I-56_Long Term Streamflow Monitoring 2021_Draft

CITY OF DURHAM
Department of Public Works
Stormwater & GIS Services
CITY OF
DURHAM
Water Quality Report #09-010
March 9t", 2022
Long Term Streamflow Monitoring (Project 09-010) Annual
Report- CY 2021
Introduction
In support of the City of Durham's (COD) Stormwater Management Plan, this project is conducted in
support of the following Assessment and Monitoring Core and Supplemental goals [1]:
Core Goals
• to assess compliance with state water quality programs, including Total Maximum Daily Loads
(TMDLs), water quality standards, and nutrient management strategies
Supplemental Goals
• To identify overall trends in water quality
• to assess the overall quality of streams within the City of Durham
• to evaluate the water quality impacts of urban stormwater on area streams
Water Quality Unit (WQU) staff currently maintain three deployed Onset HOBO U20 water level loggers
for this project. Submerged loggers are deployed in Goose Creek, which is part of the Ellerbe Creek
watershed, and Crooked Creek, which is part of the Crooked Creek watershed (Table 1, Figure 1). A third
logger, monitoring atmospheric pressure, is located at the Public Works Operation Center (PWOC).
These deployed loggers record raw pressure and temperature in 15-minute intervals. Stream stage at
the two monitoring sites is calculated by first converting the difference between atmospheric pressure
from the PWOC probe and the submerged pressure, then converting that pressure value to depth in
feet.
Table 1- Locations and parameters monitored as part of the Long Term Stream Flow Project.
Sub Basin/
Dates
Site Location
Site ID
Latitude
Longitude
Parameters
Creek Name
Deployed
Ellerbe Creek/
2001 Camden
Temperature IF,
2013 -
EL5.5GC
36.024806
-78.860902
Goose Creek
Ave
Stream Stage (FT)
Current
Crooked
Temperature
2013 —
Creek/
1015cott King Rd
CC2.5CC
35.875849
-78.943876
Stream Stage (FT)
Current
Crooked Creek
PWOC- 1100
Temperature (OF),
-
NA
Martin Luther
NA
35.954799
-78.925876
Atmospheric
King Jr Pkwy
Pressure (psi)
Current

Little River
Camden
reek ` �J
Flat
C'rk
Creek
C
Little Lick Cree r
f
Lick "reek
pp Barn
1, rier Creek (WC)
Sycamo e C ek (WC)
f 2rrC
)Stirrup Iron Cree
flr -ast Creek
A C' ek -
HOBO Logger Water Level Site
�1 r Atmospheric Reference Logger
1 Major Streams
King Rd. Water Sheds
Data Source: City of Durham N
Long Term
Map Prepared by Stonnwater and GIS Services Stream Flow
Public Works on August 2, 2018. Information
depicted hereon is for reference purposes only and is 71— r-.Monitoring Sites
,.,.., — tea �.-- .we we�..,.,..:i,.w�a ..,.,...,a.. ..V ..
Figure 1- Long term stream flow monitoring sites within the City of Durham.
2

Precipitation and Drought Conditions
Stream stage and discharge is often dependent on seasonal precipitation. For comparison of these
seasonal variances, meteorological seasons were used. The meteorological seasons are: spring (March
Vt to May 315t), summer (June Vt to August 315T), fall (September 1" to November 30th) and winter
(December 1st to February 281h). The total precipitation from December V, 2020 to November 30th, 2021
was 42.2 in. according to the United States Geological Survey's (USGS) stage and precipitation
monitoring station (USGS 0209725960, THIRD FORK CREEK AT M.L. KING PARKWAY AT DURHAM, NC).
Precipitation by month is shown below in Figure 2. In general, observations show lower total monthly
precipitation from March to May when compared to winter and summer totals. Lowest total monthly
precipitation values were recorded in November. Significant rainfall totals occurred in June and July, due
both to prevalent weather patterns and tropical systems (TS) including TS Claudette (June 20-22, 1.61
in.) and TS Elsa (July 8-9, 2.69 in.). The highest daily precipitation (2.10 in.) was observed on June 101h
but was not tied to one of these systems.
Monthly Precipitation, December 2020 to November 2021
10
7
r-
0 6
m
a 5
V
W
a 4
m
0 3
2
1
0 •
Dec-20 Jan-21 Feb-21 Mar-21 Apr-21 May-21 Jun-21 Jul-21 Aug-21 Sep-21 Oct-21 Nov-21
Month
Figure 2- Monthly total precipitation measured at USGS 0209725960 gaging station, December 2020 to November 2021.
Precipitation data collection at USGS 0209725960 only goes back to 2017, so historical data from the NC
State Climate office's monitoring station at the North Durham Water Reclamation Facility (DURH) from
2011 to 2021 was also reviewed. Historical data from the DURH monitoring station indicates that 2021
had the lowest overall total precipitation at 38.21 in., while 2020 was the wettest, with a total of 60.75
in. during that period.
Overall drought conditions remained at or below "Moderate Drought" from December 2020 to
November 2021 in Durham County (Figure 3). Abnormally dry conditions were first observed on April
27t" 2021. Following an increase in overall percent area, the abnormally dry conditions transitioned to
moderate drought on June 1", before transitioning back to abnormally dry on June 15th. Drought
conditions were absent following multiple precipitation events in the first half of July. Abnormally dry

conditions were recorded over 90% of Durham County from September 7th to October 12th and again
from November 2d to November 30th. Abnormally dry conditions transitioned to moderate drought
conditions on November 30th, and affected 37% of the County.
Drought Status by Percent Area, ❑urham County December 1, 2020t❑ November
30, 2021
100
90%
80%
70%
r�
60%
Q
50%
d
V
ai 40%
a
30%
20%
10%
0%
12/1/20
3/V21 6/V21 9/V21
Date
❑O- Abnormally Dry
❑1- Moderate Drought
Figure 3- Drought status by percent area in Durham County from December 151, 2020 to November 301h, 2021.
4

Discharge and Cross sections
Stream discharge was measured using a SonTek/YSI FlowTracker ADV meter at a minimum of 20
subsections along the established cross sections. While field staff attempt to collect measurements at
both sites on the same day, unexpected rain occurred during transit between stations, and
measurements were collected over two days. Fieldwork was completed at EL5.5GC on May 14th, and on
May 28th at CC2.5CC. Measured discharge was 0.51 cfs at EL5.5GC and 0.08 cfs at CC2.5CC.
Cross sections were collected as part of fieldwork on both days (Figure 4, Figure 5). In review of cross
sections collected from 2018 to 2021, CC2.5CC Shows minor deposition and erosional areas consistent
with creeks and streams located in the Triassic Basin. Cross sections at EL5.5GC show relatively stable
geomorphology, despite a relatively steep right bank when facing downstream. This bank is on the
outside of a bend, and is currently stabilized by large trees and roots.
5

0 5 10
74
2
3
c 4
0
5
v
w 6
7
8
9
0 10
0
2
4
r
6 -
i
0 8
v 10
w
12
14
16
CC2.5CC Cross Section Profile Facing Downstream
Horizontal Distance from Left Pin (ft.)
15 20 25 30 35 40 45
s�
i
Figure 4- Cross -sections from 2018-2021 at CC2.5CC.
EL5.5GC Cross Section Profile Facing Downstream
Horizontal Distance from Left Pin (ft.)
20 30 40
Figure 5- Cross -sections from 2018 and 2021 at EL5.5GC.
50 60
M .
2018 Profile
•••••• 2019Profile
- - - - - 2020 Profile
— — — 2021 Profile
2018 Profile
•••••• 2019Profile
- - - - - 2020 Profile
— — — 2021 Profile
0

Recorded Stream Stage
Portions of the dataset did not meet established standards for data quality. Explanations for missing
data are further discussed below:
EL5.5GC and CC2.5CC: December V,2020- March 5th, 2021
Intermittent negative values for stage data were recorded at both sites in December, and noted during
routine quarterly quality assurance checks in January of 2021. Negative stage values were observed
again in January data following data retrieval on February 3rd, 2021. Field staff removed all three loggers
from deployment for quality assurance purposes. Probes were deployed in the controlled environment
of the Stormwater Lab, and the atmospheric pressure logger from PWOC appeared to be
malfunctioning, most likely due to the age. A replacement logger was obtained and all three probes
were redeployed on February 17tn, 2021. Because of the relatively short deployment period and further
issues with the deployment of the logger at CC2.5CC, stage data from December V, 2020 to March 5tn
2021 at both sites was not included in summary statistical analysis.
CC2.5CC: July 81h- August 5th, 2021
During routine ambient monitoring on August 5tn, 2021 field staff noted that the deployed logger at
CC2.5CC had been removed from the monitoring well and was located on the streambank nearby. In
review of precipitation and logger data, a significant rain event of approximately 1.9 in. was observed on
July 81n. A concurrent rise in stream stage was observed on the same day with a recorded maximum of
4.73 ft. Large debris often become mobile during stormflow events, and it's believed that a large branch
or log may have removed the logger from the monitoring well. Field staff redeployed the logger in the
well on August 51n
EL5.5GC: August 5th- August 26th, 2021
On August 26tn, 2021 field staff found the deployed logger outside of the monitoring well at EL5.5GC. In
review of precipitation and stage data, a precipitation event of approximately 1.2 in. was observed from
August 61n_7tn Stream stage reached a maximum of 1.8 ft. on August 71n before rapidly returning to 0.1
ft. Similar sized rain events in this watershed have resulted in stream stages greater than 5.5 ft., so it is
believed that the probe was pulled out of the monitoring well sometime on August 61h. Data from
August 51n- 26tn were rejected for analysis.
Of the remaining stage data, summary statistics for each meteorological season were calculated.
Because winter begins the year prior, summary statistics by season (

Table 2 & Table 3) begin with the winter season to maintain chronological order.

Table 2- Summary statistics by season at CC2.5CC from December 15, 2020 to November 3011, 2021.
CC2.5CC
Winter
Spring
Summer
Fall
Average (ft.)
-1
0.76
0.82
0.66
Std. Dev. (ft.)
-
0.14
0.27
0.14
Min. (ft.)
-
0.06
0.56
0.51
Max. (ft.)
-
2.39
4.73
2.05
1. Summary statistics were not calculated for the period from December 1s`, 2020 to March 51h, 2021.
Table 3- Summary statistics by season at EL5.5GC from December 151, 2020 to November 30th 2021
EL5.5GC
Winter
Spring
Summer
Fall
Average (ft.)
-1
1.33
1.32
1.40
Std. Dev. ft.)
-
0.27
0.46
0.26
Min. ft.
-
1.09
1.08
1.03
Max. (ft.)
-
5.85
6.83
7.04
1. Summary statistics were not calculated for the period from December 1'`, 2020 to March 5`h, 2021.
Conclusions
Absent winter data, highest overall averages and maximum stages were observed in the summer at
CC2.5CC, and the fall at EL5.5GC. In general, higher average flows and stage are expected to occur in late
winter and early spring due to moderate to heavy seasonal rainfall patterns. Winter stage and relevant
statistics may have been higher than other seasons in 2020. However it should be noted that the spring
season of 2021 appears to deviate from this norm with relatively lower monthly precipitation totals
from March to April (Figure 2). Additionally, Durham County experienced abnormally dry to moderate
drought conditions from late April to mid -July (Figure 3), which is a majority of the summer period.
While there are minimal overall differences between seasonal stage averages at both sites, a higher
average stage may indicate that CC2.5CC is receiving input from additional sources. Lowest average
stages occurred in the fall at CC2.5CC and in the summer at EL5.5GC. In general, late summer and fall are
the periods of lowest overall stream flow and stage due to seasonally dry conditions. Stream stage by
season with daily total precipitation values are shown below in Figures 6-13. Winter graphs are included
for reference purposes only.

5
4
3
Q
v 2
0
1
0
12/1/20
CC2.5CC, Winter, December 1, 2020 to February 28, 2021
12/11/20 12/21/20 12/31/20 1/10/21 1/20/21 1/30/21 2/9/21 2/19/21
Date
Figure 6- Stage and total daily precipitation at CC2.5CC for winter.
CC2.5CC, Spring, March 1, 2021 to May 31, 2021
5 - -
4
3
t
a
v 2
0
1 —
0
3/1/21 3/11/21 3/21/21 3/31/21
I,I , 1 11 1 11
4/10/21 4/20/21 4/30/21 5/10/21 5/20/21
Date
Figure 7- Stage and total daily precipitation at CC2.5CC for spring.
2.5
2
c
1.5 c
0
(U � Precipitation
Y_
1 SL
U Stage
N
L
a Seasonal Average Stage
0.5
0
3/1/21
2.5
2
c
1.5 c
0
Precipitation
1 n Stage
U
N
L
a Seasonal Average Stage
0.5
0
5/30/21
10

5
4
3
t
a
a) 2
0
1
0
9/1/21
CC2.5CC, Summer, June 1, 2021 to August 31, 2021
6/11/21 6/21/21 7/1/21 7/11/21 7/21/21 7/31/21 8/10/21 8/20/21
Date
Figure 8- Stage and total daily precipitation at CC2.5CC for summer.
CC2.5CC, Fall, September 1, 2021 to November 30, 2021
9/11/21 9/21/21 10/1/21
2.5
2
c
1.5 c
0
M Precipitation
1 U Stage
v
L
a Seasonal Average Stage
0.5
0
8/30/21
2.5
2
c
1.5 c
0
� Precipitation
LI
1 2- Stage
U
a)
L
a Seasonal Average Stage
0.5
�- 0
10/11/21 10/21/21 10/31/21 11/10/21 11/20/21 11/30/21
Date
Figure 9- Stage and total daily precipitation at CC2.5CC for fall.
11

10
9
8
7
6
5
a
v 4
0
3
2
1
0
12/1/20
10
9
8
7
6
5
a
v 4
0
3
2
1
0
3/1/21
EL5.5GC, Winter, December 1, 2020 to February 28, 2021
►&.7
2
c
1.5 c
0
M Precipiation
1 U Stage
v
a Seasonal Average Stage
0.5
0
12/11/20 12/21/20 12/31/20 1/10/21 1/20/21 1/30/21 2/9/21 2/19/21 3/1/21
Date
Figure 10- Stage and total daily precipitation at EL5.5GC for winter.
EL5.5GC, Spring, March 1, 2021 to May 31, 2021
2.5
2
c
1.5 c
0
Precipitation
1 g Stage
d
a Seasonal Average Stage
0.5
0
3/11/21 3/21/21 3/31/21 4/10/21 4/20/21 4/30/21 5/10/21 5/20/21 5/30/21
Date
Figure 11- Stage and total daily precipitation at EL5.5GC for spring.
12

10
9
8
7
6
5
Q
v 4
0
3
2
1
0
6/1/21
10
9
8
7
6
5
a
v 4
0
3
2
1
0
9/1/21
EL5.5GC, Summer, June 1, 2021 to August 31, 2021
W
2
c
1.5 c
0
M � Precipitation
Y_
1 n U Stage
N
a Seasonal Average Stage
0.5
0
6/11/21 6/21/21 7/1/21 7/11/21 7/21/21 7/31/21 8/10/21 8/20/21 8/30/21
Date
Figure 12- Stage and total daily precipitation at EL5.5GC for summer.
EL5.5GC, Fall, September 1, 2021 to November 30, 2021
9/11/21 9/21/21 10/1/21 10/11/21 10/21/21 10/31/21 11/10/21 11/20/21
Date
Figure 13- Stage and total daily precipitation at EL5.5GC for fall.
2.5
2
c
1.5
0
Precipitation
1 L) Stage
L
a Seasonal Average Stage
0.5
0
11/30/21
13