligan, F.J., 2020, Spatially coherent regional changes in seasonal extreme streamflow events in the United States and Canada since 1950: Science Advances, v. 6, no. 49, 8 p., accessed February 21, 2024, at https://doi.org/10.1126/ sciadv.aba5939. Dudley, R.W., Hirsch, R.M., Archfield, S.A., Blum, A.G., and Renard, B., 2020, Low streamflow trends at humanimpacted and reference basins in the United States: Journal of Hydrology, v. 580, 13 p., accessed February 21, 2024, at https://doi.org/10.1016/j.jhydrol.2019.124254. Eissler, B.B., 1978, Low-flow data and frequency analysis of streams in New York excluding New York City and Long Island: New York State Department of Environment Conservation Bulletin 74, 176 p. [Also available at https://archive.org/details/usgswaterresourcesnewyork- nydec_bull_74/nydec_bull_74/page/n1/mode/2up.] England, J.F., Jr., Cohn, T.A., Faber, B.A., Stedinger, J.R., Thomas, W.O., Jr., Veilleux, A.G., Kiang, J.E., and Mason, R.R., Jr., 2019, Guidelines for determining flood flow frequency—Bulletin 17C (ver. 1.1, May 2019): U.S. Geological Survey Techniques and Methods, book 4, chap. B5, 148 p., accessed February 21, 2024, at https://doi.org/10.3133/tm4B5. Falcone, J.A., 2011, GAGES-II—Geospatial attributes of gages for evaluation streamflow: U.S. Geological Survey data release, accessed October 15, 2014, at https://doi.org/ 10.5066/P96CPHOT. Farmer, W.H., Kiang, J.E., Feaster, T.D., and Eng, K., 2019, Regionalization of surface-water statistics using multiple linear regression (ver. 1.1, February 2021): U.S. Geological Survey Techniques and Methods, book 4, chap. A12, 40 p., accessed February 21, 2024, at https://doi.org/ 10.3133/tm4A12. Feaster, T.D., and Lee, K.G., 2017, Low-flow frequency and flow-duration characteristics of selected streams in Alabama through March 2014: U.S. Geological Survey Scientific Investigations Report 2017–5083, 371 p., accessed February 21, 2024, at https://doi.org/10.3133/sir20175083.

Low-Flow Statistics for Selected Streams in New York, Excluding Long Island

Glas, R., Hect, J., Simonson, A., Gazoorian, C., Scheubert, C., 2023, Adjusting design floods for urbanization across groundwater-dominated watersheds of Long Island, NY: Journal of Hydrology, v. 618, article 129194, 18 p., accessed March 27, 2024, at https://doi.org/10.1016/j.jhydrol.2023. 129194. Gustard, A., and Demuth, S., eds., 2008, Manual on lowflow estimation and prediction—Operational hydrology report no. 50: World Meteorological Organization, Geneva, Switzerland, v. 1029, 136 p. [Also available at https:// library.wmo.int/idurl/4/32176.] Hammond, J.C., Doheny, E.J., Dillow, J.J.A., Nardi, M.R., Steeves, P.A., and Warner, D.L., 2022a, Peak-flow and low-flow magnitude estimates at defined frequencies and durations for nontidal streams in Delaware: U.S. Geological Survey Scientific Investigations Report 2022–5005, 46 p., accessed February 21, 2024, at https://doi.org/10.3133/ sir20225005. Hammond, J.C., Simeone, C., Hecht, J.S., Hodgkins, G.A., Lombard, M., McCabe, G., Wolock, D., Wieczorek, M., Olson, C., Caldwell, T., Dudley, R., and Price, A.N., 2022b, Going beyond low flows—Streamflow drought deficit and duration illuminate distinct spatiotemporal drought patterns and trends in the U.S. during the last century: Water Resources Research, v. 58, no. 9, 20 p. accessed February 21, 2024, at https://doi.org/10.1029/ 2022WR031930.

Lumia, R., Freehafer, D.A., and Smith, M.J, 2006, Magnitude and frequency of floods in New York: U.S. Geological Survey Scientific Investigations Report 2006–5112, 152 p., accessed February 21, 2024, at https://doi.org/10.3133/ sir20065112. McCabe, G.J., and Wolock, D.M., 2021, Multi‐year hydroclimatic droughts and pluvials across the conterminous United States: International Journal of Climatology, v. 41, no. 3, 15 p., accessed February 21, 2024, at https://doi.org/ 10.1002/joc.6925. New York State Department of Environmental Conservation [NYSDEC], [1998], Technical and operational guidance series 1.3.1—Total maximum daily loads and water quality based effluent limits: New York State Department of Environmental Conservation Division of Water web page, accessed August 2, 2023, at https://extapps.dec.ny.gov/docs/ water_pdf/togs131.pdf. Novak, C.E., 1985, WRD data reports preparation guide: U.S. Geological Survey Open-File Report 85-480, 333 p., accessed August 2023 at https://doi.org/10.3133/ofr85480. R Core Team, 2020, R—A language and environment for statistical computing: R Foundation for Statistical Computing web page, accessed September 2023 at https://www.R- project.org/. Seager, R., Pederson, N., Kushnir, Y., Nakamura, J. and Jurburg, S., 2012, The 1960s drought and the subsequent shift to a wetter climate in the Catskill Mountains region of the New York City watershed: Journal of Climate, v. 25, no. 19, 21 p., accessed February 21, 2024, at https://doi.org/ 10.1175/JCLI-D-11-00518.1.

Helsel, D.R., Hirsch, R.M., Ryberg, K.R., Archfield, S.A., and Gilroy, E.J., 2020, Statistical methods in water resources: U.S. Geological Survey Techniques and Methods, book 4, chapter A3, 458 p., accessed September 2023, at https://doi.org/10.3133/tm4A3. [Supersedes USGS Techniques of Water-Resources Investigations, book 4, chapter A3, version 1.1.]

Smakhtin, V.U., 2001, Low flow hydrology—A review: Journal of Hydrology, v. 240, 39 p., accessed February 21, 2024, at https://doi.org/10.1016/S0022-1694(00)00340-1.

Kirby, W., 1972, Computer‐oriented Wilson‐Hilferty transformation that preserves the first three moments and the lower bound of the Pearson type 3 distribution: Water Resources Research, v. 8, no. 5, p. 1251–1254, accessed February 21, 2024, at https://doi.org/10.1029/WR008i005p01251.

Stagnitta, T.J., Graziano, A.P., Woda, J.C., Glas, R.L., and Gazoorian, C.L., 2024, Low-flow statistics for New York State, excluding Long Island, computed through March 2022:U.S. Geological Survey data release, at https://doi.org/10.5066/P9NOM6FR.

Langbein, W.B., and Iseri, K.T., 1960, General surface-water techniques, part 1 of General introduction and hydrologic definitions—Manual of hydrology: U.S. Geological Survey Water-Supply Paper 1541-A, 29 p., accessed February 21, 2024, at https://doi.org/10.3133/wsp1541A.

Suro, T.P., and Gazoorian, C.L., 2011, Changes in low-flow frequency from 1976–2006 at selected streamgages in New York, excluding Long Island: U.S. Geological Survey Scientific Investigations Report 2011–5112, 21 p., accessed February 21, 2024, at https://doi.org/10.3133/sir20115112.

Lukasz, B.S., 2021, Methods for estimating low-flow frequency statistics, mean monthly and annual flow, and flow-duration curves for ungaged locations in Kansas: U.S. Geological Survey Scientific Investigations Report 2021–5100, 69 p., accessed February 21, 2024, at https://doi.org/10.3133/sir20215100.

U.S. Drought Monitor, 2023, Data tables—Percent area in U.S. drought monitor categories [New York]: National Drought Mitigation Center dataset, accessed August 14, 2023, at https://droughtmonitor.unl.edu/DmData/ DataTables.aspx.

References Cited 11 U.S. Environmental Protection Agency, 1986, Stream design flow for steady-state modeling (updated), chap. 1 of Design Considerations, book VI in Technical guidance manual for performing waste load allocations: U.S. Environmental Protection Agency, [variously paged; 65 p.]. [Also available at https://nepis.epa.gov/Exe/ZyPDF.cgi/P100BK6P.PDF? Dockey=P100BK6P.PDF.] U.S. Geological Survey [USGS], 2016, USGS water data for the nation: U.S. Geological Survey National Water Information System database, accessed December 19, 2023, at https://doi.org/10.5066/F7P55KJN. Vogel, R.M., and Kroll, C.N., 2020, A comparison of estimators of the conditional mean under non-stationary conditions: Advances in Water Resources, v. 143, article 103672, 10 p., accessed February 21, 2024, at https://doi.org/ 10.1016/j.advwatres.2020.103672.

Wall, G.R., Murray, P.M., Lumia, R., and Suro, T.P., 2014, Maximum known stages and discharges of New York streams and their annual exceedance probabilities through September 2011: U.S. Geological Survey Scientific Investigations Report 2014–5084, 16 p., accessed February 21, 2024, at https://doi.org/10.3133/sir20145084. Williams-Sether, T., 2021, Estimating flow-duration statistics and low-flow frequencies for selected streams and the implementation of a StreamStats web-based tool in Puerto Rico: U.S. Geological Survey Scientific Investigations Report 2021–5054, 18 p., accessed February 21, 2024, at https://doi.org/10.3133/sir20215054.

Appendix 1. Low-Streamflow Statistics for 213 Unaltered and 79 Altered Gages 13

Appendix 1. Low-Streamflow Statistics for 213 Unaltered and 79 Altered Gages

[Data from Stagnitta and others (2024). The calculated nonexceedance probabilities column refers to altered sites where no low-streamflow statistics were calculated and the tables of daily nonexceedance probabilities are available in Stagnitta and others (2024). Station names appear as listed in the U.S. Geological Survey National Water Information System (U.S. Geological Survey, 2016). CT, Connecticut; MA, Massachusetts; NJ, New Jersey; NY, New York; PA, Pennsylvania; Ave., avenue; Bl, below; Blw, below; Blvd, boulevard; Bk, brook; Br, branch; Cr, creek; E, east; L, lake; Nr, near; R, river; Rd, road; St., street; St., Saint; Trib, tributary; W, West; @, at; mi2, square mile; H0, null hypothesis; α, significance level; ≤, less than or equal to; Q, discharge; ft3/s, cubic foot per second; —, not calculated]

Site number

Station name

Drainage area (mi2)

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

7Q10 (ft3/s)

30Q10 (ft3/s)

01197500

Housatonic River Near Great Barrington, MA

282.00

Yes

108

1915–2022

67.357

87.401

01198000

Green River Near Great Barrington, MA

51.00

1953–1971, 1995–1996, 2009–2022

3.279

3.883

01198125

Housatonic River Near Ashley Falls, MA

465.00

Less than 30 years of data

1995–1996, 2009–2022

76.530

91.992

01199000

Housatonic River At Falls Village, CT

634.00

Yes

109

1914–2022

108.450

143.789

01199050

Salmon Creek At Lime Rock, CT

29.40

1963–2021

3.364

4.669

01200000

Tenmile River Near Gaylordsville, CT

203.00

Yes

1932–1989, 1993–1999, 2002–2021

12.645

16.761

01200500

Housatonic River At Gaylordsville, CT

996.00

Yes

1942–2022

153.718

195.817

01201487

Still River At Route 7 At Brookfield Center, CT

62.30

Yes

—

01201500

Still R Nr Lanesville, CT

67.50

Yes

1937–1966

15.073

18.775

01205500

Housatonic River At Stevenson, CT

1,544.00

Yes

1932–2022

138.899

267.236

01208990

Saugatuck River Near Redding, CT

21.00

1966–2022

0.314

0.552

01209700

Norwalk River At South Wilton, CT

30.00

1964–2022

1.681

2.401

01209901

Rippowam River At Stamford, CT

34.00

Yes

—

01212500

Byram River At Pemberwick, CT

25.60

Less than 30 years of data

2011–2020

0.305

0.846

01300000

Blind Brook At Rye NY

9.31

1946–1989

0.522

0.901

14 Low-Flow Statistics for Selected Streams in New York, Excluding Long Island

Table 1.1. Low-streamflow statistics for the lowest annual 7-day and 30-day average streamflow that occurs (on average) once every 10 years (7Q10 or 30Q10, respectively) for 213 unaltered and 79 altered gages.—Continued [Data from Stagnitta and others (2024). The calculated nonexceedance probabilities column refers to altered sites where no low-streamflow statistics were calculated and the tables of daily nonexceedance probabilities are available in Stagnitta and others (2024). Station names appear as listed in the U.S. Geological Survey National Water Information System (U.S. Geological Survey, 2016). CT, Connecticut; MA, Massachusetts; NJ, New Jersey; NY, New York; PA, Pennsylvania; Ave., avenue; Bl, below; Blw, below; Blvd, boulevard; Bk, brook; Br, branch; Cr, creek; E, east; L, lake; Nr, near; R, river; Rd, road; St., street; St., Saint; Trib, tributary; W, West; @, at; mi2, square mile; H0, null hypothesis; α, significance level; ≤, less than or equal to; Q, discharge; ft3/s, cubic foot per second; —, not calculated]

Site number

Station name

Drainage area (mi2)

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

7Q10 (ft3/s)

30Q10 (ft3/s)

Mamaroneck River At Mamaroneck NY

22.60

Yes

1960–1989

0.533

1.146

01301500

Hutchinson River At Pelham NY

5.78

1946–1989, 2011–2013

0.072

0.243

01302000

Bronx River At Bronxville NY

43.90

Yes

1960–1989

4.550

7.046

01302020

Bronx River At Ny Botanical Garden At Bronx NY

38.40

Yes

—

01312000

Hudson River Near Newcomb NY

192.00

Yes

1976–1982, 1984–1987, 2004–2022

34.064

52.099

01313500

Cedar R Below Chain Lakes Nr Indian Lake NY

160.00

Less than 30 years of data

1933–1940, 1942–1961

23.049

32.051

01314000

Hudson R At Gooley, Near Indian Lake NY

419.00

1918–1940, 1942–1968

56.064

71.874

01315000

Indian River Near Indian Lake NY

132.00

Yes

—

01315500

Hudson River At North Creek NY

792.00

Yes

112

1909–1940, 1942–2015, 2017–2022

215.082

279.016

01317000

Schroon River At Riverbank NY

527.00

Yes

1939–1940, 1942–1966, 1968–1970

48.871

65.714

01318500

Hudson River At Hadley NY

1,664.00

Yes

—

01319000

East Branch Sacandaga River At Griffin NY

114.00

1935–1978

4.032

6.567

01321000

Sacandaga River Near Hope NY

491.00

Yes

110

1913–2022

43.361

63.583

01325000

Sacandaga River At Stewarts Bridge Nr Hadley NY

1,055.00

Yes

—

01326500

Hudson River At Spier Falls NY

2,779.00

Less than 30 years of data

1914–1923

945.416

1,113.425

Appendix 1. Low-Streamflow Statistics for 213 Unaltered and 79 Altered Gages 15

01301000

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

Site number

Station name

Drainage area (mi2)

01327750

Hudson River At Fort Edward NY

2,810.00

Yes

—

01328000

Bond Creek At Dunham Basin NY

14.10

Yes

01329000

Batten Kill At Arlington, VT

152.00

01329490

Batten Kill Below Mill At Battenville NY

396.00

01330000

Glowegee Creek At West Milton NY

24.90

01330500

Kayaderosseras Creek Nr West Milton NY

84.20

01331095

Hudson River At Stillwater NY

3,773.00

01331500

Hoosic River At Adams, MA

01332000

North Branch Hoosic River At North Adams, MA

01332500

7Q10 (ft3/s)

30Q10 (ft3/s)

—

1949–1982

0.451

0.732

1930–1984

51.780

61.524

1924–1968, 1999–2022

78.067

94.639

Yes

1993–2022

2.265

3.750

Yes

1966–1995

18.739

24.215

Yes

—

46.70

1933–2022

12.582

15.500

40.90

1933–1990

5.227

6.978

Hoosic River Near Williamstown, MA

126.00

1942–2022

39.003

48.068

01333000

Green River At Williamstown, MA

42.60

1951–2022

4.800

6.265

01333500

Little Hoosic River At Petersburg NY

56.10

Yes

1967–1996

4.364

5.307

01334000

Walloomsac River Near North Bennington, VT

111.00

1933–2022

32.629

40.565

01334500

Hoosic River Near Eagle Bridge NY

510.00

Yes

—

01335500

Hudson River At Mechanicville NY

4,500.00

Yes

—

01335754

Hudson River Above Lock 1 Near Waterford NY

4,605.00

Yes

—

01336000

Mohawk River Below Delta Dam Near Rome NY

152.00

Yes

—

16 Low-Flow Statistics for Selected Streams in New York, Excluding Long Island

Drainage area (mi2)

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

30Q10 (ft3/s)

48.049

68.881

—

1993–2022

300.439

367.303

1993–2022

632.447

740.510

1900–1912, 1929–1946

53.898

72.375

1947–1995, 2016–2022

14.798

58.279

1951–1989, 2016–2022

2.694

3.536

Less than 30 years of data

1994–2022

0.976

1.758

35.60

Less than 30 years of data

1998–2022

1.496

2.105

Schoharie Creek Near Lexington NY

96.80

Less than 30 years of data

2001–2022

7.967

11.150

01349711

West Kill Below Hunter Brook Near Spruceton NY

4.97

Less than 30 years of data

1999–2022

0.631

0.792

01349810

West Kill Near West Kill NY

27.00

Less than 30 years of data

1999–2022

2.104

2.761

01349840

Batavia Kill Near Maplecrest NY

2.03

Less than 30 years of data

1999–2009

0.210

0.299

01349950

Batavia Kill At Red Falls Near Prattsville NY

68.60

Less than 30 years of data

1999–2022

2.534

3.590

01350000

Schoharie Creek At Prattsville NY

237.00

117

Yes

1993–2022

12.919

16.031

Station name

01343060

West Canada Creek Near Wilmurt NY

238.00

Less than 30 years of data

2003–2022

01344000

West Canada Creek At Hinckley NY

375.00

Yes

—

01346000

West Canada Creek At Kast Bridge NY

560.00

Yes

103

Yes

01347000

Mohawk River Near Little Falls NY

1,342.00

Yes

01347500

East Canada Creek At Dolgeville NY

258.00

01348000

East Canada Creek At East Creek NY

289.00

Yes

01349000

Otsquago Creek At Fort Plain NY

61.00

01349150

Canajoharie Creek Near Canajoharie NY

59.70

01349700

East Kill Near Jewett Center NY

01349705

Appendix 1. Low-Streamflow Statistics for 213 Unaltered and 79 Altered Gages 17

7Q10 (ft3/s)

Site number

Station name

Drainage area (mi2)

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

7Q10 (ft3/s)

30Q10 (ft3/s)

01350035

Bear Kill Near Prattsville NY

25.70

Less than 30 years of data

2000–2022

0.314

0.602

01350080

Manor Kill At West Conesville Near Gilboa NY

32.40

1988–2022

1.690

1.967

01350120

Platter Kill At Gilboa NY

10.90

1976–2022

1.098

1.292

01350140

Mine Kill Near North Blenheim NY

16.20

Yes

1993–2022

0.292

0.509

01350355

Schoharie Creek At Breakabeen NY

444.00

Yes

—

01350500

Schoharie Creek At Middleburgh NY

534.00

Yes

—

01351000

Fox Creek At West Berne NY

67.20

Less than 30 years of data

1926–1932, 1964–1968

0.192

0.374

01351500

Schoharie Creek At Burtonsville NY

886.00

Yes

1993–2022

14.725

19.185

01354500

Mohawk River At Freeman's Bridge At Schenectady NY

3,310.00

Yes

—

01356190

Lisha Kill Northwest Of Niskayuna NY

16.20

Less than 30 years of data

1995–1997, 2002–2012

0.258

0.867

01357499

Mohawk River Diversion To Power Plant At Crescent Dam NY

—

Yes

—

01357500

Mohawk River At Cohoes NY

3,450.00

Yes

104

1919–2022

612.572

784.144

01358000

Hudson River At Green Island NY

8,090.00

Yes

1947–1997, 2002–2022

2,828.804

3,325.255

01358500

Poesten Kill Near Troy NY

89.40

Yes

1925–1968

2.787

4.984

01359519

Normans Kill Near Westmere NY

136.00

Yes

—

01359750

Moordener Kill At Castleton–On– Hudson NY

31.60

1959–1995

2.366

2.863

18 Low-Flow Statistics for Selected Streams in New York, Excluding Long Island

Site number

Station name

Drainage area (mi2)

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

7Q10 (ft3/s)

30Q10 (ft3/s)

Valatie Kill Near Nassau NY

9.48

1992–2022

0.165

0.309

01361000

Kinderhook Creek At Rossman NY

329.00

Yes

1949–1968, 2013–2022

13.944

20.310

013621955

Birch Creek At Big Indian NY

12.50

Less than 30 years of data

2000–2022

2.281

2.729

01362200

Esopus Creek At Allaben NY

63.70

Yes

1993–2022

7.089

8.918

01362230

Diversion From Schoharie Reservoir NY

—

Yes

—

0136230002

Woodland Creek Above Mouth At Phoenicia NY

20.60

Less than 30 years of data

2005–2022

2.985

4.149

01362342

Hollow Tree Brook At Lanesville NY

1.95

Less than 30 years of data

1999–2022

0.349

0.461

01362370

Stony Clove Creek Blw Ox Clove At Chichester NY

30.90

Less than 30 years of data

1998–2022

4.948

5.756

01362487

Beaver Kill At Mount Tremper NY

25.00

Less than 30 years of data

2012–2022

1.376

2.011

01362497

Little Beaver Kill At Beechford Near Mt Tremper NY

16.50

Less than 30 years of data

1999–2022

0.496

0.885

01362500

Esopus Creek At Coldbrook NY

192.00

Yes

—

01363382

Bush Kill Blw Maltby Hollow Bk At West Shokan NY

17.00

Less than 30 years of data

2002–2022

2.867

3.543

01364500

Esopus Creek At Mount Marion NY

419.00

Yes

—

01364959

Rondout Cr Above Red Brook At Peekamoose NY

5.36

Less than 30 years of data

1998–2010

1.482

1.722

01365000

Rondout Creek Near Lowes Corners NY

38.30

Yes

1993–2022

7.397

9.446

01365500

Chestnut Creek At Grahamsville NY

20.90

Yes

1981–1987, 2000–2022

3.590

4.221

Appendix 1. Low-Streamflow Statistics for 213 Unaltered and 79 Altered Gages 19

01360640

Drainage area (mi2)

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

7Q10 (ft3/s)

30Q10 (ft3/s)

—

1959–1977

7.003

8.474

Yes

1993–2022

47.489

54.060

Less than 30 years of data

2005–2014

0.969

1.466

1939–1981

8.803

11.926

Less than 30 years of data

1945–1954, 1957–1968

0.481

0.690

1939–1977

3.672

5.101

9.74

1939–1979

0.199

0.273

Wallkill River At Pellets Island NY

380.00

Yes

1921–1968

13.337

18.656

Wallkill River Near Phillipsburg NY

415.00

Less than 30 years of data

1938–1959

22.105

29.732

01371000

Shawangunk Kill At Pine Bush NY

104.00

Yes

—

01371500

Wallkill River At Gardiner NY

695.00

Yes

1926–2022

31.801

44.524

01372200

Wappinger Creek Near Clinton Corners NY

92.40

Less than 30 years of data

1957–1975

3.390

4.891

01372300

Little Wappinger Creek At Salt Point NY

32.90

Less than 30 years of data

1957–1975

0.366

0.549

01372500

Wappinger Creek Near Wappingers Falls NY

181.00

1930–2022

6.581

9.245

01372800

Fishkill Creek At Hopewell Junction NY

57.30

Less than 30 years of data

1959–1975

1.909

2.515

01373500

Fishkill Creek At Beacon NY

190.00

Yes

—

Site number

Station name

01366500

Rondout Creek Near Lackawack NY

100.00

Yes

—

01366650

Sandburg Creek At Ellenville NY

52.80

Less than 30 years of data

01367500

Rondout Creek At Rosendale NY

383.00

Yes

101

01367800

Papakating Creek At Pellettown NJ

15.80

01368000

Wallkill River Near Unionville NY

140.00

Yes

01368500

Rutgers Creek At Gardnerville NY

59.70

01369000

Pochuck Creek Near Pine Island NY

98.00

01369500

Quaker Creek At Florida NY

01370000 01370500

20 Low-Flow Statistics for Selected Streams in New York, Excluding Long Island

Site number

Station name

Drainage area (mi2)

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

7Q10 (ft3/s)

30Q10 (ft3/s)

East Branch Croton River Near Putnam Lake NY

62.10

Less than 30 years of data

1997–2022

0.314

0.933

01374505

East Branch Croton River At Brewster NY

81.20

Yes

—

01374531

East Branch Croton River Near Croton Falls NY

86.40

Yes

—

01374559

West Branch Croton River At Richardsville NY

11.00

Less than 30 years of data

1997–2022

0.027

0.072

01374581

W Br Croton River Below Dam Near Kent Cliffs NY

22.40

Yes

—

0137462010

West Branch Croton River Near Carmel NY

42.90

Yes

—

01374654

Middle Branch Croton River Near Carmel NY

13.70

Less than 30 years of data

1997–2013

0.450

0.869

01374701

West Branch Croton River Near Croton Falls NY

80.40

Yes

—

01374781

Titicus River Below June Road At Salem Center NY

12.90

Less than 30 years of data

2008–2022

0.387

0.723

01374821

Titicus River At Purdys Station NY

23.80

Yes

Less than 30 years of data

1995–2002, 2004–2022

4.817

6.006

01374890

Cross River Near Cross River NY

17.10

Less than 30 years of data

1997–2022

0.375

0.742

01374901

Cross River At Katonah NY

29.90

Yes

—

01374930

Muscoot River At Baldwin Place NY

13.50

Less than 30 years of data

1997–2022

0.215

0.515

01374941

Muscoot River Below Dam At Amawalk NY

19.70

Yes

—

01374987

Kisco River Below Mount Kisco NY

17.60

Less than 30 years of data

1997–2009

0.573

1.482

Appendix 1. Low-Streamflow Statistics for 213 Unaltered and 79 Altered Gages 21

0137449480

Drainage area (mi2)

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

7Q10 (ft3/s)

30Q10 (ft3/s)

—

Less than 30 years of data

2005–2009, 2011–2020

2.896

3.917

1936–1986, 1988–2020

9.586

12.802

Site number

Station name

01375000

Croton R At New Croton Dam Nr Croton–On–Hudson NY

378.00

Yes

—

01376500

Saw Mill River At Yonkers NY

25.60

Yes

—

01376800

Hackensack River At West Nyack NY

30.70

Yes

—

01377000

Hackensack River At Rivervale NJ

58.00

Yes

—

01377370

Pascack Brook At Park Ridge NJ

13.40

01377500

Pascack Brook At Westwood NJ

29.60

Yes

01384000

Wanaque River At Monks NJ

40.40

Yes

—

01386000

West Brook Near Wanaque NJ

11.80

Yes

1936–1978, 2004–2022

0.635

0.948

01387000

Wanaque River At Wanaque NJ

90.40

Yes

—

01387400

Ramapo River At Ramapo NY

86.90

1981–2022

9.747

11.519

01387420

Ramapo River At Suffern NY

93.00

Yes

—

01387450

Mahwah River Near Suffern NY

12.30

1960–1995, 2007–2022

0.714

1.040

01387500

Ramapo River Near Mahwah NJ

120.00

Yes

102

1904–1906, 1924–2022

11.134

15.116

01390450

Saddle River At Upper Saddle River NJ

10.90

Yes

Less than 30 years of data

2005–2020

0.589

0.966

01390500

Saddle River At Ridgewood NJ

21.60

Yes

1956–1974, 1979–2022

2.101

3.208

01391000

Hohokus Brook At Ho–Ho–Kus NJ

16.40

Yes

—

01413398

Bush Kill Near Arkville NY

46.70

Less than 30 years of data

1999–2022

5.125

6.473

22 Low-Flow Statistics for Selected Streams in New York, Excluding Long Island

Site number

Station name

Drainage area (mi2)

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

7Q10 (ft3/s)

30Q10 (ft3/s)

Dry Brook At Arkville NY

82.20

Less than 30 years of data

1998–2022

9.492

11.969

01413500

East Branch Delaware River At Margaretville NY

163.00

Yes

1993–2022

13.491

17.346

01414000

Platte Kill At Dunraven NY

34.90

Yes

1958–1962, 1998–2022

2.312

3.135

01414500

Mill Brook Near Dunraven NY

25.20

Yes

1993–2022

2.435

3.124

01415000

Tremper Kill Near Andes NY

33.20

1938–2022

1.597

2.434

01415500

Terry Clove Kill Near Pepacton NY

13.60

Less than 30 years of data

1938–1962

0.341

0.636

01417000

East Branch Delaware River At Downsville NY

372.00

Yes

—

01417500

East Branch Delaware River At Harvard NY

458.00

Yes

—

01418000

Beaver Kill Near Turnwood NY

40.80

Less than 30 years of data

1950–1959

5.996

8.561

01418500

Beaver Kill At Craigie Clair NY

81.90

1939–1970

9.727

12.255

01419500

Willowemoc Creek Nr Livingston Manor NY

62.60

1939–1970, 2020–2022

9.971

12.210

01420000

Little Beaver Kill Nr Livingston Manor NY

20.10

1926–1981

1.947

2.629

01420500

Beaver Kill At Cooks Falls NY

241.00

108

Yes

1993–2022

44.578

55.786

01421000

East Branch Delaware River At Fishs Eddy NY

784.00

Yes

—

01421610

West Branch Delaware River At Hobart NY

16.00

Less than 30 years of data

2002–2022

1.000

1.693

01421614

Town Brook Tributary Southeast Of Hobart NY

0.76

Less than 30 years of data

2000–2009

0.044

0.067

Appendix 1. Low-Streamflow Statistics for 213 Unaltered and 79 Altered Gages 23

01413408

Drainage area (mi2)

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

7Q10 (ft3/s)

30Q10 (ft3/s)

Site number

Station name

01421618

Town Brook Southeast Of Hobart NY

14.30

Less than 30 years of data

1999–2022

0.551

0.864

01421900

West Branch Delaware River Upstream From Delhi NY

134.00

1938–1970, 1998–2022

7.581

9.737

01422500

Little Delaware River Near Delhi NY

49.80

Yes

1966–1970, 1998–2022

2.597

4.110

01422747

East Brook East Of Walton NY

24.70

Less than 30 years of data

2000–2013, 2019–2022

1.651

2.262

01423000

West Branch Delaware River At Walton NY

332.00

1952–2022

23.749

29.473

01423500

Dryden Brook Near Granton NY

8.10

Less than 30 years of data

1954–1967

0.362

0.544

0142400103

Trout Creek Near Trout Creek NY

20.20

1954–1967, 1998–2022

0.396

0.585

01424500

Trout Creek At Cannonsville NY

49.50

Less than 30 years of data

1942–1963

2.956

3.728

01425000

West Branch Delaware River At Stilesville NY

456.00

Yes

—

01425675

Oquaga Creek Near North Sanford NY

4.69

Less than 30 years of data

1971–1981

0.290

0.437

01426000

Oquaga Creek At Deposit NY

67.60

1942–1973

1.611

2.479

01426500

West Branch Delaware River At Hale Eddy NY

595.00

Yes

—

01427207

Delaware River At Lordville NY

1,590.00

Yes

—

01427500

Callicoon Creek At Callicoon NY

110.00

1942–1982, 2020–2021

6.528

8.653

01427510

Delaware River At Callicoon NY

1,820.00

Yes

1993–2022

583.426

751.390

01428000

Tenmile River At Tusten NY

45.60

Less than 30 years of data

1948–1973, 2020–2022

1.795

2.488

24 Low-Flow Statistics for Selected Streams in New York, Excluding Long Island

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

Station name

01428500

Delaware R Above Lackawaxen R Near Barryville NY

2,020.00

Yes

01428750

West Branch Lackawaxen River Near Aldenville, PA

40.60

01432900

Mongaup River At Mongaup Valley NY

76.60

01433500

Mongaup River Near Mongaup NY

200.00

Yes

01434000

Delaware River At Port Jervis NY

3,076.00

Yes

0143400680

E Br Neversink R Northeast Of Denning NY

8.93

01434017

East Branch Neversink River Near Claryville NY

22.90

01434021

W Br Neversink R At Winnisook L Nr Frost Valley NY

01434025

7Q10 (ft3/s)

30Q10 (ft3/s)

1993–2022

687.612

890.065

1988–2022

5.661

6.981

Less than 30 years of data

2004–2022

13.092

16.225

—

Yes

—

Less than 30 years of data

1992–2013, 2021–2022

2.787

3.645

1993–2022

7.067

9.129

0.83

Less than 30 years of data

1992–2013, 2021–2022

0.095

0.139

Biscuit Bk Above Pigeon Bk At Frost Valley NY

3.72

1985–2022

0.457

0.691

01434092

Shelter Creek Below Dry Creek Nr Frost Valley NY

0.59

Less than 30 years of data

1994–2007

0.056

0.092

01434498

West Branch Neversink River At Claryville NY

33.80

Less than 30 years of data

1993–2021

8.517

10.893

01435500

Neversink River At Halls Mills Near Curry NY

68.70

Less than 30 years of data

1939–1949

17.580

22.715

01436500

Neversink River At Woodbourne NY

113.00

Yes

—

01436690

Neversink River At Bridgeville NY

171.00

Yes

—

01437000

Neversink River At Oakland Valley NY

223.00

Yes

—

Appendix 1. Low-Streamflow Statistics for 213 Unaltered and 79 Altered Gages 25

Site number

Drainage area (mi2)

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

7Q10 (ft3/s)

30Q10 (ft3/s)

—

1925–2021

7.540

9.442

1923–1977, 1979–2022

16.343

21.060

1931–1932, 1939–1995

3.732

4.887

1926–1968

13.317

27.683

1940–1975

8.554

10.890

108.00

Less than 30 years of data

1942–1968

6.885

8.549

Ouleout Creek At East Sidney NY

103.00

Yes

1993–2022

7.229

8.401

Susquehanna River At Unadilla NY

982.00

Yes

—

01501000

Unadilla River Near New Berlin NY

199.00

1926–1968

14.588

18.185

01502000

Butternut Creek At Morris NY

59.70

Yes

1966–1995

5.207

6.412

01502500

Unadilla River At Rockdale NY

520.00

Yes

1987–1995, 2002–2022

64.261

79.476

01502632

Susquehanna River At Bainbridge NY

1,610.00

Less than 30 years of data

2011–2022

253.877

309.436

01502731

Susquehanna River At Windsor NY

1,820.00

Less than 30 years of data

2011–2022

295.366

351.082

01503000

Susquehanna River At Conklin NY

2,232.00

109

Yes

1993–2022

210.092

253.168

01505000

Chenango River At Sherburne NY

263.00

Yes

1984–1995, 2005–2022

29.062

35.161

Site number

Station name

01437500

Neversink River At Godeffroy NY

307.00

Yes

—

01438500

Delaware River At Montague NJ

3,480.00

Yes

—

01440000

Flat Brook Near Flatbrookville NJ

64.00

01443500

Paulins Kill At Blairstown NJ

126.00

01496500

Oaks Creek At Index NY

102.00

Yes

01497500

Susquehanna R At Colliersville NY

349.00

Yes

01498500

Charlotte Creek At West Davenport NY

167.00

01499000

Otego Creek Near Oneonta NY

01500000 01500500

26 Low-Flow Statistics for Selected Streams in New York, Excluding Long Island

Site number

Station name

Drainage area (mi2)

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

7Q10 (ft3/s) 0.881

30Q10 (ft3/s)

Canasawacta Creek Near South Plymouth NY

57.90

Less than 30 years of data

1947–1975

1.702

01505810

Chenango River At Oxford NY

458.00

Yes

—

01507000

Chenango River At Greene NY

593.00

1938–1970, 2011–2022

54.878

63.609

01507500

Genegantslet Cr At Smithville Flats NY

82.30

Yes

1940–1970

1.847

2.405

01508000

Shackham Brook Near Truxton NY

3.16

1934–1968

0.051

0.079

01508803

West Br Tioughnioga River At Homer NY

71.50

Less than 30 years of data

1968–1968, 1974–1986

13.853

17.506

01509000

Tioughnioga River At Cortland NY

292.00

Yes

1993–2022

43.386

49.876

01510000

Otselic River At Cincinnatus NY

147.00

Yes

1993–2022

11.127

13.773

01510500

Otselic River Near Upper Lisle NY

217.00

1939–1969

13.428

16.299

01511500

Tioughnioga River At Itaska NY

730.00

1931–1967

57.595

73.398

01512500

Chenango River Near Chenango Forks NY

1,483.00

109

Yes

1993–2022

143.387

174.897

01513500

Susquehanna River At Vestal NY

3,941.00

1940–1967, 2011–2022

340.914

401.221

01513831

Susquehanna River At Owego NY

4,216.00

Less than 30 years of data

2011–2022

560.713

742.825

01514000

Owego Creek Near Owego NY

185.00

1932–1978, 2019–2022

10.462

11.535

01515000

Susquehanna River Near Waverly NY

4,773.00

Yes

1987–1995, 2002–2022

491.840

633.581

01516350

Tioga River Near Mansfield, PA

153.00

1978–2022

9.747

11.714

01518000

Tioga River At Tioga, PA

282.00

Yes

1993–2022

24.728

25.377

Appendix 1. Low-Streamflow Statistics for 213 Unaltered and 79 Altered Gages 27

01505500

Site number

Station name

Drainage area (mi2)

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

7Q10 (ft3/s)

30Q10 (ft3/s)

01518500

Crooked Creek At Tioga, PA

122.00

Less than 30 years of data

1955–1974

2.342

2.839

01518700

Tioga River At Tioga Junction, PA

446.00

Yes

1978–2022

30.031

33.704

01518862

Cowanesque River At Westfield, PA

90.60

1985–2022

1.458

2.318

01520500

Tioga River At Lindley NY

771.00

Yes

—

01521500

Canisteo River At Arkport NY

30.60

Yes

1993–2022

0.838

1.056

01523500

Canacadea Creek Near Hornell NY

57.90

Yes

1942–1942, 1946–2022

3.262

5.934

01524500

Canisteo River Below Canacadea Creek At Hornell NY

158.00

Yes

1993–2022

15.892

18.503

01525500

Canisteo River At West Cameron NY

340.00

Yes

—

01525981

Tuscarora Creek Above South Addison NY

102.00

Less than 30 years of data

2002–2022

0.163

0.411

01526500

Tioga River Near Erwins NY

1,377.00

Yes

103

Yes

1993–2022

83.402

94.798

01527000

Cohocton River At Cohocton NY

52.20

1952–1981

3.076

4.313

01527500

Cohocton River At Avoca NY

152.00

Less than 30 years of data

1940–1945, 2003–2022

16.057

18.244

01528000

Fivemile Creek Near Kanona NY

66.80

Yes

1966–1995

0.902

1.385

01529000

Mud Creek Near Savona NY

76.60

Yes

1938–1982

0.727

1.098

01529500

Cohocton River Near Campbell NY

470.00

103

Yes

1993–2022

28.631

36.629

01529950

Chemung River At Corning NY

2,006.00

Yes

1976–2022

128.542

152.796

01530332

Chemung River At Elmira NY

2,162.00

Yes

—

01530500

Newtown Creek At Elmira NY

77.50

Yes

1940–2008

6.100

7.622

01531000

Chemung River At Chemung NY

2,506.00

Yes

118

Yes

1993–2022

161.212

186.809

28 Low-Flow Statistics for Selected Streams in New York, Excluding Long Island

Drainage area (mi2)

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

30Q10 (ft3/s)

1993–2022

676.552

810.977

1976–2022

14.023

20.420

Less than 30 years of data

1976–1995

14.162

17.622

Less than 30 years of data

1927–1939

13.733

25.247

1941–2022

31.965

44.540

1976–2022

5.754

7.312

Less than 30 years of data

2012–2022

103.997

129.381

1,608.00

118

Yes

1993–2022

151.297

193.224

38.80

1967–2022

5.211

6.561

Allegheny River At Kinzua Dam, PA

2,180.00

Yes

—

03012600

Allegheny River At Warren, PA

2,223.00

Yes

—

03013000

Conewango Creek At Waterboro NY

290.00

Yes

1964–1993

34.859

39.968

03014500

Chadakoin River At Falconer NY

194.00

Yes

—

03015000

Conewango Creek At Russell, PA

816.00

Yes

1993–2022

105.940

122.171

03015310

Allegheny River Bl Conewango Creek At Warren, PA

3,131.00

Yes

—

03015500

Brokenstraw Creek At Youngsville, PA

321.00

112

Yes

1993–2022

43.869

50.737

03016000

Allegheny River At West Hickory, PA

3,660.00

Yes

—

Station name

01531500

Susquehanna River At Towanda, PA

7,797.00

108

Yes

03007800

Allegheny River At Port Allegany, PA

248.00

03009680

Potato Creek At Smethport, PA

160.00

03010000

Allegheny River At Larabee, PA

530.00

03010500

Allegheny River At Eldred, PA

550.00

03010655

Oswayo Creek At Shinglehouse, PA

98.70

03010820

Allegheny River At Olean NY

1,168.00

03011020

Allegheny River At Salamanca NY

03011800

Kinzua Creek Near Guffey, PA

03012550

Appendix 1. Low-Streamflow Statistics for 213 Unaltered and 79 Altered Gages 29

7Q10 (ft3/s)

Site number

Drainage area (mi2)

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

7Q10 (ft3/s)

30Q10 (ft3/s)

Site number

Station name

03021350

French Creek Near Wattsburg, PA

92.00

1976–2022

5.110

8.360

03021410

West Branch French Creek Near Lowville, PA

52.30

Less than 30 years of data

1976–1993

2.825

4.716

03021500

French Creek At Carters Corners, PA

208.00

1911–1971

9.652

13.005

03021520

French Creek Near Union City, PA

221.00

1973–1991, 2011–2022

19.516

28.688

03025500

Allegheny River At Franklin, PA

5,982.00

Yes

—

04213500

Cattaraugus Creek At Gowanda NY

436.00

Yes

—

04214500

Buffalo Creek At Gardenville NY

142.00

Yes

1987–2007, 2014–2022

7.395

11.692

04215000

Cayuga Creek Near Lancaster NY

96.40

Yes

1993–2022

0.756

2.444

04215500

Cazenovia Creek At Ebenezer NY

04216000

Niagara River At Buffalo NY

04216200 04216418

135.00

Yes

1993–2022

7.084

12.288

263,700.00

Yes

—

Scajaquada Creek At Buffalo NY

15.80

Yes

—

Tonawanda Creek At Attica NY

76.90

1979–2022

5.873

7.880

04216500

Little Tonawanda Creek At Linden NY

22.10

1914–1968, 1979–1992

0.284

0.378

04217000

Tonawanda Creek At Batavia NY

171.00

Yes

1991–1998, 2001–2022

7.104

10.933

04217500

Tonawanda Creek Near Alabama NY

231.00

1957–1989

11.070

13.577

04217750

Murder Creek Near Akron NY

57.50

Yes

—

04218000

Tonawanda Creek At Rapids NY

349.00

1957–1965, 1981–2022

04218518

Ellicott Creek Below Williamsville NY

79.70

Yes

—

13.065

17.821

—

30 Low-Flow Statistics for Selected Streams in New York, Excluding Long Island

Drainage area (mi2)

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

30Q10 (ft3/s)

—

2010–2022

0.513

2.041

—

1957–1958, 1974–2022

18.040

22.824

1918–1972

13.583

17.599

62.00

Yes

—

Genesee River At Portageville NY

984.00

Yes

113

Yes

1993–2022

72.242

92.659

Canaseraga Creek Above Dansville NY

88.90

1976–2022

7.818

8.778

04225000

Canaseraga Creek Near Dansville NY

157.00

1912–1912, 1922–1968, 1972–1976

14.366

17.379

04225500

Canaseraga Creek At Groveland NY

185.00

Less than 30 years of data

1917–1919, 1957–1964

18.017

20.448

04226000

Keshequa Cr At Craig Colony At Sonyea NY

68.30

Less than 30 years of data

1919–1932, 1976–1977, 2018–2022

0.834

1.456

04227000

Canaseraga Creek At Shakers Crossing NY

335.00

Yes

1993–2022

27.952

34.252

04227500

Genesee River Near Mount Morris NY

1,424.00

Yes

111

Yes

1993–2022

103.165

131.183

04227995

Conesus Creek Near Lakeville NY

72.00

Yes

—

04228500

Genesee River At Avon NY

1,680.00

Yes

1993–2022

132.949

159.731

04230380

Oatka Creek At Warsaw NY

39.50

Yes

1993–2022

2.680

3.651

Station name

04219768

Eighteenmile Creek At Burt NY

84.80

Yes

—

04220045

Oak Orchard Creek Near Shelby NY

146.00

Less than 30 years of data

04220250

West Creek Near Hilton NY

31.00

Yes

—

0422026250

Northrup Creek At North Greece NY

10.10

Yes

04221000

Genesee River At Wellsville NY

288.00

04221500

Genesee River At Scio NY

308.00

04222000

Caneadea Creek At Caneadea NY

04223000 04224775

Appendix 1. Low-Streamflow Statistics for 213 Unaltered and 79 Altered Gages 31

7Q10 (ft3/s)

Site number

Station name

Drainage area (mi2)

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

7Q10 (ft3/s)

30Q10 (ft3/s)

04230500

Oatka Creek At Garbutt NY

205.00

Yes

1993–2022

24.674

25.887

04231000

Black Creek At Churchville NY

130.00

Yes

1993–2022

1.300

3.032

04231600

Genesee River At Ford Street Bridge, Rochester NY

2,474.00

Yes

—

04232000

Genesee River At Rochester NY

2,482.00

Yes

—

04232034

Irondequoit Cr At Railroad Mills Near Fishers NY

39.20

Less than 30 years of data

1993–2010, 2017–2022

9.027

10.414

04232040

Irondequoit Creek Near Pittsford NY

44.40

Less than 30 years of data

1981–1991

9.807

11.824

04232047

Irondequoit Cr @ Linden Ave., E Rochester NY

101.00

Yes

—

0423204920

East Branch Allen Creek At Pittsford NY

9.50

Yes

Less than 30 years of data

1992–2002

0.801

1.247

04232050

Allen Creek Near Rochester NY

28.90

Yes

1993–2022

3.151

5.407

0423205010

Irondequoit Cr Above Blossom Rd Near Rochester NY

142.00

Yes

—

0423205025

Irondequoit Creek At Empire Blvd, Rochester NY

151.00

Less than 30 years of data

1992–2002

29.581

38.391

04232100

Sterling Creek At Sterling NY

45.90

Yes

1967–1995, 2019–2019

1.165

1.825

04232482

Keuka Lake Outlet At Dresden NY

207.00

Yes

1966–2012, 2014–2021

9.121

12.184

04232650

Seneca River At Lock 4, Waterloo, NY

742.00

Yes

—

04232730

Seneca River Near Seneca Falls NY

785.00

Yes

—

04233000

Cayuga Inlet Near Ithaca NY

35.20

1938–2012

2.827

3.513

04233286

Sixmile Creek At Brooktondale NY

27.00

Less than 30 years of data

2004–2022

3.527

4.332

32 Low-Flow Statistics for Selected Streams in New York, Excluding Long Island

Site number

Station name

Drainage area (mi2)

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

7Q10 (ft3/s)

30Q10 (ft3/s)

Sixmile Creek At Bethel Grove NY

39.00

Less than 30 years of data

1996–2022

3.435

4.458

04234000

Fall Creek Near Ithaca NY

126.00

Yes

1993–2022

9.795

14.428

0423401815

Salmon Creek Near Ludlowville NY

87.70

Less than 30 years of data

2008–2009, 2014–2022

0.803

1.383

04234232

Great Brook Below Victor NY

16.80

Less than 30 years of data

1995–2004

0.904

1.111

04235000

Canandaigua Outlet At Chapin NY

195.00

Yes

—

04235150

Flint Creek At Potter NY

31.00

Less than 30 years of data

1965–1968, 1972–1978

0.049

0.154

04235271

Clyde River At Lock 26 Nr Clyde NY

845.00

Yes

1936–1966

31.472

67.358

04235299

Owasco Inlet Below Aurora Street At Moravia NY

106.00

Less than 30 years of data

1961–1968, 2011–2022

5.790

7.287

04235440

Owasco Outlet At Genesee St., Auburn NY

204.00

Yes

—

04235500

Owasco Outlet Near Auburn NY

206.00

Yes

—

04235600

Seneca River (Erie Canal) Near Port Byron NY

2,815.00

Yes

—

04236500

Skaneateles Creek At Willow Glen NY

75.80

Yes

—

04237496

Seneca River Near Baldwinsville NY

3,130.00

Yes

—

04237946

Onondaga Cr Trib 6 Blw Mudboil Area At Tully NY

0.32

Yes

Less than 30 years of data

1993–2011

0.148

0.220

04237962

Onondaga Creek Near Cardiff NY

35.30

Less than 30 years of data

2003–2017

5.146

6.353

04239000

Onondaga Creek At Dorwin Avenue, Syracuse NY

88.50

Yes

1991–2020

15.603

19.258

Appendix 1. Low-Streamflow Statistics for 213 Unaltered and 79 Altered Gages 33

04233300

Site number

Station name

Drainage area (mi2)

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

7Q10 (ft3/s)

30Q10 (ft3/s)

30.944

36.114

04240010

Onondaga Creek At Spencer Street, Syracuse NY

110.00

Yes

1972–2022

04240100

Harbor Brook At Syracuse NY

10.00

Yes

—

04240105

Harbor Brook At Hiawatha Boulevard, Syracuse NY

12.10

Yes

—

04240120

Ley Creek At Park Street, Syracuse NY

29.90

Yes

1974–2020

4.835

7.637

04240180

Ninemile Creek Near Marietta NY

45.10

Yes

1984–2013

1.718

2.588

04240200

Ninemile Creek At Camillus NY

84.30

Yes

—

04240300

Ninemile Creek At Lakeland NY

115.00

Yes

—

04242500

East Branch Fish Creek At Taberg NY

188.00

Yes

1979–1995, 2010–2022

35.382

46.872

04243500

Oneida Creek At Oneida NY

113.00

Yes

1993–2022

17.745

22.220

04244000

Chittenango Creek Near Chittenango NY

66.30

Yes

Less than 30 years of data

1952–1968, 2016–2022

12.433

14.873

04245000

Limestone Creek At Fayetteville NY

85.50

Yes

1941–1986

17.210

19.874

04245200

Butternut Creek Near Jamesville NY

32.20

1960–1999

4.131

4.939

04245236

Meadow Brook At Hurlburt Rd, Syracuse NY

2.94

Yes

—

04246500

Oneida River At Caughdenoy NY

1,382.00

Yes

—

04247000

Oneida River Near Euclid NY

1,439.00

Yes

—

04247055

Oswego River Near Phoenix NY

4,953.00

Yes

—

04249000

Oswego River At Lock 7, Oswego NY

5,100.00

Yes

—

04250200

Salmon River At Pineville NY

238.00

Yes

—

34 Low-Flow Statistics for Selected Streams in New York, Excluding Long Island

Site number

Station name

Drainage area (mi2)

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

7Q10 (ft3/s)

30Q10 (ft3/s)

Sandy Creek Near Adams NY

137.00

Yes

1985–1995, 2004–2022

4.333

6.574

04252500

Black River Near Boonville NY

284.00

Yes

111

Yes

1993–2022

101.409

142.394

04253296

Buck Creek Near Inlet NY

1.16

Less than 30 years of data

1990–1990, 2002–2022

0.039

0.112

04253500

Middle Branch Moose River At Old Forge NY

55.00

Yes

—

04254000

Middle Branch Moose River Near Mckeever NY

151.00

Yes

1939–1968

41.048

50.771

04254500

Moose River At Mckeever NY

363.00

Yes

1941–1970

97.272

119.089

04255500

Independence River At Sperryville NY

81.80

Less than 30 years of data

1930–1941

15.087

17.776

04256000

Independence River At Donnattsburg NY

88.70

Yes

1993–2022

22.431

30.976

04258000

Beaver River At Croghan NY

291.00

Yes

1932–1946, 1948–1981, 1983–1992, 1994–1995, 1997–2012, 2014–2022

163.256

227.654

04258500

Deer River At Copenhagen NY

89.00

Less than 30 years of data

1931–1956

2.042

4.046

04258700

Deer River At Deer River NY

97.20

Less than 30 years of data

1958–1968

2.740

7.266

04260500

Black River At Watertown NY

1,864.00

Yes

101

Yes

1993–2022

847.982

1,049.977

04261000

Oswegatchie River At Cranberry Lake NY

140.00

Yes

—

04262000

Oswegatchie River Near Oswegatchie NY

259.00

Yes

1993–2022

—

92.542

124.340

Appendix 1. Low-Streamflow Statistics for 213 Unaltered and 79 Altered Gages 35

04250750

Drainage area (mi2)

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

7Q10 (ft3/s)

30Q10 (ft3/s)

1993–2022

47.884

60.894

105

1918–2022

220.078

278.091

—

Yes

1948–1977

77.546

102.912

Less than 30 years of data

2005–2022

88.213

118.736

Yes

111

1910–1940, 1942–1958, 1960–2022

84.876

163.451

937.00

Yes

—

Raquette River At Raymondville NY

1,125.00

Yes

1945–2005, 2008–2022

325.378

468.665

04268800

West Branch St. Regis River Near Parishville NY

171.00

1960–1968, 1993–2015, 2017–2022

52.811

65.477

04269000

St. Regis River At Brasher Center NY

612.00

106

1912–1917, 1921–1996, 1999–2022

157.522

193.129

04269500

Deer River At Brasher Iron Works NY

191.00

Less than 30 years of data

1914–1916, 1960–1968

30.986

35.725

04270000

Salmon River At Chasm Falls NY

132.00

Yes

1979–1982, 1988–2013

82.979

100.504

04270200

Little Salmon River At Bombay NY

89.70

1959–1995, 2004–2022

14.102

18.757

Site number

Station name

04262500

West Branch Oswegatchie River Near Harrisville NY

258.00

Yes

105

Yes

04263000

Oswegatchie River Near Heuvelton NY

986.00

Yes

105

04264331

Saint Lawrence R At Cornwall Ont Nr Massena NY

298,800.00

Yes

—

04265000

Grass River At Pyrites NY

333.00

04265432

Grass River At Chase Mills NY

598.00

04266500

Raquette River At Piercefield NY

721.00

04267500

Raquette River At South Colton NY

04268000

36 Low-Flow Statistics for Selected Streams in New York, Excluding Long Island

Site number

Station name

Drainage area (mi2)

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

7Q10 (ft3/s)

30Q10 (ft3/s)

Chateaugay River Near Chateaugay NY

112.00

Yes

1928–1931, 1933–1940, 1942–1965

45.361

54.029

04270510

Chateaugay River Below Chateaugay NY

151.00

Yes

Less than 30 years of data

1967–1995

56.881

64.014

04271500

Great Chazy River At Perry Mills NY

243.00

Yes

1930–1968, 1991–2015, 2017–2022

18.049

25.137

04271815

Little Chazy River Near Chazy NY

50.30

1991–2014, 2017–2022

0.996

1.460

04273000

Saranac River At Saranac NY

521.00

Less than 30 years of data

1932–1943

147.731

168.782

04273500

Saranac River At Plattsburgh NY

608.00

Yes

—

04273700

Salmon River At South Plattsburgh NY

63.30

Yes

1992–2014, 2016–2022

9.956

12.170

04273800

Little Ausable River Near Valcour NY

67.80

1993–2022

3.755

6.256

04274000

W Br Ausable R Nr Lake Placid NY

116.00

Yes

—

04274500

Black Brook At Black Brook NY

49.40

Yes

1932–1961

4.423

7.381

04275000

East Branch Ausable River At Au Sable Forks NY

198.00

Yes

1972–1995, 2017–2022

39.754

53.524

04275500

Ausable River Near Au Sable Forks NY

446.00

Yes

1912–1917, 1919–1968, 1991–2015, 2017–2022

104.403

126.144

04276500

Boquet River At Willsboro NY

270.00

Yes

1925–1968, 1991–2014, 2016–2022

31.260

38.643

Appendix 1. Low-Streamflow Statistics for 213 Unaltered and 79 Altered Gages 37

04270500

Site number

Station name

Drainage area (mi2)

Altered gage

Calculated nonexceedance probabilities

Total length of available record (years)

Length Climate years of record Is the H0 rejected used to calculate after trend low-streamflow with a α≤0.1? analysis statistics (years)

7Q10 (ft3/s)

30Q10 (ft3/s)

04276842

Putnam Creek East Of Crown Point Center NY

51.60

Less than 30 years of data

1991–2014, 2019–2019

1.036

1.809

04278300

Northwest Bay Brook Near Bolton Landing NY

22.00

Less than 30 years of data

1967–1968, 1973–1997

0.655

1.007

04279000

La Chute At Ticonderoga NY

234.00

Yes

—

04280000

Poultney River Below Fair Haven, VT

187.00

Yes

1930–2022

8.545

12.200

04280350

Mettawee River Near Pawlet, VT

70.20

Less than 30 years of data

1986–2009

8.612

11.456

04280450

Mettawee River Near Middle Granville NY

167.00

1991–2022

12.594

16.946

04292500

Lamoille River At East Georgia, VT

686.00

1931–2022

154.865

201.542

04292700

Stone Bridge Brook Near Georgia Plains, VT

8.45

Less than 30 years of data

1964–1974, 1991–2000

0.338

0.674

38 Low-Flow Statistics for Selected Streams in New York, Excluding Long Island

Appendix 1. Low-Streamflow Statistics for 213 Unaltered and 79 Altered Gages 39

References Cited Stagnitta, T.J., Graziano, A.P., Woda, J.C., Glas, R.L., and Gazoorian, C.L., 2024, Low-flow statistics for New York State, excluding Long Island, computed through March 2022: U.S. Geological Survey data release, https://doi.org/10.5066/P9NOM6FR.

U.S. Geological Survey, 2016, USGS water data for the nation: U.S. Geological Survey National Water Information System data system, accessed December 19, 2023, at https://doi.org/10.5066/F7P55KJN.

For more information, contact Director, New York Water Science Center U.S. Geological Survey 425 Jordan Road Troy, NY 12180–8349 dc_[email protected] or visit our website at https://www.usgs.gov/centers/ny-water Publishing support provided by the Pembroke and Lafayette Publishing Service Centers

Stagnitta and others—Low-Flow Statistics for Selected Streams in New York, Excluding Long Island—SIR 2024–5055

ISSN 2328-0328 (online) https://doi.org/10.3133/sir20245055

Low-Flow Statistics for Selected Streams in New York, Excluding Long Island

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