Surface Water Quality Monitoring &
The Agency's Bureau of Water - Surface Water Section is
responsible for monitoring the quality of Illinois' surface water resources,
including its inland lakes, streams and rivers, and Lake Michigan. By
collecting chemical, physical and biological data, we can assess the quality
of our water resources and answer commonly asked questions like:
- Is it safe to swim in this lake?
- Can I eat the fish my kids catch in this stream?
- How does the quality of my lake or stream compare to the others in
- Is the water safe to drink?
- Since I'm buying lakefront property, what can you tell me about the
quality of this lake?
- Are the fish found in my stream indicative of good water quality?
- What are the causes and sources of pollution found in my water?
The Agency receives federal funds through the U.S. Environmental Protection
Agency (USEPA) to conduct various monitoring programs on an annual basis.
These funds are authorized through the Federal Clean Water Act (CWA).
Since the 1970's, the CWA has had a national goal of making all of the
nation's surface waters "fishable and swimmable." To determine whether
that goal is being attained, funds are provided to state agencies like
Illinois EPA to monitor and assess the quality of surface waters. Simply
put, we try to assess as many miles of streams and acres of inland lakes
as possible to determine if they are "Good," "Fair," or "Poor" in quality,
and whether or not they are safe to fish and swim in. Assessment results
are electronically reported annually to USEPA pursuant to CWA Section
305(b). When published, these reports are entitled, "Illinois Water Quality
The monitoring programs detailed below are conducted by Illinois EPA
biologists located in our Des Plaines, Springfield, and Marion regional
offices. Typically, monitoring is carried out between the months of April
through October, but under some programs, is carried out throughout the
entire year. Water and sediment chemistry, physical characteristics (i.e.,
stream or lake size, water depth), water clarity, macroinvertebrate (aquatic
bugs) and fish populations, habitat quality (i.e., stream riffles and
pools, amount of aquatic vegetation), and other types of data are all
collected, depending on the goals or answers we want to obtain from the
individual monitoring program.