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Questions or comments? Contact Holly Hudson.

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Illinois Volunteer Lake Monitoring Program

The Illinois' Volunteer Lake Monitoring Program (VLMP) brings together citizens, state agency staff, and regional and local government staff to monitor and investigate the quality of Illinois' lakes. VLMP data is used by the Illinois Environmental Protection Agency (IEPA) in its biennial assessment of the state's waters as required by the federal Clean Water Act, as well as by lake scientists, planners, consultants, and the volunteers themselves for a wide variety of purposes. A primary goal of the VLMP is to familiarize volunteers with lake processes and the cause and effect relationships that exist between lakes, watersheds, weather, and human activities. Through the VLMP's hands-on educational structure, the data and information gathered can effectively assist in local lake and watershed management decision-making. Thanks to the many volunteer monitors around the state, data is available on many more lakes than could otherwise be monitored by state agency staff. 

The primary lake monitoring tool is a Secchi disk, an 8-inch diameter plate painted black and white in opposite quadrants, attached to a calibrated line. The disk is simply lowered into the lake water and the depth to which the disk remains visible is recorded.  By regularly recording Secchi disk transparency measurements, changes in water transparency during the monitoring season as well as from year to year provide a wealth of information about lake quality. 

Secchi transparency monitoring typically is done twice a month from May through October at three in-lake locations. Volunteers need only have a boat and anchor to participate. All monitoring equipment, data forms, instructional materials (including a comprehensive Training Manual), and other supplies are provided to the volunteers. Volunteers will be engaged in the following activities:

  • Measure water transparency (clarity) to assess the amount of suspended sediment and algae in the lake.
  • Record water color, aquatic plant growth, and several other factors relating to lake, weather, and watershed conditions at the time of monitoring.
  • Watch for several types of aquatic invasive species and blue-green algal blooms, and report potential sightings.
  • Depending on resources, collect water samples for analysis by IEPA to gather more detailed information on suspended material in the lake (sediment, algae, etc.) as well as levels of nutrients (phosphorus, nitrogen) that can promote nuisance aquatic plant and algae growth.

CMAP coordinates the VLMP for the counties of Cook, DuPage, Kane, Kendall, McHenry, and Will, and partners with the Lake County Health Department who oversees the program in Lake County. The 2014 monitoring season marks the 34th year of this popular IEPA program. CMAP provides volunteer training, technical assistance, educational materials, data management, and assistance to IEPA in newsletter and annual report preparation.

Become a Volunteer

If you are interested in monitoring a lake or pond that you live by or frequently visit, it's easy to join the VLMP!  You can either fill out IEPA's online registration form or contact northeastern Illinois VLMP Coordinator Holly Hudson at CMAP (312-386-8700 or hhudson@cmap.illinois.gov). Training sessions are conducted during May, so the best time to sign up is between January and March of the year you'd like to begin.  

Volunteer Resources

  • IEPA Volunteer Lake Monitoring Program Training Manual
  • VLMP Website
  • Harmful Algal Bloom Report Form
  • EPA's Harmful Algal Blooms and Algal Toxins webpage.
  • Illinois EPA's Lakes Unit (217-782-3362)
  • VLMP Secchi transparency data can be viewed and downloaded from here.
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