Sedgwick County TMDL Issues

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Sedgwick County TMDL Issues

• TAG Wichita
• October 6, 2006

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Current Issues

• 1. Cowskin Creek
• 2. Arkansas River Bacteria
• 3. Future 303d Listings

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Cowskin Creek

• Western Sedgwick County Historic Dairy Country
• Urbanizing Watershed
• Biological TMDL done in 2000
• Initial Wasteload Allocation for NW 3
• Revised Wasteload Allocation for 4
• Sediment and Channel Obstructions

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Three Distinct Streams

• Lowest Reaches Appear Best in Quality and
  Bio-Support
• Middle Reaches are Sluggish and Turbid
• Upper Reaches are Stagnant and Hyper-Eutrophic
• Headwaters have denuded banks and are largely
  effluent dependent

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Cowskin Biology

•  
• Historical Average Range (1990 - 2005) for
  biological data
• Kansas Biotic Index (KBI) 3.29 (3.15-3.48)
•  
• Macroinvertebrate Biotic Index (MBI) 4.65 (4.18
  -5.61)
•  
• Ephemeroptera, Plecoptera, and Trichoptera
  (EPT) Taxa 41 (12 - 66 )
• EPT Taxa present 10 (6-15)

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Cowskin Chemistry
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Potential Impact of 3
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Average Nutrients from Area NPDES
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TMDL Expectations of Nutrient Treatment
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Wichita Concerns

• 1. TN Limits too Low 8-10 mg/l
• 2. Phosphorus Trading between 3 4
• 3. Obstructions and Impoundments are a Principal
  Stressor Residential Dams
• 4. Upper Watershed Land Use and Livestock
  Contributions
• 5. Urban Stormwater

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Lower Cowskin
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Cowskin at 3
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3 Effluent
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Cowskin Above 3
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Rural Cowskin
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Arkansas River Bacteria
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2006 Impaired Waters

• 1. Arkansas River PCBs pH
• 2. Little Arkansas River Hg Cu
• 3. Cowskin Creek Cu, Pb, Atrazine
• Note Atrazine in Little Ark and Ark being
  handled by 4B Watershed Plan in Little Ark

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Current and Future Activities

• 1. Complete Revision and Submission of Cowskin
  TMDL (with 5 others)
• 2. Complete Little Ark 4B Plan
• 3. Third Round TMDLs in 2011 (two listing cycles)
• 4. Comprehensive Assessment to Delist with 2012
  list.

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High Priorities

• Arkansas River
• Little Arkansas River
• Whitewater River
• Lake Afton
• Cheney Lake