20080868 Ver 2_Section II A Q1 Flow 2021 PCS Creeks Report_20220605

II. CORPS PERMIT SPECIAL CONDITION S - SIX QUESTIONS
A. Question 1-Has mining altered the amount or timing of water flows within the
creeks?
1.0 History of Flow Monitoring
Monitoring since 1998 showed that the upper systems (unidirectional stream
portion) of the study creeks are driven primarily by local precipitation and baseflow. The lower
estuarine portions of the systems (bidirectional creek portion) are wind -tide driven and subject to
region -wide precipitation and Tar River discharge.
Unidirectional flow data were collected via weirs in Jacks Creek, Tooley Creek,
and Huddles Cut in various combinations of years for each creek by Skaggs et al. from 1999-
2010. Permitted mine continuation either removed, or otherwise made ineffective, the previous
weir locations and installation of new weirs further downstream was not possible in areas of
bidirectional flow.
To overcome the challenge of bidirectional flow, yet continue to monitor watershed
contribution of flow in the study creeks, Skaggs proposed a water balance approach to measure
the flows from the unidirectional portion of a watershed to the bidirectional. The proposed
example used the long-term average of annual flow generated from their model used in the weir
study and the 2003 Jacks Creek data previously collected and applied that information to the
entire 228-acre watershed of the creek. The Skaggs water balance proposal, Determining Flows
in Small Watersheds and Bays on South Creek, was included as Appendix C of the Draft Plan of
Study for Potential Effects of Headwater Wetland Reduction on Downstream Aquatic Functions
and Utilization of Tributaries to South Creek, Durham Creek, and Porter Creek (CZR and Skaggs
2009) which was provided to regulatory agencies for review in December 2009.
The Jacks Creek water balance example estimated that the unidirectional portion
of the upstream watershed delivered approximately 1.2 percent (with long term average annual
outflow; 2009 Skaggs proposal Table 4) to 2.9 percent (with the highest annual watershed outflow
year in 53 years; 2009 Skaggs proposal Table 8) of the total flow into and out of the downstream
bidirectional portion of the system. This percentage had not been previously quantified and was
lower than many may have predicted or expected. In a phone conversation between CZR and
Dr. Skaggs on 6 April 2020 about these percentages, important points in the Jacks Creek water
balance example were noted:
• The long-term simulation for Jacks Creek watershed showed 2003 as the
year with the largest outflow in 53 years and was used for the water balance
example for that reason.
• Estimated total tidal fluctuation to and from the bidirectional bay in the year
2003 was 34 times greater than estimated watershed outflow/runoff to the
bay.
• Estimated total tidal fluctuation to and from the bidirectional bay with use
of the annual long-term average was 80.9 times greater than estimated
watershed outflow/runoff to the bay.
• The estimated percent annual contribution of the unidirectional watershed
to only the outflow to the bidirectional bay is double the contribution to the
I I -A-1

total inflow plus outflow to the bay (tidal fluctuation) (e.g., 2.4 percent of
long-term annual average or 5.8 percent of the highest outflow year in 53
years).
After review of the draft plan of study and Skaggs' 2009 proposal and more
discussion among/between PCS and agencies, the proposal was not implemented in the creeks
study, and the final PCS creeks plan of study (CZR 2011) did not contain Skaggs' 2009 Appendix
C. With the restrictions to continued use of weirs and the understanding of the low percent
contribution of upstream flow to the primary nursery areas (the bidirectional bays in Skaggs'
proposal), the Science Panel understood and agreed that no additional weirs could be added,
and flow no longer needed to be monitored.
The very shallow and intermittent nature of the upper systems of these creeks did
not allow the use of traditional stream gauges. When the 2011 creeks study plan was
implemented, as a potential solution to this issue, PCS elected to try a new product in beta
development, a low flow gauge, to monitor the unidirectional portions of the systems. Low flow
units were installed in the upper portions of two creeks in 2011 (Duck Creek and Porter Creek).
Shortly afterwards, product development was stalled, and delivery and deployment of additional
units were uncertain. Additionally, the accuracy of the data appeared questionable and the
installed units were removed in 2013. Like the earlier flow documented by weirs in the
unidirectional reaches of Jacks Creek, Tooley Creek, and Huddles Cut, flow events recorded by
the low -flow gauges in Duck Creek and Porter Creek appeared to be related to precipitation and
baseflow.
Beginning in March 2012, during visits to other equipment located at or near the
low -flow beta gauge locations and other intended gauge locations, biologists made qualitative
observations of flow (none, low, medium, or high) and noted water depths. For the creeks added
in 2011 and 2012, there was no earlier flow data for comparison, but flow observation information
continued to be collected in lieu of low -flow gauges and observations will be compared pre- and
post -Mod Alt L where possible. Pre- and post -Mod Alt L comparisons to the weir records of flow
are not possible because the locations of most of the weirs were well upstream of the current flow
observation locations. Following the August 2015 Science Panel meeting, flow observations
began in Huddles Cut at the three salinity monitoring locations (HS1, HS2, and HS3); however,
since all three of these locations are subject to frequent bi-directional flow (particularly HS3), flow
direction is also noted. As the salinity monitors are downloaded every two weeks, the opportunity
for flow observation at the Huddles Cut locations is doubled compared to other creek flow
locations, which are visited once a month when hydrology monitors are downloaded. Videos of
flow are also taken throughout the year, which are available upon request from CZR.
Flow presence and water depth are recorded during each site visit but wind can
affect these data; therefore, these flow observations should not be construed as evidence of flow
derived only from the basin upstream of the observation point. The observation data have not
been scrutinized to determine if a wind event may have been solely responsible for water flow
into the basin (and perhaps counted as flow) which then, upon a change in wind direction or
speed, had begun to flow downslope out of the system and was then observed as flow (seiche-
like effect).
2.0 Requests from the 2019 Science Panel Meeting
At the August 2019 Science Panel meeting, new questions arose about the
Skaggs' aforementioned 1 to 3 percent upstream contribution conclusion; therefore, that 2009
I I -A-2

Appendix C from the draft creeks study plan was included in the 2019 creeks report for further
context (Supplement 1, 2019). For additional context, Supplement 1 also contained graphics
which depicted the past and current monitoring locations (including Skaggs' weirs) in Jacks and
Tooley Creeks and in Huddles Cut on 1999, 2001, and 2019 aerial photos. Upstream and
downstream photographs taken at the upper and lower limits of the intermittent jurisdictional
streams as determined in 2001 for Huddles Cut and Jacks Creek were also included in
Supplement 1 of the 2019 report; these photographs showed the character of the impacted
streams at those locations. Tooley Creek 2001 stream determination photographs were either
not well labeled or not available, so only a few selected photos from Tooley Creek 2000 vegetation
photos in proximity to the upper and lower stream limits on the east prong were included. Report
appendices always contain representative photographs of conditions at the vegetation survey
plots, but only a few of these photographs are in the vicinity of the 2001 stream determination
photographs.
As shown on the past and current monitoring location graphic for Huddles Cut, the
lower limits of the jurisdictional intermittent streams in Huddles Cut did not connect directly to
perennial streams but to wetlands mapped as bottomland hardwood forest with no discernible
stream channel. Although coastal plain small stream swamp forest (blackwater) was a more
appropriate community description for this part of the Huddles Cut system, it had been decided
that the same communities used in the 1996 NEPA permit documents would remain for continuity.
In contrast, Tooley Creek and Jacks Creek 2001 stream determinations contained no wetland
breaks between jurisdictional stream types.
a. 2021 Flow Videos, Observations, and Summary
Also, in response to comments raised at the August 2019 Science Panel
meeting, for the 2020 and onward reports, flow videos were used to determine the events which
captured inflow (upstream flow direction vs downstream outflow from the watershed). As
bidirectional flow is more likely at the flow observation locations in Huddles Cut, the previous
reports' flow observation tables for Huddles Cut had already included wind direction and
estimated wind speed (Appendix B, Table B-2 on the flash drive). Because flow can be difficult
to see, it is also often difficult to detect in the videos and the data form was modified in May 2020
to record flow direction to confirm sites with bidirectional flow.
The original intent of observed flow documentation was only to provide
documentation about flow during the time of visits to download nearby equipment, not for
extensive comparative evaluation. For 2021, of the 18 observation sites, flow was not observed
at one site, Jacobs Creek. Most observations of monthly flow occurred in the months of January
through April (nine to 15 sites with flow per month during this period) and the least number of
sites/month were documented in May, June, July, and September through December (one to
three sites with flow per month). (Appendix B, Tables B-1 and B-2 only on flash drive). A summary
of 2021 flow observations at 18 locations in 10 creeks is presented below:
II-A-3

Creek (Flow Station)
# of
visits
Minimum #
of inflow
events
# of visits
with flow
Jacks (JW2B/F)
13
0
1
Jacks (JW7B/F)
13
0
6
Jacobs (JCBW1B/F)
13
0
0
Drinkwater (DWW1 B/F)
13
0
3
Tooley (TW2/F)
13
0
4
Tooley (TW5/F)
13
0
4
Long (LOCW1B/F)
13
0
7
Long (LOCW2B/F)
13
0
5
Porter (PCWS/F)
13
0
3
DCUT11 (DC11W2B/F)
13
0
2
DCUT19 (DC19W2A/F)
13
0
4
Duck (DKCW1B/F)
13
0
5
Duck (DKCW2B/F)
13
0
5
Duck (DKCW3B/F)
13
0
4
Duck (DKCW4B/F)
13
0
8
Huddles Cut (HS1)
20
2
12
Huddles Cut (HS2)
20
0
9
Huddles Cut (HS3)
23
12
23
For summary comparison, since the 2016 report, the number of flow events
was converted into percentages of visits for pre- and post -Mod Alt L years at Jacks Creek, Jacobs
Creek, Drinkwater Creek, Porter Creek, and DCUT11 along with observations at four control
creeks and included in the flow appendices. Since the 2018 report, the summary comparison
table has been included in this Q1 section as Table II -Al; however, comparisons of percentages
from year to year should be considered cautiously, as both the number of visits and rainfall
amounts were highly variable.
Flow observations during 2021 from the 18 sites (impact and control
creeks) are documented in Appendix B and Table II -Al , and notes on flow at each impact creek
are also characterized below.
i. Jacks Creek — Flow events were within the range of previous post -Mod Alt L
monitoring years and recorded during one visit at JW2 (upstream site) and six visits
at JW7 (downstream site), during January through April, late June, and August.
ii. Jacobs Creek — No flow events have ever been observed at this site since it was
established, which includes two pre -Mod Alt L monitoring years and seven post -
Mod Alt L years.
iii. Drinkwater Creek — Flow events were within the range of past post -Mod Alt L years
and flow was documented during January, February, and August. Although water
was often present at this site, it was disconnected from lower portions of the
channel during drier conditions.
iv. Tooley Creek — Four flow events were documented at both monitoring sites in
2021, which was the same as 2020. No upstream (inflow) flow events were noted
this year at either site.
v. Huddles Cut — Flow events were documented in Huddles Cut during all months of
I I -A-4

2021; however, 2021 had the lowest number of events for HS1 and HS2 since
2016 (all Huddles Cut flow data are from post -Mod Alt L years). Huddles Cut is
the study creek with the most documented flow events and most documented
upstream (inflow) events, primarily because the sites are located much lower in
the drain compared to other creeks and therefore more influenced by wind.
vi. Porter Creek — Three flow events were documented in 2021 (January, February,
and April) which was the same as three of the six post -Mod Alt L monitoring years.
vii. DCUT11 —Two flow events were documented (January and February), which was
the same as the past two years of post -Mod Alt L monitoring years.
b. Unobserved flow
A request to revisit the flow observations and antecedent rainfall to tease
out potential unobserved flow events was also proposed at the August 2019 meeting. In fall of
2019, CZR attempted to reformat the flow observations in conjunction with antecedent rainfall
under several scenarios for analysis. It quickly became evident that it would remain unknown
what flow may have occurred before, after, or between the observation, and what contribution
antecedent rainfall actually had on any flow (observed or unobserved). At the Science Panel
meeting in August of 2020, suggestions for other ways to evaluate flow were offered and
discussed; therefore, an attempt to evaluate flow using instruments already in the field could
potentially add greater understanding of flow during times outside of biologist observations.
Water level data recorded from Level TROLLs in the vicinity of flow
observation locations were used to estimate periods of flow in conjunction with observed flow
events. The most upstream flow observation locations from four impact creeks (Jacks Creek well
JW2B, Drinkwater Creek well DWW1 B, Porter Creek well PCWS, and DCUT11 well DC11 W2B)
were used to investigate potential unobserved flow events. These locations have wells nearby
and are least likely to be affected by wind inflow which causes a bi-directional pattern of flow.
Every four weeks (-13 times a year), flow stations are visited to observe flow in conjunction with
downloading well data. The lowest well depth with observed flow was used to establish the lowest
water level depth at which the creek flows at that location. With that depth, well data are sorted
using noon reads for the whole year from highest read to the established lowest depth of flow.
Using noon reads from the well data creates a daily water depth and the majority of flow station
visits occur three hours before or after the noon read, with the Level TROLL water depth changing
less than 0.25 inch outside of heavy rainfall events. The number of days with flow for each year
were compiled into Table II-A2 and these data can be compared with an average of the pre -
versus post -Mod Alt L years to determine potential changes in flow. For certain years where no
flow was observed by biologists, an average of the lowest well water depths with observed flow
from the most appropriate years was used to find flow days. Rainfall totals for the years were
included to show whether an increase or decrease in flow could be attributed to rain. This
replicable process is conservative in many ways but reviews flow at a few upstream creeks and
provides insight for pre- and post -Mod Alt L differences.
i. Jacks Creek Pre- and Post -Mod Alt L
Jacks Creek- JW2B (pre -Mod Alt L 2012 to 2014): Throughout the
first two years of monitoring flow, no events were documented by biologists. These years had an
unusually low number of days with flow which could have been a product of no flow observed
and/or low rainfall for 2013. During the final year of pre -Mod Alt L data collection (2014), there
I I-A-5

were 132 days with flow which is the third highest year of flow days. Pre -Mod Alt L averages: 58
days with flow and 50.03 inches of rainfall.
Jacks Creek- JW2B (post -Mod Alt L 2015 to 2021): There was no
flow observed during the first four years of post -impact monitoring, so the water depth for
unobserved flow was estimated using depths from 2014, 2019, and 2020 (years with documented
flow events closest to those years with no observations). The average number of days with flow
is more than twice the pre -Mod Alt L number with an average of 5.14 inches more rainfall. Post -
Mod Alt L averages: 119 days with flow and 55.17 inches of rainfall.
ii. Drinkwater Creek Pre- and Post -Mod Alt L
Drinkwater Creek- DWW1 B (pre -Mod Alt L 2012): There is only one
year of pre -impact data which limits the pre- data set and confidence of comparison. Flow was
observed in 2012; however, the average number of days with flow was lower than post -Mod Alt L
years. Pre -Mod Alt L averages: 71 days with flow and 55.62 inches of rainfall.
Drinkwater Creek- DWW1 B (post -Mod Alt L 2013 to 2021): The first
year of post -Mod Alt L flow monitoring only had one flow event to establish a lowest water depth
at the time of observed flow. That lack of flow data coupled with the lowest rainfall total of the 10
years made 2013 the lowest number of days with flow (5) for the creeks in Table II-A2. The post -
Mod Alt L years averaged 57 more days than the pre -Mod Alt L year with 2.21 inches less average
rainfall. Post -Mod Alt L averages: 128 days with flow and 53.41 inches of rainfall.
Porter Creek Pre- and Post -Mod Alt L
Porter Creek- PCWS (pre -Mod Alt L 2012 to 2015): The four years
of pre -Mod Alt L data ranged from 98 (2013) to 208 (2015) days with flow. The only issue with
the well data is that from January 2012 to August 2014 the Ecotone well was the instrument
closest to the flow station. While being the best data logger at the time, the Ecotone was not as
accurate at measuring water levels as the current Level TROLL well. The control for Porter Creek,
Duck Creek, had proportional amounts of rainfall and number of days with flow to Porter. The
number of days with flow at Duck Creek ranged from 75 (2013) to 174 (2015) at DKCW1B with
an average 47.48 inches of rainfall. Pre -Mod Alt L averages: 141 days with flow and 51.34 inches
of rainfall.
Porter Creek- PCWS (post -Mod Alt L 2016 to 2021): The number of
days with flow for the six years of post -Mod Alt L ranged from 37 (2020) to 95 (2021). The 77
fewer days in the average pre- vs post -Mod Alt L number of days with flow shows a reduction in
flow at the upper end of Porter Creek. The control, Duck Creek, ranged from 95 (2019) to 279
(2018) days with flow for the same years as post -Mod Alt L at Porter Creek. Duck Creek showed
an increase in days with flow whereas Porter decreased. Post Mod Alt L averages: 63 days with
flow and 58.89 inches of rainfall.
iv. DCUT11 Creek Pre- and Post -Mod Alt L
DCUT11-DC11W2B (pre -Mod Alt L 2013 to 2017): The five years
of pre -Mod Alt L data ranged from 11 (2013) to 152 (2016) days with flow and an average of 51.62
inches of rainfall. The control for DCUT11, DCUT19, had similar totals of rainfall and number of
days with flow to DCUT11. The number of days with flow at DCUT19 ranged from 62 (2017) to
194 (2015) at DC19W2A with an average 49.74 inches of rainfall. Pre -Mod Alt L averages: 108
days with flow and 51.62 inches of rainfall.
DCUT11-DC11 W2B (post -Mod Alt L 2018 to 2021): The number of
I I -A-6

days with flow for the four years of post -Mod Alt L ranged from 43 (2019) to 178 (2018). The 19
fewer days in the average pre- vs post -Mod Alt L number of days with flow shows a reduction in
flow at DCUT11. The control, DCUT19, ranged from 33 (2020) to 106 (2019) days with flow using
the same years as post -Mod Alt L for DCUT11. Both DCUT11 and DCUT19 had a similar
decrease in flow events (an average of 4.6 flow events/year in the pre- compared to 2.5 [DCUT11]
and 3.0 [DCUT19] flow events in the post -Mod Alt L), and both had decreases in the estimated
number of days with flow in the post -Mod Alt L. Post -Mod Alt L averages: 89 days with flow and
62.13 inches of rainfall.
Answer: Jacks, Jacobs, Drinkwater, Porter creek, and DCUT11 are the only creeks with
pre- and post -Mod Alt L flow observation data, and no flow has ever been observed at the
Jacobs Creek site. The number of observed flow events per year for these creeks is
relatively similar between pre- and post -Mod Alt L years; however, the estimated number
of days with flow is higher in the post -Mod Alt L for Jacks (three years of pre- and seven
years of post -Mod Alt L data) and Drinkwater [one year of pre- (2012) and nine years of
post -Mod Alt L data] creeks. Average annual rainfall is higher in all post -Mod Alt L years
except for Drinkwater Creek, yet DCUT11 and Porter Creek show a decrease in the number
of estimated flow days. Both DCUT11 and its control creek, DCUT19, had the same average
number of flow events per year in pre -Mod Alt L (4.6/year) while post -Mod Alt L (2.5-
3.0/year) data had a decrease in flow events. The estimated number of flow days at two
sites in Duck Creek, the control creek for Porter Creek, increased in the post- period, using
the same evaluation period for Porter. The estimated number of flow days in Porter Creek
decreased about 76 percent in the post -Mod Alt L years despite the approximate 14 percent
increase in rainfall. Although the estimated number of flow days has decreased in the
post -Mod Alt L years for Porter, the longest wetland hydroperiod for the well closest to the
flow site (PCW5) has remained similar; 15.3 percent in the pre- (2007-2015) and 16.8 percent
in the post -Mod Alt L years (2016-2021). Reasons for the reduced flow events and wetland
hydroperiods at DCUT11, DCUT19, and Porter Creek and increased flow events at Jacks
and Drinkwater creeks are unclear at this time and additional data may help to understand
and explain. Flow data results are to be used cautiously, as the data are qualitative and
were not initially intended to be used for quantitative pre- versus post- comparisons.
I I-A-7

Table II -Al. Observed flow events conducted in conjuction with hydrology and salinity monitoring 2012-2021. Post Mod -Alt L years are highlighted yellow. In a portion of 2014, monitoring efforts were reduced and no flow
stations were visited in September and October. No flow observations were conducted in November 2018.
Jacks Creek Jacobs Creek (JCBW1)
Year
Flow
events
# of visits
% of visits
w/ flow
Rainfall
(in)
JW2
JW7
JW2
JW7
JW2
JW7
2012
17
17
0.0
17.6
55.6
2013
14
14
0.0
42.9
41.6
2014
10
10
10.0
50.0
52.9
2015
LO��I,-LOCOCO
0 c, O 0 CO N
13 13
0.0 38.5
56.8
2016
9 13
0.0 30.8
52.7
2017
13 13
0.0 53.8
46.6
2018
10 10
0.0 70.0
40.5
2019
13 13
23.1 38.5
54.9
2020
13 13
15.4 46.2
67.0
2021
13 13
7.7 46.2
51.7
e Access to JW2 flow station was limited due to the
progression of the mine and MSHA requirements.
Tooley Creek
Year
Flow
events
# of visits
% of visits
w/ flow
Rainfall
(in)
TW2
TW5
TW2
TW5
TW2
TW5
2012
0
3
17
17
0
17.6
53.4
2013
0
0
14
14
0
0
46.6
2014
0
0
10
10
0
0
45.6
2015
0
0
13
13
0
0
59.6
2016
0
0
13
13
0
0
57.6
2017
2
1
13
13
15.4
7.7
44.5
2018
3
5
10
11
30.0
45.5
45.5
2019
2
3
13
13
15.4
23.1
52.5
2020
4
4
13
13
30.8
30.8
66.9
2021
4
4
13
13
30.8
30.8
47.5
Porter Creek (PCW5)
Year
Flow
events
# of visits
% of visits
w /flow
Rainfall
(in)
2012
6
22
27.3
52.1
2013
5
14
35.7
43.4
2014
7
10
70.0
50.9
2015
8
13
61.5
59.0
2016
2
13
15.4
55.9
2017
3
13
23.1
48.9
2018
4
12
33.3
67.6
2019
6
13
46.2
56.7
2020
3
13
23.1
73.2
2021
3
13
23.1
51.0
DCUT11 (DC11W2B)
Year
Flow
events
# of visits*
% of visits
w/ flow
Rainfall
(in)
2013
2
14
14.3
43.4
2014
3
10
30.0
50.9
2015
7
13
53.8
59.0
2016
6
13
46.2
55.9
2017
5
13
38.5
48.9
2018
4
11
36.4
67.6
2019
2
13
15.4
56.7
2020
2
13
15.4
73.2
2021
2
13
15.4
51.0
Year
Flow
events
# of
visits
of
visits w/
flow
Rainfall
(in)
2012
2013
0
0
17
14
0
0
55.6
41.6
2014
2015
2016
2017
2018
2019
2020
2021
0
0
0
0
0
0
0
0
10
13
13
13
11
13
13
13
0
0
0
0
0
0
0
0
52.9
56.8
52.7
46.6
46.6
54.9
67.0
51.7
Drinkwater Creek (DWW1B)
Year
Flow
events
# of
visits
of
visits w/
flow
2012
4
17
23.5
Rainfall
(in)
55.6
2013
2014
2015
2016
2017
2018
2019
2020
2021
1
0
2
2
3
5
5
3
3
14
10
13
13
13
11
13
13
13
7.1
0.0
15.4
15.4
23.1
45.5
38.5
23.1
23.1
41.6
52.9
56.8
52.7
46.6
47.6
54.9
67.0
51.7
Huddles Cut
Year
Flow events
# of visits
of
visits w/
flow
Rainfall
(in)
HS1
HS2
HS3
HS1
HS2
HS3
HS1
HS2
HS3
2015'
3
1
8
9
9
9
33.3
11.1
88.9
57.1
2016
9
7
14
19
18
17
47.4
38.9
82.4
56.5
2017
16
13
18
23
23
22
69.6
56.5
81.8
46.5
2018
16
13
18
23
23
22
69.6
56.5
81.8
47.5
2019
15
15
23
26
26
26
57.7
57.7
88.5
41.4
2020`
16
11
22
23
22
22
69.6
50.0
100
66.5
2021
12
9
23
20
20
23
60.0
45.0
100
47.7
b Flow obervations began in September 2015.
Flow was not documented for two visits at HS1 and three
visits for HS2 and HS3
Long Creek (control)
Year
Flow
events
# of visits
% of visits
w/ flow
Rainfall
(in)
1B
2B
1B
2B
1B
2B
2012
1
2
17
17
5.9
11.8
53.4
2013
2
5
14
14
14.3
35.7
46.6
2014
3
4
10
10
30.0
40.0
45.6
2015
5
5
13
13
38.5
38.5
59.6
2016
5
5
13
13
38.5
38.5
57.6
2017
5
2
13
13
38.5
15.4
44.5
2018
5
9
11
11
45.5
81.8
45.5
2019
6
6
13
13
46.2
46.2
52.5
2020
7
7
13
13
53.8
53.8
66.9
2021
5
5
13
13
38.5
38.5
47.5
Duck Creek (control)
Year
Flow events
# of visits
% of visits w/ flow
Rainfall (in)
1Bd
2Be
3Bd
4Be
1Bd
2Be
3Bd
4Be
1Bd
2Be
3Bd
4Be
2012
3
6
6
11
20
20
20
20
15.0
30.0
30.0
55.0
52.8
2013
4
4
3
6
14
14
14
14
28.6
28.6
21.4
42.9
36.2
2014
3
3
3
3
10
10
10
10
30.0
30.0
30.0
30.0
43.1
2015
7
7
11
11
13
13
13
13
53.8
53.8
84.6
84.6
57.9
2016
6
7
9
11
13
13
13
13
46.2
53.8
69.2
84.6
62.7
2017
7
8
12
13
13
13
13
13
53.8
61.5
92.3
100
45.9
2018
8
7
7
9
10
10
10
10
80.0
70.0
70.0
90.0
46.9
2019
4
4
5
8
13
13
13
13
30.8
30.8
38.5
61.5
39.6
2020
8
8
6
11
13
13
13
13
61.5
61.5
46.2
84.6
54.5
2021
5
5
4
8
13
13
13
13
38.5
38.5
30.8
61.5
48.7
d upstream
e downstream
DCUT19 (control; DC19W2A)
Year
Flow
events
# of visits*
% of visits
w/ flow
Rainfall
(in)
2013
4
14
28.6
40.4
2014
3
10
30.0
53.3
2015
8
13
61.5
56.0
2016
5
13
38.5
55.5
2017
3
13
23.1
44.8
2018
4
11
36.4
52.4
2019
4
13
30.8
40.1
2020
0
13
0.0
65.2
2021
4
13
30.8
48.0
II-A-8

/ 4$
o I
E$G
� (/
e
2 D
§ 7
CIS
§�2
O \
yU\
12_1
E
4
• css 0
7
k�o
0-
ƒ �s
k 0o
\\
/ o
g
/ 2k
a) 0
g
� U Q-
a)
% $ >
2 I a %
k$ as
Zr)
U § •c
% Zr)2 \
5 /
a \ )
4 $ / \
\0a�
I ¥ \
\ / $ .ƒ
• = 5
�wo-
y a 2
$
E a) 0
• U0
2a
�£I2
QCD- §
IWD
ZIt0
I -as \ i
DCUT19
# of Days
with Flow
at
DC19W2A
G
e
/
e
@
55
/
\
@
/
R
/ 2
F a
o re w
40.38
53.34
55.96
4
a
upup=
43.59
CO
w
40.09
\
a
48.03
49.74
9
e
CI
# of Days
with Flow
at
DC11W2B
_
/
/
/
/
/
@
g
@
/
89
_
Saco
= Ca
��w
43.39
7
e
LC)
58.96
55.93
48.90
E
G
CO
56.67
73.21
f
/
e
62.13
Duck Creek
G_©�
4 7 j§
It
§
59
73
207
\
216
/
157
a
S
104
=
2
209
# of Days
with Flow
at
DKCW 1 B
j
r
/
/
/
/
279
+
\
/
/
159
o 2
0 § 2
52.79
±
$
43.08
57.87
62.73
@
$
§
§
39.56
54.47
p
#
47.48
m
§
Porter Creek
# of Days
with Flow
at PCWS
/
m/\
43
4
E
77
37
g
/
G
Porter
Rainfall
Totals
52.06
43.39
7
\
58.96
55.93
48.90
E
§
56.67
73.21
f
e
f
e
m
\
Drinkwater Creek
# of Days
with Flow
at DWW2B
R\\
234
CO
Q
=
o=_/
r
r
=
4
R
_
2
PA2
Rainfall
Totals
@
§
41.60
52.87
r
\
52.70
E
#
E
\
54.86
67.02
51.73
@
§
§
/
Jacks Creek
§m
E §
222
It co
R
34*
/
\
\
®
0
\
/
/
§
2
�c2/
\
41.60
52.87
\
52.70
\
\
54.86
67.02
51.73
50.03
55.17
GI
p
CV
\
2013
2014
r
\
2016
2017
=
\
2019
2020
§
\
Pre -Mod Alt L Average
Post -Mod Alt L Average
" no flow events observed; average well depth of applicable years of observed flow used to estimate flow days
"" only one flow event observed for the year
H- -9