Link_Eco._Responses_&_Flow Deficits_to_Eco._Condition

RELEVANCE:
NEED TO LINK ECOLOGICAL
RESPONSES (E.G., EPT RICHNESS) AND
FLOW DEFICITS (I.E., QUANTILE
REGRESSIONS) TO ECOLOGICAL
CONDITION
DWQ HAS ESTABLISHED INVERTEBRATE CONDITION
CLASSES BASED ON EPT TAXA RICHNESS
• DWQ uses EPT richness as one means of establishing
condition classes:
• DWQ has condition rankings for most sites and dates used in
EF-SAB analyses
Mountain Piedmont Coastal Plain
Excellent >35 >27 >23
Good 28-35 21-27 18-23
Good-Fair 19-27 14-20 12-17
Fair 11-18 7-13 6-11
Poor 0-10 0-6 0-5
THEREFORE, WE CAN CALCULATE 90TH PERCENTILE
FOR CONDITION CLASSES IN EACH ECOREGION
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Mountains: 66 (Blue Ridge), Piedmont: 45, Coastal Plain: 63 (Mid Atlantic Coastal Plain) + 65
(Southern Plain)
STANDARDIZE FOR 90TH PERCENTILE CONDITION IN
EACH CONDITION CLASS WITHIN EACH ECOREGION
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DERIVE STATE-WIDE CONDITION CLASSES BASED ON
AVERAGE STANDARDIZED VALUES
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STATE-WIDE CONDITION CLASSES BASED ON 90TH
PERCENTILE
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EPT richness1
Excellent ≥ 0.868
Good 0.868 - 0.675
Good-Fair 0.675 - 0.469
Fair 0.469 - 0.249
Poor < 0.249
Screening criteria: if a planned water withdrawal results in a flow deficit
(annual, summer, winter, etc.) that pushes the site into a lower condition
class then a site-specific flow-ecology study is warranted (e.g.,
PHABSim).
1EPT taxa richness scaled by 90th percentile in mountains, Piedmont, and Coastal Plain
STATE-WIDE CONDITION CLASSES BASED ON 90TH
PERCENTILE
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Note: Thresholds for
Good-Fair to Fair and Fair
to Poor are not reached
within 100% decrease in
Annual EcoDeficit
ADVANTAGES OF APPROACH
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• Data-driven approach for establishing ecological flows
• Relates back to NC DWQ concept of biological condition
classes
• Uses state-wide flow-biology relationships for fish and benthos
(based on RTI flow-biology methodology) to support
determination of ecological flows
• Guards against further degradation, while taking into account
of current conditions
• On-going process (adaptive management)