Illinois EPA Phase I – Diagnostic Study
Clean Lakes Program Lake Paradise
March 2004
Final Report
77
Biological Parameters
Indicator Bacteria
Pathogenic bacteria, pathogenic protozoan cysts, and viruses have been isolated from
wastewaters and natural waters. The sources of these pathogens are the feces of humans and of
wild and domestic animals. Identification and enumeration of these disease-causing organisms
in water and wastewater are not recommended because no single technique is currently available
to isolate and identify all the pathogens. In fact, concentrations of these pathogens are generally
low in water and wastewater. In addition, the methods for identification and enumeration of
pathogens are labor intensive and expensive.
Instead of direct isolation and enumeration of pathogens, total coliform (TC) has long
been used as an indicator of contamination of the water that poses a potential public health risk.
Fecal coliform (FC), which is more fecal-specific, has been adopted as a standard indicator of
contamination in natural water in Illinois and many other states. Both TC and FC are used in
standards for drinking water and natural waters. Fecal streptococcus (FS) is used as a pollution
indicator in Europe. FC/FS ratios have been employed for identifying pollution sources in the
United States. Fecal streptococci are present in the intestines of warm-blooded animals and of
insects, and they are present in the environment (water, soil, and vegetation) for long periods of
time.
The Illinois Pollution Control Board has adopted the following general-use water quality
standards for FC in lakes and streams are (Section 302.209, IEPA, 1999):
“a. During the months May through October, based on a minimum of five samples
taken over not more than a 30-day period, fecal coliforms (STORET number
31616) shall not exceed a geometric mean of 200 per 100 mL, nor shall more than
10 percent of the samples during any 30-day period exceed 400 per 100 mL in
protected waters. Protected waters are defined as water that, due to natural
characteristics, aesthetic value, or environmental significance, are deserving of
protection from pathogenic organisms. Protected waters must meet one or both of
the following conditions:
1) They presently support or have the physical characteristics to support
primary contact.
2) They flow through or adjacent to parks or residential areas.”
Table 34 presents the results of analyses for indicator bacteria for samples collected from
the tributary (inflow), in-lake, and spillway of Lake Paradise. All sampling locations are shown
in Figure 6. One per 100 mL was used instead of zero for non-detect samples in calculating
geometric mean for data collected during the study period.
