Final project report submitted to Iowa Nutrient Research Center
February 13, 2016
Distribution, transport, and biogeochemical transformations of agriculturally derived
nitrogen and phosphorus in Cedar River watershed
Mohammad Iqbal, Professor of Geology and Environmental Science, Department of Earth
Science, University of Northern Iowa, Cedar Falls, IA 50614 (m.iqbal@uni.edu; 319-273-2998)
INTRODUCTION
This is the final project report (year 1 and 2 combined). The primary objective of this
study was to calculate nitrogen (N) and phosphorus (P) loading from farmlands within the Cedar
River watershed during the period 2013 - 2015. Additionally, temporal and spatial distributions
of nutrients were studied. The project was conducted in two phases. During phase 1, the highly
agricultural part of the watershed from Charles City to LaPorte City was studied by sampling 18
sites (sites 1-18). During phase 2, additional 10 sites were sampled from Brandon to the last
point in Cedar River at Columbus Junction, Iowa (sites 19-28). Data from both Phase 1 (Figures
1 - 48) and Phase 2 (Figures 49 - 62) are presented in this report with separate descriptions of
important observations. This is to be noted that Phase 1 activities comprise most part of the
project since the intensely agricultural sub-watersheds are in this area.
Data online:
We have uploaded all data from Phase 1 and Phase 2 to our hydrology website for public
viewing and comments. There are google interactive maps that show the watershed areas and
sites 1 through 24. Please go to www.uni.edu/hydrology and click water quality data under Cedar
River Monitoring Plan (see Local Hydrologic data Collection to the right side of the page). Click
each site number to see the details of that site. Click past data to review all data for the site.
There is also a limited graphing capability added (click Graphical data). At this time the temporal
variation in each parameter can be seen. We expect to add more graphical capability over time.
The long term goal of the online posting is to allow the public to see the interrelationships of
water quality parameters and understand the overall hydrologic characteristics of the watershed.
1
The uploaded data should be considered as unofficial since we are still experimenting with the
website functionality. We are accepting public comments on posted data.
PROJECT ACTIVITIES
Phase 1 study (2013-14)
During Phase 1, total 18 sites have been sampled once a week from April 5 through
October 31 of 2014. All lab analyses have been completed in the hydrology lab of the
Department of Earth Science, University of Northern Iowa. Time sensitive parameters were
analyzed at the field sites with portable sensors. A set of 48 graphs (Fig 1 – 48) have been
attached to this report that represent our data from phase 1. Based on the obtained data, we
developed sub-watershed maps around each sampling site. We also gathered published land use
information for the watershed to research into nutrient mass balance for the area. When
necessary, data were compiled to produce spatial distribution maps by using GIS mapping tools.
The sampling team went out to the area for sampling as soon as the fields were exposed from
snow cover.
All 18 sites were sampled once a week for stream water and sediments from the
beginning of April to the end of October, 2014. These 18 sites are located all the way from
Charles City to LaPorte City, Iowa covering the main channel Cedar, Little Cedar River, Shell
Rock River, West Fork Cedar River, Black Hawk Creek, and Wolf Creek. A base map is
attached to this report (Fig. 1). From each site, thirty (30) sets of samples were collected and
analyzed for total dissolved solids (TDS), total suspended solids (TSS), dissolved oxygen (DO),
turbidity, total phosphorus (TP), and dissolved nitrogen. Each set of sampling involved over 250
miles of driving in the study area. To ensure efficient sampling, the 18 sites were divided into
two groups (Group A and Group B). Group A included sites 1 through 9 comprising the areas
from Cedar Falls further north to Charles City and Group B included sites 10 through 18 from
Cedar Falls further south to LaPorte City. Two student assistants were given the responsibilities
to do the sampling on the same day where they followed identical field methods. Each time the
same sensing probes were used per site to make sure the data were consistent. These two
students are Sushil Tuladhar, a graduate student in Geography, and Kevin Rupp, an
undergraduate student in Earth Science. Sushil Tuladhar has largely coordinated this project by
2
way of field work, lab analysis, and data compilation. Two other undergraduate students,
Madison Pike and Ashly Lembke were involved in gathering land use data from the area. All
students received appropriate training on sampling protocol and lab analytical procedure.
Key Observation:
(1) Baseline: Toward the beginning of the project (October to December, 2013), several sites in
the watershed were sampled for baseline data on N, TP, chloride, sulfate, TDS and TSS. The
baseline data for phosphorus in bottom sediments ranged from 122.6 to 543.5 µgP/gm of dry wt.
The highest value was observed in Beaver Creek. All other sites had comparable TP values. TP
in baseline water samples ranged from 14 to 185 µg/L. Dissolved NO3-N in all sites were below
4.2 mg/L. In general, all baseline parameters showed stable values as expected in off season
samples.
(2) Seasonal trends: Figures 2 – 21 are attached to this report to portray the observed data on
multiple parameters from April through the end of October, 2014. The graphs show temporal and
spatial trends in TSS, TP and N. As expected, the actual loads of TSS, TP and N during the
growing season are considerably higher than the baseline.
The average distribution of TSS within the watershed is shown in figures 2 through 6.
Most sites show initial high loads of TSS in April and early May and then it appears to peak
again in late June and July. The first rush of TSS can be attributed to the snow melt episodes
causing soil loss from the agricultural fields that are not adequately covered by crops. This is
more prominent in the intensely farmed northern part of the watershed (Fig. 2). According to the
water clarity criteria in the Midwestern streams, 20 mg/L is considered clear and levels higher
than 80 mg/L is considered cloudy. In reference to these levels, the upper reaches of the Cedar
River watershed have exceedingly high TSS during the early season (average 116.5 mg/L). The
average drops to 59 mg/L further south of Cedar Falls/Waterloo where the percentage of
agricultural lands is much lower. Also, the southern part of the study area is characterized by
lower drainage density. The second TSS peaks are attributed to the rain events during the midsummer to mobilize field soils. High surface runoff is expected to be the primary cause of soil
loss from the fields. Flash flooding associated with intense rain events can bring large pulses of
eroded soils to the watershed. The area had 5.02 inches of rain that fell from June 16th through
3
the 19th. The data collected on June 21st showed a rise in average TSS concentration from 30
mg/L to 71 mg/L (sites 1 – 9) toward the northern part of the study area (Fig. 2). From sites 10 18 further south the average jumped from 23 mg/L to 122 mg/L (Fig. 3). The average TSS loads
during the mid-season appear to be much higher in the downstream areas (187 mg/L, Fig 3). This
is probably because the farm fields in the north by then are more stabilized with crops to prevent
soil erosion.
Figures 7 – 14 show temporal and spatial trends in total phosphorus (TP) during the early,
middle and late seasons. Loads of TP directly correlate with the transport of TSS in the
watershed during the entire sampling period. Phosphorus is heavily adsorbed to soil particles and
is transported to the streams with eroded soils. This reiterates the importance of soil conservation
practices to achieve the ultimate goals of nutrient reduction. The 4-day intense rains (discussed
above) prior to the 6/21 sampling resulted in 134% and 142% increases in the TP loads over the
northern (sites 1 – 9) and the southern (sites 10 – 18) parts of the area, respectively (Fig. 7, 8).
After the month of July, even though the concentrations of TSS did not show any significant
variations the TP values consistently went up through the early part of September. It could be
due to one of several reasons. It could be the incoming soluble reactive phosphorus (SRP) from
groundwater through base flow. Many streams in the U.S. reportedly have high SRP
concentrations in groundwater during the fall when soils are relatively warm and dry. The high
SRP could be caused by mineralization and accumulation of phosphorous through the summer.
Also, applied manure in areas where water table is shallow could result in higher SRP in
groundwater, which eventually discharges into the streams. This issue needs to be further
investigated by additional sampling of groundwater and conducting source inventories.
Alternatively, the increase of TP might be due to the slow release of phosphorus from the stream
bed sediments to the water column. In the fall, high loads of plant leaves as well as residual
organic debris to the streams can cause the water to turn low in oxygen through the organic
decay process. In anoxic condition, some minerals that adsorb phosphorus can dissolve, thereby
releasing excess P to the water column. All 18 sites showed average TP concentrations
exceeding the 100 µg/L maximum contaminant level (MCL) as recommended by the USEPA for
surface water (Fig. 11). The 3-week plot in Fig. 12 shows a dramatic influx of TP to the streams
in response to the 5 inch rain that fell from June 16th through the 19th. The loads of TP in
tons/day are shown in Figures 13 and 14. The TP loads measured at 11 sites where discharge
4
data are available from USGS stream-gaging stations range from 0.005 tons/day at Site 15
(Black Hawk Creek at Hudson) on October 10, 2014 to 34 tons/day at Site 12 (Cedar River @
Cedar Falls) on June 21, 2014. The average TP loads of these 11 sites is 1.06 tons/day. With this
rate, the estimated total load of phosphorus in the watershed from the beginning of April through
the end of October (7 months) is 223 tons. Spatial distribution of TP concentrations and loads
over these 11 sites are shown in Fig. 24 and 25. Detailed TP load calculations are shown in Fig.
35.
Spatial and temporal distributions of NO3-N are shown in Fig. 15 through 23. Because
nitrogen is highly soluble in water, influx of nitrogen at all sites are more episodic than
phosphorus (Fig 15 and 16). Strong pulses of nitrogen are primarily associated with rain events
causing higher levels of dissolved nitrogen in the streams. This includes immediate surface
runoff and baseflow. It is also important to understand that a well-integrated system of drainage
tiles below the farm fields offers a favorable condition for nitrogen pulses to the streams. In
general, nitrogen loads are high from early to mid-summer due to the rapid conversion of
fertilizer nitrogen into nitrate before the crops enter the period of maximum uptake. The levels of
nitrogen start to rise again toward the later part of fall. This is primarily derived from the residual
organic nitrogen converting into nitrate through the process of nitrification (Fig 17 and 18). The
high nitrogen levels in the fall are also due to the fact that nitrogen uptake by crops is
considerably reduced by mid to late August. Nitrogen loads in the watershed range from 0.25
tons/day at site 15 (Black Hawk Creek in Hudson) on October 10, 2014 to 1061 tons/day at site
13 (Cedar River at Waterloo) on June 21, 2014 (Fig 20 and 21). The highest load was observed
immediately after the 5 inch rain from June 16 – 19 as discussed in the previous section. This is
an intriguing example how a large fraction of the available nitrogen can be lost from the
agricultural fields as a result of intense rain events, especially in mid-season when the nutrient
would be otherwise used up in crop yield. The average nitrogen load of the 11 sites where
discharge data are available is 45 tons/day. With this rate, the total load of nitrogen in the
watershed from the beginning of April through the end of October is 9450 tons. The relative
distribution of nitrogen in the watershed during early, middle and late seasons are shown in
figure 22. The mid-season concentrations are considerably higher than the other two seasons.
Given that the fields are already in their maximum uptake mode, these high loads in the midseason reiterate the urgent need for best management practices in the area. In terms of
5
concentration levels, sites 3, 4, and 5 along the Shell Rock River show the lowest amounts of
nitrogen moving through the streams. Fig. 23 shows the spatial distributions of NO3-N loads (in
red circles) at the 11 sites where discharge data are available from the USGS stream gaging
stations. From sampling site 1 through 13, the total nitrogen loads along the main course of the
river gradually increase downstream. Detailed N load calculations are shown in Fig. 34.
(3) Phosphorus loading and rainfall: Phosphorus shows three definite periods of influx into the
river that coincides with the early, middle and late seasons. These three phases of high P loads
directly correlate with the seasonal rain events in the area. In the attached graphs (Fig. 26 – 29),
P transport from some of the heavily farmed areas is compared with the rainfall observed at the
nearest weather stations. When the P concentrations are compared with the concentrations of
total suspended solids (TSS) in the river, direct correlations are observed. P is heavily adsorbed
to soil particles and is transported to the streams with eroded soils. During early and mid-season,
TSS is the primary vehicle for P to move from the agricultural fields to the watershed. However,
a close observation reveals that the primary mechanism of P transport changes during the late
season. After the month of July, even though the concentrations of TSS continue to drop with
minor pulses, the TP values consistently go up through the beginning of September (Fig. 30). It
is attributed to the incoming soluble reactive phosphorus (SRP) from groundwater through base
flow. During the fall when soils are relatively warm and dry, streams receive high levels of SRP.
Also, applied manure in areas where water table is shallow could result in higher SRP in
groundwater. Fig. 31 – 33 show spatial distribution of P, N and TSS in the study area. The data
are average concentrations per site over the entire period of phase 1 study.
(4) Nutrient loading per sub-watershed: Figure 38 shows the 13 sub-watersheds delineated within
the study area based on hydrologic characteristics. Fig. 39 – 42 show nutrient loss from 7 subwatersheds that form the primary system of tributaries and directly contribute N and P to the
main course of the Cedar River. The contributing sub-watersheds are Little Cedar River, Cedar
River above Charles City, Shell Rock River, West Fork Cedar River, Beaver Creek, Black Hawk
Creek and Wolf Creek. The calculated average stream output of NO3-N is 22 lbs/acre (Fig. 39),
ranging from 16 to 30 lbs/ac. The total loss of NO3-N from these 7 contributing sub-watersheds
has been calculated as 33,500 tons/yr (i.e., from early April to late Oct). This load is 16.7% of
the state’s total stream output of N reported by Libra, Wolter and Langel in their 2004 nutrient
6
budget report (Fig. 40). The calculated average loss of P is 0.41 lbs/acre (Fig. 41), ranging from
0.28 to 0.48 lbs/ac. The total loss of P from the area has been calculated as 646 tons for the year
(Fig. 42). This load is 6% of the state’s total stream output of P reported by Libra, Wolter and
Langel (2004). For detailed calculations of loss per acreage, total stream output and loss
comparison among NO3-N, TP and TSS, refer to Fig. 34 – 37. Temporal and spatial distributions
of phosphorus in stream sediments are shown in Fig. 43 – 46. Both upstream (sites 1-9) and
downstream (sites 10-18) locations show high loading of P in bottom sediments during April and
early May which then drops in June and July. After the month of July, the upstream sites show
relatively low and constant movement of sediment P whereas the downstream sites show a
gradual increase in loads until the beginning of October. Considering all 18 sites in phase 1,
movement of TSS in the stream is moderately correlated with TP, but not with phosphorus in
bottom sediments (Fig. 47).
Phase 2 study (2014-15)
Phase 2 of the project was conducted from early April to late October, 2015. We selected
ten (10) new sites (S19 through S28) in Brandon, Vinton, Urbana, Palo, Marion, Cedar Rapids,
Cedar Bluffs, West Branch, Conesville, and Columbus Junction, Iowa. Sites 23 (Indian Creek,
Marion) and 26 (Hoover Creek, West Branch) are on two tributaries of Cedar River. The rest of
the sites are on the main channel. We have sampled sites 19 - 24 once every 2 weeks and sites
25-28 every 3 weeks from April 4 through October 30. Stream bed sediments have also been
collected from these sites every 3rd week. Data have been gathered for nitrogen, total suspended
sediments (TSS), temperature, pH, total dissolved solids, conductivity, dissolved oxygen and
total phosphorus (both water and stream sediments). The data from these 10 new sites were done
to finish the project and get a more complete picture of nutrient loading in the Cedar River
watershed. However, the farmed acreage in phase 2 study area is much smaller than the areas
covered in phase 1. Most of our data analysis and investigations in this project were focused on
the work performed during phase 1. The data discussed in this section primarily deal with
observation made over sites 19 – 24. The sites further south of Cedar Rapids (sites 25 – 28) are
far away and beyond the scope of this project. For these 4 sites, we have provided some basic
data in a table at the end of the report.
7
Figure 48 shows the sampling locations during the second phase of the project. Each site
was visited for their accessibility, making sure that they were close to a bridge for sampling
convenience. Water and sediment sample analyses were done in the hydrology lab at UNI.
Discharge data are taken from the published USGS records. Each site has been defined based on
the surrounding land use characteristics, topography, and soil types. Mass calculations of TSS,
TP and NO3-N were done for sites 20, 22, 23 and 24.
Key observation:
(1) TSS loading: Fig. 49 - 50 show the temporal and spatial variations in the total suspended
solids (TSS) observed in the stream. In general, from Brandon all the way downstream to Cedar
Rapids the sites show spatially uniform concentrations of TSS. This is unlike what we found
during phase 1 study where sites showed considerable spatial variations at a given time of
sampling. The sub-watersheds studied during phase 1 are characterized by most intensive
agricultural activities in the watershed. Relatively high rate of soil erosion as well as variable
conservation practices along the waterways is attributed to this difference in the average TSS
distribution between phase 1 and 2. Temporally, the TSS value shows the highest average during
mid-June (192 mg/L, Fig. 49). Figure 51 shows the detailed calculations of TSS as per daily
loads and loss per acreage.
(2) TP loading: Temporal distribution of total phosphorus (TP) shows sharp rise in concentration
at different times (Fig. 52). Some of these peaks correspond with rainfall events while others do
not. The relative increase in TP during the late season is attributed to the incoming soluble
reactive phosphorus (SRP) from groundwater through baseflow. SRP in U.S. streams are known
to form through mineralization of dry, P-loaded soils and applied manures. Frequently, SRP
forms in shallow aquifers, which eventually discharges into the streams. The details of SRP
mechanism have been discussed in the previous sections of this report (i.e., phase 1). The early
season peaks in TP that are not linked to rainfall events could be the result of the application
patterns. It is not clear how much of the TP from bottom sediments would be a factor in such a
well oxygenated stream system. Detailed calculations of TP loads at selected sites are shown in
Fig. 54.
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(3) NO3-N loading: Figures 55 and 56 show the distribution of nitrate-nitrogen at six sites from
Brandon to Cedar Rapids. In addition to the nitrogen pulse during April application, increased
concentrations were observed during late May, early June and early July. Even though the plant
uptake is expected to be high during these time periods, especially during May and early June,
the high levels of dissolved N seem to be associated with rain events. Nitrogen is highly soluble,
so rainfall can trigger rapid loss of N from the agricultural fields. In addition to the applied
fertilizers during the early season, parts of the organic nitrogen from the previous year are
subject to nitrification as the soil gets higher moisture content. The late June (6/28) sampling
shows much lower concentrations of N, which is attributed to the high plant uptake along with
low rainfall amounts. Site 23 (Indian Creek at Marion) shows the highest fluctuations in nitrogen
concentrations, ranging from 2.12 mg/L on June 28 to 23.58 mg/L on June 13 (Fig. 55, 56).
Figure 57 shows the details of NO3-N calculations at sites 20, 22, 23 and 24. The average N
loads vary from 3.3 tons/day at site 23 (Indian Creek at Marion) to 152.8 tons/day at site 24
(Cedar River at Cedar Rapids). When compared to their sub-watershed areas, the N loads from
April through October range from 13.58 lbs/acre at site 20 (Cedar River at Vinton) to 32.01
lbs/acre at site 23 (Indian Creek at Marion). Load comparison per acreage for N, TP and TSS is
shown in Fig. 58. Additionally, TP-TSS relationships are presented in Fig. 59-61. Data show
TSS as the primary vehicle for the loss of TP from agricultural fields. Fig. 62 shows data
recorded at sites 25, 26, 27 and 28 during early, middle and late seasons of 2015.
Reference:
R.D. Libra, C.F. Wolter and R.J. Langel, 2004. Nitrogen and phosphorus budgets for Iowa and
Iowa watersheds. Iowa Geological Survey, Technical Information Series 47, Iowa Department of
Natural Resources, 43 p.
9
Figure 1: Phase 1 sampling locations (sites 1 – 18)
10
Temporal distributions of TSS (Group A sites)
1000
140
120
100
100
80
71.00
57.25
45.98
10
60
47.32
35.23
37.15
33.18
43.06
24.02
26.82
36.57
29.45
29.92
24.01
25.85
20.24
22.80
27.06
18.85
40
24.54
23.18
10.90
10.28
19.38
7.30
1
20
13.42
6.24
2.76
5.47
0
CedarRiver@ Charles City
LittleCedarRiver near Ionia
ShellRockRiver@ Marble Rock
ShellRockRiver@ Marble Rock
ShellRockRiver@ Shell Rock
WestForkCedarRiver near Kesley
WestForkCedarRiver@ Finchford
CedarRiver@ Waverly
CedarRiver@ Janesville
Average
Figure 2: Temporal distributions of total suspended solids (TSS) at sites 1 through 9 (Group A)
11
Average Concentration (mg/L)
Log Concentration (mg/L)
116.51
Temporal distributions of TSS (Group B sites)
1000
200
186.56
Log Concentration (mg/L)
160
140
100
121.85
120
100
80
71.99
59.45
10
51.08
60
36.60
28.79
31.39
51.00
37.29
25.62
23.06
26.72
22.93
22.21
22.88
20.88
29.19
22.44
18.37
20.99
1
40
29.87
26.72
13.78
7.81
10.30
5.98
12.82
6.37
8.64
20
0
BeaverCreek@ New Hartford
BeaverCreek@ Cedar Falls
CedarRiver@ Cedar Falls
CedarRiver@ Waterloo
BlackHawkCreek@ Waterloo
BlackHawkCreek@ Hudson
CedarRiver@ Gilbertville
WolfCreek near Dysart
CedarRiver near La Porte City
Average
Figure 3: Temporal distributions of TSS at sites 10 through 18 (Group B)
12
Average Concentration (mg/L)
180
Spatial distributions of TSS (Group A sites)
Log Concentration (mg/L)
1000
100
10
1
Cedar
River@Charles
City
4/5
7/26
4/19
8/2
Little Cedar River
near Ionia
4/25
8/9
5/3
8/17
Shell Rock
River@Marble
Rock
5/10
8/23
Shell Rock River Shell Rock@Shell West Fork Cedar West Fork Cedar
near Clarksville
Rock
River near Kesley River@Finchford
5/17
8/29
5/26
9/5
6/1
9/12
Figure 4: Spatial distributions of TSS at sites 1 through 9 (Group A)
13
6/8
9/19
6/15
9/26
6/21
10/3
6/28
10/10
Cedar
River@Waverly
7/5
10/15
Cedar
River@Janesville
7/12
10/25
7/19
10/31
Spatial distributions of TSS at sites 10 through 24 (Group B sites)
Log Concentration (mg/L)
1000
100
10
1
Beaver Creek@New
Beaver
Cedar River@Cedar
Cedar
Hartford
Creek@Cedar Falls
Falls
River@Waterloo
4/5
7/26
4/19
8/2
4/25
8/9
5/3
8/17
5/10
8/23
5/17
8/29
Black Hawk
Creek@Waterloo
5/26
9/5
6/1
9/12
Figure 5: Spatial distributions of TSS at sites 10 through 18 (Group B)
14
6/8
9/19
Black Hawk
Creek@Hudson
6/15
9/26
Cedar
River@Gilbertville
6/21
10/3
6/28
10/10
Wolf Creek near Cedar River near La
Dysart
Porte City
7/5
10/15
7/12
10/25
7/19
10/31
15
Main River
Figure 6: Average TSS concentrations at all sites during phase 1 (April – October, 2014)
Tributaries
Wolf Creek near Dysart
Black Hawk Creek@Hudson
Black Hawk Creek@Waterloo
Beaver Creek@Cedar Falls
Beaver Creek@New Hartford
West Fork Cedar River@Finchford
West Fork Cedar River near Kesley
Shell Rock@Shell Rock
Shell Rock River near Clarksville
Shell Rock River@Marble Rock
Little Cedar River near Ionia
Cedar River near La Porte City
Cedar River@Gilbertville
Cedar River@Waterloo
Cedar River@Cedar Falls
Cedar River@Janesville
Cedar River@Waverly
Cedar River@Charles City
Concentrations (mg/L)
Average TSS Concentrations
120
90
60
30
0
Temporal distributions of Total Phosphorus at sites 1 through 9 (Group A sites)
500
160%
134%
450
140%
120%
Concentrations (µg/L)
400
100%
350
80%
300
68%
55%
60%
47%
250
34%
40%
20%
200
21%
11%
0%
0%
150
-2%
-2%
100
2%
-15%
-6%
-19%
-19% -21%
50
-40%
-18%
-2%
3%
2%
-27%
-36%
20%
-20%
-39%
-11%
0%
-20%
-40%
-39%
-47%
0
-60%
Cedar River@Charles City
Little Cedar River near Ionia
Shell Rock River@Marble Rock
Shell Rock River near Clarksville
Shell Rock@Shell Rock
West Fork Cedar River near Kesley
West Fork Cedar River@Finchford
Cedar River@Waverly
Cedar River@Janesville
%change
Figure 7: Temporal variations in total phosphorus (TP) at sites 1 through 9 (Group A)
16
Temporal distributions of Total Phosphorus at sites 10 through 18 (Group B sites)
500
200%
450
142%
Concentrations (µg/L)
400
150%
350
300
100%
250
200
50%
28%
15%
150
7%
1%
0%
100
48%
32% 32%
-13%
-16%
0%
-3%
-7%
9%
3%
8%
4%
9%
-13%
-12%
50
-26%
0
-15%
-34%
-12%
-18%
-28%
-40%
-37%
0%
-22%
-50%
Beaver Creek@New Hartford
Beaver Creek@Cedar Falls
Cedar River@Cedar Falls
Cedar River@Waterloo
Black Hawk Creek@Waterloo
Black Hawk Creek@Hudson
Cedar River@Gilbertville
Wolf Creek near Dysart
Cedar River near La Porte City
%change
Figure 8: Temporal variations in total phosphorus (TP) at sites 10 through 18 (Group B)
17
Spatial distributions of total phosphorus at sites 1 through 9 (group A sites)
500
4/5
5/17
6/21
7/26
8/29
10/3
Recommended Level
450
Concentratoins (µg/L)
400
350
4/19
5/26
6/28
8/2
9/5
10/10
4/25
6/1
7/5
8/9
9/12
10/15
5/3
6/8
7/12
8/17
9/19
10/25
5/10
6/15
7/19
8/23
9/26
10/31
300
250
200
150
100
50
0
Cedar
River@Charles
City
Little Cedar River
near Ionia
Shell Rock
River@Marble
Rock
Shell Rock River Shell Rock@Shell West Fork Cedar West Fork Cedar
near Clarksville
Rock
River near Kesley River@Finchford
Figure 9: Spatial variations in total phosphorus (TP) at sites 1 through 9 (Group A)
18
Cedar
River@Waverly
Cedar
River@Janesville
Spatial distributions of total phosphorus at sites 10 through 18 (Group B sites)
450
4/5
5/17
6/21
7/26
8/29
10/3
Recommended Level
400
Concentratoins (µg/L)
350
4/19
5/26
6/28
8/2
9/5
10/10
4/25
6/1
7/5
8/9
9/12
10/15
5/3
6/8
7/12
8/17
9/19
10/25
5/10
6/15
7/19
8/23
9/26
10/31
300
250
200
150
100
50
0
Beaver
Creek@New
Hartford
Beaver
Cedar River@Cedar
Cedar
Creek@Cedar Falls
Falls
River@Waterloo
Black Hawk
Creek@Waterloo
Black Hawk
Creek@Hudson
Figure 10: Spatial variations in total phosphorus (TP) at sites 10 through 18 (Group B)
19
Cedar
Wolf Creek near Cedar River near La
River@Gilbertville
Dysart
Porte City
Main River
20
Tributaries
Figure 11: Average total phosphorus concentrations at all sites during phase 1 (April – October, 2014)
WolfCreek near Dysart
BlackHawkCreek@Hudson
BlackHawkCreek@Waterloo
BeaverCreek@Cedar Falls
BeaverCreek@New Hartford
WestForkCedarRiver@Finchford
WestForkCedarRiver near Kesley
ShellRockRiver@Shell Rock
ShellRock River near Clarksville
ShellRockRiver@Marble Rock
LittleCedarRiver near Ionia
CedarRiver near La Porte City
CedarRiver@Gilbertville
CedarRiver@Waterloo
CedarRiver@Cedar Falls
CedarRiver@Janesville
Cedar River@Waverly
CedarRiver@Charles City
Concentrations (µg/L)
Average Total Phosphorus Concentrations
250
200
150
100
50
0
Phosphorus Concentrations
[Jun15-28, 2014]
0
50
100
Concentrations (µgP/L)
200
250
150
300
Cedar River@Charles City
Little Cedar River near Ionia
Shell Rock River@Marble Rock
Shell Rock River near Clarksville
Shell Rock@Shell Rock
West Fork Cedar River near Kesley
West Fork Cedar River@Finchford
Cedar River@Waverly
Cedar River@Janesville
Beaver Creek@New Hartford
Beaver Creek@Cedar Falls
Cedar River@Cedar Falls
Cedar River@Waterloo
Black Hawk Creek@Waterloo
Black Hawk Creek@Hudson
Cedar River@Gilbertville
Wolf Creek near Dysart
Cedar River near La Porte City
6/15
6/21
6/28
USEPA Recommended Level
Figure 12: Three-week comparison of total phosphorus during Phase 1 study.
21
350
400
450
Total phosphorus (TP) Loads at selected sites from Group A
100
4/5
4/19
4/25
5/3
5/10
5/17
5/26
6/1
6/8
6/15
6/21
6/28
7/5
7/12
7/19
7/26
8/2
8/9
8/17
8/23
8/29
9/5
9/12
9/19
9/26
10/3
10/10
10/15
10/25
10/31
Loads (tons/day)
10
1
0.1
0.01
Cedar River @ Charles Cedar River @ Waverly Cedar River @ Janesville Little Cedar River near Shell Rock River at Shell West Fork Cedar River @
City
Ionia
Rock
Finchford
Figure 13: Total Phosphorus loads (in tons/day) at selected sites from Group A
22
Total phosphorus Loads at selected sites from Group B
100
4/5
4/19
4/25
5/3
5/10
5/17
5/26
6/1
6/8
6/15
6/21
6/28
7/5
7/12
7/19
7/26
8/2
8/9
8/17
8/23
8/29
9/5
9/12
9/19
9/26
10/3
10/10
10/15
10/25
10/31
Loads (tons/day)
10
1
0.1
0.01
Cedar River @ Cedar Falls
Cedar River @ Waterloo
Beaver Creek @ New Hartford Black Hawk Creek @ Hudson
Figure 14: Total phosphorus loads (in tons/day) at selected sites from Group B
23
Wolf Creek near Dysart
Temporal distributions of NO3-N
[Group A sites]
25
120%
107%
100%
96%
80%
64%
54%
60%
15
40%
26%
37%
14%
10
13%
-10%
0%
-34%
-30%
-31%
12%
20%
0%
-2%
-10%
-20%
-28%
-6%
-10%
-2%
-22%
-10%
5
11%
9%
6%
21%
-28%
0
-20%
-12%
-22%
-40%
-60%
Cedar River@Charles City
Shell Rock River near Clarksville
West Fork Cedar River@Finchford
%Change
Little Cedar River near Ionia
Shell Rock@Shell Rock
Cedar River@Waverly
Figure 15: Temporal distributions of NO3-N concentrations at sites 1 through 9 (Group A)
24
Shell Rock River@Marble Rock
West Fork Cedar River near Kesley
Cedar River@Janesville
% Change
Concentrations (mg/L)
20
Temporal distributions of NO3-N
[Group B sites]
25
120%
103%
93%
100%
92%
20
60%
15
40%
40%
31%
27%
23%
10
21%
20%
14%
-6%
-10%
5
25%
0%
-17%
-19%
-8%
-32%
-25%
-23%
-20%
-24%
0
Beaver Creek@New Hartford
Black Hawk Creek@Waterloo
Cedar River near La Porte City
Beaver Creek@Cedar Falls
Black Hawk Creek@Hudson
%Change
-3%
-16%
-27%
-6%
-19%
Cedar River@Cedar Falls
Cedar River@Gilbertville
Figure 16: Temporal distributions of NO3-N concentrations at sites 10 through 18 (Group B)
25
-7%
-9%
11%
0%
-14%
-20%
-40%
Cedar River@Waterloo
Wolf Creek near Dysart
% Change
Concentrations (mg/L)
80%
Spatial distributions of NO3-N (Group A sites)
25
Concentrations (mg/L)
20
15
10
5
0
Cedar
Little Cedar River Shell Rock
Shell Rock River
River@Charles
near Ionia
River@Marble near Clarksville
City
Rock
Shell
Rock@Shell
Rock
West Fork Cedar West Fork Cedar
Cedar
Cedar
River near Kesley River@Finchford River@Waverly River@Janesville
4/5
4/19
4/25
5/3
5/10
5/17
5/26
6/1
6/8
6/15
6/21
6/28
7/5
7/12
7/19
7/26
8/2
8/9
8/17
8/23
8/29
9/5
9/12
9/19
9/26
10/3
10/10
10/15
10/25
10/31
Figure 17: Spatial variations in NO3-N concentrations at sites 1 through 9 (Group A)
26
Spatial distributions of NO3-N (Group B sites)
25
Concentrations (mg/L)
20
15
10
5
0
Beaver
Creek@New
Hartford
Beaver
Cedar
Cedar
Creek@Cedar Falls River@Cedar Falls River@Waterloo
Black Hawk
Creek@Waterloo
Black Hawk
Cedar
Wolf Creek near
Creek@Hudson River@Gilbertville
Dysart
4/5
4/19
4/25
5/3
5/10
5/17
5/26
6/1
6/8
6/15
6/21
6/28
7/5
7/12
7/19
7/26
8/2
8/9
8/17
8/23
8/29
9/5
9/12
9/19
9/26
10/3
10/10
10/15
10/25
10/31
Figure 18: Spatial variations in NO3-N concentrations at sites 10 through 18 (Group B)
27
Cedar River near
La Porte City
Main River
28
Tributaries
Figure 19: Average NO3-N concentrations at all sites during Phase 1 (April – October, 2014)
Wolf Creek near Dysart
Black Hawk Creek@Hudson
Black Hawk Creek@Waterloo
Beaver Creek@Cedar Falls
Beaver Creek@New Hartford
West Fork Cedar River@Finchford
West Fork Cedar River near Kesley
Shell Rock@Shell Rock
Shell Rock River near Clarksville
Shell Rock River@Marble Rock
Little Cedar River near Ionia
Cedar River near La Porte City
Cedar River@Gilbertville
Cedar River@Waterloo
Cedar River@Cedar Falls
Cedar River@Janesville
Cedar River@Waverly
Cedar River@Charles City
Concentrations (mg/L)
Average NO3-N Concentrations
14
12
10
8
6
4
2
0
NO3-N Loads at sites 1 through 9 (Group A sites)
1000
Loads (tons/day)
100
10
1
0.1
Cedar River @ Charles City
Cedar River @ Waverly
Cedar River @ Janesville
Little Cedar River near Ionia
Shell Rock River @ Shell
Rock
4/5
4/19
4/25
5/3
5/10
5/17
5/26
6/1
6/8
6/15
6/21
6/28
7/5
7/12
7/19
7/26
8/2
8/9
8/17
8/23
8/29
9/5
9/12
9/19
9/26
10/3
10/10
10/15
10/25
10/31
Figure 20: NO3-N loads (in tons/day) at sites 1 through 9 (Group A)
29
West Fork Cedar River @
Finchford
NO3-N Loads at sites 10 through 18 (Group B sites)
10000
Loads (tons/day)
1000
100
10
1
0.1
Cedar River @ Cedar Falls
Cedar River @ Waterloo
Beaver Creek @ New Hartford
Black Hawk Creek @ Hudson
Wolf Creek near Dysart
4/5
4/19
4/25
5/3
5/10
5/17
5/26
6/1
6/8
6/15
6/21
6/28
7/5
7/12
7/19
7/26
8/2
8/9
8/17
8/23
8/29
9/5
9/12
9/19
9/26
10/3
10/10
10/15
10/25
10/31
Figure 21: NO3-N loads (in tons/day) at sites 10 through 18 (Group B)
30
Figure 22: Seasonal distributions of NO3-N (Phase 1)
31
Figure 23: Average NO3-N load distributions at 11 sites where discharge data are available (see report)
32
Figure 24: Seasonal distributions of total phosphorus (TP)
33
Figure 25: Average TP load distributions at 11 sites where discharge data are available (see report)
34
Precipitation Vs Total Phosphorus Concentration
500
25
450
400
20
300
15
250
200
10
Precipitation (mm)
Concentration (µg/L)
350
150
100
5
50
CedarRiver @ CharlesCity
LittleCedarRiver near Ionia
ShellRockRiver @ MarbleRock
10/31
10/25
10/15
10/3
10/10
9/26
9/19
9/12
9/5
8/29
8/23
8/9
8/17
8/2
7/26
7/19
7/5
7/12
6/28
6/21
6/15
6/8
6/1
5/26
5/17
5/10
5/3
4/25
4/5
0
4/19
0
Precipitation
Figure 26: Temporal variations in TP as compared to rainfall [Weather Station: Charles City (Floyd)]
35
Precipitation Vs Total Phosphorus Concentration
400
18
350
16
Concentration (µg/L)
12
250
10
200
8
150
6
100
Precipitation (mm)
14
300
4
2
0
0
4/5
4/19
4/25
5/3
5/10
5/17
5/26
6/1
6/8
6/15
6/21
6/28
7/5
7/12
7/19
7/26
8/2
8/9
8/17
8/23
8/29
9/5
9/12
9/19
9/26
10/3
10/10
10/15
10/25
10/31
50
ShellRockRiver @ Clarksville
CedarRiver @ Waverly
ShellRockRiver @ ShellRock
Precipitation
WestForkCedarRiver near Kesley
Figure 27: Temporal variations in TP as compared to rainfall [Weather Station: Alison (Butler)]
36
Precipitation Vs Total Phosphorus Concentration
[Main Channel]
400
18
350
16
Concentration (µg/L)
Precipitation (mm)
14
300
12
250
10
200
8
150
6
100
4
CedarRiver @ Janesville
CedarRiver @ Gilbertville
CedarRiver @ CedarFalls
CedarRiver @ LaPorteCity
10/31
10/25
10/15
10/3
10/10
9/26
9/19
9/12
9/5
8/29
8/23
8/9
8/17
8/2
7/26
7/19
7/12
7/5
6/28
6/21
6/8
6/15
6/1
5/26
5/17
5/3
5/10
0
4/25
0
4/5
2
4/19
50
CedarRiver @ Waterloo
Precipitation
Figure 28: Temporal variations in TP as compared to rainfall [Weather Station: Waterloo Municipal Airport (Black Hawk)]
37
18
400
16
350
14
300
12
250
10
200
8
150
6
100
4
50
2
0
0
Precipitation (mm)
450
4/5
4/19
4/25
5/3
5/10
5/17
5/26
6/1
6/8
6/15
6/21
6/28
7/5
7/12
7/19
7/26
8/2
8/9
8/17
8/23
8/29
9/5
9/12
9/19
9/26
10/3
10/10
10/15
10/25
10/31
Concentration (µg/L)
Precipitation Vs Total Phosphorus Concentration
[Tributaries]
WestForkCedarRiver @ Finchford
BeaverCreek @ NewHartford
BeaverCreek @ CedarFalls
BlackHawkCreek @ Waterloo
BlackHawkCreek @ Hudson
Precipitation
Figure 29: Temporal variations in TP as compared to rainfall [Weather Station: Waterloo Municipal Airport (Black Hawk)]
38
4/5
4/19
4/25
5/3
5/10
5/17
5/26
6/1
6/8
6/15
6/21
6/28
7/5
7/12
7/19
7/26
8/2
8/9
8/17
8/23
8/29
9/5
9/12
9/19
9/26
10/3
10/10
10/15
10/25
10/31
Average TP Concentration (µg/L)
350
140
300
120
250
100
200
80
150
60
100
40
50
20
0
0
Sampling dates
Figure 30: Relationships between total suspended solids and total phosphorus (Sites 1 – 18)
39
Average TSS Concentration (mg/L)
Relationship between TSS and TP
Figure 31: Average T concentrations at sites 1 – 18 (Phase 1)
40
Figure 32: Average NO3 - N concentrations at sites 1 – 18 (Phase 1)
41
Figure 33: Average TSS concentrations at sites 1 – 18 (Phase 1)
42
Monthly Average NO3-N Loads (tons/day)
Site_ID
Name of sites
April
May
June
July
August
September
October
Average
Load
(tons/day)
Total Load
(for 7
months)
Subwatershed_Area
(acre)
Total Loads
[tons/acre]
(for 7
months)
Total Loads
[pounds/acre]
(Apr-Oct)
S1
Cedar River @ Charles
City
29.42
77.94
103.54
21.97
3.73
8.36
9.43
36.343
7631.986
686563.5123
1.E-02
22.23
S2
Little Cedar River
12.64
23.11
29.33
8.42
0.55
2.55
3.78
11.485
2411.752
189413.6103
1.E-02
25.47
S5
Shell Rock River
20.07
90.30
114.19
45.45
4.37
10.03
8.42
41.833
8784.963
1091331.079
8.E-03
16.10
S8
Cedar River @ Waverly
32.23
132.96
167.51
52.09
5.25
11.70
11.52
59.037
12397.731
996235.3056
1.E-02
24.89
S7
West Fork Cedar River
Cedar River @
Janesville
18.36
81.04
72.59
75.08
6.31
10.18
8.88
38.919
8172.921
542370.3165
2.E-02
30.14
38.65
142.87
171.19
59.72
5.58
11.92
13.34
63.325
13298.158
1067863.985
1.E-02
24.91
4.28
18.26
34.88
25.78
1.57
1.40
3.80
12.852
2698.919
251845.5994
1.E-02
21.43
20.43
93.29
98.32
64.34
18.73
35.76
36.18
52.437
11011.704
3007499.163
4.E-03
7.32
3.78
7.74
35.03
17.36
1.18
0.47
1.23
9.544
2004.138
209267.6794
1.E-02
19.15
77.44
334.64
376.52
222.71
28.56
26.51
29.82
156.602
32886.370
3260286.826
1.E-02
20.17
2.88
6.64
19.40
21.54
2.21
2.27
3.69
8.377
1759.240
190907.6582
9.E-03
18.43
S9
S10
S12
S15
Beaver Creek
Cedar River @ Cedar
Falls
S13
Black Hawk Creek
Cedar River @
Waterloo
S17
Wolf Creek
Figure 34: NO3 – N load calculations at 11 selected sites (shown from upstream to downstream locations)
43
Monthly Average Phosphorus Loads (tons/day)
Site_ID
Subwatersheds
April
May
June
July
August
September
October
Average
Load
(tons/day)
Total
Load
(for 7
months)
Subwatershed_Area
(acre)
Total Loads
[tons/acre]
(for 7
months)
Total Loads
[pounds/acre]
(Apr-Oct)
S1
Cedar River @ Charles
City
0.875
0.665
2.057
0.251
0.122
0.188
0.138
0.614
128.861
686563.5123
2.E-04
0.375
S2
Little Cedar River
0.522
0.183
0.480
0.076
0.018
0.066
0.040
0.198
41.527
189413.6103
2.E-04
0.438
S5
Shell Rock River
0.917
1.066
3.150
1.102
0.199
0.451
0.142
1.004
210.803
1091331.079
2.E-04
0.386
S8
Cedar River @ Waverly
1.322
1.392
3.780
0.635
0.168
0.369
0.154
1.117
234.643
996235.3056
2.E-04
0.471
S7
West Fork Cedar River
Cedar River @
Janesville
0.444
0.734
1.820
0.966
0.098
0.183
0.077
0.617
129.618
542370.3165
2.E-04
0.478
1.685
1.607
3.561
0.711
0.170
0.402
0.188
1.189
249.722
1067863.985
2.E-04
0.468
Beaver Creek
Cedar River @ Cedar
Falls
0.084
0.160
1.246
0.304
0.032
0.032
0.055
0.273
57.393
251845.5994
2.E-04
0.456
2.753
4.292
9.233
3.431
0.486
1.204
0.472
3.124
656.135
3007499.163
2.E-04
0.436
0.075
0.068
1.267
0.173
0.026
0.018
0.027
0.236
49.653
209267.6794
2.E-04
0.475
S13
Black Hawk Creek
Cedar River @
Waterloo
3.210
4.143
7.978
3.683
0.571
1.448
0.614
3.092
649.393
3260286.826
2.E-04
0.398
S17
Wolf Creek
0.062
0.065
0.382
0.230
0.039
0.049
0.060
0.127
26.619
190907.6582
1.E-04
0.279
S9
S10
S12
S15
Figure 35: TP load calculations at 11 selected sites (shown from upstream to downstream locations)
44
Monthly Average TSS Loads (tons/day)
Site_ID
Name of sites
Average Load
(tons/day)
Total Load
(for 7
months)
Subwatershed_Area
(acre)
Total Loads
[tons/acre]
(for 7
months)
Total Loads
[pounds/acre]
(Apr-Oct)
April
May
June
July
August
September
October
38.05
16.36
42.21
16.20
21.20
7.80
3.42
20.748
4357.113
686563.5123
6.E-03
12.69
S1
Cedar River @ Charles
City
S2
Little Cedar River
156.07
48.90
52.56
26.43
17.80
24.75
10.12
48.091
10099.158
189413.6103
5.E-02
106.64
S5
Shell Rock River
47.64
28.69
37.21
25.98
22.70
14.47
5.02
25.957
5451.064
1091331.079
5.E-03
9.99
S8
Cedar River @ Waverly
42.51
36.15
56.19
32.85
19.43
14.93
6.68
29.819
6261.981
996235.3056
6.E-03
12.57
S7
West Fork Cedar River
64.02
39.69
44.01
44.43
25.83
30.09
14.92
37.570
7889.651
542370.3165
1.E-02
29.09
S9
Cedar River @ Janesville
35.97
41.52
55.73
33.17
31.38
17.08
3.58
31.205
6552.973
1067863.985
6.E-03
12.27
S10
Beaver Creek
28.12
54.20
60.06
45.34
21.81
15.69
14.33
34.221
7186.390
251845.5994
3.E-02
57.07
S12
Cedar River @ Cedar Falls
39.21
32.44
65.03
33.83
24.56
11.45
5.94
30.349
6373.332
3007499.163
2.E-03
4.24
S15
Black Hawk Creek
24.18
19.14
86.31
44.64
12.17
8.20
10.63
29.324
6158.088
209267.6794
3.E-02
58.85
S13
Cedar River @ Waterloo
31.66
28.43
38.17
29.18
22.16
15.05
7.72
24.623
5170.738
3260286.826
2.E-03
3.17
S17
Wolf Creek
29.49
43.61
239.40
83.60
14.46
24.20
34.20
66.995
14069.037
190907.6582
7.E-02
147.39
Figure 36: TSS load calculations at 11 selected sites (shown from upstream to downstream locations)
45
Site_ID
Name of sites
Total NO3-N Loads
[pounds/acre] (Apr-Oct)
Total TP Loads
[pounds/acre] (Apr-Oct)
Total TSS Loads
[pounds/acre] (Apr-Oct)
S1
Cedar River @ Charles City
22.23
0.375
12.69
S2
Little Cedar River
25.47
0.438
106.64
S5
Shell Rock River
16.10
0.386
9.99
S8
Cedar River @ Waverly
24.89
0.471
12.57
S7
West Fork Cedar River
30.14
0.478
29.09
S9
Cedar River @ Janesville
24.91
0.468
12.27
S10
Beaver Creek
21.43
0.456
57.07
S12
Cedar River @ Cedar Falls
7.32
0.436
4.24
S15
Black Hawk Creek
19.15
0.475
58.85
S13
Cedar River @ Waterloo
20.17
0.398
3.17
S17
Wolf Creek
18.43
0.279
147.39
Figure 37: NO3 – N, TP and TSS load comparison in 11 selected sites (shown from upstream to downstream loactions)
46
Figure 38: Phase 1 study area with delineated sub-watersheds
47
Figure 39: NO3 – N loads per acre and percent row crops shown for each sub-watershed (Phase 1)
48
Figure 40: Total NO3 – N loads for the year and percent row crops shown for each sub-watershed (Phase 1)
49
Figure 41: TP loads per acre and percent row crops shown for each sub-watershed (Phase 1)
50
Figure 42: Total TP loads for the year and percent row crops shown for each sub-watershed (Phase 1)
51
Temporal Distributions of Total Phosphorus in Sediments
800
120%
100%
700
100%
80%
Concentrations (µgP/gdw)
600
60%
500
40%
35%
400
17%
20%
0%
0%
-14%
300
-6%
-26%
200
-45%
100
-20%
-40%
-48%
-60%
-60%
0
-80%
4/5
4/19
5/10
Cedar River@Charles City
Shell Rock River near Clarksville
West Fork Cedar River@Finchford
%change
6/1
7/19
8/9
8/29
9/19
Little Cedar River near Ionia
Shell Rock@Shell Rock
Cedar River@Waverly
10/10
10/31
Shell Rock River@Marble Rock
West Fork Cedar River near Kesley
Cedar River@Janesville
Figure 43: Temporal distributions of TP in stream sediments at 9 selected sites from Group A
52
Temporal Distributions of Total Phosphorus in Sediments
800
80%
64%
700
60%
48%
600
40%
Concentrations (µgP/gdw)
36%
500
20%
0%
400
0%
0%
300
-17%
-20%
-15%
200
-37%
-40%
-55%
100
-58%
0
-60%
-80%
4/5
4/19
5/10
Beaver Creek@New Hartford
Black Hawk Creek@Waterloo
Wolf Creek near Dysart
6/1
7/19
8/9
8/29
9/19
Beaver Creek@Cedar Falls
Black Hawk Creek@Hudson
Cedar River near La Porte City
10/10
10/31
Cedar River@Cedar Falls
Cedar River@Gilbertville
%change
Figure 44: Temporal distributions of TP in stream sediments at 8 selected sites from Group B
53
Spatial distributions of Total Phosphorus in sediments
800
4/5
4/19
5/10
6/1
7/19
8/9
8/29
9/19
10/10
10/31
Concentratoins (µgP/gdw)
700
600
500
400
300
200
100
0
Cedar
Little Cedar River
Shell Rock
Shell Rock River Shell Rock@Shell West Fork Cedar West Fork Cedar
Cedar
Cedar
River@Charles
near Ionia
River@Marble near Clarksville
Rock
River near Kesley River@Finchford River@Waverly River@Janesville
City
Rock
Figure 45: Spatial distributions of TP in stream sediments at 9 selected sites from Group A
54
Spatial distributions of Total Phosphorus in sediments
800
4/5
4/19
5/10
6/1
7/19
8/9
8/29
9/19
10/10
10/31
Concentratoins (µgP/gdw)
700
600
500
400
300
200
100
0
Beaver
Creek@New
Hartford
Beaver
Cedar
Black Hawk
Creek@Cedar Falls River@Cedar Falls Creek@Waterloo
Black Hawk
Cedar
Wolf Creek near
Creek@Hudson River@Gilbertville
Dysart
Figure 46: Spatial distributions of TP in stream sediments at 8 selected sites from Group B
55
Cedar River near
La Porte City
Relationship of TPwater and TPsediment with TSS
500
800
TPwater
TPsediments
700
400
600
R² = 0.1189
TPwater
400
200
300
200
100
100
R² = 0.0004
0
0
0
100
200
300
400
TSS
Figure 47: Relationships of dissolved P and adsorbed P with TSS
56
500
600
TPsediments
500
300
Figure 48: Map showing 10 sites from Phase 2 of the study (sites 19 – 28)
57
Temporal Distributions of TSS
1000
250
Log Concentration (mg/L)
192.17
150
110.01
10
100
1
41.68
54.45
46.03
50.78
42.77
39.49
45.55
41.98
50
50.67
26.85
27.48
13.94
16.04
17.12
0
4-Apr
0
18-Apr 2-May 15-May 30-May 13-Jun 28-Jun
11-Jul
26-Jul
8-Aug 21-Aug
4-Sep
Cedar River near Brandon
Cedar River @ Vinton
Cedar River near Urbana
Indian Creek @ Marion
Cedar River @ Cedar Rapids
Average
Figure 49: Temporal distributions of TSS (Phase 2)
58
18-Sep
8-Oct
23-Oct 30-Oct
Cedar River @ Palo
Average Concentration (mg/L)
200
100
TSS Distributions at Selected Sites
of the Study Area
1000
Log Concentration (mg/L)
4-Apr
18-Apr
2-May
15-May
30-May
13-Jun
28-Jun
11-Jul
26-Jul
8-Aug
21-Aug
4-Sep
18-Sep
8-Oct
23-Oct
30-Oct
100
10
1
Cedar River near Brandon Cedar River @ Vinton Cedar River near Urbana
Cedar River @ Palo
Figure 50: Spatial distributions of TSS (Phase 2)
59
Indian Creek @ Marion
Cedar River @ Cedar
Rapids
Monthly Average TSS Loads (tons/day)
ID
April
May
June
July
Aug
Sep
Oct
Average
Load
(tons/day)
Name of sites
Total Load
(for 7
months)
Subwatershed_Area
(acre)
Total Loads
[tons/acre] (for
7 months)
Total Loads
[pounds/acre]
(Apr-Oct)
S20
Cedar River at Vinton
769.55
580.49
3498.83
585.58
375.20
724.25
110.67
949.224
199336.973
3823736.241
5.E-02
104.26
S22
Cedar River at Palo
760.85
3804.01
3222.36
758.09
716.78
758.09
156.11
1453.755
305288.535
4019579.024
8.E-02
151.90
S23
Indian Creek at Marion
0.13
0.46
162.50
1.57
0.55
11.67
0.42
25.330
5319.304
43572.91438
1.E-01
244.16
S24
Cedar River at Cedar Rapids
361.48
534.07
9758.98
401.85
236.39
530.18
193.00
1716.565
360478.630
4126629.079
9.E-02
174.71
Figure 51: Load calculations of TSS at sites 20, 22, 23 and 24
60
Temporal Distributions of Total Phosphorus
450
150%
129%
400
89%
Concentrations (µg/L)
350
100%
58%
300
53%
50%
250
200
0%
37%
31%
1%
0%
-1%
150
-45%
-21%
100
-19%
-55%
-31%
-46%
-40%
-50%
50
0
-100%
4-Apr
18-Apr 2-May 15-May 30-May 13-Jun 28-Jun
11-Jul
26-Jul
8-Aug 21-Aug 4-Sep
Cedar River near Brandon
Cedar River @ Vinton
Cedar River near Urbana
Indian Creek @ Marion
Cedar River @ Cedar Rapids
%change
Figure 52: Temporal distributions of total phosphorus at selected sites (Phase 2)
61
18-Sep
8-Oct
23-Oct 30-Oct
Cedar River @ Palo
Total Phosphorus Distributions at Six Sites
of the Study Area
450
400
4-Apr
13-Jun
21-Aug
30-Oct
18-Apr
28-Jun
4-Sep
Recommended Level
2-May
11-Jul
18-Sep
15-May
26-Jul
8-Oct
30-May
8-Aug
23-Oct
Concentratoins (µg/L)
350
300
250
200
150
100
50
0
Cedar River near Brandon Cedar River @ Vinton
Cedar River near Urbana
Cedar River @ Palo
Figure 53: Spatial distributions of total phosphorus at selected sites (Phase 2)
62
Indian Creek @ Marion
Cedar River @ Cedar
Rapids
Monthly Average Phosphorus Loads (tons/day)
ID
April
May
June
July
Aug
Sep
Oct
Average
Load
(tons/day)
Name of sites
Total Load
(for 7
months)
Subwatershed_Area
(acre)
Total Loads
[tons/acre] (for
7months)
Total Loads
[pounds/acre]
(Apr-Oct)
S20
Cedar River at Vinton
3.86
2.45
8.51
1.25
1.63
1.54
0.70
2.849
598.312
3823736.241
2.E-04
0.31
S22
Cedar River at Palo
2.61
2.89
14.34
1.72
2.33
2.67
0.71
3.897
818.321
4019579.024
2.E-04
0.41
S23
Indian Creek at Marion
Cedar River at Cedar
Rapids
0.00
0.01
0.36
0.02
0.01
0.03
0.01
0.062
13.001
43572.91438
3.E-04
0.60
2.67
2.42
13.73
1.26
1.93
2.80
0.70
3.644
765.264
4126629.079
2.E-04
0.37
S24
Figure 54: Load calculations of TP at sites 20, 22, 23 and 24
63
Temporal distributions of NO3-N concentrations
25
300%
250%
246%
200%
183%
15
150%
141%
74%
10
50%
0%
5
100%
77%
-12% -3%
17%
7%
-29%
-23%
-45% -44%
0%
-39%
-50%
-79%
0
-100%
4-Apr 18-Apr 2-May 15-May 30-May 13-Jun 28-Jun 11-Jul
Cedar River near Brandon
Cedar River @ Palo
%Change
26-Jul 8-Aug 21-Aug 4-Sep 18-Sep 8-Oct 23-Oct 30-Oct
Cedar River @ Vinton
Indian Creek @ Marion
Cedar River near Urbana
Cedar River @ Cedar Rapids
Figure 55: Temporal distributions of NO3-N at selected sites (Phase 2)
64
Percent change (%)
Concentrations (mg/L)
20
NO3-N concentrations at six sites of the study area
25
Concentrations (mg/L)
20
15
10
5
0
Cedar River near
Brandon
4-Apr
26-Jul
Cedar River @ Vinton
18-Apr
Cedar River near
Urbana
2-May
15-May
8-Aug
21-Aug
4-Sep
Cedar River @ Palo
30-May
Indian Creek @
Cedar River @ Cedar
Marion
Rapids
13-Jun
28-Jun
11-Jul
18-Sep
8-Oct
Figure 56: Spatial distributions of NO3-N at selected sites (Phase 2)
65
23-Oct
30-Oct
Monthly Average NO3-N Loads (tons/day)
ID
Name of sites
April
May
June
July
Aug
Sep
Oct
Average
Load
(tons/day)
Total Load
(for 7
months)
Subwatershed_Area
(acre)
Total Loads
[tons/acre] (for
7months)
Total Loads
[pounds/acre]
(Apr-Oct)
S20
Cedar River at Vinton
142.47
194.68
234.23
137.83
38.28
81.84
36.25
123.655
25967.447
3823736.241
7.E-03
13.58
S22
Cedar River at Palo
127.42
216.01
313.88
126.08
42.80
101.16
40.39
138.247
29031.867
4019579.024
7.E-03
14.45
S23
Indian Creek at Marion
Cedar River at Cedar
Rapids
0.21
1.69
19.48
1.26
0.05
0.11
0.46
3.321
697.380
43572.91438
2.E-02
32.01
128.94
229.23
404.73
129.77
39.95
96.71
40.58
152.842
32096.881
4126629.079
8.E-03
15.56
S24
Figure 57: Load calculations of NO3-N at sites 20, 22, 23 and 24
66
ID
Name of sites
Sub-watershed Area
(acre)
Total NO3-N
Loads
[pounds/acre]
(Apr-Oct)
Total TP Loads
[pounds/acre]
(Apr-Oct)
Total TSS Loads
[pounds/acre]
(Apr-Oct)
S20
Cedar River at Vinton
3823736.241
13.58
0.31
104.26
S22
Cedar River at Palo
4019579.024
14.45
0.41
151.90
S23
Indian Creek at Marion
43572.91438
32.01
0.60
244.16
S24
Cedar River at Cedar Rapids
4126629.079
15.56
0.37
174.71
Figure 58: Loads comparison of NO3-N, TP and TSS at sites 20, 22, 23 and 24 (Phase 2)
67
Relationship between TSS and TP
450
y = 0.4784x + 149.78
R² = 0.1474
400
350
TSS (mg/L)
300
250
200
150
100
50
0
0
50
100
150
200
250
300
Total phosphorus (µg/L)
Figure 59: Relationships between TSS and TP (Phase 2)
68
350
400
450
500
Relationship of TPwater and TPsediment with TSS
450
900
400
800
350
700
300
600
250
500
200
400
R² = 0.0015
150
TPsediments
TPwater
R² = 0.1474
300
100
200
50
TPwater
TPsediments
0
0
50
100
150
200
250
300
350
400
100
0
450
TSS
Figure 60: Relationships of dissolved TP and sediment-adsorbed TP with TSS (Phase 2)
69
Spatial distributions of total phosphorus in sediments
1000
2-May
13-Jun
11-Jul
21-Aug
18-Sep
mg/kg (dry wt)
800
600
400
200
0
S19
S20
S21
S22
S23
Sites
Figure 61: Spatial distributions of phosphorus in stream sediments at sites 19 – 24
70
S24
Site_ID
Site 25
Site 26
Site 27
Site 28
Date
4.4.15
4.4.15
4.4.15
4.4.15
pH
9.09
7.98
9.15
8.88
Temp
14.00
11.20
14.00
14.30
DO
11.50
14.86
15.29
11.08
Conductivity
618
585
611
597
TDS
420
411
420
405
Turbidity
17.00
2.70
12.80
26.70
TSS
50.89
0.50
60.30
71.05
Chloride
43.61
17.16
40.68
27.20
Sulfate
44.28
13.62
43.82
38.29
NO3-N
3.90
5.34
3.47
3.14
T. Phosphorus
290.0
120.0
230.0
180.0
Site 25
Site 26
Site 27
Site 28
8.8.15
8.8.15
8.8.15
8.8.15
8.86
8.29
8.88
8.81
25.60
21.80
26.50
26.40
9.26
8.52
9.96
8.11
591
631
558
528
407
437
385
381
32.80
14.60
46.20
41.20
51.20
18.90
62.00
95.20
27.95
20.37
25.22
24.04
34.91
26.07
32.25
31.50
6.08
5.33
5.83
6.02
260.0
180.0
190.0
200.0
Site 25
Site 26
Site 27
Site 28
10.30.15
10.30.15
10.30.15
10.30.15
9.28
7.92
9.35
9.33
10.60
13.30
11.30
10.70
11.70
8.43
11.92
10.98
594
636
524
520
408
441
362
354
25.80
4.85
46.00
54.20
47.78
4.00
73.50
121.37
35.62
16.99
31.54
33.85
36.79
17.67
36.21
35.45
5.89
6.21
4.20
3.42
120.0
160.0
60.0
60.0
Fig. 62: Data recorded at sites 25, 26, 27 and 28 during early, middle and late seasons of 2015 (Phase 2)
71