Little Sioux River Watershed Biotic Stressor Identification Report April 2015 Authors Editing and Graphic Design Paul Marston Sherry Mottonen Jennifer Holstad Contributors/acknowledgements Michael Koschak Kim Laing The MPCA is reducing printing and mailing costs by Chandra Carter using the Internet to distribute reports and Chuck Regan information to wider audience. Visit our website Mark Hanson for more information. Katherine Pekarek-Scott MPCA reports are printed on 100% post-consumer Colton Cummings recycled content paper manufactured without Tim Larson chlorine or chlorine derivatives. Chessa Frahm Brooke Hacker Jon Lore Cover photo: Clockwise from Top Left: Little Sioux River at site 11MS010; County Ditch 11 at site 11MS078; Cattle around Unnamed Creek at site 11MS067 Project dollars provided by the Clean Water Fund (From the Clean Water, Land and Legacy Amendment) Minnesota Pollution Control Agency 520 Lafayette Road North | Saint Paul, MN 55155-4194 | www.pca.state.mn.us | 651-296-6300 Toll free 800-657-3864 | TTY 651-282-5332 This report is available in alternative formats upon request, and online at www.pca.state.mn.us Document number: wq-ws5-10230003a Contents Executive summary ............................................................................................................... 1 Introduction .......................................................................................................................... 2 Monitoring and assessment ...........................................................................................................2 Stressor Identification process ........................................................................................................3 Common stream stressors ..............................................................................................................3 Report format ................................................................................................................................4 Overview of the Little Sioux River Watershed ........................................................................ 5 Background ...................................................................................................................................5 Monitoring overview .....................................................................................................................6 Summary of biological impairments ...............................................................................................6 Hydrological Simulation Program - FORTRAN (HSPF) Model ................................................... 8 Candidate cause: Low dissolved oxygen ....................................................................................... 10 Water quality standards ..................................................................................................................................... 10 Types of dissolved oxygen data .......................................................................................................................... 10 Overview of dissolved oxygen in the Little Sioux River Watershed ................................................................... 11 Sources and causal pathways for low dissolved oxygen .................................................................................... 11 Candidate cause: High phosphorus .............................................................................................. 11 Water quality standards ..................................................................................................................................... 11 Total phosphorus concentrations in the Little Sioux River Watershed .............................................................. 12 Sources and causal pathways for high phosphorus ........................................................................................... 12 Candidate cause: High nitrate - nitrite ......................................................................................... 12 Water quality standards ..................................................................................................................................... 12 Ecoregion data ................................................................................................................................................... 12 Collection methods for nitrate and nitrite ......................................................................................................... 12 Nitrate and nitrite in the Little Sioux River Watershed ...................................................................................... 13 Sources and causal pathways for nitrate and nitrite ......................................................................................... 13 Candidate cause: Altered hydrology/connectivity/geomorphology ............................................... 13 Altered hydrology/connectivity/geomorphology in the Little Sioux River Watershed ...................................... 13 Candidate cause: High turbidity/total suspended solids ............................................................... 15 Water quality standards ..................................................................................................................................... 15 Turbidity in the Little Sioux River Watershed .................................................................................................... 15 Sources and causal pathways for turbidity ........................................................................................................ 16 Candidate cause: Lack of habitat .................................................................................................. 16 Water quality standards ..................................................................................................................................... 17 Habitat characteristics in the Little Sioux River Watershed ............................................................................... 17 Sources and causal pathways model for habitat................................................................................................ 18 Subwatersheds with biological impairments ........................................................................ 19 Little Sioux River Minor Watershed............................................................................................... 19 Biology in Little Sioux River Minor Watershed ................................................................................................... 20 Candidate cause: Low dissolved oxygen ........................................................................................................... 21 Candidate cause: High phosphorus ................................................................................................................... 24 Candidate cause: High nitrates ......................................................................................................................... 25 Candidate cause: High turbidity/TSS ................................................................................................................. 26 Candidate cause: Lack of habitat ...................................................................................................................... 29 Conclusions ........................................................................................................................................................ 31 Ocheyedan River Minor Watershed .............................................................................................. 33 Biology in the Ocheyedan River ......................................................................................................................... 34 Candidate cause: Low dissolved oxygen ........................................................................................................... 35 Candidate cause: High phosphorus ................................................................................................................... 37 Candidate cause: High nitrates ......................................................................................................................... 38 Candidate cause: High turbidity/TSS ................................................................................................................. 39 Candidate cause: Lack of habitat ...................................................................................................................... 41 Conclusions ........................................................................................................................................................ 43 Summary and recommendations ......................................................................................... 44 Appendix 1.1 – MPCA fish IBI class criteria for Little Sioux River Watershed streams ............ 46 Appendix 1.2 – MPCA macroinvertebrate IBI class criteria for Little Sioux River Watershed streams ............................................................................................................................... 46 Appendix 2.1 – Table of Metric Values for Impaired Sites ..................................................... 47 Appendix 3.1 – Weight of evidence table for Little Sioux River Minor Watershed ................. 48 Appendix 3.2 – Weight of evidence table for Ocheyedan River Minor Watershed ................. 50 Works Cited........................................................................................................................