Lake Water Quality – E. coli Monitoring Results

E. coli is a naturally occurring bacterium that originates in the intestines of humans and other animals. It can be found virtually everywhere, including in raw water supplies. While some strains of E. coli are "friendly" to humans and are a necessary component of our digestive process, others can cause serious illness or even death. E. coli is ubiquitous (found virtually everywhere) and it's presence is easy to test for. The presence of large quantities of E. coli is often considered to be an indicator of the possible presence of high levels of other, potentially harmful, microorganisms, including Leptospira, the bacteria that causes leptospirosis.

Under normal conditions, CWLP tests for E. coli in the raw lake water every two weeks from the spring through the fall.  If readings are abnormally high, more frequent samples will be taken. Results of each of these tests since March 24, 1999, are listed in the table below.

Testing stations are located as follows:

A. Near the water intake tower near Spaulding Dam
B. In the main basin of the lake, midway between Lindsay Bridge and the C&IM
Railroad bridge
C. Just west of the C&IM Railroad bridge
D. In the upper (Lick Creek) arm, between Woodside Bridge and the I-55 bridge
E. In the lower (Sugar Creek) arm near the Wildlife Sanctuary

A map showing the location of each test site and the most recent reading for each site is available.

Links to other lake water quality topics can be found at the end of this table. 

The standard used by the State of Illinois calls for bathing beaches to be closed when E. coli levels exceed 235.

na: Lake level was too low to take a reading

 TESTING STATION
TEST DATE A
B
C
D
E
August 25, 2010 4 0 0 14 50
August 11, 2010 1 1 1 0 0
July 22, 2010 8 13 38 130 137
July 8, 2010 0 0 2 9 7
June 30, 2010 3 3 1 7 10
June 24, 2010 31 31 249 689 461
June 16, 2010 461 55 2419 2419 1553
June 10, 2010 2 0 3 6 5
May 28, 2010 365 62 80 275 649
May 27, 2010 1,203 122 150 461 >2,419
May 19, 2010 19 411 914 389 317
May 4, 2010 1 2 0 3 10
October 20, 2009 11 60 44 48 82
September 15, 2009 2 0 0 1 4
August 25, 2009 4 1 0 3 7
August 6, 2009 2 0 1 1 1
July 23, 2009 2 0 0 1 1
July 8, 2009 0 0 0 3 3
June 24, 2009 0 0 0 0 0
June 9, 2009 4 1 2 1 1
May 28, 2009 13 3 15 56 435
May 14, 2009 30 5 38 121 214
October 20, 2008 1 3 3 2 20
September 25, 2008 1 1 2 3 2
September 18, 2008 1 4 47 65 30
September 10, 2008 7 1 2 4 6
August 28, 2008 5 0 2 0 1
August 20, 2008 0 0 0 0 1
August 7, 2008 5 2 0 3 9
July 23, 2008 7 2 10 16 13
July 15, 2008 4 0 6 4 68
July 2, 2008 17 3 6 10 53
June 18, 2008 9 12 50 14 23
June 12, 2008 45 41 127 67 161
June 10, 2008 55 111 248 291 308
June 5, 2008 17 55 579 770 >2419
June 4, 2008 33 44 816 1203 >2419
May 21, 2008 1 1 0 1 2
May 16, 2008 11 5 9 45 40
October 9, 2007 3 2 16 15 23
Sept. 19. 2007 5 0 7 0 16
August 28, 2007 7 0 3 4 20
August 7, 2007 16 2 1 1 2
July 25, 2007 1 0 0 0 1
July 11, 2007 1 0 0 0 0
June 27, 2007 5 0 0 2 7
June 11, 2007 0 1 3 10 0
May 23, 2007 14 0 1 0 1
May 10, 2007 0 0 0 3 1
October 18, 2006 25 21 32 26 40
Sept. 27, 2006 53 9 1 3 16
Sept. 14, 2006 7 1 2 9 10
August 29, 2006 9 3 3 12 2
August 15, 2006 2 0 0 2 5
July 31, 2006 5 0 0 1 11
July 13, 2006 20 2 12 12 19
June 27, 2006 44 0 1 3 10
June 13, 2006 1 0 1 4 5
May 31, 2006 0 0 0 0 2
May 18, 2006 6 13 6 7 0
October 27, 2005 10 7 48 39 16
Sept. 29, 2005 9 1 48 37 49
Sept. 20, 2005 10 12 4 0 9
August 30, 2005 30 1 2 7 11
August 16, 2005 12 3 0 2 12
July 29, 2005 0 0 1 0 1
July 21, 2005 16 1 1 2 0
July 14, 2005 5 2 5 6 4
June 28, 2005 0 0 0 1 7
June 16, 2005 35 3 14 15 54
May 31, 2005 0 0 2 0 0
May 17, 2005 0 1 1 1 1
October 14, 2004 12 9 15 6 28
September 28, 2004 13 0 6 3 13
September 16, 2004 3 1 1 4 44
August 30, 2004 4 2 9 1 19
August 10, 2004 1 0 2 2 1
July 21, 2004 0 0 2 0 4
July 7, 2004 57 4 25 20 40
June 22, 2004 15 5 4 2 0
June 8, 2004 3 0 1 2 6
May 26, 2004 0 0 15 75 105
May 11, 2004 6 1 1 1 18
April 26, 2004 1 12 4 6 17
November 12, 2003 19 65 7 15 15
October 22, 2003 4 5 4 5 7
October 7, 2003 8 1 1 2 1
September 26, 2003 4 0 2 5 4
September 10, 2003 4 2 3 2 19
September 3, 2003 44 21 114 166 272
August 26, 2003 5 1 0 1 7
August 7, 2003 0 0 0 0 1
July 23, 2003 3 0 0 1 2
July 09, 2003 16 0 2 11 5
June 25, 2003 12 1 1 20 6
June 6, 2003 5 4 2 4 1
May 21, 2003 5 17 60 32 59
May 13, 2003 10 186 368 582 551
April 29, 2003 0 0 2 1 0
November 13, 2002 6 435 4 0 2
September 24, 2002 1 0 0 3 7
August 21, 2002 21 1 12 10 11
August 15, 2002 21 0 10 10 7
August 1, 2002 5 1 3 0 4
July 16, 2002 3 0 2 1 0
July 1, 2002 6 0 1 6 15
June 20, 2002 23 12 27 23 40
June 18, 2002 20 40 54 49 102
June 13, 2002 687 153 2,419 2,419 2,419
June 6, 2002 29 5 13 26 28
May 30, 2002 60 26 56 272 365
May 23, 2002 34 61 33 52 55
May 15, 2002 349 326 649 435 488
May 10, 2002 25 102 108 2,419 1,983
April 30, 2002 12 101 2,098 960 1,539
November 16, 2001 0 4 2 3 9
October 30, 2001 11 7 7 13 35
October 19, 2001 15 11 30 10 66
September 26, 2001 6 5 9 2 10
September 12, 2001 6 1 0 3 2
August 29, 2001 2 1 4 2 5
August 15, 2001 4 0 1 2 1
July 24, 2001 4 0 3 2 16
July 12, 2001 9 0 0 11 3
June25, 2001 11 0 2 1 2
June15, 2001 12 9 12 11 19
June14, 2001 16 17 22 20 33
June 11, 2001 13 40 46 46 50
June 8, 2001 580 5460 4720 5830 6010
June 7, 2001 276 3440 4610 4610 2910
May 25, 2001 6 2 12 7 2
May 9, 2001 3 0 1 2 2
April 26, 2001 0 0 21 2 5
October 11, 2000 24 2 39 34 35
September 26, 2000 12 19 33 38 219
September 6, 2000 2 3 3 1 2
August 23, 2000 24 1 1 4 7
August 9, 2000 7 1 4 9 20
July 26, 2000 4 0 3 2 7
July 13, 2000 25 1 3 17 6
July 6, 2000 15 9 17 23 123
June 29, 2000 16 0 28 91 96
June 27, 2000 21 10 58 411 770
June 9, 2000 13 3 5 na na
May 31, 2000 23 2 23 na na
May 24,2000 13 2 13 na na
May 10, 2000 9 4 23 na na
September 27,1999 18 2 1 4 9
August 30, 1999 15 5 6 2 9
August 16, 1999 17 2 5 5 8
August 2, 1999 3 2 4 2 12
July 19, 1999 15 2 2 6 2
July 6, 1999 8 0 4 3 12
June 21, 1999 7 1 4 3 12
June 16, 1999 2 2 25 39 113
June 14, 1999 3 1 12 29 579
June 7, 1999 14 1 11 5 12
May 24, 1999 3 1 6 13 6
May 10, 1999 3 1 1 5 2
May 3, 1999 0 0 26 47 74
April 26, 1999 11 2 14 10 55
April 20, 1999 1 3 918 765 641
March 24, 1999 <1 1 <1 1 <1

To read about other lake water quality issues, select one of the links below.
 



Lake Water Quality

Last updated: 08/26/10