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Volunteer Monitoring

More than 1,200 natural lakes and reservoirs grace outdoor Indiana.  Regular monitoring of all these lakes is beyond the means of our state agencies.  The Volunteer Lake Monitoring Program was created to enlist the aid of citizens in protecting these crown jewels.  

Citizen volunteers work as partners with IDEM and SPEA to implement this important program.

Boat Photo
Secchi illustration
Graphic courtesy of Minnesota Pollution Control Agency

About the Program

The volunteer lake monitoring program was started in 1989.  The goals of the program are to:


What the volunteers do

Volunteers collect water transparency data using an 8-inch, circular, black & white disk attached to a fiberglass measuring tape. This tool is called a Secchi disk. About once every two weeks during the summer, volunteers boat to a designated spot on their lakes to collect transparency readings. The volunteer lowers the disk into the water until it is no longer visible and notes that depth from the markings on the tape. The disk is then lowered a little further and then raised back up until it is just visible. This second depth reading is averaged with the first, and the final number is recorded on a data sheet.  Volunteers can send in their data on pre-posted data cards, via e-mail, and direct entry onto our web page.


What does the Secchi disk measure?

The Secchi disk is a measure of the amount of suspended material in the water.  This suspended material may be living algae, eroded soil from the watershed, re-suspended lake sediments, or other materials.  The more suspended material in the water, the more turbid the lake and the less transparency.  Poor Secchi disk transparency has been linked to lake eutrophication. Illustrations of what a Secchi disk measures
Taking a Secchi disk transparency recording at Griffy Reservior Graduate students Thomas Parr and Moira Rojas measure Secchi disk transparency at Griffy Reservoir in Monroe County. Indiana Clean Lakes Program volunteers each complete multiple Secchi disk recordings each year.


Expanded Volunteers

Expanded volunteers for the Indiana Clean Lakes Program also collect Chlorophyll-a samples as well as total phosphorous water samples. Expanded volunteers use an integrated sampler (right) to collect water from the upper water column to be filtered (below) for Chlorophyll-a.

Filtering Chl-a

An integrated sampler is being used to collect water from the surface water at Griffy Reservoir