Rock River Watershed Biotic Stressor Identification Report April 2015 Authors Michael Koschak Contributors / acknowledgements Chandra Carter Chuck Regan Mark Hanson Brooke Hacker Paul Marston Colton Cummings Katherine Pekarek-Scott Tim Larson Cover photo: Top: Rock River at site 11MS001, Lower Right: North Branch Chanarambie Creek at site 11MS123, Lower Left: Unnamed Creek at site 11MS096 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-ws5-10170204a Contents Executive summary ............................................................................................................................6 Introduction ......................................................................................................................................9 Monitoring and assessment ................................................................................................................. 9 Stressor identification process ............................................................................................................ 10 Common stream stressors .................................................................................................................. 10 Report format ................................................................................................................................... 11 Overview of Rock River Watershed................................................................................................... 12 Background ....................................................................................................................................... 12 Monitoring overview ......................................................................................................................... 13 Summary of biological impairments ................................................................................................... 14 Hydrological Simulation Program - FORTRAN (HSPF) Model ................................................................ 16 Candidate causes ............................................................................................................................. 17 Candidate cause: Low dissolved oxygen ............................................................................................. 17 Water quality standards ................................................................................................................... 17 Types of dissolved oxygen data ........................................................................................................ 17 Overview of dissolved oxygen in the Rock River Watershed .............................................................. 18 Sources and causal pathways for low dissolved oxygen ..................................................................... 18 Candidate cause: High phosphorus ..................................................................................................... 18 Water quality standards ................................................................................................................... 18 Total phosphorus concentrations in the Rock River Watershed ......................................................... 18 Sources and causal pathways for high phosphorus ............................................................................ 19 Candidate cause: High nitrate - nitrite ................................................................................................ 19 Water quality standards ................................................................................................................... 19 Ecoregion data ................................................................................................................................. 19 Collection methods for nitrate and nitrite ......................................................................................... 19 Nitrate and nitrite in the Rock River Watershed ................................................................................ 19 Sources and causal pathways for nitrate and nitrite .......................................................................... 20 Candidate cause: Altered hydrology/connectivity/geomorphology ..................................................... 20 Altered hydrology/connectivity/geomorphology in the Rock River Watershed .................................. 20 Candidate cause: Turbidity/total suspended solids ............................................................................. 20 Water quality standards ................................................................................................................... 21 Turbidity in the Rock River Watershed .............................................................................................. 21 Sources and causal pathways for turbidity ........................................................................................ 22 Candidate cause: Lack of habitat........................................................................................................ 22 Water quality standards ................................................................................................................... 23 Habitat characteristics in the Rock River Watershed ......................................................................... 23 Sources and causal pathways model for habitat ................................................................................ 24 Subwatersheds with biological impairments ..................................................................................... 25 Ash Creek .......................................................................................................................................... 25 Biology in Ash Creek ......................................................................................................................... 26 Candidate cause: Low dissolved oxygen ............................................................................................ 27 Candidate cause: High phosphorus ................................................................................................... 28 Candidate cause: High nitrates ......................................................................................................... 29 Candidate cause: High turbidity/TSS ................................................................................................. 29 Candidate cause: Lack of habitat ...................................................................................................... 30 Weight of evidence .......................................................................................................................... 31 Conclusion .......................................................................................................................................31 Champepadan Creek ......................................................................................................................... 32 Overview .........................................................................................................................................32 Biology in Champepadan Creek ........................................................................................................ 34 Candidate cause: Low dissolved oxygen ............................................................................................ 36 Candidate cause: High phosphorus ................................................................................................... 37 Candidate cause: High nitrates ......................................................................................................... 38 Candidate cause: High turbidity/TSS ................................................................................................. 40 Candidate cause: Lack of habitat ...................................................................................................... 41 Conclusion .......................................................................................................................................43 Chanarambie Creek Watershed .......................................................................................................... 44 Overview .........................................................................................................................................44 Biology in Chanarambie Creek Watershed ........................................................................................ 45 Candidate cause: Low dissolved oxygen ............................................................................................ 48 Candidate cause: High phosphorus ................................................................................................... 51 Candidate cause: High nitrates ......................................................................................................... 54 Candidate cause: High turbidity/TSS ................................................................................................. 56 Candidate cause: Lack of habitat .....................................................................................................