ILLINOIS WATER AND
CLIMATE SUMMARY
APRIL 2017 OVERVIEW
April 2017
(411(:65+1-4(
Figure 1
Statewide departures from normal
Temperatures and precipitation in April were above the long-term average
in Illinois. Mean streamflow statewide was above the median for the month.
Shallow groundwater levels were above the long-term average depths.
Air temperatures averaged 56.5 degrees in April, 3.9 degrees above
the long-term average (Figure 1). The northwest and northeast crop
reporting districts (CRDs) had the lowest monthly temperature with
52.8 degrees. The highest average of 60.2 degrees was reported in the
southwest district.
Precipitation averaged 6.43 inches, 2.65 inches above the longterm average (Figure 1). The east CRD received the least amount with an
average of 4.73 inches. The wettest for the month was the southwest
district with 8.91 inches.
Soil moisture was high at the end of April with network averages
ranging from 0.44 water fraction by volume (wfv) at 2 inches to 0.43 wfv
at 59 inches. Levels were above the field capacity at most monitoring
locations.
Mean provisional streamflow aggregated statewide was above the
long-term median flow for April, about 160 percent of median (Figure 1).
Monthly mean discharge values ranged generally from normal for the
month in southern Illinois to above normal in northern Illinois. River stages
exceeded local flood stages in mid-April and at the end of the month at
many Illinois River stations, on middle and lower Mississippi River reaches
along the Illinois border, and at Cairo on the Ohio River.
Water surface levels at the end of April were above or near the full
pool or target level at all reporting reservoirs. At the end of April, Rend
Lake was 5.1 feet above the spillway level, Carlyle Lake was 1.0 foot
above the May 1 target level, and Lake Shelbyville was 0.1 foot above the
May 1 target level.
Lake Michigan’s level was above its long-term mean for the month.
Shallow groundwater levels statewide were above normal this month
with an average departure of 1.8 feet (Figure 1). An increase of 1.7 feet in
departure was observed from the deviation in normal groundwater levels
between March and April. Levels averaged 1.7 feet above March levels
and were 1.5 feet above April levels of last year.
Water and Atmospheric Resources Monitoring Program | www.isws.illinois.edu/warm
Contact Jennie R. Atkins: (217) 333-4966, email: [email protected]
WEATHER/CLIMATE INFORMATION
Precipitation was above normal in April, averaging
6.43 inches or 2.65 inches above the long-term
average. April 2017 was the second wettest on record.
Most stations reported totals of 5 inches or more.
Twelve stations, all in southern Illinois, had totals of
more than 10 inches.
The majority of the rain fell in the last week of the
month. The state averaged 4.25 inches from April
23 to 30, more than 60 percent of the month’s total.
The last weekend, April 28–30, was especially wet.
Most stations reported three-day totals of more than
3 inches. A Carbondale station in Jackson County
recorded 9.03 inches that weekend, 5.21 inches on
April 29.
This year has been wetter than average for most
of the state. Illinois received 12.86 inches in January–
April, 2.00 inches above the long-term average.
Severe weather reports from the NOAA Storm
Prediction Center totaled 100 in April with four reports
for tornadoes, 34 for hail, and 62 for wind. (A single
event may generate multiple reports.)
Illinois was drought free at the end of April. The
May 2 report from the U.S. Drought Monitor listed
0 percent of the state as abnormally dry or in drought.
—Jim Angel and Jennie Atkins
The following description of precipitation,
temperature, and snowfall (in winter) comes from
data compiled by a number of networks that report to
the National Oceanic and Atmospheric Administration
(NOAA). There are over 650 reporting sites in Illinois
alone. These data are provisional and may change
slightly over time.
Temperatures averaged 56.5 degrees for April,
3.9 degrees above the long-term average. Highs
reached into the 80s at most stations. The month’s
highest temperature was 89 degrees, recorded on
April 20 at the Kaskaskia Lock and Dam in Randolph
County. Monthly lows were in the 20s and 30s. Two
stations, Aurora in Kane County and Neoga 4NW in
Shelby County, tied for April’s lowest temperature with
22 degrees.
So far, every month in 2017 has had above-average
temperatures. January–April temperatures averaged
43.2 degrees, 5.4 degrees above the long-term
average. It was the second warmest January–April on
record. The warmest year on record was 2012 with an
average of 44.4 degrees.
Growing Degree Days (DD, base 50, since April 1)
ranged from 150 to 450 DD across Illinois, 20 to 80 DD
above the long-term average.
Table 1. Temperature and Precipitation for April 2017
Temperature
(°F)
Departure
from long-term average
(1981 – 2010)
Precipitation
(in)
Illinois
56.5
+ 3.9
6.43
CRD 1 (northwest)
52.8
+ 3.1
5.39
CRD 2 (northeast)
52.8
+ 3.6
5.45
CRD 3 (west)
55.8
+ 3.6
5.82
CRD 4 (central)
56.3
+ 4.4
5.44
CRD 5 (east)
55.6
+ 4.3
4.73
CRD 6 (west southwest)
58.3
+ 4.3
7.80
CRD 7 (east southeast)
57.7
+ 3.7
6.98
CRD 8 (southwest)
60.2
+ 4.0
8.91
CRD 9 (southeast)
60.1
+ 4.0
7.67
_______________
Notes:
Data from NOAA’s National Centers for Environmental Information, accessed 5/8/2017.
2
Departure
from long-term average
(1981 – 2010)
+ 2.65
+ 1.96
+ 2.01
+ 2.06
+ 1.82
+ 1.12
+ 4.01
+ 3.00
+ 4.72
+ 3.31
Figure 2a
Illinois precipitation, temperature, and their departures from average for April 2017
Source: cli-MATE, Midwestern Regional Climate Center. http://mrcc.illinois.edu/CLIMATE accessed on May 1, 2017
Figure 2b
Illinois growing degree days and departure from average for April 2017
Source: Midwestern Regional Climate Center. http://mrcc.illinois.edu accessed on: May 1, 2017
3
Figure 3
Illinois precipitation and precipitation departure from average for
year to date (top), last 6 months (middle), and last 3 months (bottom)
Source: cli-MATE, Midwestern Regional Climate Center. http://mrcc.illinois.edu/CLIMATE accessed on May 1, 2017
4
Figure 4
U.S. Drought Monitor report for Illinois
Source: U.S. Drought Monitor. http://droughtmonitor.unl.edu accessed on May 4, 2017
ILLINOIS CLIMATE NETWORK (ICN)
8 inches. Temperatures under bare soil ranged from
85.2 to 34.9 degrees at 2 inches and 85.4 to 34.4 at
4 inches.
Precipitation was heavy across the network in
April, averaging 7.70 inches, which is 4.42 inches
higher than in March and 4.10 inches higher than April’s
long-term average. Station totals were 50 to more than
200 percent greater than their long-term averages.
The majority of the rain fell the last week of the
month when the network received 4.94 inches, or
64 percent of the month’s total. The highest totals
were in southern Illinois where Carbondale reported
14.05 inches, the largest amount of precipitation for
the month.
Soil moisture steadily declined for the first three
weeks of April. Levels at 2 inches fell 30 percent from
April 1 to April 25. Heavy precipitation the last week led
to soil moisture increases of more than 50 percent to
end the month with a network average of 0.44 water
fraction by volume (wfv).
Similar patterns were seen in soil moisture levels
at 4 and 8 inches. Slight increases also occurred at
20-inch depths. Soil moisture remained high at 39 and
59 inches with April 30 averages of 0.44 and 0.43 wfv,
respectively.
—Jennie Atkins
The Illinois Climate Network (ICN) consists of 19
stations across the state that collect hourly weather
and soil information. ICN data for April are presented in
Table 2.
Wind speeds were slightly lower than in March,
averaging 8.3 mph for the network. Bondville had
the highest average wind speed with 13.5 mph. The
highest wind gust was 53.9 mph, recorded at the Olney
station on April 26.
Air temperatures rose 14 degrees from March to
an average of 58.1 degrees, and 4.7 degrees above
the long-term average. Highs reached into the 80s at
all except one station with monthly lows in the 30s.
The month’s highest temperature was 86.4 degrees
recorded at Belleville on April 19. The lowest was
30.6 degrees, which was reported at Freeport on
April 1.
Soil temperatures rose 10 to 13 degrees from the
March averages to the mid- to high 50s. Temperatures
were 3 to 4 degrees above the long-term network
averages. Lows reached into the 30s under bare soil
but remained above freezing at all stations. Under
sod, temperatures ranged from 74.1 to 40.2 degrees
at depths of 4 inches and 75.4 to 41.3 degrees at
5
Table 2. Data from the Illinois Climate Network (ICN), April 2017
Station
Ave Wind
Speed
(mph)
Ave Wind
Direction
(°)
Maximum
Wind Gust
(mph)
8.2
8.7
13.5
7.6
7.5
5.4
10.7
4.7
7.6
5.8
11.8 M
6.6
8.5
7.4
5.7
10.6
7.0
7.8
11.9
165.2
171.6
168.1
169.8
178.6
165.0
171.5
164.1
157.0
166.6
174.5 M
164.8
177.1
181.5
164.6
172.4
171.0
154.8
163.8
36.4
36.2
42.8
39.1
39.3
29.5
44.1
34.4
39.6
31.7
46.2 M
53.9
45.4
38.2
34.2
44.0
37.4
37.1
43.2
Belleville
Big Bend
Bondville
Brownstown
Carbondale
Champaign
DeKalb
Dixon Springs
Fairfield
Freeport
Monmouth
Olney
Peoria
Perry
Rend Lake
Snicarte
Springfield
St. Charles
Stelle
Maximum Air
Temperature
(°F)
Minimum Air Average Air
Temperature Temperature
(°F)
(°F)
86.4
84.0
82.4
85.1
83.6
82.7
80.3
85.2
86.0
79.1
82.0 M
82.5
83.2
86.1
85.9
83.8
86.1 M
80.3
79.1
38.8
32.0
32.1
36.2
34.2
33.0
31.3
35.3
36.6
30.6
32.4 M
32.6
37.5
35.2
35.1
32.3
38.3 M
31.0
32.6
61.0
55.4
57.3
60.9
61.3
57.0
52.7
63.0
62.3
52.3
56.0 M
59.9
59.0
59.3
61.6
57.5
60.4 M
52.7
54.9
Table 2 continued
Station
Belleville
Big Bend
Bondville
Brownstown
Carbondale
Champaign
DeKalb
Dixon Springs
Fairfield
Freeport
Monmouth
Olney
Peoria
Perry
Rend Lake
Snicarte
Springfield
St. Charles
Stelle
Total Solar
Average
Radiation
Relative
(MJ/m2)
Humidity (%)
514.8
482.0
538.3
507.3
571.5
508.6
472.5
513.1
512.2
471.1
511.7 M
525.9
507.3
514.6
524.2
503.1
453.2 M
472.7
506.6
71.9
72.8
73.2
67.1
70.2
69.1
70.1
69.9
69.9
71.1
70.2
72.2
71.2
70.0
69.8
70.5
66.7
68.7
74.1
Total
Average
Precipitation Dew Point
(in)
(°F)
8.80
6.28
5.65
8.85
14.05
6.17
6.18
8.25
7.50
5.15
6.33 M
7.77
8.31
7.57
10.35
7.67
7.49
8.32
5.55
Total Potential
Evapotranspiration
(in)
50.6
45.3
47.4
48.6
50.1
45.8
41.7
51.8
51.2
41.9
44.8 M
49.7
48.3
47.9
50.5
46.6
47.4 M
41.4
45.7
4.2
3.74
4.22
4.19
4.59
3.85
3.66
4.11
4.23
3.40
4.08 M
4.09
4.00
4.15
4.18
4.10
3.79 M
3.60
3.8
_______________
Notes:
M = Missing data.
6
Ave Soil
Ave Soil
Ave Soil
Ave Soil
Temperature Temperature Temperature Temperature
at 4" under at 8" under at 2" under at 4" under
Sod (°F)
Sod (°F)
Bare Soil (°F) Bare Soil (°F)
58.9
53.6
55.6
57.2
60.1
59.5
50.6
62.5
59.9
54.3
53.6 M
59.6
55.5
57.5
60.4
58.2
58.0
52.9
54.3
57.6
53.4
54.6
55.7
59.8
58.0
50.7
62.2
59.2
51.7
52.7 M
59.0
55.8
56.7
60.5
58.0
56.5
51.2
53.5
60.5
55.8
58.7
58.6
61.0
60.0
54.8
64.7
62.6
55.4
55.7 M
60.7
56.4
58.6
62.5
62.0
59.2
53.7
55.5
58.8
54.8
57.9
58.4
60.5
59.3
53.6
61.3
58.2
51.9
55.4 M
60.2
55.9
58.1
61.9
57.9
58.5
54.4
53.6
Figure 5
April soil moisture levels at ICN stations.
2 in,
4 in, and
8 in
7
Figure 5
April soil moisture levels at ICN stations.
2 in,
4 in, and
8 in
8
OTHER PRECIPITATION NETWORKS
184 percent of the 24-year (1993-2016) IVWA April
network average of 3.43 inches. The Imperial Valley
Water Authority funds this 20-station precipitation
network operated by the Illinois State Water Survey.
Cook County. During April 2017, precipitation
in Cook County was well above normal (Figure 6b).
Total monthly precipitation amounts were greatest in
the east-central portion of the network and lowest
along the southern edge of the network. Precipitation
values ranged from 6.75 inches at site #4 (Skokie, near
Lincoln Ave and Oakton St) to 4.28 inches at site #24
(Matteson, near S. Cicero Ave and Lincoln Hwy). The
April 2017 network average of 5.56 inches is about
155 percent of the 27-year (1990 –2016) April network
average of 3.59 inches. The Illinois State Water Survey
operates this 25-station precipitation network funded
by the U.S. Army Corps of Engineers.
—Erin Bauer
Imperial Valley. Average network precipitation
during April 2017 was 6.35 inches, well above average
(Figure 6a). Total monthly precipitation amounts were
largest along the southern edge of the network. The
smallest gage totals were along the eastern edge of
the IVWA boundary and north of Havana, IL. Monthly
gage totals varied 2.54 inches across the network,
from 7.83 inches (site 21) northeast of Revis Hill
Prairie Nature Preserve to 5.29 inches (site 7) east of
Green Valley. For most gages, over half of the monthly
precipitation came during the April 29 storm with
gage storm totals ranging from 4.20 inches over a
40-hour period to 2.96 inches. The 1981–2010, 30-year
average precipitation amounts for April at Havana and
Mason City are 3.67 and 3.61 inches, respectively. The
April 2017 network average of 6.35 inches is about
0TWLYPHS=HSSL`>H[LY(\[OVYP[`
7YLJPWP[H[PVUPUJOLZ
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a. Imperial Valley
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b. Cook County
(WYPS
Figure 6
Long-term raingage network precipitation totals (inches) for April 2017
9
SURFACE WATER INFORMATION
the long-term mean for the month (about 130 percent
of the mean). Monthly mean discharge values ranged
generally from normal for April in southern Illinois to
above normal in the north.
Water-Supply Lakes and Major Reservoirs.
Table 5 lists reservoirs in Illinois, their normal pool or
target water surface elevation, and other data related
to observed variations in water surface elevations.
Reservoir levels are obtained from a network of
cooperating reservoir operators who are contacted
each month by ISWS staff for the current water
levels. Reservoir levels are reported in terms of their
difference from normal pool (or target level). The
average of the month-end readings for the period of
record is reported in terms of the difference from
normal pool or target level (column 6 of Table 5), and
the number of years of record for each reservoir also is
given (column 7). Most reservoirs serve as public water
supplies, with the exceptions noted in the last column.
Compared to end-of-March water levels at 26
reservoirs for which levels were reported last month
and this month, reported end-of-April water levels were
lower at one reservoir, higher at 22 reservoirs, and
about the same as at the end of last month at three
reservoirs. For the 28 reservoirs with measurements
reported at the end of April, water levels were below
normal target pool or spillway level at two reservoirs,
at about the full pool level at four reservoirs, and
above the seasonal target or fixed spillway levels at
22 reservoirs. (Note that some operators do not report
differences above the spillway level when water is over
the spillway/full pool.)
Major Reservoirs. Compared to water levels
at the end of March, at the end of April the water
level at Rend Lake was 3.3 feet higher, Carlyle Lake
was 2.6 feet higher, and the Lake Shelbyville level
was 5.5 foot higher. At the end of April, Rend Lake
was 5.1 feet above the spillway level, Carlyle Lake
was 1.0 foot above the May 1 target level, and Lake
Shelbyville was 0.1 foot above the May 1 target level.
(Lake Shelbyville’s and Carlyle Lake’s target operating
levels increased from March to May.)
Great Lakes. Current month mean and endof-month values are provisional and are relative to
International Great Lakes Datum 1985. The April 2017
mean level for Lake Michigan was 579.6 feet. The
monthly mean level one year ago (April 2016) was
579.9 feet. The long-term average lake level for April
is 578.7 feet, based on 1918-2015 data. In this period
of record, the lowest mean level for Lake Michigan for
April occurred in 1964 at 576.2 feet, and the highest
level for April occurred in 1986 at 581.5 feet. The
month-end level of Lake Michigan was 579.9 feet.
All values are provided by the U.S. Army Corps of
Engineers Detroit District.
—Bill Saylor
River and stream discharge and stage data are
obtained from gaging stations operated by the U.S.
Geological Survey (USGS) or the U.S. Army Corps of
Engineers (USACE). The USGS gaging station network
is supported, in part, by the Illinois Department of
Natural Resources Office of Water Resources, the
Illinois State Water Survey (ISWS), and the USACE.
Provisional discharge data are obtained from the USGS.
Table 3 lists the provisional peak stage for the
current month compared with the flood stage at
selected streamgaging stations located on the Illinois,
Mississippi, and Ohio Rivers. Peak stage is represented
here by morning readings posted daily by the USACE
or the National Weather Service. Flood stage is defined
locally for each gage location.
In mid-April, the Illinois River crested above the
flood stage at most stations below the Fox River
confluence, the Mississippi River crested above the
flood stage at locations below the Des Moines River
confluence to the Ohio River confluence (except at St.
Louis), and the Ohio River reached the flood stage at
Cairo. At the end of April, the Illinois River was rising
and above local flood stages from Ottawa to La Salle,
and from Havana to the Mississippi River. Also by the
end of the month, the Mississippi River had risen above
flood stage at most stations from New Boston to the
Ohio River confluence, and the Ohio River was above
local flood stages below Paducah, Kentucky.
Provisional monthly mean flows for 26 streamgaging stations located throughout Illinois are shown in
Table 4. Mean values posted by the USGS are listed if
available; otherwise, daily mean discharge data posted
by the USGS are used to estimate the mean flow for
the month. Long-term mean flows for each month are
published by the USGS. The month’s median flow for
each station listed in Table 4 was determined by ranking
the April mean flow for each year of record, and selecting
the middle value, 50 percent exceedence probability.
The statewide percent of historical mean flow
and percent of historical median flow are calculated
by dividing the sum of the average flows this month
at stations in Table 4 by the sum of the historical
mean and median flows calculated for the month,
respectively, at the same stations. This method
is intended to weight individual observations
proportionately in the aggregate comparison. (The
Illinois River and Rock River stations are excluded from
the statewide calculation because other rivers listed in
Table 4 contribute to their flow.)
Mean provisional flow aggregated statewide, using
the available monthly mean data shown this month
in Table 4, was above the median value for April
(approximately 160 percent of the median) and above
10
Table 3. Peak Stages for Major Rivers during April 2017
River
River
mile*
Flood stage
(feet)*
Peak stage
(feet)**
Date
Morris
La Salle
Peoria
Havana
Beardstown
Hardin
263.1
224.7
164.6
119.6
88.6
21.5
16
20
18
14
14
25
15.6
24.5
21.3
19.3
20.0
27.8
07
08
11
12
13-14
30
Dubuque
Keokuk
Quincy
Grafton
St. Louis
Chester
Thebes
579.9
364.2
327.9
218.0
180.0
109.9
43.7
17
16
17
18
30
27
33
15.4
14.0
18.0
20.9
28.8
30.8
34.2
29-30
30
30
30
09
10
30
Station
Illinois
Mississippi
Ohio
Cairo
2.0
40
43.3
30
________________
Notes:
* River mile and flood stage from River Stages in Illinois: Flood and Damage Data, Illinois Department of Natural Resources, Office of Water
Resources, August 2004 (and Addendum, February 2007).
**Peak stage based on daily a.m. readings, not instantaneous peak. Stage data obtained from U.S. Army Corps of Engineers.
Table 4. Provisional Mean Flows, April 2017
Station
Drainage
area
(sq mi)
Years
of
record
2017
mean flow
(cfs)
Long-term flows
Mean*
Median
(cfs)
(cfs)
Flow condition
Rock River at Rockton
6363
81
10,720
7688
6878
above normal
Rock River near Joslin
9549
73
18,240
11,190
10,252
above normal
Pecatonica River at Freeport
1326
97
1843
1291
1058
above normal
Green River near Geneseo
1003
78
1829
1073
960
above normal
Edwards River near New Boston
445
78
837
557
422
above normal
Kankakee River at Momence
2294
99
4723
3463
3508
above normal
Iroquois River near Chebanse
2091
92
4313
3174
2962
above normal
Fox River at Dayton
2642
97
6270
3353
2956
much above normal
Vermilion River at Pontiac
579
72
1181
809
672
above normal
Spoon River at Seville
1636
99
3194
1911
1532
above normal
LaMoine River at Ripley
1293
93
1902
1590
1279
normal
Bear Creek near Marceline
349
72
547
424
304
above normal
Mackinaw River near Congerville
767
67
1833
1060
928
above normal
Salt Creek near Greenview
1804
74
3387
2373
1955
above normal
Sangamon River at Monticello
550
104
852
796
674
normal
South Fork Sangamon near Rochester
867
66
1525
1070
770
above normal
Illinois River at Valley City
26,743
77
52,410
37,230
33,940
above normal
Macoupin Creek near Kane
868
87
1869
1142
674
above normal
Vermilion River near Danville
1290
94
2537
1880
1571
above normal
Kaskaskia River at Vandalia
1940
46
1845
2562
1960
normal
Shoal Creek near Breese
735
72
954
1034
696
normal
Embarras River at Ste. Marie
1516
102
2218
2275
1768
normal
Skillet Fork at Wayne City
464
96
1133
820
669
normal
Little Wabash below Clay City
1131
101
1464
1718
1194
normal
Big Muddy at Plumfield
794
45
953
1519
1313
normal
Cache River at Forman
244
92
643
586
518
normal
________________
Notes:
Source streamflow data are obtained from the U.S. Geological Survey.
N/A = not available (due to ice or equipment problems).
Much below normal flow = 90-100% chance of exceedence.
Below normal flow = 70-90% chance of exceedence.
Normal flow = 30-70% chance of exceedence.
Above normal flow = 10-30% chance of exceedence.
Much above normal flow = 0-10% chance of exceedence.
*As reported in U.S. Geological Survey (USGS) Water Resources Data, Illinois, Water Year 2015.
11
Percent
Days of
chance of data this
exceedence month
24
15
19
13
23
20
27
7
22
18
37
28
17
22
36
29
20
21
28
56
41
42
31
45
66
36
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
Table 5. Reservoir Levels in Illinois, April 2017
Reservoir
County
Normal pool
or target
level (feet)
Current level
difference from normal
or target (feet)
Monthly
change
(feet)
Average difference
from normal
or target (feet)
Years
of
record
March
reported pumpage
(million gallons)
Altamont
Effingham
582.0
+0.4
+0.5
-0.4
31
5.5
Bloomington
McLean
719.5
+0.6
+1.1
-0.6
29
N/A
Carlinville
Macoupin
N/A
+0.1
+1.4
N/A
N/A
23.1
Carlyle(1)
Clinton
443.0
+1.0
+2.6
+1.0
39
N/A
Decatur(1,3)
Macon
612.5
+0.2
+1.1
-0.4
33
981.8
Evergreen(4)
Woodford
720.0
+0.8
+0.5
-0.9
26
N/A
Glenn Shoals(2)
Montgomery
590.0
+3.0
+2.8
+0.5
22
w/Hillsboro
Highland
Madison
500.0
+3.0
+2.8
+0.2
28
28.9
Hillsboro(2)
Montgomery
589.0
+0.4
+0.2
+0.2
22
28.0
Jacksonville(2)
Morgan
644.0
+0.1
N/A
-0.1
19
w/Mauvaise Terre
Kinkaid
Jackson
420.0
+0.9
+0.9
+0.2
28
45.3
Lake of Egypt
Williamson
500.0
+2.1
+1.8
+0.3
23
N/A
Mattoon
Coles
632.0
+0.1
+0.1
-0.1
21
w/Paradise
Mauvaise Terre(2)
Morgan
588.5
+0.5
N/A
+0.1
21
no meter
Mt. Olive (new)
Macoupin
600.0
0.0
0.0
0.0
10
w/Mt. Olive (old)
Mt. Olive (old)
Macoupin
654.0
0.0
0.0
-0.2
19
5.0
Pana
Christian
641.6
+0.5
+0.5
-0.4
32
N/A
Paradise
Coles
685.0
+0.1
+0.1
-0.2
27
54.3
Paris (east)
Edgar
660.0
+0.6
+0.5
0.0
32
Not PWS
Paris (west)
Edgar
660.1
+0.6
+0.5
+0.2
22
w/Paris (east)
Raccoon(1)
Marion
477.0
-0.3
-0.8
N/A
N/A
101.1
Rend
Franklin
405.0
+5.1
+3.3
+3.8
39
N/A
Salem(3)
Marion
546.5
+0.4
+0.7
-0.5
22
21.7
Shelbyville(1)
Shelby
594.0
+0.1
+5.5
-0.5
39
Not PWS
Sparta(3)
Randolph
497.0
-0.1
+0.5
-0.7
20
N/A
Spring(3,4)
McDonough
654.0
N/A
N/A
+0.2
33
48.3
Springfield(1,3)
Sangamon
559.6
+0.7
+0.7
0.0
33
N/A
Taylorville
Christian
590.0
0.0
+0.3
+0.1
24
60.8
Vermilion(4)
Vermilion
581.7
0.0
0.0
-0.2
31
176.6
_______________
Notes:
Normal pool and target level datum is NGVD 1929.
Current levels reported represent water surface levels at the end of the month, not the monthly average.
Average difference from normal or target level is the arithmetic average of reported month-end values for the period of record indicated.
Years of record = total number of monthly readings included in month-end average. Total period of record may be longer.
Not PWS = not a public water supply.
N/A = not available.
(1)
Target operating level may vary. Seasonal target levels this month represent May 1 values.
(2)
Instrumentation not available to measure height of water elevation above spillway.
(3)
Natural inflow can be supplemented by other sources.
(4)
Normal pool elevations have changed during period of record reported.
12
GROUNDWATER INFORMATION
Comparison to Previous Month. Shallow
groundwater levels were above those of the previous
month. Levels averaged 1.7 feet above and ranged from
0.8 feet below to 5.8 feet above levels of March.
Comparison to Same Month, Previous Year.
Shallow groundwater levels in April were above levels
measured one year ago. Levels averaged 1.5 feet above
this month and ranged from 0.3 feet below to 5.50 feet
above levels of April 2016.
—Ken Hlinka
Comparison to Average Levels. Shallow
groundwater levels in 13 observation wells, which are
remote from pumping centers, were above normal for
the month of April. Levels averaged 1.8 feet above and
ranged from 2.5 feet below to 5.4 feet above normal
levels (Table 6). One well, S.E. College (Saline County),
reported its highest measurement for April.
Table 6. Month-End Shallow Groundwater Level Data Sites, April 2017
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Well name
Galena
Mt. Morris
Crystal Lake
Fermi Lab
Good Hope
Snicarte
Coffman
Greenfield
Janesville
St. Peter
SWS #2
Boyleston
Sparta
SE College
Bondville
County
JoDaviess
Ogle
McHenry
DuPage
McDonough
Mason
Pike
Greene
Coles
Fayette
St. Clair
Wayne
Randolph
Saline
Champaign
_______________
Notes:
** Highest level of record for the month
N/A = Data not available.
Well depth
(feet)
25.00
55.00
18.00
17.00
30.00
42.00
28.00
20.70
11.00
15.00
80.00
23.00
27.00
11.00
21.00
Deviation from
This month’s reading 15-year avg. Period of record
Previous
(depth to water, feet) level (feet)
avg. (feet)
month (feet)
Previous
year (feet)
18.45
12.18
3.12
1.42
3.75
36.14
10.91
6.87
0.06
NA
11.59
NA
0.17
**0.00
3.99
+1.15
+6.62
+0.54
+3.75
+0.94
+1.34
-1.95
+1.85
+4.14
NA
-0.38
NA
+3.76
+2.52
-0.61
+2.15
+5.42
+0.85
+3.37
+1.51
+0.62
-2.53
+0.54
+4.37
NA
+1.56
NA
+4.41
+2.31
-1.03
+1.21
+4.45
+0.32
-0.01
+1.60
-0.82
+1.37
+5.76
+5.40
NA
-0.68
NA
+1.24
+0.44
+0.12
+5.53
+0.61
+2.65
+1.65
+1.34
+3.66
NA
-0.15
NA
+1.96
-0.65
+0.79
-0.25
Averages
+1.82
+1.81
+1.66
+1.47
Data sources for information in this publication include the following:
CPC - Climate Prediction Center, http://www.cpc.ncep.noaa.gov/index.php
ISWS - Illinois State Water Survey, http://www.isws.illinois.edu
MRCC - Midwestern Regional Climate Center, http://mrcc.isws.illinois.edu
NCDC - National Climatic Data Center, http://www.ncdc.noaa.gov
NWS - National Weather Service, http://www.nws.noaa.gov
USACE - U.S. Army Corps of Engineers, http://rivergages.com, http://www.lre.usace.army.mil/greatlakes/hh
USGS - U.S. Geological Survey, http://waterdata.usgs.gov/il/nwis
WARM - Water and Atmospheric Resources Monitoring Program, http://www.isws.illinois.edu/warm
13
Illinois State Water Survey
2204 Griffith Drive • Champaign, IL 61820
Tel (217) 333-2210 • www.isws.illinois.edu