(BMPs) to Clean Water Jim Solstad, Retired Division of Ecological - - PowerPoint PPT Presentation

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(BMPs) to Clean Water Jim Solstad, Retired Division of Ecological - - PowerPoint PPT Presentation

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Altered Hydrology: Going Beyond Best Management Practices (BMPs) to Clean Water Jim Solstad, Retired Division of Ecological and Water Resources Cedar River Watershed District October 16, 2017 1 GSSHA Gridded Surface Subsurface

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Altered Hydrology: Going Beyond Best Management Practices (BMPs) to Clean Water

Jim Solstad, Retired Division of Ecological and Water Resources

Cedar River Watershed District – October 16, 2017 1

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GSSHA – Gridded Surface Subsurface Hydrologic Analysis

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Collaborative for Sediment Source Reduction Greater Blue Earth River Basin

Summary of Findings (March 2017):

  • “Achieving water quality standards will require priority investment in more

temporary water storage to reduce high river flows and bluff erosion. This is a critical component of a strategy to reduce sediment in the Minnesota River.”

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  • Dr. Shawn Schottler Clean Water Council presentation

(March 20, 2017):

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Perennial Cover …. Cover Crops …. “Soil Health”

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Miller, T. P. , J. R. Peterson, C. F. Lenhart, and Y. Nomura. 2012. The Agricultural BMP Handbook for Minnesota. Minnesota Department of Agriculture.

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BWSR Targeted Watershed Program: Dobbins Creek Cedar River Watershed District

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Prime Farmland …. if drained

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High Water Table Extensive subsurface drainage

Optional Tagline Goes Here | mn.gov/websiteurl 8

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Existing riparian corridor ….. few depressions

3/5/2019 9

570 ft 140 ft

Few depressions Well-defined floodplain

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BMPs of choice:

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Water and Sediment Control Basins (WASCOBs) Grassed Waterways Buffers

Photo courtesy USDA NRCS Photo courtesy MN NRCS

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Model Scenarios

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Riparian Corridor (No BMPs) with BMPs

Corn Soybeans Developed Forest Grassland

Example Land Use Maps

  • Riparian Corridor

(No BMPs)

  • Conservation Tillage
  • With BMPs
  • BMPs w/ 30%

Perennial Cover

  • 100% Perennial Cover
  • Prairie
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Computed Flows

(2.6” rainfall – June 2015)

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Computed Flows

(4.6” rainfall – September 2010)

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Average Peak Flow Reduction

8 summer rainfall events (2009-2015)

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0% 10% 20% 30% 40% 50% 60% 70% 80%

No Perennial Cover Exist Riparian Corridor Conservation Tillage with BMPs BMPs with 30% "Soil Health" 100% "Soil Health" Prairie

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Sediment Entering Channels

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50 100 150 200 250 300 350

No Perennial Cover Exist Riparian Corridor Conservation Tillage With BMPs BMPs & 30% "Soil Health" 100% "Soil Health" Prairie

Lbs / Acre / Year

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WEPP: Water Erosion Prediction Project

3/5/2019

Chapter 7: Soil Component X 2.4

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A very small percent of the landscape controlled by the proposed WASCOBs

Optional Tagline Goes Here | mn.gov/websiteurl 17

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Average Annual Flow

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2 4 6 8 10 12 Prairie Existing w/o Tile Existing w-Tile Inches Total Water Yield Total Tile Flow

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Cover Crops/Soil Health ….. Subsurface Drainage

3/5/2019 19

Increased infiltration

  • Higher water table
  • Increased tile flow

Partially Offset by

  • Greater spring and fall

plant transpiration

  • Higher soil water holding

capacity

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Take Home Message re: Altered Hydrology

  • Traditional BMPs: “individually effective, collectively not enough”
  • Widespread adoption of perennial cover (cover crops, 2nd crop; “soil

health”) will move a long ways to achieving whatever “altered hydrology” goal is established.

  • Significant reduction in surface runoff and associated erosion
  • Potential increase in subsurface flow where tile are present

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Questions / Comments?

Jim Solstad, Retired Division of Ecological and Water Resources

Cedar River Watershed District – October 16, 2017 21