Compliance Strategies for Oregons Temperature Standard First The Calculations.

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Compliance Strategies for Oregons Temperature
StandardFirst The Calculations.

• St. Patricks Day, 2004

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Case Study Cottage Grove, OR
Discharge to Coast Fork of Willamette River Water
Quality Limited for Temperature 1.8 mgd
ADWF Little Water for Mixing in Summer
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First Thing Check the Maps and Tables

• Part of New Standard
• Establish Beneficial Uses
• Establish Applicable Criteria
• Critical Fish Use Designations
• Emergence Use Designations Critical Periods

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For Cottage Grove

• No spawning in Coast Fork (whew!)
• Salmon and Trout Rearing and Migration Habitat
• OAR 340-41-0028 (4) (c)
• Seven-day-average maximum temperature
• 18C or 64.4F

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Effluent and Coast Fork Temperatures
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Evaluate the Situation

• River exceeds temperature criteria
• TMDL not yet developed
• Effluent is cooler than river, but exceeds
  criteria - 71 F
• 7Q10 Flow in Coast Fork
• Treatment plant ADWF 1.8 mgd (2.8 cfs)

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Human Use Allowance

• OAR 340-41-0028(12)(b)
• Prior to completion of TMDL
• No single source
• 0.3 C increase
• 25 percent of stream flow or mixing zone
• whichever more restrictive
• Following TMDL
• Cumulative increase of 0.3 C

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No TMDL Yet so

• 25 of 7Q10 Flow or 12.5 cfs
• 0.3 C increase after mixed
• Use criteria temp (18 C) for river water
  temperature since above criteria
• ADWF is 2.8 cfs
• Effluent temp is 21.7 C

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Tmz Te DTs 1 D

• Where
• Tmz is temperature at edge of mixing zone
• D is dilution (12.5cfs/2.8 cfs) or 4.5
• Te is effluent temperature (7 day avg. of max)
  (21.7)
• Ts is stream temperature or criteria temp (18 C)

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Dilution to Meet Human Use Allowance
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If Tmz is greater than 18.3 C
then T stands for trouble
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thats Trouble my friends, right here in River
City
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And the answer is
18.7 C
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So What Can We Conclude?

• Not enough water in Coast Fork to provide
  sufficient dilution for effluent
• Thermal load will be established in permit
• Choices for City are limited
• Move outfall (or City!)
• Reduce volume of discharge
• Reduce effluent temperature
• Increase stream flow
• Offset thermal effect

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Finding a Solution in Cottage Grove

• Produce Level IV Reclaimed Water
• Change plans from UV to Hypochlorite
• Build Pump Station and Reuse Pipeline
• Irrigate Golf Course and other land
• Reduce irrigation withdrawals on river

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Coast Fork has no Spawning but if it did

• More Stringent Criteria (13 C)
• Cold Water Protection Required
• Rolling 60 day average during spawning
• 0.5 C above average if 10 12.8 C
• 1.0 C above average if
• Options
• Show that greater increase will not impact the
  survival of eggs or timing of emergence

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Summary

• Maps to define applicable criteria
• Status of TMDL
• Collect data on stream and effluent
• Determine restrictive mixing condition
• 25 of 7Q10
• Mixing zone
• Impact Greater than 0.3 C?