The water chemistry of two Appalachian streams, Little Tumbling Creek (LTC) and North Fork Stony Creek (NFSC), was studied to develop acid mitigation plans. Both streams have low pH and buffering capacity due to geology with few minerals. LTC was treated with limestone, increasing pH and buffering slightly, but not to targets. Additional limestone of varying sizes is recommended. NFSC needs similar treatment, and 100 tons of limestone is calculated to offset acidity based on LTC results. The goal is to improve water chemistry and reestablish aquatic life in both streams.

1. A Tale of Two Appalachian Highland Streams: Acid Mitigation Planning and Results
Lindsay A. House and Daniel M. Downey
Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, VA 22807
A Tale of Two Appalachian Highland Streams: Acid Mitigation Planning and Results
Lindsay A. House and Daniel M. Downey
Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, VA 22807
The water chemistry of two Appalachian Mountain streams with good physical and thermal habitat in
southwest Virginia, Little Tumbling and North Fork Stony Creeks (LTC and NFSC), was assessed for
this study. Both streams discharge from watershed geology with little natural carbonate bearing
minerals and are acidic due to the combination of the lack of buffer and acid precipitation that
contains anthropogenic nitric and sulfuric acids. Aquatic life has been adversely affected by
acidification for both streams. A long term remediation project for LTC resulted in treatment with
limestone (CaCO3, 60 tons) to offset stream acidity levels in January 2012. Similar remediation of
NFSC is planned. The purpose of the present study was to evaluate stream water chemistry for LTC
pre/post limestone treatment and upstream/downstream to establish the effectiveness of the
treatment for improving water chemistry. These results were used to determine the amount of
limestone necessary for the NFSC liming. Physical size, watershed geology and discharge values have
been established for the streams. Water samples were collected and analyzed for pH, acid
neutralizing capacity (ANC), and Ca2+
concentration. The average pH/ANC/Ca values of Little Tumbling
Creek samples upstream and downstream of the liming site were 4.90/-10.5/46.2 and 5.67/8.9/74.3
and, respectively, which were lower than target values. The average pH/ANC/Ca of North Fork Stony
Creek samples was 5.39/-4.3/1.6. A limestone consumption half life (1.62 yr-1
) has been determined
for the LTC Liming. The results were used to recommend that 40 and 100 tons of limestone be added
to LTC and NFSC, respectively for acid mitigation.
The water chemistry of two Appalachian Highland streams, Little Tumbling Creek (LTC) and North Fork
Stony Creek (NFSC), was studied and interpreted to develop and evaluate acid mitigation plans. Both
streams are similar in size, elevation, watershed characteristics and are located on public property.
The goals of this study are to modify the existing LTC limestone treatment plan (“liming’) and to
propose a treatment plan for NFSC, using the former project as a model. Little Tumbling Creek is
located in the Clinch Mountain Wildlife Management Area in Smyth and Tazewell Counties, Virginia.
Data collected for several decades revealed acidification of the stream and a reduction of fish
populations as a result of changes in water chemistry due to atmospheric acid deposition. The
combustion of fossil fuels releases SOx and NOx gases into the atmosphere, which react with water to
form anthropogenic atmospheric acid. Therefore, rainfall in this area is more acidic (pHave = 4.5) than
unpolluted precipitation (pHave = 5.5). The pH observed for surface water results from the equilibria of
the carbonate-bicarbonate-carbonic acid system. Gaseous atmospheric CO2 dissolves in water to
produce carbonic acid solutions. When minerals weather and produce carbonate (CO3
2-
) reaction with
CO2 produces bicarbonate (HCO3
-
), the primary base in natural water providing the acid neutralizing
capacity (ANC). Little Tumbling Creek discharges from low carbonate geology with little natural
buffering capacity and low pH and ANC values. A proposed liming project to increase ANC in LTC was
delayed ten years until an access road was built to deliver limestone to the remote location. In
January 2012, 60 tons of quarry mined limestone (93% CaCO3, 12 x 120 mesh) were placed at one
location near the headwaters of LTC, providing a time release treatment. The increased pH and ANC
enabled survival of post treatment introduced brook trout. However, the target values pH>6.5 and
ANC>25 have not yet been consistently achieved, and the longevity of the increase may be short term.
One objective for the present study was to determine why the target values have not been attained
and what modifications for the liming project should be made. It is desired that initial amounts,
particle sizes and timing of limestone introductions will enable repetition to be in three or four year
intervals. The limestone treatment of Little Tumbling Creek has guided the development of an acid
mitigation plan for NFSC. North Fork Stony Creek, located in the Giles Co. Virginia, in the George
Washington National Forest also discharges from low carbonate geology with low pH and ANC values.
A public road crosses the upper reach of the stream and will serve as a convenient access location for
liming. The second objective of this study was the proposal of a liming and monitoring plan for NFSC,
based on the results of the LTC project.
Little Tumbling Creek
•The pH increased from 4.92 pre-liming to 5.99 post-liming.
•The ANC increased from -7.7 μeq/L pre-liming to 24.8 μeq/L post-liming.
•Ca2+
concentrations increased from 52.0 μeq/L pre-liming to 115.1 μeq/L post-liming.
•Ca/H ratio increased pre-liming to post-liming
•Aluminum concentrations decreased post-liming.
•Partially achieved target pH, ANC, Ca/H values, but not fully. This is due to tributaries T1-T4 titrating
out ANC.
•The calculated half-life (1.62 yr-1
) indicates that additional limestone must be introduced to the
stream. 40 tons of additional limestone must be introduced in order to fully achieve target pH, ANC,
and Ca/H values.
•20 tons of limestone per year is required to offset the 403 keq/yr H &NH4 influx.
North Fork Stony Creek
•The pH values for Upper and Lower sites were low at 5.07 and 5.31, respectively. These values are
similar to the pre-liming pH of LTC.
•Watershed area (2243 ha) is similar to the watershed area of LTC (2308 ha).
•Due to similar characteristics (pH, watershed area, etc.), LTC can be used as a model for developing
an acid mitigation plan for NFSC.
•20 tons of limestone per year is required to offset the 392 keq/yr H & NH4 influx.
Site ID Distance
(km)
pH ANC (μeq/L) Ca (μeq/L) Ca/H Al
LTC 1 0 5.96 14.6 77.1 70.32 33
LTC 1A 0.97 5.59 4.9 64.2 24.98 42
LTC 1B 0.88 5.59 5.7 65.9 25.64 48
LTC 2 1.43 5.65 8.9 67.0 29.93 42
LTC 3 0.80 5.54 4.9 67.6 23.44 51
LTC 3B 0.58 5.30 1.6 64.9 12.95 64
LTC 3A 0.40 5.58 6.1 69.4 26.39 54
LTC 4 2.30 5.81 8.5 77.9 50.30 54
LTC 5 2.29 5.99 24.8 115.1 112.48 81
LTC 6 0.32 5.10 -2.0 62.7 7.89 124
LTC 7 0.48 4.92 -7.7 52.0 4.33 136
LTC 8 1.24 4.67 -21.9 24.0 1.12 213
T1 4.78 -14.6 27.4 1.65 179
T2 5.13 2.4 20.2 2.72 55
T3 5.48 -2.0 68.1 20.57 2
T4 5.08 -5.3 19.4 2.33 10
NFSC Lower 5.31 -6.9 1.5 0.31 12
NFSC Upper 5.07 -1.6 1.6 0.19 19
LTC NFSC
Watershed Area (ha) 2308 2243
Total Stream Reach (km) 11.9 6.3
Average Precipitation (m/year) 1.26 1.26
Uppermost elevation (m) 1125 989
Lowermost elevation (m) 690 786
Discharge (m3
/year) 1.7 x 107
1.7 x 107
H & NH4 influx (keq/year) 403 392
Treatment Stream Reach (km) 9.9 5.6
Limestone Treatment Requirement
(tons/year)
20 20
Figure 1. Sampling sites for Little Tumbling Creek. Stream discharges west to east.
Watershed shown in red. Limestone introduced at site 6.
Figure 2. Sampling sites on North Fork Stony Creek. Stream discharges to west, then
southwest. Watershed shown in red. Limestone proposed for introduction at NFSC
Upper site (public road)..
Table 1 : Comparison of Physical Attributes for Little Tumbling and North Fork Stony Creeks
After liming Little Tumbling Creek, pH, ANC, and Ca2+
concentrations increased. However, the limestone treatment
was not as effective as expected. In order to further increase pH, ANC, and Ca2+
concentrations, the existing
limestone treatment plan must be modified by introducing additional limestone of varying particle size. The
calculated amount of limestone necessary to offset the H & NH4 influx is 40 tons. The results of the liming of Little
Tumbling Creek will be used to guide the proposal for limestone treatment of North Fork Stony Creek. Using Little
Tumbling Creek as a model, 100 tons of limestone was calculated as the amount of limestone needed to offset
acidity levels in North Fork Stony Creek. A low-cost plan for limestone treatment will be developed and aquatic life
will be reestablished in North Fork Stony Creek.
United States Forest Service – George Washington and Jefferson National Forests
Virginia Department of Game and Inland Fisheries
Bill Kittrell, Virginia Department of Game and Inland Fisheries
George Palmer, Virginia Department of Game and Inland Fisheries
Dawn Kirk, US Forest Service Fisheries Biologist
Steve DeFranco, US Forest Service
National Science Foundation – CHE-1062629
Table 2 : Water Chemistry Values for Little Tumbling Creek, Tributaries and North Fork Stony
Creek. The distances provided for LTC samples are relative to the lower boundary of the
Management Area for samples collected on July 10, 2013.
Figure 6. Observed changes in pH (left) and ANC (right) for LTC for the upper “control” sample site and a
downstream site for quarterly samples. Target values are indicated for each parameter on the graph along with
discharge readings at the time of sample collection from a nearby stream.
Figure 7. Net calcium values for quarterly samples downstream of the liming site obtained by subtracting baseline
calcium from observed calcium. Exponential decay curve fit gave a half life value of 1.62 years for limestone
consumption.
Figure 8. Observed changes in pH (left) and ANC (right) for LTC for the upper “control” sample site and a
downstream site for synoptic samples collected on July 10, 2013.
Figure 3. Photo of LTC Site 5. Figure 5. Photo of LTC
sampling site.
Figure 6. Photo of NFSC Upper site.
Introduction Abstract
Conclusion
Results and Discussion
Acknowledgments
Figure 4. Photo of LTC 5 and the Beaver Ponds.