The U.S. Geological Survey (USGS) Central Midwest Water Science Center (CMWSC) completed a report (Over and others, 2023) documenting methods for peak-flow frequency analysis in Illinois following Bulletin 17C guidelines. The methods are used to provide estimates of peak-flow quantiles for 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities (AEPs) for selected USGS streamgages. This data release presents peak-flow frequency analyses for selected streamgages in Illinois, Indiana, and Wisconsin, based on data through water year 2017 (a water year is the period from October 1 to September 30 and is designated by the year in which it ends; for example, water year 2017 was from October 1, 2016, to September 30, 2017). References Cited: 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., https://doi.org/10.3133/tm4B5. Over, T.M., Marti, M.K., O'Shea, P.S., Sharpe, J.B., 2023, Estimating peak-flow quantiles for selected annual exceedance probabilities in Illinois (Report No. FHWA-ICT-23-014). Illinois Center for Transportation. https://doi.org/10.36501/0197-9191/23-019.

This dataset contains annual peak-flow data, PeakFQ specifications, and results of flood-frequency analyses of annual peak flows for 368 selected streamflow gaging stations (streamgages) operated by the U.S. Geological Survey (USGS) in the Great Lakes and Ohio River basins. "PeakFQinput_all.txt" contains annual peak-flow data, ending in water year 2013, for all 368 streamgages in the study area. Annual peak-flow data were obtained from the USGS National Water Information System (NWIS) database (https://nwis.waterdata.usgs.gov/usa/nwis/peak). "PeakFQspec_all.psf" contains PeakFQ specifications for all 368 streamgages in the study area. The specifications were developed by hydrologists in the various USGS Water Science Centers that participated in the study. "PeakFQoutput_all.PRT" contains the results of flood-frequency analyses of annual peak-flow data, for each of the 368 streamgages in the study area, that were conducted using the Expected Moments Algorithm (England and others, 2018). Using the annual peak-flow data in "PeakFQinput_all.txt" and the specifications in "PeakFQspec_all.psf", "PeakFQoutput_all.PRT" was generated in version 7.2 of USGS flood-frequency analysis software PeakFQ (https://water.usgs.gov/software/PeakFQ/; Veilleux and others, 2014). Results of the flood-frequency analyses were used to estimate regional skew for the study area using Bayesian Weighted Least Squares / Bayesian Generalized Least Squares (B-WLS / B-GLS) regression.

This dataset contains annual peak-flow data, PeakFQ specifications, and results of flood-frequency analyses of annual peak flows for 368 selected streamflow gaging stations (streamgages) operated by the U.S. Geological Survey (USGS) in the Great Lakes and Ohio River basins. "PeakFQinput_all.txt" contains annual peak-flow data, ending in water year 2013, for all 368 streamgages in the study area. Annual peak-flow data were obtained from the USGS National Water Information System (NWIS) database (https://nwis.waterdata.usgs.gov/usa/nwis/peak). "PeakFQspec_all.psf" contains PeakFQ specifications for all 368 streamgages in the study area. The specifications were developed by hydrologists in the various USGS Water Science Centers that participated in the study. "PeakFQoutput_all.PRT" contains the results of flood-frequency analyses of annual peak-flow data, for each of the 368 streamgages in the study area, that were conducted using the Expected Moments Algorithm (England and others, 2018). Using the annual peak-flow data in "PeakFQinput_all.txt" and the specifications in "PeakFQspec_all.psf", "PeakFQoutput_all.PRT" was generated in version 7.2 of USGS flood-frequency analysis software PeakFQ (https://water.usgs.gov/software/PeakFQ/; Veilleux and others, 2014). Results of the flood-frequency analyses were used to estimate regional skew for the study area using Bayesian Weighted Least Squares / Bayesian Generalized Least Squares (B-WLS / B-GLS) regression.

This data release presents a peak-flow frequency analysis (Eash and others, 2013) for U.S. Geological Survey streamgage 05465500 Iowa River at Wapello, Iowa. These methods are used to provide estimates of peak-flow quantiles corresponding to the 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities (AEPs). Annual peak-flow data used in the peak-flow frequency analysis for this streamgage was retrieved from the U.S. Geological Survey National Water Information System database (U.S. Geological Survey, 2022) and used with USGS flood-frequency analysis software PeakFQ (Veilleux and others, 2014). This data release contains annual peak-flow data (05465500_ffa_2022_WATSTORE.txt), PeakFQ specifications (05465500_ffa_2022.psf), and a series of tables describing the methods and results of the peak-flow frequency analysis (Wapello_ffa_2022.xlsx)

This data release presents a peak-flow frequency analysis (Eash and others, 2013) for U.S. Geological Survey streamgage 05465500 Iowa River at Wapello, Iowa. These methods are used to provide estimates of peak-flow quantiles corresponding to the 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities (AEPs). Annual peak-flow data used in the peak-flow frequency analysis for this streamgage was retrieved from the U.S. Geological Survey National Water Information System database (U.S. Geological Survey, 2022) and used with USGS flood-frequency analysis software PeakFQ (Veilleux and others, 2014). This data release contains annual peak-flow data (05465500_ffa_2022_WATSTORE.txt), PeakFQ specifications (05465500_ffa_2022.psf), and a series of tables describing the methods and results of the peak-flow frequency analysis (Wapello_ffa_2022.xlsx)

This data release presents a peak-flow frequency analysis (Eash and others, 2013) for U.S. Geological Survey streamgage 06810000 Nishnabotna River above Hamburg, Iowa. These methods are used to provide estimates of peak-flow quantiles for 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities (AEPs). Annual peak-flow data used in the peak-flow frequency analysis for this streamgage was retrieved from the U.S. Geological Survey National Water Information System database (U.S. Geological Survey, 2021) and used with USGS flood-frequency analysis software PeakFQ (Veilleux and others, 2014). This data release contains annual peak-flow data (nishnabotna_2020_WATSTORE.txt), PeakFQ specifications (nishnabotna_ffa_2020.psf), and a series of tables describing the methods and results of the peak-flow frequency analysis (nishnabotna_ffa_2020.xlsx). References Cited: Eash, D.A., Barnes, K.K., and Veilleux, A.G., 2013, Methods for estimating annual exceedance-probability discharges for streams in Iowa, based on data through water year 2010: U.S. Geological Survey Scientific Investigations Report 2013-5086, 63 p. with appendix., http://pubs.usgs.gov/sir/2013/5086/. U.S. Geological Survey, 2021, USGS water data for the Nation: U.S. Geological Survey National Water Information System database, accessed March 10, 2021, at https://doi.org/10.5066/F7P55KJN. Veilleux, A.G., Cohn, T.A., Flynn, K.M., Mason, R.R., Jr., and Hummel, P.R., 2014, Estimating magnitude and frequency of floods using the PeakFQ 7.0 program: U.S. Geological Survey Fact Sheet 2013–3108, 2 p., https://dx.doi.org/10.3133/fs20133108.

This data release presents a peak-flow frequency analysis (Eash and others, 2013) for U.S. Geological Survey streamgage 06810000 Nishnabotna River above Hamburg, Iowa. These methods are used to provide estimates of peak-flow quantiles for 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities (AEPs). Annual peak-flow data used in the peak-flow frequency analysis for this streamgage was retrieved from the U.S. Geological Survey National Water Information System database (U.S. Geological Survey, 2021) and used with USGS flood-frequency analysis software PeakFQ (Veilleux and others, 2014). This data release contains annual peak-flow data (nishnabotna_2020_WATSTORE.txt), PeakFQ specifications (nishnabotna_ffa_2020.psf), and a series of tables describing the methods and results of the peak-flow frequency analysis (nishnabotna_ffa_2020.xlsx). References Cited: Eash, D.A., Barnes, K.K., and Veilleux, A.G., 2013, Methods for estimating annual exceedance-probability discharges for streams in Iowa, based on data through water year 2010: U.S. Geological Survey Scientific Investigations Report 2013-5086, 63 p. with appendix., http://pubs.usgs.gov/sir/2013/5086/. U.S. Geological Survey, 2021, USGS water data for the Nation: U.S. Geological Survey National Water Information System database, accessed March 10, 2021, at https://doi.org/10.5066/F7P55KJN. Veilleux, A.G., Cohn, T.A., Flynn, K.M., Mason, R.R., Jr., and Hummel, P.R., 2014, Estimating magnitude and frequency of floods using the PeakFQ 7.0 program: U.S. Geological Survey Fact Sheet 2013–3108, 2 p., https://dx.doi.org/10.3133/fs20133108.

This data release presents a peak-flow frequency analysis for U.S. Geological Survey streamgage 05481510 Bluff Creek at Pilot Mound, Iowa. The annual peak-flow record at this streamgage consists of both a discrete crest-stage period and a continuous partial-record period. The streamgage, which is in the Des Moines River Basin, is located on 130th Street in Pilot Mound, Iowa. Drainage area at the streamgage is 23.5 square miles. Annual peak-flow data are available for the period 1966-2021. The peak of record, 1,290 cubic feet per second, occurred on June 16, 1990. The annual peak-flow data used in the frequency analysis were downloaded from the U.S. Geological Survey National Water Information System database (U.S. Geological Survey, 2022) and the procedures for the flood frequency analyses are described in Eash and others (2013). The program PeakFQ version 7.4 was used for these analyses, a description of this program can be found in Flynn and others (2006) and Veilleux and others (2014). References Cited: Eash, D.A., Barnes, K.K., and Veilleux, A.G., 2013, Methods for estimating annual exceedance-probability discharges for streams in Iowa, based on data through water year 2010: U.S. Geological Survey Scientific Investigations Report 2013-5086, 63 p. with appendix., http://pubs.usgs.gov/sir/2013/5086/. Flynn, K.M., Kirby, W.H., and Hummel, P.R., 2006, User’s Manual for Program PeakFQ Annual Flood-Frequency Analysis Using Bulletin 17B Guidelines: U.S. Geological Survey, Techniques and Methods Book 4, Chapter B4; 42 pgs., accessed on July 1, 2022, at https://pubs.usgs.gov/tm/2006/tm4b4/tm4b4.pdf. U.S. Geological Survey, 2022, USGS water data for the Nation: U.S. Geological Survey National Water Information System database, accessed September 12, 2022, https://doi.org/10.5066/F7P55KJN. [Site information directly accessible at https://waterdata.usgs.gov/nwis/inventory/?site_no=05481510&agency_cd=USGS&]. Veilleux, A.G., Cohn, T.A., Flynn, K.M., Mason, R.R., Jr., and Hummel, P.R., 2014, Estimating magnitude and frequency of floods using the PeakFQ 7.0 program: U.S. Geological Survey Fact Sheet 2013–3108, 2 p., https://doi.org/10.3133/fs20133108.

This data release presents a peak-flow frequency analysis for U.S. Geological Survey streamgage 05481510 Bluff Creek at Pilot Mound, Iowa. The annual peak-flow record at this streamgage consists of both a discrete crest-stage period and a continuous partial-record period. The streamgage, which is in the Des Moines River Basin, is located on 130th Street in Pilot Mound, Iowa. Drainage area at the streamgage is 23.5 square miles. Annual peak-flow data are available for the period 1966-2021. The peak of record, 1,290 cubic feet per second, occurred on June 16, 1990. The annual peak-flow data used in the frequency analysis were downloaded from the U.S. Geological Survey National Water Information System database (U.S. Geological Survey, 2022) and the procedures for the flood frequency analyses are described in Eash and others (2013). The program PeakFQ version 7.4 was used for these analyses, a description of this program can be found in Flynn and others (2006) and Veilleux and others (2014). References Cited: Eash, D.A., Barnes, K.K., and Veilleux, A.G., 2013, Methods for estimating annual exceedance-probability discharges for streams in Iowa, based on data through water year 2010: U.S. Geological Survey Scientific Investigations Report 2013-5086, 63 p. with appendix., http://pubs.usgs.gov/sir/2013/5086/. Flynn, K.M., Kirby, W.H., and Hummel, P.R., 2006, User’s Manual for Program PeakFQ Annual Flood-Frequency Analysis Using Bulletin 17B Guidelines: U.S. Geological Survey, Techniques and Methods Book 4, Chapter B4; 42 pgs., accessed on July 1, 2022, at https://pubs.usgs.gov/tm/2006/tm4b4/tm4b4.pdf. U.S. Geological Survey, 2022, USGS water data for the Nation: U.S. Geological Survey National Water Information System database, accessed September 12, 2022, https://doi.org/10.5066/F7P55KJN. [Site information directly accessible at https://waterdata.usgs.gov/nwis/inventory/?site_no=05481510&agency_cd=USGS&]. Veilleux, A.G., Cohn, T.A., Flynn, K.M., Mason, R.R., Jr., and Hummel, P.R., 2014, Estimating magnitude and frequency of floods using the PeakFQ 7.0 program: U.S. Geological Survey Fact Sheet 2013–3108, 2 p., https://doi.org/10.3133/fs20133108.

The U.S. Geological Survey Central Midwest Water Science Center completed a report (Over and others, 2023) documenting the methods, results, and applications of an updated flood-frequency study for the State of Illinois. This data release contains data related to the analysis completed to determine peak-flow quantiles (flood frequency estimates) at streamgages in Illinois for 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities (AEPs), as well as data used to develop regional regression equations that relate the peak-flow quantiles and the basin characteristics of selected streamgages in Illinois, Indiana, and Wisconsin, based on data through water year 2017 (a water year is the period from October 1 to September 30 and is designated by the year in which it ends; for example water year 2017 was from October 1, 2016 to September 30, 2017). There is one set of equations for each of Illinois’ seven hydrologic regions, and, for each region, one equation for each AEP. These regional equations allow the estimation of peak-flow quantiles at ungaged locations throughout the state and their uncertainties. This data release contains a figure of the study area in addition to seven tables that provide both input data and results in tabular format. See metadata for detailed information.