HomeMy WebLinkAbout20080868 Ver 2_Section II A Q1 Flow 2020 PCS Creeks Report_20210701II. 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
2003 year 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
I I -A-1
to only the outflow to the bidirectional bay is double the contribution to the
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
does not allow 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 was 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 are no earlier flow data for comparison, but flow observation
information will continue 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 will not be 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), wind 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 at the flow observation points
throughout the year, which are available upon request from CZR.
Flow presence and water depth are recorded during each site visit but
determination of the primary influences upon observed flow is sometimes difficult due to
proximity to open water or wind effect at many stations. 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).
I I -A-2
2.0 Requests from the 2019 Science Panel Meeting
At the August 2019 Science Panel meeting, new panel members were curious
about the Skaggs' aforementioned 1 to 3 percent upstream contribution conclusion; therefore,
that 2009 Appendix C from the draft creeks study plan was included in the 2019 creeks report
for further context (Supplement 1 for that report). For additional context, especially for the new
panel members, 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 in Supplement 1. 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 subtype was a
better and 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. 2020 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 CD/DVD). 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 in an effort 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 2020, of the 18 observation sites flow was not observed
at two sites, Jacobs and DCUT19. As expected, most observations of monthly flow occurred in
the months of November through May (nine to 14 sites with flow per month during this period)
and the least number of sites/month were documented in July and August (4 site with flow in
each month). Of the 18 sites monitored, 14 had observed flow in December 2020 and 11 had
observed flow in January, February, April, and November. Only five sites had documented flow
in July or August (Huddles — all sites, Duck — 4B, and DCUT11). (Appendix B, Tables B-1 and
B-2 on CD/DVD). A summary of 2020 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
1
2
Jacks (JW7B/F)
13
0
6
Jacobs (JCBW1B/F)
13
0
0
Drinkwater (DWW1 B/F)
13
0
3
Tooley (TW2/F)
13
1
4
Tooley (TW5/F)
13
2
4
Long (LOCW1B/F)
13
0
7
Long (LOCW2B/F)
13
0
7
Porter (PCWS/F)
13
0
3
DCUT11 (DC11W2B/F)
13
0
2
DCUT19 (DC19W2B/F)
13
0
0
Duck (DKCW1B/F)
13
0
8
Duck (DKCW2B/F)
13
0
8
Duck (DKCW3B/F)
13
0
6
Duck (DKCW4B)
13
0
11
Huddles Cut (HS1)
23
2
16
Huddles Cut (HS2)
22
0
11
Huddles Cut (HS3)
22
9
22
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 2020 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.
Jacks Creek — Flow events were within the range of previous post -Mod Alt L
monitoring years and recorded during two visits at JW2 (upstream site) and six
visits at JW7 (downstream site), mostly between November and April. Upstream
flow (inflow) was documented at JW2 on 22 September 2020. Although Skaggs'
study documented bidirectional flow in this system, inflow is atypical at that site
and dependent on wind.
ii. Jacobs Creek — No flow events have ever been observed at this site since
established, which includes two pre -Mod Alt L monitoring years and seven post -
Mod Alt L years.
Drinkwater Creek — Flow events were within the range of past post- Mod Alt L
years and flow was documented during April, May, and November. Although
water was often present at this site, it was disconnected from lower portions of
I I -A-4
the channel during drier conditions.
iv. Tooley Creek — Four flow events were documented at both monitoring sites in
2020, which is one more than the previous high at TW2 in 2018 and one less
than the previous high at TW5 in 2018. Upstream (inflow) flow events were noted
at both sites.
v. Huddles Cut — Flow events were documented in Huddles Cut during all months
of 2020 and were within the range of past monitoring years (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 (April, May, and December),
which is within the range of past post -Mod Alt L monitoring years.
vii. DCUT11 — Two flow events were documented (July and December), which is
within the range of past pre- and post -Mod Alt L monitoring years.
b. Skaggs 2006 simulations for Huddles Cut and CZR observations
Long term simulations were conducted by Skaggs et al. on the Huddles
Cut data collected in the watershed from 2001-2005 in conjunction with the DRAINMOD
simulation model (1951-2004 data). The results predicted flow would occur in the Huddles Cut
watershed in January, February, and March in about 90 percent of the years, in April and
December in about 60 percent of the years, and from May to November in only 30 to 45 percent
of the years; however, some of the largest monthly and daily flows were predicted to occur in
August, September, and October as a result of tropical storms and hurricanes. CZR monthly
flow observations comprise a five-year period of "data" and were compared to the model's
predictions as shown below:
Skaggs' Model Predictions of Flow in Huddles Cut Watershed
and CZR Flow Observation Percentages 2016-2020
Model Predictions CZR Observations
HS1 HS2 HS3
Jan -Feb -Mar (90% of years) 80.0% 86.7% 93.3%
Apr and Dec (60% of years) 70.0% 70.0% 100%
May to Nov (30-45% of years) 77.1 % 65.7% 88.6%
Since most flow stations are only visited once or twice a month, it can be
assumed there were more flow events than those CZR observed. It should be noted that the
model and percentages were based on former drainage basins (not existing) at former weir
locations located farther upstream than current flow observation sites. The highest percentage
of flow events in 2020 were observed at HS3, which is about 200 feet from the Pamlico River
and subject to frequent inflow from the river. Data used for the Skaggs' 2006 model were from
I I-A-5
sites well upstream of HS1 and HS2, which are even farther upstream from HS3.
c. 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.
Using Level TROLLs to monitor water level changes where flow
observations occur could be a potential surrogate measure of flow. The three most upstream
flow observation locations (in the vicinity of Porter Creek well PCWS, Drinkwater Creek well
DWW1B, and Jacks Creek well JW2B; post -Mod Alt L year for each) were used to investigate
potential unobserved flow events. These locations have wells nearby and are those 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. Water depths at the well during the
time of observed flow is noted for each visit throughout the year. The lowest depth with
observed flow at the well was used to establish a lowest depth at which the creek flows at that
well. With that depth, well data is 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 that can then be sorted from the established lowest water depth with flow to the
highest water depth for the whole year. 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 are compiled into
Table II-A2 and these data can be compared with an average of the pre- versus post -Mod Alt L
years to potentially determine if flow has changed. For certain years where no flow was
observed by biologists, an average of the lowest well water depths with observed flow from all
the years was used to find flow days. Rainfall totals for the years are 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 impacts.
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
have an unusually low number of days with flow which could be 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
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 2020): There was no
flow observed the 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. The average number
of days with flow is more than twice the pre -Mod Alt L number with only 5.72 inches more
rainfall. Post -Mod Alt L averages: 122 days with flow and 55.75 inches of rainfall.
I I -A-6
ii. Drinkwater Creek Pre- and Post -Mod Alt L
Drinkwater Creek- DWW1B (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 2020): The
first year of post -impact 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 nine years made 2013 the lowest (5) number of days with flow for the creeks in Table II-A2.
The post -Mod Alt L years averaged 55 more days than the pre -Mod Alt L year with 2.0 inches
less average rainfall. Post -Mod Alt L averages: 126 days with flow and 53.62 inches of rainfall.
iii. 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 and an average
of 51.34 inches of rainfall. 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 2020): The number
of days with flow for the five years of post -Mod Alt L ranged from 37 (2020) to 77 (2019). The
85 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 in the same years as post -Mod Alt L for Porter. Duck Creek showed
an increase in days with flow whereas Porter decreased. Post Mod Alt L averages: 56 days
with flow and 60.46 inches of rainfall.
iv. DCUT11 Creek Pre- and Post -Mod Alt L
DCUT11-DC11 W2B (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 proportional amounts 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-DC11W2B (post -Mod Alt L 2018 to 2020): The number
of days with flow for the three years of post -Mod Alt L ranged from 43 (2019) to 178 (2018).
The 85 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, DCUT19, ranged from 33
(2020) to 106 (2019) days with flow in the same years as post -Mod Alt L for DCUT11. Both
DCUT11 and DCUT9 had the same decrease in flow events (an average of 4.6 flow events/year
in the pre- and 2.6 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: 102 days with flow
and 65.83 inches of rainfall.
I I-A-7
d. Water Depth
At the annual science panel meetings, the subject of water depths at the
wetland monitoring wells and unknowns about the amount of hydrological input from the
adjacent floodplain (as opposed to upstream input, or "flow", at any given location previously
measured by Skaggs et al.) have been discussed. It is common knowledge that water depth
within creeks and wetlands can be affected by many different environmental variables, such as
precipitation and wind, as well as geomorphology of individual creeks or wetlands, location in
the regional landscape, and human activities such as timber removal. In addition, the effects of
these variables may differ depending on certain attributes of the creek or wetland. For example,
wind speed and direction likely affects water depths more in areas further downstream. For the
2016 report, additional analysis was performed with 2016 water depth data collected from the
Tooley Creek and Huddles Cut monitors.
It was concluded that regional environmental differences in Tar River
discharge, changes in wind tides, and local precipitation have a large effect on the fluctuations
of flow within these creeks, which make it difficult to attribute change directly to the activities of
the mine. Changes in flow duration can be directly correlated to the combined effects of rainfall
and Tar River discharge especially as it relates to the downstream systems. Also, it is difficult to
monitor and record some of the variables that could influence flow. Multiple linear regression
models of the effect of three variables (Tar River discharge, precipitation, and wind) on water
depth in Huddles Cut and Tooley Creek conducted for the 2016 report showed that wind
direction and rainfall were the two most important predictors of water depths. No further
analyses were performed for subsequent reports.
Answer: Jacks, Jacobs, Drinkwater, DCUT11, and Porter creeks 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 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 year of pre- and six years of
post -Mod Alt L data) and Drinkwater (one year of pre- and eight years of post -Mod Alt L
data) creeks. Average annual rainfall is higher in all post -Mod Alt L years, 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 number of average flow events per year in
the pre (4.6/year) and post (2.6/year) periods and had a decrease in flow events in the
post -Mod Alt L. Two flow events were observed in DCUT11 and none in DCUT19 during
2020. Rainfall at the DCUT sites was 15-20 inches higher in 2020 compared to 2019, yet
the longest wetland hydroperiod at the well closest to the flow site showed reductions in
2020 (DC11W2B was 17.6 percent in 2019 and 7.0 in 2020; DC19W2A was 22.3 percent in
2019 and 9.4 percent in 2020). 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 60 percent in the post -Mod Alt L years despite the approximate 17
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 (PCWS) has remained similar; 20.8 percent in the pre- and 17.02
percent in the post -Mod Alt L years. Reasons for the reduced flow events and wetland
hydroperiods at DCUT11 and Porter Creek are unclear at this time and additional data
should 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-
post- comparisons.
II-A-8
Table II -Al. Observed flow events conducted in conjuction with hydrology and salinity monitoring 2012- 2020. 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 (JCBWI)
Year
Flow
events
# of visits
% of visits
w/ flow
Rainfall
(in)
JW2
JW7
JW2
JW7
JW2
JW7
2012
0
3
17
17
0.0
17.6
55.6
2013
0
6
14
14
0.0
42.9
41.6
2014
1
5
10
10
10.0
50.0
52.9
2015
0
5
13
13
0.0
38.5
56.8
2016
0a
4
9
13
0.0
30.8
52.7
2017
0
7
13
13
0.0
53.8
46.6
2018
0
7
10
10
0.0
70.0
40.5
2019
3
5
13
13
23.1
38.5
54.9
2020
2
6
13
13
15.4
46.2
67.0
a 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
53.4
0
3
17
17
0
17.6
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
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
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
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
0
0
0
0
0
0
0
10
13
13
13
11
13
13
0
0
0
0
0
0
0
52.9
56.8
52.7
46.6
46.6
54.9
67.0
Drinkwater Creek (DWW1B)
Year
Flow
events
# of
visits
% of
visits w/
flow
Rainfall
(in)
2012
4
17
23.5
55.6
2013
2014
2015
2016
2017
2018
2019
2020
1
0
2
2
3
5
5
3
14
10
13
13
13
11
13
13
7.1
0.0
15.4
15.4
23.1
45.5
38.5
23.1
41.6
52.9
56.8
52.7
46.6
47.6
54.9
67.0
Huddles Cut
Year
Flow events
# of visits
% of visits w/
flow
Rainfall
(in)
HS1 1 HS2 1HS3
HS1
HS2
HS3
HS1
HS2
HS3
2015b
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
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
Duck Creek (control)
Year
Flow events
# of visits
% of visits w/ flow
Rainfall (in)
1 Bd
2Be
3Bd
4Be
1 Bd
2Be
3Bd
4Be
1 Bd
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
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
II-A-9
data at the time of observation
k_c
8
w e
U %
2 ®
8-I
7
0)
H 0
D�
U \
D o
e �
± §
§ e
2 ° (13
%
/ k
@ 73
C k
/-0
$ a
2U ClCr)
� 0 a)
e 0 f L-
a) (13
c / /
a)
/ y — .-
2
SDI\
0 _
)7
o $ % \
4 a)% I
U
\/E/
/ 2 .$ k
\Itr[ \
-o w0
y$-c)w
I / D
a)-0DI
- CIS�
ƒ2w
I a)U
Zo0_a
� \ 2
�I
? .\ / \
=U:
° o 'Q
\
w 2 2 e
Duck Creek
cn ca \ ° co \
IJ-
Itci
214
59
G
207
\
216
243
157
242
/
230
( m
ca o \ \ {
ci
§
75
154
174
/
/
279
95
\
/
168
02
0 J 2
52.79
%
§
43.08
57.87
p
§
45.92
2
§
S
$
54.47
47.48
51.05
Porter Creek
cn
co CI = 2
0 » 2 a
#
105
98
/
208
43
49
R
k
37
141
56
= k §
0 & 1-
\
@
43.39
50.94
58.96
0
§
48.90
G
\
56.67
&
\
f
5
60.46
DCUT19
> oCV
CI LT-
n 2
2 §
# , k
G
&
194
&
@
55
/
«
m
0
65
/ 2
= F —
Ci
40.38
7
\
55.96
55.45
43.59
/
§
40.09
65.20
49.74
S
§re
_
§
0
§ CV
CI LT- a § Cn
2 % §
Q
/
136
/
0
178
43
85
108
102
DCUT11
Rainfall
Totals
43.39
50.94
58.96
G
§
48.90
G
\
56.67
&
\
@
/
Cr)
§
Drinkwater Creek
# of Days
with Flow
at DWW2B
R
\
/
R
136
98
/
/
/
R
_
2
PA2
Rainfall
Totals
2
§
41.60
52.87
56.75
52.70
G
$
56.55
54.86
67.02
2
§
2
\
Jacks Creek
(§m
o §
222
# , _
k
34*
/
\
\
0
106*
N-
136
58
/
a $ "
§
2
Si
41.60
52.87
56.75
52.70
G
CO
56.55
54.86
67.02
50.03
R
§
k
a
\
Cr)
\
2014
e
\
2016
2017
CO
\
2019
2020
Pre -Mod Alt L Average
Post -Mod Alt L Average
* no flow events observed; average well depth for all years with observed flow used to estimate flow days
** only one flow event observed for the year
H- d 0