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2007 Water Resources Report

This report provides an analysis of river flow and lake levels, TMDL study findings, floodplain mapping revisions, and essential information on dredging techniques. It covers relevant topics such as sediment allocation, target phosphorus loads, hydraulic vs. mechanical dredging, and project costs.

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2007 Water Resources Report

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  1. 2007 Water Resources Report Rob Montgomery River Flow & Lake Levels TMDL Study Floodplain mapping revisions Dredging 101

  2. Rock River FlowJuly 2005 – July 2007

  3. Rock River Flow1990 – 2007

  4. Lake Koshkonong StageJuly 2005 – July 2007

  5. Lake Koshkonong Stage1990 - 2007 100-yr 864

  6. Rock River TMDL Study • TMDL = Total Maximum Daily Load • Load allocations for sediment and phosphorus for impaired streams and waterbodies • Analyzing target phosphorus loads • 0.08 mg/L for wadeable streams • 0.125 mg/L for non-wadeable • Allocations to point and non-point sources

  7. Rock River TMDL Study • DNR to submit TMDL to USEPA, funded by USEPA • Technical analysis ongoing, technical advisory committee meeting upcoming • Lake Koshkonong will benefit, but changes will be slow in coming

  8. Floodplain Mapping Revisions • Generally based on new topography, but old hydraulic analysis • Dane County, Rock County: new maps, 90 day appeal period over • Jefferson County: Appeal period not yet announced

  9. Dredging 101 • Dredging can increase water depths and supply fill • Expensive • Usually conducted in critical navigation areas only • Substantial permit requirements

  10. Types of Dredging Mechanical (excavated) • Usually used for smaller areas • Slower production than hydraulic • Smaller disposal area Hydraulic (suction – pumping) • Most cost-effective, especially for large areas • Usually requires large disposal area

  11. Mechanical Dredging JF Brennan

  12. Hydraulic Dredging Dredge Disposal Area Return Flow Dredge discharge pipeline Dredge

  13. Hydraulic Dredge Discharge pipeline Pump Cutterhead JF Brennan Company

  14. Hydraulic Dredge Disposal Areas • Often 1.5 x Dredge volume • Sediment dewatering return flow • Land acquisition State of North Carolina

  15. Final use of dredge spoil area • Spoil properties important • Open Space, Agricultural, Wildlife area Applied Marine Sciences

  16. In-Lake dredge spoil placement to create habitat • Dredge spoil placed behind confinement berms • Would involve substantial permitting process on Lake Koshkonong Corps of Engineers Project at Pointe Mouillee, MI Lake Erie

  17. Factors Affecting Hydraulic Dredging Project Costs • Dredge spoil site acquisition, preparation • Access and mobilization • Dredge material properties • Pumping system • Restoration • Permit Conditions • Costs could range from <$10/cy to >$20/cy

  18. Hypothetical Hydraulic Dredging Project • 1000 ft x 300 ft (~7 Ac) x 2 ft depth = 22,000 cy • Disposal – 3 ft depth – 8 acres • Dredge & place: 22,000cy x $20/cy = $440,000 • Property acquisition: 8 acres x $20,000 = $160,000 • Total: ~ $400,000 to $600,000 • Actual project costs could vary WIDELY

  19. Implementing a Dredging Project on Lake Koshkonong PLANNING • Prioritizing navigation improvement areas • Identify habitat improvement opportunities • Effects on wind driven waves and ice push • Funding • Permit strategy • Planning level engineering, costing DESIGN • Sediment characterization • Permitting • Acquisition of land and access • Specialist contractor

  20. Questions Thank You

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