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Total Dissolved Solids: The Challenges Ahead. US EPA Region 3 Freshwater Biology Team Wheeling, WV. FBT Members Amy Bergdale, Frank Borsuk, Kelly Krock, Maggie Passmore, Greg Pond, Louis Reynolds Assist the states in methods development, bioassessment, biocriteria

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total dissolved solids the challenges ahead

Total Dissolved Solids: The Challenges Ahead

US EPA Region 3

Freshwater Biology Team

Wheeling, WV

freshwater biology team epa r3 eaid oma
FBT Members

Amy Bergdale, Frank Borsuk, Kelly Krock, Maggie Passmore, Greg Pond, Louis Reynolds

Assist the states in methods development, bioassessment, biocriteria

Assist EPA R3 in use of biological data

WQS, monitoring, TMDLs, NPDES, superfund, etc.

Perform special studies

Freshwater Biology Team, EPA R3, EAID, OMA
background
Background
  • Many states have identified “ionic toxicity”, conductivity and/or total dissolved solids (TDS) as a stressor or pollutant in their integrated lists.
  • EPA has also identified TDS (and component ions) as a stressor impairing aquatic life.
  • EPA lacks aquatic life criteria for TDS mixtures.
  • Some TMDLs have been deferred due to lack of criteria.
  • We also need criteria for effluent limits for discharge permits.
what we know
What We Know
  • Some component ions are toxic to aquatic life.
  • Ex. Mount et al 1997 , acute endpoints

K+ > HCO3- =Mg2+ > Cl- > SO42-

  • Laboratory fish are more tolerant than laboratory inverts.
  • Test duration important.
  • Chronic endpoints important.
  • Resident fish are more tolerant than resident inverts.
slide5

Mount et al

1997.

C. Dubia

More

Sensitive to

TDSthan

D. magna or

fatheads.

what we know6
What We Know
  • Ion mixtures have varying toxicity
  • Ion mixtures source specific
    • Alkaline coal mine drainage (HCO3- , Mg2+,Ca2+, SO42-)
    • Marcellus Shale Brine (Na+, Cl-,SO42-)
    • Coal Bed Methane (Na+, HCO3- ,SO42-)
what we know7
What We Know
  • Effects synergistic, additive, or ameliorative
  • Depends on the ions and their concentrations
  • In some systems (e.g. Appalachian headwater streams) lab controlled toxicity tests are not a good predictor of instream aquatic life use impairment.
two webinars on tds 2009
Two Webinars on TDS (2009)
  • Toxicity testing approaches to develop criteria for individual ions
    • Surrogate organisms
    • Iowa: chloride and sulfate
    • Illinois: sulfate
  • Empirical approaches
    • bioassessment and water quality data to develop a criterion for an ion mixture:
    • Ex. Alkaline mine drainage in southern WV and KY Appalachian streams.
the case for single ion criteria
The Case for Single Ion Criteria
  • Lab experiments are controlled
  • Other stressors are excluded
  • Toxicity testing data deemed more “defensible”
  • Pollutant specific criteria instead of integrative parameters such as TDS or conductivity
    • Easier to implement than narrative criteria
    • Easier to check compliance
    • Permit writers understand it
  • Can still incorporate site-specific conditions
  • Resources will focus on source reduction
  • Regulating TDS “futile”; Ion mixtures too complex.
illinois sulfate criterion16
Illinois Sulfate Criterion

Illinois states that “Sensitive organisms reside in receiving streams with sulfate concentrations of 2,000 mg/L.”

the case for an empirical approach
The Case for an Empirical Approach
  • Context is important.
  • Aquatic life in small Appalachian streams is not the same as in Iowa or Illinois!
  • We must protect the resident aquatic life uses.
  • Unlike Illinois, we routinely see aquatic life use impairment downstream of alkaline mine drainage.
  • Elevated TDS, hardness and alkalinity, in the absence of other stressors (e.g. habitat, low pH, metals violations).
  • TDS and component ions are strongly correlated to this impairment.
slide18
Context is Important. What aquatic life are we trying to protect? What is the natural water quality? What is the effluent quality?

PA

OH

WV

KY

VA

slide19

NPDES discharge

Bio-Monitoring

Effluent Dominated Streams

slide20

Heptageniidae

Epeorus

Ephemerella

E. Fleek, NC DWQ

Mayflies represent ~25-50% of Abundance; ~1/3rd biodiversity

In natural, undegraded Appalachian streams

Heptageniidae

Heptagenia

Ephemerellidae

we use conductivity as a surrogate for tds

4500

y = 0.7821x - 28.661

4000

2

3500

R

= 0.9754

3000

2500

TDS

2000

1500

1000

500

0

0

500

1000

1500

2000

2500

3000

3500

4000

4500

Conductivity

We use conductivity as a surrogate for TDS

KY Appalachian

Headwaters

(sandstone)

west virginia data

3.5

3

2.5

2

4

log SO

1.5

1

y = 1.2148x - 1.042

R2 = 0.94

0.5

0

1.5

1.7

1.9

2.1

2.3

2.5

2.7

2.9

3.1

3.3

3.5

log Cond

West Virginia Data
using empirical data
Using Empirical Data
  • Note
    • conductivity of 500-1000 uS/cm approximates sulfate of 200-400 mg/l
    • Iowa sulfate criteria ranges 500-2000 mg/l
    • Illinois sulfate criteria in range of 1000-1500 mg/l
slide25

Resident Mayflies Very Sensitive

(Eastern Kentucky Coalfields)

80

70

Reference

60

Mined

50

Mined/Residential

40

%Ephemeroptera

Note: strong nonlinear “threshold” response

30

20

10

0

0

500

1000

1500

2000

2500

Conductivity

slide26

Independent Datasets Confirm Sensitivity

(West Virginia southern coal fields)

90

80

70

60

50

% Mayflies

40

Mined

Unmined

30

20

10

0

0

500

1000

1500

2000

2500

3000

Conductivity

epa eis data wv based on mean monthly wq concentrations n 13 months
EPA EIS data (WV)based on mean monthly WQ concentrations (n=13 months)

TDS and

Ions strongly

Correlated

To mayflies

And impairment

slide28

Is aquatic life in small Appalachian streams more sensitive to TDS pollution than that in midwestern streams?

Sensitive Mayflies:

40

70

Epeorus

Ephemerella

Ameletus

Drunella

Cinygmula

Paraleptophlebia

60

30

50

40

20

% Sensitive Mayflies

30

% Ephemerella

20

10

10

0

0

0-200

0-200

>1000

>1000

400-600

400-600

200-400

200-400

600-1000

600-1000

CONDUCTIVITY

CONDUCTIVITY

slide29

What aquatic life is found in the midwest? Perhaps more TDS-tolerant invertebrates?

Facultative/Tolerant Mayflies:

80

Isonychia, Tricorythodes, Baetis, Caenis

70

60

50

40

% Tolerant Mayflies

30

20

10

0

0-200

>1000

400-600

200-400

600-1000

CONDUCTIVITY

50

40

30

20

%Isonychia

10

0

0-200

>1000

400-600

200-400

600-1000

CONDUCTIVITY

the case for an empirical approach30
The Case for an Empirical Approach
  • The concentrations of ions that are correlated with high probability of aquatic life use impairment are much lower than the toxicity testing data imply would be protective.
    • Suggests that common toxicity testing organisms are not as sensitive as resident aquatic invertebrates.
    • Many of the toxicity test results have been based on acute tests. The tests and endpoints should be chronic and the toxicity tests should test sensitive life stages.
  • There may be seasonal issues due to insect life cycles.
  • Empirical data may help us determine the more sensitive resident species.
  • Bioassessment endpoints are the best tool to capture the total effect of a complex ion mixture.
examples of ambient toxicity
Examples of ambient toxicity

Chronic effects were detected in samples with field conductivity >1800 µS/cm.

There is NO dilution capacity in these streams.

chronic effects levels
Chronic Effects Levels

Estimated conductivity at EC25 % ranged from 448-1243 with an average of 820 µS/cm.

This range is slightly higher than where we see effects with resident biota.

c dubia more tolerant than resident aquatic life
C. dubia more tolerant than resident Aquatic Life

Ref for GLIMPSS

Not tox tested

All sites were rated impaired using the genus level GLIMPSS (<66) , which directly measures aquatic life use impairment. The resident biota are more sensitive than the WET surrogate, C. dubia. Can’t use C. dubia alone to express “safe” thresholds, but it can be used as an indicator of the more toxic discharges.

using empirical data34
Using Empirical Data
  • Linear regression
  • Quantile regression
  • Conditional Probability Analysis
  • Regression Trees
  • Note
    • conductivity of 500-1000 uS/cm approximates sulfate of 200-400 mg/l
    • Iowa sulfate criteria ranges 500-2000 mg/l
    • Illinois sufate criteria in range of 1000-1500 mg/l
slide36

Ex: Quantile Regression (summer)

IMPAIRMENT THRESHOLD

N=535

slide37

Ex: Quantile Regression (spring)

IMPAIRMENT THRESHOLD

N=276

ex conditional probability approach paul and mcdonald 2005
Ex. Conditional Probability ApproachPaul and McDonald (2005)
  • CPA relies on a large dataset to develop criteria.
    • Simply asks “what is the probability of impairment given conductivity value ≥ x”?
      • P(y|x) where y is impairment threshold (IBI), and x is some TDS or conductivity value.
  • J. Paul (EPA, RTP, in review) found
    • 100% chance of MAHA sites being impaired when conductivity >575 and
    • 100% chance of Florida streams impaired when conductivity >750
slide39

Ex: CPA: WV DEP data: Summer pH>6

Probability of

Impairment

Over 90% when

Cond > 500

Probability of impairment

N=949

RBP HAB>130

Conductivity

ex regression tree mtm vf eis
Ex: Regression Tree (MTM/VF EIS)

Split Variable PRE Improvement

1 SULFATE 0.726 0.726

2 Mn DISS 0.758 0.032

3 CONDUCTIVITY 0.819 0.062

4 SULFATE 0.855 0.036

5 ZINCTOTAL 0.872 0.017

6 MAGNESIUM 0.882 0.010

%EPHEM

Mean=20.45

SD=18.236

N=64

SULFATE<350.66

88.2% variance

Mean=4.04

Mean=34.94

SD=5.945

SD=11.947

N=30

N=34

Mn DISS.<0.0074

CONDUCTIVITY<433.1

Mean=1.45

Mean=12.5

Mean=23.83

Mean=38.4

SD=2.040

SD=6.720

SD=6.393

SD=11.196

N=23

N=7

N=8

N=26

SULFATE<15.6

Mean=34.0

Mean=44.1

SD=9.799

SD=10.179

N=14

N=12

ZINC<0.023

MAGNESIUM<6.9

Mean=29.66

Mean=40.13

Mean=39.95

Mean=48.33

SD=9.077

SD=7.688

SD=11.966

SD=6.533

N=9

N=5

N=6

N=6

All Ions, Metals, pH, Hardness

how do these empirical results compare to iowa s sulfate criteria
How do these empirical results compare to Iowa’s Sulfate Criteria?

We have not reviewed any bioassessment data from Iowa.

R3 Empirical examples suggest impairment at sulfate 200-400 mg/l

water quality based approach to pollution control
Water Quality Based Approachto Pollution Control

Determine

Protection Level

(EPA Criteria/State WQS)

Measure Progress

Conduct WQ

Assessment

(Identify Impaired Waters)

Monitor and Enforce

Compliance

(including instream bioassessments)

Set Priorities

(Rank/Target Waterbodies)

Establish Source

Controls

(Point Source, NPS)

Evaluate Appropriateness

of WQS for Specific Waters

(Reaffirm WQS)

Define and Allocate

Control Responsibilities

(TMDL/WLA/LA)

recommendations
Recommendations
  • Do not rely solely on toxicity testing to determine protective limits.
  • Consider chronic toxicity testing endpoints.
  • Consider dilution ratios.
  • Combine toxicity testing and empirical data approaches when field data are available.
recommendations44
Recommendations
  • Prepare a technical support document on TDS
    • reflects acute and chronic toxicity testing literature
    • offers some examples of empirical datasets and how they would be used to characterize aquatic life, and develop, refine or evaluate criteria and permits.
recommendations45
Recommendations
  • Always use bioassessments to assess aquatic life uses downstream of discharges with TDS.
  • These data should feed back into the permit and possibly result in site specific criteria.
    • Reflect all toxicants in discharge
    • Protect actual aquatic life that should be residing in that stream type
ongoing research surrogates
Toxicity of TDS to surrogate lab organisms

Review literature for TDS

Develop empirical datasets between TDS and aquatic life

Acute and chronic tests with mining effluent and reconstituted salts and surrogate organisms (e.g. C. dubia)

USGS Columbia Lab, Duluth EPA Lab

Preliminary Data…

Ongoing Research - Surrogates

Hassell et al 2006

ongoing research natives
Metal and osmotic ecophysiology

Deploy insects in situ – sample individuals in a time course

Measure growth, metal and electrolyte content, subcellular compartmentalization of metals

Explain any differences in metal tolerance, bioaccumulation and toxicity

Laboratory Exposures

Monitor oxygen consumption, osmoregulatory status and Adenosine triphosphate (ATP) levels

Characterize “energetic costs” to living in high conductivity

Outcome

Provide information on whether metal uptake is contributing to impairment

Provide information on mechanism for TDS impairment

North Carolina State

Ongoing Research - Natives

Buckwalter et al, 2007

discussion
Discussion
  • Where do we go from here?
  • Technical Barriers?
  • Non-Technical Barriers?
  • What do you need from EPA?
  • What can you expect from EPA?
  • How do we advance aquatic life criteria?
  • How do we advance TMDL development?