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Minnesota Water Science Center |

U.S. Geological Survey, Open-File Report 2007-1033

By Thomas A. Winterstein, Allan D. Arntson, and Gregory B. Mitton

In cooperation with the Minnesota Pollution Control Agency

The 1-, 7-, and 30-day low-flow series were determined for 120 continuous-record streamflow stations in Minnesota having at least 20 years of continuous record. The 2-, 5-, 10-, 50-, and 100-year statistics were determined for each series by fitting a log Pearson type III distribution to the data. The methods used to determine the low-flow statistics and to construct the plots of the low-flow frequency curves are described. The low-flow series and the low-flow statistics are presented in tables and graphs.

Abstract

Introduction

Methods Used to Compute Low-Flow Statistics

References Cited

Appendix 1. Log-normal plots of low-flow frequency statistics

Appendix 2. Log Pearson type III plots of low-frequency statistics

Appendix 3. Output from the computer program SWSTAT

- Map showing continuous-record streamflow stations used in low-flow analysis in Minnesota, 2006.
- Example of output from the computer program SWSTAT.

3–6. Graphs showing:

3. | Low-flow frequency curves plotted along a normal probability axis showing effects of skews on the shape
of the curve. |

4. | Low-flow frequency curve with skew equal to zero plotted along a normal probability axis. |

5. | Low-flow frequency curves plotted along a Pearson type III probability axis showing effects of skew on the position of the 0.50 probability line. |

6. | One-day low-flow frequency curves for continuous-record streamflow station 05279000, South Fork Crow River near Mayer, Minnesota, showing the effects of zero values on the shape of the frequency curve. |

- Continuous-record streamflow stations used in the analysis.

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Cover 1 through page 17 - 22 pages (679 KB) (8.5" by 11" paper)

Appendix 1 - 120 pages (1.71 MB) (8.5" by 11" paper)

Appendix 2 - 120 pages (1.39 MB) (8.5" by 11" paper)

Appendix 3 - 505 pages (1.84 MB) (8.5" by 11" paper)

Cover 4 (20.7 KB) (8.5" by 11" paper)

**Suggested Citation:**

Winterstein, T.A., Arntson, A.D., and Mitton, G.B., 2007, Methods Used to Compute Low-Flow Frequency
Characteristics for Continuous-Record Streamflow Stations in Minnesota, 2006: U.S. Geological Survey Open-File Report
2007-1033, 762 p.

For more information about USGS activities in Minnesota, visit the USGS Minnesota Water Science Center home page.

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