Using Transparency Tube Data in Minnesota Stream Turbidity Assessments

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Using Transparency Tube Data in Minnesota Stream
Turbidity Assessments
6th Annual Water Monitoring Conference February
17th, 2006 Laurie Sovell, MN Pollution Control
Agency
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Began in 1998
17 volunteers 22 sites
2005 Participation
412 volunteers
677 sites
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Citizen Stream-Monitoring Program Goals

• Collect valuable water quality data

• Provide a basic program with
• statewide interpretation of data

• Compliment existing citizen efforts

• Facilitate awareness of water quality issues

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What CSMP volunteers do

• Visit an established spot on a nearby stream
  once a week from April - Sept. and measure

• Transparency

• Precipitation (recorded daily)

• Stream Stage

• Perception Information

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Measuring Transparency

• Fill T-tube with stream water

• Release water through valve until secchi
• symbol on bottom is visible

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Rainfall

• Rain gauge installed at
• volunteers home

• Emptied recorded daily

• Volunteers are asked to monitor stream more
  frequently after large rainfall events

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Stream Stage
Required Visual estimate of water level

• Optional
• Tape down distance from bridge or culvert
• Water level height (e.g. gauge reading)

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Perception Information

• Appearance
• Recreational Suitability

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Appearance Ranking Scale

• 1A Clear
• 1B Tea-colored dissolved organic matter
• 2 Cloudy some sediment
• 3 Muddy high sediment load
• 4 Green algae growth
• 5 Green AND Muddy a combination of cloudy
  brown due to high sediment levels and green from
  algae growth

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Recreational Suitability Ranking Scale

• 1 Very Good Beautiful, could not be better
• 2 Good Very minor aesthetic problems
  excellent for body-contact recreation
  (swimming, wading, etc.)
• 3 Fair Body-contact recreation and aesthetic
  enjoyment slightly impaired
• 4 Poor Recreation potential and level of
  enjoyment substantially reduced (would not
  swim but boating/canoeing okay)
• 5 Very Poor Swimming and aesthetic enjoyment
  of stream nearly impossible

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Uses for CSMP Data

• Individuals get to know their stream
• Local Govts. screen for water quality problems,
  prioritize efforts

• State stream assessment program
• (305b 303d listing)

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Performance Requirements for usingTransparency
as Violation Trigger for Turbidity Standard

• Maximize detection of real violations - 85
  actual violations detected
• (upper left quadrant of Fig. 4)

• Minimize incorrectly assigned violations -
  9 false positives
• (lower left quadrant)

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Criteria for Incorporating Transparency Tube
Readings into Turbidity Assessment
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Criteria for Incorporating Transparency Tube
Readings into Turbidity Assessment (cont.)
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Impact on Assessments

• 88 reaches assessed using T-tube data!!
• 55 of these proposed as impaired
• Another 28 proposed as fully supporting
• Additional 190 reaches with enough T-tube data to
  meet criteria, but professional corroboration not
  available

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More Information

• CSMP Instruction Manual and fact sheet at
  http//www.pca.state.mn.us/water/csmp.html
• Laurie Sovell
• CSMP Coordinator
• 651.296.7187
• laurie.sovell_at_pca.state.mn.us