1 Watonwan River Watershed Hydrology, Connectivity, and Geomorphology Assessment Report Report wq-ws3-07020010d MINNESOTA DEPARTMENT OF NATURAL RESOURCES Table of Contents DIVISION OF ECOLOGICAL AND WATER RESOURCES 2014 2 Table of Figures ............................................................................................................................................. 4 Table of Tables .............................................................................................................................................. 8 List of Acronyms ............................................................................................................................................ 9 Executive Summary ..................................................................................................................................... 11 Introduction ................................................................................................................................................ 12 Study Background ................................................................................................................................... 12 Hydrology ................................................................................................................................................ 14 Connectivity ............................................................................................................................................ 15 Geomorphology ...................................................................................................................................... 17 Methods ...................................................................................................................................................... 17 Hydrology ................................................................................................................................................ 17 Discharge Analysis ............................................................................................................................... 17 Precipitation ........................................................................................................................................ 19 Double Mass Curve ............................................................................................................................. 19 Web-based Hydrograph Analysis Tool ................................................................................................ 19 Ground Water Usage .......................................................................................................................... 19 Connectivity ............................................................................................................................................ 20 Longitudinal Connectivity ................................................................................................................... 20 Lateral Connectivity ............................................................................................................................ 20 Geomorphology ...................................................................................................................................... 20 Field Methods ..................................................................................................................................... 20 Office Methods ................................................................................................................................... 23 Results ......................................................................................................................................................... 24 Hydrology ................................................................................................................................................ 24 Discharge Analysis ............................................................................................................................... 24 Precipitation ........................................................................................................................................ 27 Double Mass Curve ............................................................................................................................. 30 Web-based Hydrograph Analysis Tool ................................................................................................ 30 Ground Water Usage .......................................................................................................................... 33 Connectivity ............................................................................................................................................ 36 Longitudinal Connectivity ................................................................................................................... 36 3 Lateral Connectivity ............................................................................................................................ 36 Geomorphology ...................................................................................................................................... 41 North Fork Watonwan ........................................................................................................................ 42 Upper Watonwan River ...................................................................................................................... 48 Judicial Ditch #1 .................................................................................................................................. 51 Lower Saint James Creek .................................................................................................................... 55 Upper Saint James Creek .................................................................................................................... 59 South Fork Watonwan River ............................................................................................................... 62 Willow Creek ....................................................................................................................................... 67 Middle Watonwan River ..................................................................................................................... 71 Lower Perch Creek .............................................................................................................................. 75 Upper Perch Creek .............................................................................................................................. 79 Lower Watonwan River (downstream of gage station near Garden City) .......................................... 83 Bank Assessment for Non-point Source Consequences of Sediment (BANCS) Model Results .............. 89 Channel Changes via GIS Investigation ................................................................................................... 95 Conclusions ................................................................................................................................................. 98 Restoration and Protection Strategies ........................................................................................................ 99 4 Table of Figures Figure 1. Light Detection and Ranging (LiDAR) imagery depicting the west-to-east slope of the watershed’s landscape with the major and minor tributaries of the watershed. ...................................... 13 Figure 2. Five components of a healthy watershed. All components are interrelated; a disruption of any one of the components can have an effect on the rest of the components. ............................................. 13 Figure 3. Three spatial dimensions of connectivity: longitudinal (red), lateral (green), and riparian (orange). Dams and bridges are two of several structures that disrupt each of these three dimensions of connectivity. Rapidan Dam, Blue Earth River image courtesy of Google Earth, 2014. .............................. 16 Figure 4. Measurements used to classify a representative stream reach. Once measurements of entrenchment, bankfull width to depth ratio, sinuosity, and slope at a riffle cross section have been established, a conclusion on stream type can be made. Additional measurements are taken to determine whether the stream is stable within its current state or if it is in a successional state to adapt to its current climate, hydrology, and land use (Rosgen 1997). ................................................................. 18 Figure 5. Light Detection and Ranging (LiDAR) imagery depicting the west-to-east slope of the watershed’s landscape with the spatial location of geomorphology sites included. ................................. 22 Figure 6. Average monthly discharge in the Watonwan watershed. ......................................................... 25 Figure 7. Average precipitation and runoff (i.e. discharge/area) in the Watonwan watershed. ............... 25 Figure 8. Annual total discharge and precipitation values over time. ........................................................ 26 Figure 9. Flow duration curve of Watonwan monthly discharge values. ................................................... 28 Figure 10. Flow duration curve plotted as discharge over watershed area. .............................................. 28 Figure 11. Number of days where flows are at or above high flow volumes (Q10) compared to annual precipitation