the effects of specific conductance of water on the benthic macroinvertebrate community downstream...
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THE EFFECTS OF SPECIFIC CONDUCTANCE OF WATER ON THE BENTHIC MACROINVERTEBRATE COMMUNITY DOWNSTREAM OF
COAL MINING ACTIVITIES__________________________________
R.R. Maggard
Downstream effects of mountaintop coal mining: comparing biological conditions using family- and genus-level macroinvertebrate bioassessment tools
______________________________________________________________________
Gregory J. Pond1, Margaret E. Passmore2, Frank A. Borsuk3,Lou Reynolds4, AND Carole J. Rose5
Region 3, US Environmental Protection Agency, 1060 Chapline Street, Wheeling, West Virginia 26003 USA
J. N. Am. Benthol. Soc., 2008, 27(3):717–737 ©2008 by The North American Benthological SocietyDOI: 10.1899/08-015.1Published online: 8 July 2008
ABSTRACT_______________________________________________• Regulatory agencies have been attempting to blame
Mountaintop Coal Mining and the associated valley fills for impairment of streams by narrative water quality standards– Trying to connect moderate (500 µs/cm) to high (1000 µs/cm)
specific conductance to impairment of benthic macroinvertebrate communities
• Not enough information to draw conclusions
• This Study conducted in Southern West Virginia in four (4) adjacent watersheds– Results conflict with Pond et al. 2008
• Specific conductivity unrelated to benthic macroinvertebrate communities
INTRODUCTION________________________________________
_
• Pond et al. 2008:– Categorized mining impacts based on specific
conductivity in relation to SO4 concentrations
1. Low < 500 µs/cm
2. Medium 500-1000 µs/cm
3. High > 1000 µs/cm– “Within the mined site data set, we found no evidence that
MMI’s (multimetric indices) were significantly correlated with the number of valley fills upstream or distance from the fill (p>0.05), but these indicators appeared to be related to our inexact estimates of the amount of mining in the watershed.”
INTRODUCTION (cont’d)_______________________________________
• This study is based on exact information– The exact degree and age of mining-related
disturbance in the watershed– The exact stage of any reclamation in the
watershed
• Estimation of mining related disturbance based upon predetermined specific conductance or sulfate values WILL NOT BE UTILIZED
METHODOLOGY___________________________________________
• Past studies have paid little attention to the type of mining occurring, the targeted seam being mined, size and stage of construction of valley fills, and reclamation status
• This study analyzes in detail:– Land uses that may contribute to elevated conductivities
• Investigate relationship between land use and conductivity
– Data collected in four (4) adjacent watersheds located in Southern West Virginia
• Near Kiahsville in Wayne County on tributaries of Trough Fork
SITE DESCRIPTIONS: BIG BRANCH
______________________________________________• Watershed: 165 ACRES
• Surface disturbance: NEGLIGIBLE
• Discharge: HIGH CONDUCTIVITY WATER
• Source: INDISCRETE SEEPAGE THROUGH A 200-FOOT-WIDE OUTCROP BARRIER AS A RESULT OF A FLOODED UNDERGROUND MINE
– Mine was sealed in 2000
– Targeted the 5-Block coal seam
• Allows for evaluation of water chemistry changes in absence of sediment pond construction, valley fill construction, and other misc. land clearing activities
SITE DESCRIPTIONS: TOMBLIN BRANCH
________________________________________
• Watershed: 295 ACRES
• Surface disturbance: NEGLIGIBLE
• Discharge: LOW CONDUCTIVITY WATER
• Source: REFERENCE STREAM (RECEIVES NO MINING-RELATED DISCHARGES)– Located across the hollow from Big Branch
• Selected as a reference site
SITE DESCRIPTIONS: ROCKY BRANCH
______________________________________________
• Watershed: 129 ACRES
• Surface disturbance: NEGLIGIBLE
• Discharge: HIGH CONDUCTIVITY WATER
• Source: SEEPAGE ON THE DOWN-DIP OUTCROP CONTRIBUTING TO BASE FLOW AS A RESULT OF A FLOODED UNDERGROUND MINE
– Mine sealed in 2001
– Targeted the 5-Block coal seam
• Selected for its similarity to Big Branch
SITE DESCRIPTIONS: VANCE BRANCH______________________________________________
• Watershed: 404 ACRES
• Surface disturbance: PREVIOUS DISTURBANCE OF 275 ACRES
• Discharge: HIGH CONDUCTIVITY WATER
• Source: TYPICAL SURFACE MINE WITH TWO (2) VALLEY FILLS AND FOUR (4) SEDIMENT PONDS– Surface Mine has been reclaimed since 2000– Targeted the 5-Block coal seam
• Selected to represent surface disturbance due to surface mining
METHODS OF INVESTIGATION_____________________________________________• All 4 sites evaluated for benthic macroinvertebrates,
aquatic habitat, and water chemistry– Modified EPA/620/R-94/004F and EPA 841-B-99-002
were followed
• Five (5) sampling events have been conducted for Big Branch and Tomblin Branch sites:– Fall 2007, Spring 2008, Summer 2008, Fall 2008, and
Winter 2009
• Two (2) sampling events have been conducted for Rocky Branch and Vance Branch sites:– Fall 2008 and Winter 2009
METHODS OF INVESTIGATION (cont’d)
----------------------------------------------------Parameters evaluated for each site:
– Water chemistry
– Physical water quality
– Habitat assessment
– Benthic macroinvertebrate collection
– Benthic macroinvertebrate metrics
PHYSICAL DESCRIPTIONS AND HABITAT EVALUATIONS – BIG BRANCH_______________________________________________• BENTHIC SAMPLING LOCATION: 38° 02’ 24.9”, 82° 13’
08.1”– Coarse Particulate Organic Matter (CPOM): moderate– Large Woody Debris (LWD): Sparse– SUBSTRATE: 5% sand, 75% gravel, 20% cobbles
• Sub-optimal to optimal aq. Habitat
• STREAM FLOW (ft3/s): 0.525 to 0.26• TEMPERATURE (°C): 0.2 to 18.8• pH: 7.09 to 7.77• DISSOLVED OXYGEN (DO in mg/l): 8.39 to 13.6• CONDUCTIVITY (µs): 543 to 1,550• HABITAT SCORE: 136 to 156 (mean = 146) suboptimal
aquatic habitat
PHYSICAL DESCRIPTIONS AND HABITAT EVALUATIONS – TOMBLIN BRANCH_______________________________________________• BENTHIC SAMPLING LOCATION: 38° 02’ 39.6”, 82° 13’
28.6”– Coarse Particulate Organic Matter (CPOM): moderate– Large Woody Debris (LWD): Sparse– SUBSTRATE: 5% sand, 54% gravel, 40% cobbles, 1% boulder
• Sub-optimal to optimal aq. Habitat
• STREAM FLOW (ft3/s): No flow to 0.441• TEMPERATURE (°C): 0.7 to 21.2• pH: 5.93 to 6.72• DISSOLVED OXYGEN (DO in mg/l): 1.4 to 14.7• CONDUCTIVITY (µs): 49 to 470• HABITAT SCORE: 68 to 127 (mean = 109) marginal to
suboptimal aquatic habitat
PHYSICAL DESCRIPTIONS AND HABITAT EVALUATIONS – ROCKY BRANCH_______________________________________________• BENTHIC SAMPLING LOCATION: 38° 02’ 16.2”, 82° 14’
37.3”– Coarse Particulate Organic Matter (CPOM): moderate– Large Woody Debris (LWD): moderate– SUBSTRATE: 15% sand, 15% gravel, 60% cobble, 10% boulder
• Sub-optimal to optimal aq. Habitat
• STREAM FLOW (ft3/s): 0.018 to 0.079• TEMPERATURE (°C): 0.2 to 10.8• pH: 7.58 to 6.45• DISSOLVED OXYGEN (DO in mg/l): 11.8 to 15.4• CONDUCTIVITY (µs): 663 to 1,650• HABITAT SCORE: 132 to 139, suboptimal aquatic habitat
PHYSICAL DESCRIPTIONS AND HABITAT EVALUATIONS – VANCE BRANCH_______________________________________________• BENTHIC SAMPLING LOCATION: 38° 02’ 11.0”, 82° 14’
03.1”– Coarse Particulate Organic Matter (CPOM): moderate– Large Woody Debris (LWD): moderate– SUBSTRATE: 1% sand, 19% gravel, 20% cobble, 60% boulder
• Sub-optimal to optimal aq. Habitat
• STREAM FLOW (ft3/s): 0.268 to 1.331• TEMPERATURE (°C): 4.1 to 16.8• pH: 7.54 to 7.91• DISSOLVED OXYGEN (DO in mg/l): 10.2 to 13.1• CONDUCTIVITY (µs): 2,090 to 2,100• HABITAT SCORE: 134 to 139, suboptimal aquatic habitat
PHYSICAL AND CHEMICAL WATER QUALITY ANALYSIS – BIG BRANCH____________________________________________________
• PHYSICAL– Analyzed seasonally– Adequate stream flow, desirable DO, near-neutral to alkaline pH,
moderately-high to highly elevated conductivity• CHEMICAL
– Minor acidity, adequate alkalinity to offset acidity– High levels of TDS, sulfate and hardness– Trace amounts of nitrate/nitrite, iron, manganese, and aluminum– Magnesium exceeds recommended levels– Conductivity considered high
• Parameters highest in Fall 2008 when proportion of mine waters to natural stream waters were at highest level
• OVERALL: Desirable except for conductivity, hardness, and magnesium
PHYSICAL AND CHEMICAL WATER QUALITY ANALYSIS – TOMBLIN BRANCH____________________________________________________
• PHYSICAL– Analyzed seasonally– Adequate DO and low conductivity– Can be non-flowing in summer months
• CHEMICAL– Lower pH than Big Branch, very little alkalinity to offset acidity– Modest levels of TDS, sulfate and hardness– Low levels of nitrate/nitrite, hardness, sulfate, chloride, and almost all
other metals– Conductivity considered very low
• Low pH during Spring 2008 and limiting DO levels in Fall 2008• OVERALL: Desirable except for limiting flow
PHYSICAL AND CHEMICAL WATER QUALITY ANALYSIS – ROCKY BRANCH____________________________________________________
• PHYSICAL– Analyzed ONLY TWICE– Stream flow low but adequate, desirable DO– Can be non-flowing in summer months
• CHEMICAL– pH somewhat acidic to somewhat alkaline– Conductivity high and wide-ranging– High level of hardness, TDS, sulfate, and magnesium in Fall 2008, lower
in Winter 2009– Almost all metals (such as Al, Fe, Mn, and Se) were quite low– Few parameters were at or just above limiting levels (hardness, sulfate,
TDS, conductivity, and Mg during low flow
• Some factors may be limiting to aquatic life• OVERALL: Some factors may be limiting during low flow
periods – water quality more desirable during Winter 2009
PHYSICAL AND CHEMICAL WATER QUALITY ANALYSIS – VANCE BRANCH____________________________________________________
• PHYSICAL– Analyzed ONLY TWICE– Adequate to desirable stream flow, desirable DO levels
• CHEMICAL– Somewhat alkaline pH – Conductivity highly elevated– Little to some acidity, adequate levels of alkalinity– High levels of hardness, TDS, sulfate, and Mn during both sampling
events– Almost all metals were quite low and within acceptable ranges (high Mn
in Winter 2009)
• Some factors may be limiting to aquatic life• OVERALL: Some factors may be limiting during low flow
periods – water quality considered undesirable due to a few key constituents
BENTHIC MACROINVERTEBRATE RESULTS – BIG BRANCH
________________________________________
• TOTAL ABUNDANCE: 470 individuals in Winter 2009 to 2,383 in Fall 2008
• TOTAL TAXA: 28 to 43– High percentage of shredders (20.9% to 61.7%)
• WVSCI: 62.8 to 86.4
• OVERALL: Desirable results
BENTHIC MACROINVERTEBRATE RESULTS – TOMBLIN BRANCH
________________________________________• TOTAL ABUNDANCE: 187 to 505• TOTAL TAXA: 7 to 34
– Population of highly sensitive individuals in Spring 2008
– Shredders ranged from 2.5% to 30.1%
• WVSCI: Scores ranged from 25.2 to 91.4• OVERALL: 4 out of 5 sampling events
resulted in poor outcomes, flow definitely the limiting factor
BENTHIC MACROINVERTEBRATE RESULTS – ROCKY BRANCH
________________________________________• TOTAL ABUNDANCE: 90 individuals in
Winter 2009 to 377 individuals in Fall 2008• TOTAL TAXA: 20 to 28
– Population was fairly sensitive in Winter 2009– Shredders over 30.0% in both sampling events
• WVSCI: 61.5 to 64.8• OVERALL: Scores not so bad considering
Fall 2008 was a drought and other sampling event was during winter
BENTHIC MACROINVERTEBRATE RESULTS – VANCE BRANCH
________________________________________• TOTAL ABUNDANCE: 467 individuals in Winter
2009 to 499 individuals in Fall 2008• TOTAL TAXA: 12 to 13
– Population was considered facultative to tolerant– Shredders were 3.4% to 4.3%– Collectors/Filters ranged from 43.7% to 36.2%
• WVSCI: 44.2 to 48.8• OVERALL: Scores not so bad considering Fall 2008
was a drought and other sampling event was during winter
DISCUSSION_______________________________________
• OBSERVATIONS - TOMBLIN BRANCH:
– Undisturbed reference stream
– Rated very healthy during periods of adequate stream flow (WV-SCI of 91.4)
– Rated poorly when stream flow was low (WV-SCI as low as 25.2)
DISCUSSION_______________________________________• OBSERVATIONS - BIG BRANCH:
– Receives perennial down-dip outcrop seepage
– Scored fairly well throughout various seasons
– Contained mayflies, stoneflies, and caddisflies
– Desirable results even when water chemistry variables were elevated (“sometimes mine water is better than little or no water”)
DISCUSSION_______________________________________
• OBSERVATIONS - ROCKY BRANCH:
– Perennial flow receiving flow from outcrop seepage
– Scored moderately well and contained some mayflies, stoneflies, and caddisflies
– Scored lower than Big Branch, but higher than Tomblin Branch during the same time frames (“at times, mine water may be better than little to no water”)
DISCUSSION_______________________________________________
• OBSERVATIONS - VANCE BRANCH:
– Perennial stream located directly downstream of fills and sediment ponds in heavily mined watershed
– Contained a moderate number of individuals, but undoubtedly, water quality associated with sediment ponds and disturbances have affected stream noticeably
– Scored higher than Tomblin Branch during the same time frames (“at times, mine water may be better than little to no water”)
F IG UR E 3. E P A Habitat
0
20
40
60
80
100
120
140
160
180
200
F all 2007 S pring 2008 S ummer 2008 F all 2008 Winter 2009
Hab
itat S
core
B ig B ranc h
T omblinB ranc hR oc ky B ranc h
Vanc e B ranc h
F IG UR E 4. % E P T of T otal Abundance
43.7
69.9
30.6
56.254.3
4.4
22.4
1.3 0.8
12.89.0
58.9
36.5 36.4
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
F all 2007 S pring 2008 S ummer 2008 F all 2008 Winter 2009
B ig B ranc h
T omblinB ranc hR oc ky B ranc h
Vanc e B ranc h
F IG UR E 5. % S hredders
24.5
61.7
29.6
51.2
20.9
27.830.1
4.32.5
11.8
32.6 31.3
3.4 4.3
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
F all 2007 S pring 2008 S ummer 2008 F all 2008 Winter 2009
B ig B ranc h
T omblinB ranc hR oc ky B ranc h
Vanc e B ranc h
F IG UR E 6. % C ollector/F ilterers
14.7
0.72.5
5.1
11.3
1.3
27.8
0.83.3
43.1
36.2
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
50.0
F all 2007 S pring 2008 S ummer 2008 F all 2008 Winter 2009
B ig B ranc h
T omblinB ranc hR oc ky B ranc h
Vanc e B ranc h
F IG UR E 9. # Mayfly Individuals
19
29
4
32
46
128
12
0
20
40
60
80
100
120
140
F all 2007 S pring 2008 S ummer 2008 F all 2008 Winter 2009
B ig B ranc h
T omblinB ranc hR oc ky B ranc h
Vanc e B ranc h
F IG UR E 10. # Mayfly G enera
2
6
1 1
3
10
2
0
2
4
6
8
10
12
F all 2007 S pring 2008 S ummer 2008 F all 2008 Winter 2009
B ig B ranc h
T omblinB ranc hR oc ky B ranc h
Vanc e B ranc h
F IG UR E 11. % Mayflies
0.9 1.40.2
1.3
9.8
25.4
1.0
13.3
0.0
5.0
10.0
15.0
20.0
25.0
30.0
F all 2007 S pring 2008 S ummer 2008 F all 2008 Winter 2009
B ig B ranc h
T omblinB ranc hR oc ky B ranc h
Vanc e B ranc h
F IG UR E 7. # S tonefly Individuals
539
1312
417
1124
131
10
202
6 4 1812 160
200
400
600
800
1000
1200
1400
F all 2007 S pring 2008 S ummer 2008 F all 2008 Winter 2009
B ig B ranc h
T omblinB ranc hR oc ky B ranc h
Vanc e B ranc h
F IG UR E 8. # S tonefly G enera
5
6
4
7 7
2
5
3
1
22 2
1
0
1
2
3
4
5
6
7
8
F all 2007 S pring 2008 S ummer 2008 F all 2008 Winter 2009
B ig B ranc h
T omblinB ranc hR oc ky B ranc h
Vanc e B ranc h
F IG UR E 12. WV-S C I
75.7
86.4
62.8
81.683.8
54.0
91.4
36.9
25.2
33.7
61.564.8
44.248.8
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
F all 2007 S pring 2008 S ummer 2008 F all 2008 Winter 2009
B ig B ranc h
T omblinB ranc hR oc ky B ranc h
Vanc e B ranc h
F IG UR E 13. % S ens itive Individuals
0
10
20
30
40
50
60
70
80
F all 2007 S pring 2008 S ummer 2008 F all 2008 Winter 2009
B ig B ranc h
T omblinB ranc hR oc ky B ranc h
Vanc e B ranc h
F IG UR E 14. C onductivity (us )
0
500
1000
1500
2000
2500
F all 2007 S pring 2008 S ummer 2008 F all 2008 Winter 2009
Co
nd
ucti
vity
B ig B ranc h T omblin B ranc hR oc ky B ranc h Vanc e B ranc h
F IG UR E 15. # of T axa
30
38
28
43
31
23
34
18
9
28
20
12
7
13
0
5
10
15
20
25
30
35
40
45
50
F all 2007 S pring 2008 S ummer 2008 F all 2008 Winter 2009
B ig B ranc h
T omblinB ranc hR oc kyB ranc hVanc eB ranc h
CONCLUSIONS__________________________
• A comparison of the data presented in this study to that presented by Pond et al. 2008 raises several questions:
CONCLUSIONS___________________________________• Big Branch exhibits high specific
conductivity with not mountaintop mining or valley fill construction– However, it continued to have a mayfly
community• Is it possible that the reductions observed by
Pond et al. 2008 are not attributed to high conductivity but the effects of sediment ponds or changes in vegetation?– These are temporary effects that can be more
easily remediated if deemed necessary
CONCLUSIONS___________________________________• Vance Branch displayed a dramatic increase
in filter feeders– The expected benthic community present
immediately downstream of an impounding structure (such as a sediment pond)
• Are large populations of mayflies expected to be found below such structures?
CONCLUSIONS___________________________________
• Recommendation:
– Regulatory agencies need to reconsider the issue of biological impairment and the methods currently utilized to measure its severity
– Examine the success stories as well as the alleged failures
– Agency and industry collaboration needed