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Overview• Biotic Ligand Model (BLM) is a relatively new tool from
EPA for developing site-specific criterion-based copper standards. It is the best tool available for the task.
• Hearing process has provided an opportunity to work closely with stakeholders to gain insights regarding acquisition of input data and interpretation of model output. The Division appreciates the cooperative approach.
Status Review
Proponent Segments Status CommentAurora US16i Withdrawn Additional data
neededParker CC01 Temp Mod Additional data
neededPlum Creek US10a Temp Mod Additional data
neededMetro US15 &
MS01aSite-specific stds
Adoption recommended
Centennial US16g & 14 Site-specific stds
Adoption recommended
UTSD BT02 Reviewed stds Let stand
What Makes a Good Proposal?• Metro is a good case study
•Spatial coverage brackets significant hydrologic features and extends far enough to support proposal
•Temporal coverage spans enough years to incorporate seasonal and hydrologic variability
•Large sample size improves precision of result
•Longevity plan will support review of standards at next basin hearing
Results with Confidence Intervals
0
10
20
30
40
50
60
70
0 10 20 30 40
Acu
te FM
B, u
g/L
River Miles below Metro
Wrap-up• Expecting more copper proposals based on BLM
• Process should be easier to navigate next time because there is greater clarity regarding expectations for data collection and analysis
• Future proposals to benefit from:
•Revised guidance from Division
•Revised documentation and expanded model output from EPA
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