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Nitrogen in Dodge County Ground and Surface Waters

Explore the rock layers beneath Dodge County to understand groundwater aquifers and potential contamination risks. Learn about the geological formations and protective layers affecting water quality in different townships.

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Nitrogen in Dodge County Ground and Surface Waters

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  1. Nitrogen in Dodge County Ground and Surface Waters

  2. To better understand ground water, it’s important to visualize the rock layers, most of which serve as drinking water aquifers, which exist under Dodge County, moving from deepest to shallowest. Source: Minnesota DNR

  3. Source: Minnesota DNR

  4. Source: Minnesota DNR

  5. Source: Minnesota DNR

  6. Source: Minnesota DNR

  7. Source: Minnesota DNR

  8. Source: Minnesota DNR

  9. Let’s cut through the rock layers and expose them from a side view.

  10. Ellington Concord Milton WEST EAST 1300 1300 Elevation Above Sea Level (ft) 1200 1200 SOIL, SAND & GRAVEL GALENA LIMESTONE 1100 1100 DECORAH SHALE 1000 1000 ST. PETER SANDSTONE 900 900 PRAIRIE DU CHIEN DOLOMITE/SANDSTONE 0 1 2 3 4 5 6 Miles Generalized Geographic Formations Underlying Ellington, Concord and Milton Townships Subsurface Geologic Cross-Section In general, the thicker soils in the western portion of the county provide more protection from surface contaminants reaching the rock layers. Source: Dodge County Environmental Atlas

  11. Ellington Concord Milton WEST EAST 1300 Shallow Well, < 50 Ft. to Bedrock 1300 1200 1200 SOIL, SAND & GRAVEL Elevation Above Sea Level (ft) GALENA LIMESTONE 1100 ~60% of all wells 1100 DECORAH SHALE 1000 1000 ST. PETER SANDSTONE ~15% of all wells 900 900 PRAIRIE DU CHIEN DOLOMITE/SANDSTONE ~ 10% of all wells 0 1 2 3 4 5 6 Miles Deep river valleys in the eastern portion of the county can erode the protective shale layer, exposing the layers below to contamination. Subsurface Geologic Cross-Section Generalized Geographic Formations Underlying Ellington, Concord and Milton Townships Source: Dodge County Environmental Atlas

  12. Claremont Wasioja Mantorville EAST WEST Elevation Above Sea Level (ft) 1300 1300 SOIL, SAND & GRAVEL 1200 1200 1100 1100 GALENA LIMESTONE 1000 1000 DECORAH SHALE 900 900 ST. PETER SANDSTONE PRAIRIE DU CHIEN DOLOMITE/SANDSTONE 0 1 2 3 4 5 6 Miles Subsurface Geologic Cross-Section Generalized Geographic Formations Underlying Claremont, Wasioja, and Mantorville Townships Source: Dodge County Environmental Atlas

  13. Ripley Ashland Canisteo WEST EAST Elevation Above Sea Level (ft) 1300 1300 SOIL, SAND & GRAVEL 1200 1200 1100 1100 GALENA LIMESTONE 1000 1000 900 900 DECORAH SHALE ST. PETER SANDSTONE PDC Subsurface Geologic Cross-Section Generalized Geographic Formations Underlying Ripley, Ashland, and Canisteo Townships Source: Dodge County Environmental Atlas

  14. WEST Westfield Hayfield Vernon EAST Elevation Above Sea Level (ft) 1300 1300 SOIL, SAND & GRAVEL 1200 1200 CEDAR VALLEY-MAQUOKETA LIMESTONE 1100 1100 1000 1000 GALENA LIMESTONE 900 900 DECORAH SHALE ST. PETER SANDSTONE PDC 0 1 2 3 4 5 6 Miles Subsurface Geologic Cross-Section Generalized Geographic Formations Underlying Westfield, Hayfield, and Vernon Townships Source: Dodge County Environmental Atlas

  15. MN Dept. of Health Drinking Water Standard – 10mg/L Levels Beyond 10 mg/L Cause Health Risks to Infants and Expectant Mothers Source: Minnesota Dept. of Health; Dodge County Environmental Services

  16. Presence of Coliform Bacteria in Well Water Indicates Surface Contaminants and Disease-Causing Organisms May be Present. E. Coli is a More Serious Disease-Causing Type of Coliform Bacteria. Source: Minnesota Dept. of Health; Dodge County Environmental Services

  17. High nitrate wells occur most frequently in the Highly Sensitive Groundwater Area, where depth-to-bedrock is less than 50 ft, or where underground sand lenses exist. Source: Minnesota DNR; Dodge County Environmental Services

  18. Nitrate levels > 1 mg/l in the St. Peter Sandstone are a reason for concern. Source: Dodge County Environmental Services

  19. Areas of Dodge County where the St. Peter Sandstone is shallow and vulnerable to surface contamination. Source: Minnesota DNR

  20. Comparative Surface Water Nitrogen Load by Subwatershed Source: MPCA – Draft Zumbro Watershed WRAPS Document 2015

  21. Source: MPCA - Nitrogen in Minnesota Surface Waters June 2013

  22. Statewide Nitrogen Sources to Land Source: MPCA - Nitrogen in Minnesota Surface Waters June 2013

  23. Source: MPCA - Nitrogen in Minnesota Surface Waters June 2013

  24. MN Nutrient Reduction Strategy Source: MPCA – Minnesota Nutrient Reduction Strategy December 2014

  25. Phophorous & Nitrogen Goals for the Mississippi Basin Source: MPCA – Minnesota Nutrient Reduction Strategy December 2014

  26. Reducing Nitrogen Losses 1 2 3 1 Fertilizer and Tillage Practices 2 Drainage Practices 3 Cover Crop Practices Source: MPCA – Minnesota Nutrient Reduction Strategy December 2014

  27. Nitrate-Related Ground Water Projects: Dodge County Volunteer Nitrate Monitoring Network • A grant-funded network operating across SE MN since 2007. • Approximately 100 private well owners participate in Dodge County, sampling their wells every 6 months. • The Dodge County network is sub-divided into one baseline, and three targeted, groups. The targeted groups are: • Wells monitoring areas near known high-nitrate wells. 2) Wells monitoring areas near existing sinkholes. 3) Wells monitoring the region along the Decorah Edge.

  28. Source: Dodge County Environmental Services

  29. Source: Dodge County Environmental Services

  30. Dodge County Volunteer Nitrate Monitoring Network Results MN Dept. of Health Drinking Water Limit = 10 mg/l 0 – 1 mg/l is considered back- ground level Nitrate Level (mg/l) The recent upward trend in nitrate level may be due , in part, to recent near-drought conditions, which tend to concentrate nitrate in the drinking water aquifers. Source: Dodge County Environmental Services

  31. Nitrate-Related Surface Water Programs & Projects: Dodge County 50-Foot Stream Buffer Program Before After Buffers provide a deterrent to the movement of soil and nutrients into the stream.

  32. Nitrate Level (mg/l) Date Field tile drainage is diverted through the woodchips, where a high percentage of nitrate is removed. Source: Dodge County Environmental Services

  33. Using Saturated Buffers for Nitrate Removal Field tile water runs through a perforated tile parallel to the buffered ditch or stream, allowing limited drainage through the buffer, which reduces nitrate levels. Source: Dodge County Environmental Services

  34. Dodge County Saturated Buffer MN-4: 2014 Results 14.0 12.1 6.8 4.2 Nitrate Levels (mg/L) 9.9 Source: Dodge County Environmental Services

  35. Edge-of-Field Monitoring Stations MN Dept. of Ag. Grant Site Discovery Farms Site Water samples are gathered and analyzed, providing accurate information to producers on nutrients that leave their fields during snow-melt and runoff events. Source: Dodge County Environmental Services

  36. Most Recent Pollution Results for Minnesota Waters Source: MPCA – Swimmable, Fishable, Fixable? April 2015

  37. Most Recent Pollution Results for Minnesota Waters Source: MPCA – Swimmable, Fishable, Fixable? April 2015

  38. Most Recent Pollution Results for Minnesota Waters Source: MPCA – Swimmable, Fishable, Fixable? April 2015

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