20080868 Ver 2_Section III B Wetland Hydrology 2021 PCS Creeks Report_20220605

B. WETLAND HYDROLOGY
Section II-B contains summary information about pre- and post -Mod Alt L hydrology for
Jacks Creek, Jacobs Creek, Drinkwater Creek, Tooley Creek, Huddles Cut, Porter Creek, and
DCUT11 as it pertains to one of the six permit questions, while this section contains additional
summary information about hydrology in each monitored creek. Although the study officially
began in 1998 and data collection for some parameters occurred in both 1998 and 1999, due to
CAMA permits for pier construction, the official start date for some parameters, including
hydrology, was May 1999; therefore, the first full year of wetland hydrology data was 2000 and
years with incomplete data were not included in wetland hydroperiod analysis.
Many upstream and interstream locations are largely influenced by rainfall and seasonal
high-water conditions. Interstream areas are usually wetter during the winter season with a
seasonally higher water table which affects the early portion of the growing season, when many
wells experience the longest wetland hydroperiod of the year. During other times of the year,
rainfall events may have less effect on water levels and sites that are wet for large periods of the
growing season are usually lower in elevation and closer to downstream waterbodies. Large
amounts of Tar River discharge can influence water levels at lower elevation wells closer to larger
downstream waterbodies (Pamlico River, South Creek, Porter Creek and Durham Creek).
Rainfall data are collected from a variety of sites as described in Section I-F and identified
in Table I-F2, and those rain gauges closest to each study creek are used to assist with
hydroperiod evaluations. Wetland hydroperiods documented from all Level Trolls during the 2021
growing season are found in Table III-B1. The longest wetland hydroperiod from each site in
2021 compared to average pre, post, and all years of data for impact creeks, and all years of data
for control creeks are found in Table III-B2. The following section examines the longest
hydroperiods in each creek.
1.0 Wetland Hydroperiods by Creek
a. Broomfield Swamp Creek
The first year of hydrology data was collected in 2019, which was the first
pre -Mod Alt L year for Broomfield Swamp Creek. In 2021, total annual rainfall was 49.30 inches
(Table I-F2). Two wells were monitored, both within the floodplain on the south side of the creek;
BSCW2 is approximately 700 feet further downstream from BSCW1. In 2021, the longest
hydroperiod for the upstream well (BSCW1) was 46 days (18.0 percent) and the hydroperiod for
BSCW2 was 129 days (50.4 percent) (Table III-B1).
b. SCUT1
Hydrology data collection in this tributary to South Creek also began in
2019. Rainfall data for SCUT1 were obtained from the same rain gauge as Broomfield Swamp
Creek due to its proximity. In 2021, total annual rainfall was 49.30 inches (Table I-F2). Two wells
were monitored, both within the floodplain on the west side of the creek; SCUT1W2 is
approximately 500 feet downstream of SCUT1W1. Both wells experienced longest hydroperiods
in 2021 of 129 days (50.4 percent) (Table III-B1).
c. Jacks Creek
Years of hydrology data included in this report are 2000-2005 and 2011-
2021. Mod Alt L activities began and were completed in the Jacks Creek drainage basin in 2015;
all previous years are pre -Mod Alt L. During all these years of monitoring in Jacks Creek, total
annual rainfall ranged from 34.87 (2001) to 61.47 inches (2005) with an average of 51.70 inches
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(Table I-F2). Total annual rainfall for 2021 was 51.73 inches, which was 0.03 inches more than
the average rainfall for all years.
In 2021, the three most downstream wells on the east prong of Jacks Creek
(JW9A, JW9B, and JW10) recorded a hydroperiod for the entire growing season (Table III-B1 and
Figure III-B1). The longest hydroperiod for the most upstream well on the east prong (JW7A) was
18.4 percent (47 days) of the growing season. Wells farther downstream on the east prong (JW7B
and JW8) had hydroperiods for 25.0 percent (64 days) of the growing season. On the main prong,
hydroperiods for the more upper reach wells JW1, JW2A, and JW2B were 25.0 percent (64 days
of the growing season, JW3 was 26.6 percent (68 days) of the growing season, and downstream
wells JW4, JWSA, JWSB, and JW6 recorded hydroperiods for the entire growing season.
d. Jacobs Creek
Two wells in the upper reaches of Jacobs Creek have been monitored
since 2011. Mod Alt L activities in the drainage basin began in 2014 and were completed in 2015.
The wells are located within 100 feet of each other, at more or less equivalent geomorphic
positions in the creek system. As measured by the PA2 rain gauge, total annual rainfall for 2021
was 51.73 inches, which was 0.97 inches less than the average rainfall for all years (Table I-F2).
Both of the wells recorded a wetland hydroperiod in 2021 (Table III-B1 and
Figure III-B2). The only other recorded instance of a wetland hydroperiod at Jacobs Creek wells
was in March 2014, a year with above average rainfall. The longest hydroperiod in 2021 for
JCBW1A was 21.5 percent (55 days) of the growing season and the longest hydroperiod for
JCBW1 B was 24.6 percent (63 days) of the growing season (Table III-B1 and Figure III-B3). The
2021 hydroperiods appear to be in response to monthly rainfall totals in January and February
that were above the WETS 70th percentile leading into the growing season. To date, hydroperiods
in Jacobs Creek are the shortest among all creeks monitored for this project.
e. Drinkwater Creek
Three wells in Drinkwater Creek have been monitored since 2011. Pre -
Mod Alt L years include 2011 and 2012. As measured by the PA2 rain gauge, total annual rainfall
over the 11 years ranged from 41.60 (2013) to 67.02 inches (2020) with an average of 52.70
inches (Table I-F2). Total annual rainfall for 2021 was 51.73 inches, which was 0.97 inches less
than the average rainfall for all years. In 2021, hydroperiods ranged from 13.3 (DWW1 C) to 26.2
(DWW1B) percent of the growing season (Table III-B1 and Figure III-B2). One of the wells
(DWW1B) is in the middle of the stream channel and the other two are outside of the stream
channel on either side of the creek floodplain.
Hydroperiods at DWW1B throughout the years ranged from 26.2 percent
(67 days) in 2021 to 100 percent (256 days) in 2020. In 2021, the longest wetland hydroperiod
at DWW1B decreased to 67 days (26.2 percent of the growing season) making it the shortest
hydroperiod recorded at DWW1B. Hydroperiods at DWW1A throughout the years ranged from
19 percent (49 days) in 2013 to 34 percent (88 days) in 2012. In 2021, two hydroperiods were
recorded for DWW1A, with the longest being 19.5 percent (50 days) of the growing season. At
DWW1 C, hydroperiods ranged from 9 percent (24 days) in 2014 to 18 percent (47 days) in 2018.
In 2021, one hydroperiod was recorded for DWW1 C, with 13.3 percent (34 days) of the growing
season.
To potentially understand the behavior of DWW1A and DWW1C, relative
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elevations across the floodplain between the two wells were collected every 10 feet with a sight
level and stadia rod (a total of nine measurements including the sight -level location). That exercise
showed DWW1C to be approximately 3.5 inches higher in elevation than DWW1A. LiDAR
indicates that the topography perpendicular to the axis of the creek at this monitoring array is
different on either side, which is not uncommon. According to LiDAR, beyond DWW1A, there are
several polygons of somewhat higher elevation compared to the land beyond DWW1C; these
higher features could affect runoff from some rainfall events in the vicinity of DWW1A and
contribute to the different behavior of these two wells.
f. Long Creek (control)
Two wells in two small and narrow branches of a minor prong on the south
side from the main channel of Long Creek have been monitored since 2011. As measured by the
Tooley Creek gauge (across South Creek), total annual rainfall over the nine years ranged from
40.61 (2013) to 66.88 (2020) inches with an average of 51.85 inches (Table I-F2). In 2021, total
annual rainfall was 47.51 inches, which was 4.34 inches lower than the average rainfall for all
years. The longest hydroperiod in 2021 for LOCW1B was 73 percent (187 days) of the growing
season (Table III-B1 and Figure III-B3). LOCW2B is located further upstream on the main branch
of the prong and has always had a shorter hydroperiod than LOCW1A. In 2021, LOCW2B had a
hydroperiod for 22.3 percent (57 days) of the growing season, which was the shortest hydroperiod
recorded since monitoring began in 2011.
g. Tooley Creek
Years of hydrology data included in this evaluation are 2000-2001 and
2010-2021, with 2000-2001 and 2010-2011 as pre -Mod Alt L years. Total annual rainfall ranged
from 35.71 (2001) to 66.88 (2020) inches with an average of 51.51 inches (Table I-F2). In 2021,
total annual rainfall was 47.51 inches, which was 4.0 inches lower than the average rainfall for all
years.
In 2021, the two most downstream wells, TW2 and TW3 (Table III-B1 and
Figure III-B4), on the east prong had longer hydroperiods than 2020. TW2 and TW3 both had
hydroperiods for 100 percent (256 days) of the growing season. The most upstream well on the
east prong, TW1, had a hydroperiod for 24.6 percent (63 days) of the growing season, which was
shorter than the hydroperiods for 2020. For the west prong, in 2021, the two most upstream wells
(TW5 and TW6) had longer hydroperiods than 2020. TW5 had a hydroperiod for 50.0 percent
(128 days) of the growing season and TW6 had a hydroperiod for 15.2 percent (39 days) of the
growing season. The most downstream well on the west prong, TW4, had a hydroperiod for 50.0
percent (128 days) of the growing season, which was shorter than in 2020.
h. Huddles Cut
Years of hydrology data included in this evaluation are 2000-2001, 2007-
2021; post -Mod Alt L began in 2010. Total annual rainfall over all years ranged from 32.18 (2001)
to 68.14 (2003) inches with an average of 49.62 inches (Table I-F2). In 2021, total annual rainfall
was 47.66 inches, which was 1.96 inches lower than the average rainfall for all years. There have
been seven years in the main prong (2014, and 2016 - 2021) and six years in the west prong
(2016-2021) when every well recorded hydroperiods for 100 percent (256 days) of the growing
season (Figures III-B5 and III-B6).
i. Main Prong
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Continuous hydroperiods for all wells over the 15 years ranged from
27.7 percent (HMW10 in 2011) of the growing season (71 days) to 100 percent (256 days) with
an average of approximately 91.8 percent or 235 days (Figure III-B5). As evident in Figure III-B5,
the longest hydroperiod for many wells was shorter from 2007 through 2011 than in the years
prior and after. In 2013, the hydroperiod for HMW10, a well located on a small branch east of
the other transects in the main prong, decreased to about half of the growing season, while all
other wells had hydroperiods for the entire growing season. In the higher than average rainfall
(57.07 inches) year of 2015, a well located about midway up the main prong and in a small
crenulation on the west side of the swamp (HMW9) decreased to just over half of the growing
season while all other wells had hydroperiods for the entire growing season. The explanation for
the decrease at this site in 2015 is unknown and not likely related to deep water well pump
operations discussed in Section III.B.2.0. Wells HMW11 and HMW12, both closer to deep well
pumps, were not affected in 2013 when the pumps were on, and pumps in the area were off in
January 2014; therefore, should not have affected 2015 data. Since 2016, all wells recorded
hydroperiods for the entire growing season.
ii. West Prong
Longest hydroperiods for all wells over the 15 years ranged from 0
days (HWW9 in 2013, the most upstream well) to 100 percent (256 days) with an average of
approximately 71.5 percent or 183 days (Figure III-B6). Until 2016, the more upstream wells on
the west prong tended to have shorter wetland hydroperiods than the downstream wells, and
water levels appeared to be more influenced by rainfall than the wells further downstream.
However, since 2016 all wells recorded hydroperiods for the entire growing season.
i. Porter Creek
Wetland hydrology data were collected at Porter Creek at six wells in the
beginning of the 2006 growing season for another PCS project, and three additional wells were
installed downstream of the other six wells in early 2011. Since no other creek in the study was
monitored in 2006, only Porter Creek well data from 2007 forward were included in this report,
and pre -Mod Alt L years include 2007-2015. Mine activities in the Porter Creek drainage basin
began in 2016, the first post -Mod Alt L year. Total annual rainfall over all years ranged from 36.16
(2007) to 73.21 (2020) inches with an average of 53.05 inches. In 2021, total annual rainfall was
51.04 inches, which was 2.01 inches lower than the average rainfall for all years.
The six most upstream wells had hydroperiods that ranged from 5.07
percent (13 days, four wells in 2009), to 26.2 percent (67 days, three wells in 2008), with an
average of approximately 16.2 percent or 41 days (Figure III-B7). Hydroperiods have decreased
slightly over the past three years (2019-2021) at all six upstream wells. The three downstream
units were installed in 2011 with one in the middle of the creek channel (PCW9B) and two on
either side of the creek channel in the wide floodplain but nearby (PCW9A and PCW9C).
Hydroperiods at these three wells were much longer than other Porter Creek wells for all years
since monitoring began. PCW9B had a hydroperiod for the entire growing season every year
since monitoring began. For all years excluding 2017, PCW9A had longer hydroperiods than
PCW9C. The increase in hydroperiod length at PCW9C in 2017 was likely due to beaver dams
near the wells, and the beaver(s) were removed in late 2017 (Table III-B1). The longest
hydroperiod at PCW9C has decreased from year to year since the beavers were removed in late
2017. In 2020, the year with the highest rainfall since 2007, the longest hydroperiod at PCW9A
increased by 142 days to 256 days of the growing season in 2020 and 2021. In 2021 the longest
hydroperiods at PCW9C decreased by 37 days from 2020, continuing a trend of decreasing
hydroperiods from the previous year that began in 2018.
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j. DCUT11
Hydrology data collection in this tributary to Durham Creek began in 2013.
Mod Alt L activities occurred in this drainage basin for the first time in 2018. Data from the Porter
Creek rain gauge were used for this creek due to its close proximity. Total annual rainfall since
2013 ranged from 43.39 (2013) to 73.21 (2020) inches with an average of 56.29 inches. In 2021,
total annual rainfall was 51.04 inches, which was 5.24 inches lower than the average rainfall for
all years (Table I-F2).
The eight wells are in three different arrays along the creek and exhibited
a wide range of hydroperiods in 2021 that appear to be influenced by rainfall (Table III-B1 and
Appendix B). As would be expected, the wells located in the channel (DC11 W1 B, DC11W2B,
and DC11W3B) all had longer hydroperiods than the wells of the same array located in the
floodplain. The downstream wells with hydroperiods ranging from 50.4 percent (129 days) to 100
percent (DC11W3A, DC11W3B, and DC11W3C) had longer hydroperiods than the more
upstream wells. In 2021, all wells except DC11W3B, which has had hydroperiods that span the
entirety of the growing season for all years, and DC11 W1 B, which had a decrease in hydroperiod
of 3 days in 2021, had longer hydroperiods than 2020 (Figure III-B8). Wetland hydroperiods for
the upstream DCUT11 wells are among some of the shortest of all monitored creeks, and in this
part of the system, the stream is incised with a narrow floodplain which is not as well connected
to overbank flow events. Seven of the eight wells have seen a reduced hydroperiod between pre
and post Mod Alt L years, and wells DC11W1A and DC11W2A had no wetland hydroperiods in
2021.
k. DCUT19 (control)
Hydrology data collection in this tributary to Durham Creek also began in
2013. Total annual rainfall during monitoring years ranged from 40.09 (2019) to 65.20 (2020)
inches with an average of 50.49 inches (Table I-F2). In 2021, total annual rainfall was 2.46 inches
less than the average rainfall for all years.
Hydroperiods for the four wells in the two most upstream arrays
(DC19W1 A, DC19W1 B, DC19W2A, and DC19W2B) were similar to one another each year from
2013-2021, with the exception of 2020 which had hydroperiods shorter than any previous year
(Figure III-B9). In 2021 hydroperiods ranged from 18.4 percent (47 days) to 18.8 percent (48
days) with an average of 18.3 percent (47 days) of the growing season. The most downstream
array of wells (DC19W3A and DC19W3B) had longer hydroperiods than the more upstream wells
(Table III-B1). The longest of the five hydroperiods recorded for DC19W3A in 2021 was 123 days
(48.0 percent) of the growing season, which was 133 days shorter than 2020. DC19W3B had a
hydroperiod for the entire growing season for 2014-2018 and 2020-2021 but was reduced to 131
days in 2019.
I. Duck Creek (control)
Hydrology data collection at eight wells in three arrays and one additional
well began in 2011. Total annual rainfall ranged from 36.16 (2013) to 62.73 (2016) inches with
an average of 49.16 inches (Table I-F2). In 2021, total annual rainfall was 48.72 inches, 0.44
inches less than the average rainfall for all years.
All of the wells in 2021 at Duck Creek had shorter hydroperiods than 2020
and hydroperiods at the more downstream wells were generally longer than the upstream wells
(Figure III-B10). Hydroperiods for the three upstream wells (DKCW1B, DKCW2A, DKCW2B)
III-B-5

ranged in percentage of the growing season from 17.6 percent (45 days) to 20.7 percent (53 days)
and hydroperiods for the five downstream wells (DKCW3A, DKCW3B, DKCW4A, DKCW4B,
DKCW4C) ranged in percentage of the growing season from 18.4 percent (47 days) to 41.0
percent (105 days) (Table III-B1).
2.0 PCS Deep Wells and Water Levels in CZR Wetland Level TROLLs
In previous reports a dynamic multiple linear regression model was used to
compare water depth to rainfall, wind speed, wind direction, and discharge across three different
time periods: pre, during, and post deep well pump operation. Deep well pumps consist of 20-
inch diameter wells drilled down to approximately 250 feet to depressurize the Castle Hayne
Aquifer in the vicinity of the active mine. These deep wells pumps are turned on and off as needed
in association with the active mine areas and can pump 3,000 gallons/minute. CZR monitors
water level data collected from shallow monitoring wells (In Situ Level TROLLs) in the wetlands
and waters surrounding the mine. Level TROLLs measure water levels across a range of
approximately 5 feet with most data collected from —24 to +24 inches at each location
(configuration/installation varies by site conditions).
No adverse trends on hydroperiods were detected or attributed to the deep well
pump operation during past evaluations; and thus, this same evaluation was not repeated for this
report because of past results and because the influence of estuarine wind -driven water and/or
discharge from the Pamlico River are not the primary influence at these sites. When discharge
and wind parameters were removed from the evaluation, the remaining data sets (water level and
rainfall) both violated the statistical assumption of normality (were not normally distributed) despite
attempts to normalize. In addition, the statistical power of the non -parametric tests was very low,
which was attributed to many positive and negative water level readings, as well as many absent
water level readings (those lower than the range of detection for these shallow monitoring wells).
To aid in evaluation of potential effects of deep well pumps on nearby wells,
hydrology graphs of water levels from wells in the vicinity of Porter and DCUT11 were depicted
along with each deep well pump operation (on/off dates). These data and graphics allow for
observation of seasonal water level fluctuations and responses to rainfall along with the on/off
periods when deep well pumps are active.
a. Porter Creek
The analysis of pump operation in deep wells and wetland hydrology for
Porter Creek was first examined in the 2018 report. Six Level TROLLs (PCW4, PCWS, PCW6,
PCW9A, PCW9B, and PCW9C) were evaluated in this report to show water level graphics in
relation to nearby deep wells (March 2016 — December 2021 data) with pre, during, and post
periods of pump operation. Locations of deep wells and Level TROLLs in Porter Creek are shown
in Figure III-B11 and operation dates of pumps are shown in Table III-B3.
Porter Creek water levels at six Level TROLLs (PCW4, PCWS, PCW6, PCW9A, PCW9B, and
PCW9C) were graphed for each Level TROLL from 2016 to 2021 along with horizontal bars above
the graphs to show the operation periods of the deep well pumps closest to the two arrays of CZR
wells (Figure III-B12). Pre, during, and post time periods for these six wells are depicted along
with on/off dates for deep well pumps in proximity to CZR Level TROLLs (Table III-B3).
III-B-6

b. DCUT11
The analysis of pump operation in deep wells and wetland hydrology for
DCUT11 has not been evaluated in past reports due to the lack of post pumping data, but was
included in this year's report. Five Level TROLLs (DC11W1A, DC11W1B, DC11W2A, DC11W2B,
DC11W2C) closest to nearby deep wells were used to show changes in shallow water levels for
periods prior, during, and post active pumping between March 2016 through December 2021.
Graphs of the water levels for each Level TROLL along with horizontal bars above the graphs to
show the operation periods of the pumps in deep wells are depicted in Figure III-B13. Locations
of deep wells and Level TROLLs in DCUT11 are shown in Figure III-B11 and operation dates of
pumps are shown in Table III-B3.
c. Conclusions
As in previous years, deep well pump activity does not appear to affect
hydroperiods at the wetland shallow monitoring wells. Water levels at Porter Creek and DCUT11
respond to rainfall events and seasonal patterns (winter wet and lower levels after spring leaf -out
and during the summer) much like those in other wetlands throughout the area.
III-B-7

Jacks Creek
- JW1
+ JW2A
JW2B
A JW3
✓ JW4
* JW5A
x JW5B
o JW6
❑ JW7A
• JW7B
• JW8
• JW9A
X JW9B
® JW10
I Total annual
rainfall
Longest Hydroperiod (days)
250-
200-
150
100
50 -
0
® fli * # ! ! #F ® * # * * •
v
A
e
4
00 O^ O� 00 O� Oh �O �^ ^, tO N� ^h t\O
100
- - 80
- - 60
40
- 20
0
Total Annual Rainfall (in)
Yea r
Figure III-B1. Longest hydroperiod for each well in Jacks Creek by year with total annual
rainfall for each year (PA2 rain gauge).
- JCBW1A
+ JCBW1B
DWW1A
A DWW1 B
v DWW1C
I I Total annual
rainfall
Hydroperiod Length (days)
Jacobs and Drinkwater Creeks
250 -
200 -
150 -
100 -
50 _
A
A
f t t
2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021
100
- 80
- - 60
- 40
- 20
- 0
Yea r
Figure III-B2. Longest hydroperiod for each well in Jacobs and Drinkwater creeks by year
with total annual rainfall for each year (PA2 rain gauge).
III-B-8
Total Annual Rainfall (in)

o LOCW1B
x LOCW2B
i i Total annual
rainfall
Hydroperiod Length (days)
Long Creek
250 -
200 -
150 -
100 -
50 -
0 0 0 0
2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021
100
- 80
- 60
- 40
- 20
- 0
Total Annual Rainfall (in)
Year
Figure III-B3. Longest hydroperiod for each well in Long Creek by year with total annual
rainfall (Tooley Creek rain gauge).
4. TW1
x TW2
o TW3
O TW4
it TW5
❑ TW6
1 1 Total annual
rainfall
Longest Hydroperiod (days)
Tooley Creek
0
2000 2001 002 2009 2010 20112012 2013 2014 2015 2016 2017 2018 2019 2020 2021
Year
Total Annual Rainfall (in)
Figure III-B4. Longest hydroperiod for each well in Tooley Creek by year with total annual
rainfall (Tooley Creek rain gauge).
III-B-9

250
HMW1
+ HMW2 - 200
o HMW3
✓ HMW4 0
* HMW5 Q 150
a HMW6 2
❑ HMW7
® HMW8
• HMW9 100
e HMW10
HMW11 °
x HMW12 50
Total annual rainfall
Huddles Cut Main Prong
• • • • • • • • • • • • •
•
ai
•
A
100
- 80
- 60
- 40
- 20
VVVVVV
0
Total Annual Rainfall (in)
Year
Figure III-B5. Longest hydroperiod for each well in Huddles Cut Main Prong by year with
total annual rainfall (Huddles Cut rain gauge).
250
o HWW2 200
✓ HWW3
• HWW4 0
O HWW5 a) 150
❑ HWW6 0
L
® HWW7 -
• HWW8 2
e HWW9 in 100
I Total annual o)
rainfall o
J
50
Huddles Cut West Prong
® • W ® ® ® • • • • • •
v
ER
- D
A
100
- - 80
- - 60
40
- 20
�o � � �o � �o �o � �o r r rto V V V
0
Total Annual Rainfall (in)
Year
Figure III-B6. Longest hydroperiod for each well in Huddles Cut West Prong by year with
total annual rainfall (Huddles Cut rain gauge).
III-B-10

Porter Creek
250 -
- PCW9A T 200 -
o PCW9B m -
' PCW9C a -
A PCW4
✓ PCW5 a) 150 -
* PCW6 J -
❑ PCW1 0 _
• PCW2 _
• PCW3 0 100 -
1 Total annual a
rainfall 1
50 -
0
0 0 0 0 0 0 0 0 0 O O_
F
e
2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021
100
- - 80
60
40
- 20
0
Total Annual Rainfall (in)
Year
Figure III-B7. Longest hydroperiod for each well in Porter Creek by year with total
annual rainfall (Porter Creek rain gauge).
DCUT11
250 -
- DC11W1A N _
o DC11W1B m 200 -
' DC11W2A -
o DC11W2B o _
✓ DC11W2C -
* DC11W3A o 150 =
❑ DC11W3B 0
• DC11W3C 1
I I Total annual m 100 -
rainfall 0) -
c _
0
J
50 -
v
fiE
A
v
v
2013 2014 2015 2016 2017 2018 2019 2020 2021
100
- 80
- 60
- 40
- 20
0
Total Annual Rainfall (in)
Year
Figure III-B8. Longest hydroperiods for each well in DCUT 11 by year with total
annual rainfall (Porter Creek rain gauge).
III-B-11

- DC19W1A
O DC19W1B
' DC19W2A
• DC19W2B
✓ DC19W3A
tr DC19W3B
I Total annual
rainfall
Longest Hydroperiod (days)
DCUT19
250 -
200 -
150 -
100 -
50 -
tr tr tz iz tr • *
it
100
- 80
- 60
- 40
- 20
2013 2014 2015 2016 2017 2018 2019 2020 2021
0
Total Annual Rainfall (in)
Year
Figure III-B9. Longest hydroperiod for each well in DCUT19 by year with total
annual rainfall (Durham Creek rain gauge).
250
+ DKCW1B
x DKCW2A >, 200
o DKCW2B -
O DKCW3A
�r DKCW3B
❑ DKCW4A a 150
O DKCW4B
- DKCW4C T
Total annual N 100
rainfall m
0)
c
0
J
50
Duck Creek
0 Q 0 0
100
- 80
- 60
- - 40
- 20
2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021
0
Total Annual Rainfall (in)
Year
Figure III-B10. Longest hydroperiod for each well in Duck Creek by year with total
annual rainfall (Duck Creek rain gauge).
III-B-12

ocations of dee. wells and Level TRSLLs in Bonnerton area
III-B-13

DW1108
DW1109
DW1ao
a0
20
L 10
i D
-10-�
3D
16
I
t
1 V
fI
Y
I
IL
—
-00
PCW4
2016 2017 2018 2019 2020 2021
Water Depth (inches)
DW1112
DW1113
DW1114
r*Nry
\
IY4i41
fk
PCW9A
2016 2017 2018 2019 2020 2021
Dw1109
DW11OS
40
ao
m
L 10
1
3 ..
RO
i
0w1110
III
III
1.
AhI
-0o
PCW5
2016 2017 2018 2019 2020 2021
DW1112
10 -
—
0w1113
40
ao
f.
t° �' 20
m
DW 1114
iiiiii11114141itliikli
PCW9B
2016 2017 2018 2019 2020 2021
12,111108
50"
_
0W1109
a0
m
L 10
L
o
20
Dw1110
I
I
-90
PCW6
ra
2016 2017 2018 2019 2020 2021
ow1111
DW1113
50
40
S.
i
s m
0
10
0
0W1114
I
PCW9C
2016 2017 2018 2019 2020 2021
Figure III-B12. Hydrology of Level TROLLs in Porter Creek and times of deep well pump operation. Gray line shows Level TROLL data collected every 1.5 hour and blue line shows a 2-month moving average of
hydrology data. Horizontal lines indicate pump operation dates for nearest deep wells around the mine in Bonnerton.
III-B-14

Dw1121
90
aD
tD-
-1D '
[1 W
1122
+I+I
aD-
DC11W1A
.
2016 2017 2018 2019 2020 2021
Water Depth finches)
gitk o d 3 S s
Dw1121
Dw2122
0 r
al \
DC11 W2A
2016 2017 2018 2019 2020 2021
Li,
DW1121
sD
L 10
g D
m
1
L
rlr�'__
1
DW1122
JD-
aD
_'
DC11W1B
2016 2017 2018 2019 2020 2021
O W 1121
m
so •
i
Li
_LL,
DW1122
DC11W2B
2016 2017 2018 2019 2020 2021
Dw1121
90
20
10
L 0
o'
m4411
3.,D
zD
30
rD
r
E
r
^
nwu22
�...�
4
L��
'IL
DC11
t
W2C
2016 2017 2018 2019 2020 2021
Figure III-B13. Hydrology of Level TROLLs in DCUT11 and times of deep well pump operation. Gray line shows Level TROLL data collected every 1.5 hour and blue line shows a 2-month moving
average of hydrology data. Horizontal lines indicate pump operation dates for nearest deep wells around the mine in Bonnerton.
III-B-15

Table III-B1. Wetland hydroperiods during the 2021 growing season* at Level TROLLS in 12
study creeks. (ml=manual well.
Level TROLL
Dates
Number of
consecutive days
Highest percentage
of growing season
Broomfield Swamp
Creek (BSCW)
BSCW1
3/14-4/28, 6/3-6/30, 10/29-11/21
46, 29, 24
18.0
BSCW2
3/14-5/17, 5/26-7/4, 7/19-11/24
65, 40, 129
50.4
South Creek
Tributary SCUT1
(SCUT1 W )
SCUTW1
3/14-5/12, 5/30-7/13, 7/19-11/24
60, 45, 129
50.4
SCUTW2
3/14-5/19, 5/30-7/5, 7/19-11/24
67, 37, 129
50.4
Jacks Creek (JW)
JW1 (m)
3/14-5/16, 5/26-7/17, 7/28-9/5, 10/29-11/24
64, 53, 41, 27
25.0
JW2A
3/14-5/16, 5/26-7/17, 7/28-9/5, 10/29-11/24
64, 53, 41, 27
25.0
JW2B
3/14-5/16, 5/26-7/17, 7/28-9/5, 10/29-11/24
64, 53, 41, 27
25.0
JW3
3/14-5/7, 5/26-7/17, 7/19-9/12, 9/18-11/24
55, 53, 57, 68
26.6
JW4 (m)
3/14-11/24
256
100.0
JW5A
3/14-11/24
256
100.0
JWSB
3/14-11/24
256
100.0
JW6 (m)
3/14-11/24
256
100.0
JW7A
3/14-4/29, 6/2-6/17
47, 16,
18.4
JW7B
3/14-5/16, 5/26-7/6, 7/27-8/14, 9/18-10/3, 10/7-10/22, 10/29-11/24
64, 42, 19, 16, 16, 27
25.0
JW8 (m)
3/14-5/16, 5/26-7/6, 7/27-8/14, 9/18-10/3, 10/7-10/22, 10/29-11/24
64, 42, 19, 16, 16, 27
25.0
JW9A
3/14-11/24
256
100.0
JW9B
3/14-11/24
256
100.0
JW10 (m)
3/14-11/24
256
100.0
Jacobs Creek (JCBW)
JCBW1A
3/14-5/7, 6/3-7/2
55, 30
21.5
JCBW1B
3/14-5/156/3-7/11
63, 39
24.6
Drinkwater Creek
(DW W )
DWW1A
3/14-5/2, 6/3-7/3
50, 31,
19.5
DWW1B
3/14-5/19, 5/30-7/24, 8/2-9/12, 11/7-11/24
67, 56, 42, 18
26.2
DWW1C
3/14-4/16
34
13.3
Tooley Creek (TW)
TW1
3/14-5/15, 5/30-7/14, 7/27-9/12, 9/18-10/5, 10/7-11/24
63, 46, 48, 18, 21
24.6
TW2 (m)
3/14-11/24
256
100.0
TW3
3/14-11/24
256
100.0
TW4
3/14-5/20, 5/26-7/14, 7/20-11/24
68, 50, 128
50.0
TW5 (m)
3/14-5/2, 5/6-5/19, 5/30-7/5, 7/20-11/24
50, 14, 37, 128
50.0
TW6
3/15-4/22, 5/30-7/30, 7/22-8/13, 9/16-10/3, 10/6-10/20, 10/29-11/17
39, 32, 23, 18, 15, 20
15.2
Long Creek (LOCW)
LOCW1B
3/14-9/16, 9/21-11/24
187, 65
73.0
LOCW2B
3/14-5/9, 6/2-7/5, 8/3-8/19, 8/22-9/6, 10/29-11/17
57, 34, 17, 18, 20
22.3
Huddles Main (HMW)
HMW1 (m)
3/14-11/24
256
100.0
HMW2
3/14-11/24
256
100.0
HMW3 (m)
3/14-11/24
256
100.0
HMW4 (m)
3/14-11/24
256
100.0
HM W5
3/14-11/24
256
100.0
HMW6
3/14-11/24
256
100.0
HMW7 (m)
3/14-11/24
256
100.0
HMW8
3/14-11/24
256
100.0
HMW9
3/14-11/24
256
100.0
HMW10
3/14-11/24
256
100.0
HMW11 (m)
3/14-11/24
256
100.0
HMW 12
3/14-11/24
256
100.0
III-B-16

Table III-B1 (concluded).
Level TROLL
Dates
Number of
consecutive days
Highest percentage
of growing season
Huddles West (HWW)
HWVV2
3/14-11/24
256
100.0
HVVVV3 (m)
3/14-11/24
256
100.0
HWW4
3/14-11/24
256
100.0
HWW5 (m)
3/14-11/24
256
100.0
HWW6 (m)
3/14-11/24
256
100.0
HVVVV7
3/14-11/24
256
100.0
HVVVV8
3/14-11/24
256
100.0
HWW9 (m)
3/14-11/24
256
100.0
Porter Creek (PCW)
PCW1
3/14-4/12
30
11.7
PCW2
3/14-4/16
34
13.3
PCW3
3/14-4/13
31
12.1
PCW4
3/14-4/16
34
13.3
PCWS
3/14-4/22
40
15.6
PCW6
3/14-4/17
35
13.7
PCW9A
3/14-11/24
256
100.0
PCW9B
3/14-11/24
256
100.0
PCW9C
3/14-4/30, 5/30-7/4, 7/27-8/31, 10/7-10/24, 10/26-11/24
48, 36, 36, 18,
30
18.8
Durham Creek
Tributary DCUT11
(DC11 W)
DC11W1A
no wetland hydroperiod
3
1.2
DC11 W1 B
3/14-4/21
39
15.2
DC11W2A
no wetland hydroperiod
11
4.3
DC11W2B
3/14-4/17
35
13.6
DC11W2C
3/16-4/8
24
9.4
DC11W3A
3/14-7/16, 7/19-11/24
125, 129
50.4
DC11W3B
3/14-11/24
256
100.0
DC11W3C
3/14-5/23, 5/28-7/15, 7/19-11/24
71, 49, 129
50.4
Durham Creek
Tributary DCUT19
(DC19W)
DC19W1A
3/14-4/29
47
18.4
DC19W1B
3/14-4/29
47
18.4
DC19W2A
3/14-4/29
47
18.4
DC19W2B
3/14-4/30
48
18.8
DC19W3A
3/14-7/14, 7/27-8/13, 9/20-10/3, 10/7-10/21, 10/23-11/19
123, 18, 14, 15,
28
48.0
DC19W3B
3/14-11/24
256
100.0
Duck Creek (DKCW)
DKCW1B
3/14-4/27, 6/4-7/13, 7/27-8/26
45, 40, 31
17.6
DKCW2A
3/14-5/1, 6/4-7/14, 7/27-8/30
49, 41, 35
19.1
DKCW2B
3/14-5/5, 6/4-7/15, 7/27-9/2
53, 42, 38
20.7
DKCW3A
3/14-4/29, 6/4-6/17, 7/27-8/13
47, 14, 18
18.4
DKCW3B
3/14-5/8, 7/27-8/28
56, 33
21.9
DKCW4A
3/14-5/23, 6/3-9/4
71, 94
36.7
DKCW4B
3/14-5/28, 5/30-9/11
76, 105
41.0
DKCW4C
3/14-5/23, 5/30-9/4
71, 98
38.3
*To properly compare Alt E monitoring hydroperiods to Mod Alt L, the former growing season of 256 days (14 March - 24 November)
was used with agency approval.
III-B-17

Table III-B2. Longest wetland hydroperiod from 2021 compared to average, pre-,
post-, and all years of data for impacts creeks, and for all years for control creeks.
Rainfall (inches)
Impact Creek
Level Troll
Longest Hydroperiod
(% of Growing Season)
Average
Pre
Average
Post
Average
All Years*
2021
Average
Pre
Average Average
Post All Years*
2021
56.16
NA
56.16
49.3
Broomfield Swamp Creek (BSCW)
BSCVVI
BSCW2
21.0
67.8
NA
NA
21.0
67.8
18.0
50.4
49.26
55.17
51.7
51.73
Jacks Creek (JW)
JVVI (m)
JVV2A
JW2B
JW3
JW4 (m)
JW5A
JW513
JVVG (m)
JVV7A
JVV7B
JVVB (m)
JVV9A
JVV9B
JVV10 (m)
35.0
35.1
43.0
34.9
59.0
50.5
100.0
70.4
23.9
39.0
64.9
87.1
91.0
86.6
31.9
38.1
41.8
32.7
53.7
43.0
86.8
92.5
18.5
36.0
66.7
100.0
93.4
100.0
33.7
36.3
42.2
34.0
56.8
47.4
84.0
79.5
21.7
37.1
65.6
92.4
92.5
92.1
25.0
25.0
25.0
26.6
100.0
100.0
100.0
100.0
18.4
25.0
25.0
100.0
100.0
100.0
46.89
54.89
52.7
51.73
Jacobs Creek (JCBW)
JCBVVIA
JCBW1B
2.5
2.2
5.4
5.6
4.6
4.7
21.5
24.6
49.53
53.41
52.7
51.73
Drinkwater Creek (DWW)
DVVWIA
DVWV1B
DVVW1C
30.7
42.4
11.5
22.4
52.3
14.0
23.9
50.5
13.5
19.5
26.2
13.3
50.03
52.69
51.51
47.51
Tooley Creek (NM)
T/V1
TVV2 (m)
TN3
T V4
TW5 (m)
TVV6
25.3
39.6
78.6
58.3
17.9
13.9
16.2
66.2
68.0
61.4
46.6
12.9
18.8
58.6
71.1
60.5
38.4
13.2
24.6
100.0
100.0
50.0
50.0
15.2
47.82
50.82
49.62
47.62
Huddles Main (HMW)
HMW1 (m)
HMVV2
HMVV3 (m)
HMVV4 (m)
HMW5
HMV
HMVV7 (m)
HMVVB
HMVV9
HMW10
HMW11 (m)
HMW12
0 0 0 0 0 0 0 0 0 0 0 0
d d d d d d d d d d d d
0 0 0 0 0 0 0 0 0 0 0 0
m� ti m Wm N W ti N W m Nm O N
m m N N ti o 0 0 0 th N W
8i g m m m
o m a ti N O N N N 1
N
47.82
50.82
49.62
47.62
Huddles West (HWW)
HVWV2
HVW V3 (m)
HMN V4
HMWW (m)
HMWVG (m)
HMNN7
HMWVB
HMWV9 (m)
55.6
67.1
78.3
84.7
83.8
90.0
81.2
35.3
72.1
79.6
81.3
91.0
90.3
92.5
71.5
53.3
67.3
75.9
80.4
89.2
88.4
91.8
74.4
48.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
49.15
58.89
53.05
51.04
Porter Creek (PCW)
PCVVI
PCVV2
PCVV3
PCVV4
PCW5
PCVVG
PCVV9A
PCVV9B
PCVV9C
14.7
17.5
16.8
15.7
15.3
17.3
48.4
100.0
31.7
13.9
15.6
14.8
16.1
16.8
16.3
67.1
100.0
44.3
14.0
16.7
16.0
15.6
15.6
17.0
58.6
100.0
38.6
11.7
13.3
12.1
13.3
15.6
13.7
100.0
100.0
18.8
51.62
62.13
56.29
51.04
Durham Creek Tributary DCUT11 (DC11W)
DCIIVVIA
DCIIVVIB
DC11MV2A
DC11VV2B
DC11VV2C
DC11 M V3A
DC11VV3B
DC11VV3C
8.0
30.1
9.7
25.0
12.5
78.1
100.0
75.3
1.1
18.5
4.2
14.3
9.6
55.7
100.0
55.9
4.9
24.9
7.2
20.2
11.2
68.1
100.0
66.7
1.2
15.2
4.3
13.6
9.4
50.4
100.0
50.4
III-B-18

Table III-B2 (concluded).
Rainfall (inches)
Control Creek
Level Troll
Longest Hydroperiod
(% of Growing Season)
Average All Years*
2021
Average All Years*
2021
50.49
48.72
Durham Creek Tributary DCUT19 (D19W)
D 19-1 A
D19-1 B
D 19-2A
D 19-2 B
D 19-3A
D19-3B
21.5
21.2
21.6
22.3
51.8
93.3
18.4
18.4
18.4
18.8
48.0
100.0
49.16
48.72
Duck Creek (DKCW)
DKCW1B
DKCW2A
DKCW2B
DKCW3A
DKCW3B
DKCW4A
DKCW4B
DKCW4C
23.4
37.6
33.9
32.7
39.1
46.6
60.5
49.0
17.6
19.1
20.7
18.4
21.9
36.7
41.0
38.3
56.16
49.3
South Creek Tributary SCUT1 (SCUTIW)
SCU1W1
SCUTW2
50.3
50.8
50.4
50.4
51.85
47.51
Long Creek (LOCW)
LOCW1B
LOCW2B
72.2
36.2
73.0
22.3
* includes 2021 data
III-B-19

Table III-B3. Operation dates for the pumps within deep water wells in proximity to the Level TROLLs
in Porter Creek and DCUT11.
Deep Well Level TROLL Site
Date Pump On
Date Pump Off
DW1108*
DW1109
DW1110
DW1112
DW1113
DW1114
DW1121
DW1122
Porter Creek
PCW4, 5, 6
PCW4, 5, 6
PCW4, 5, 6
PCW9A, 9B, 9C
PCW9A, 9B, 9C
PCW9A, 9B, 9C
DCUT11
DC11W1A, 1B, 2A, 2B, 2C
DC11W1A, 1B, 2A, 2B, 2C
October 2017/November
2019
February 2017
February 2017
April 2018
October 2017
December 2017
April 2019
September 2019
August 2018/August
2020
May 2018
October 2018
March 2021
December 2019
February 2019
March 2020
March 2021
*DW1108 operated for two periods October 2017 — August 2018 and November 2019 — August 2020 that are included in
this evaluation
III-B-20