Monitoring Methods

Tier 1

Volunteers in Tier 1 measure water clarity (transparency) using a Secchi disk. The disk consists of a weighted metal or plastic plate, eight inches in diameter which is painted black and white in alternate quadrants and attached to a calibrated rope or measuring line. The disk is lowered into the lake and the depth at which it is no longer visible is noted. This depth is called the “Secchi depth.” It is most useful to document changes in the transparency of your lake water over a period of years to develop meaningful trends in transparency. Monitoring is conducted twice a month from May - October, typically at three in-lake sites. The volunteer also records a series of field observations relating to other important environmental characteristics of the lake, such as water color, weather conditions during monitoring and in the previous 48 hours, presence and amount of aquatic plants at each site and the lake as a whole, presence or absence of aquatic exotics, site depth and watershed activities. The volunteer also documents recent lake management activities, such as, dredging or applying chemicals and notes any recreational lake usage which could impact the lake.

Tier 2

After completing Tier 1 for at least one year, volunteers may enter a rotation which allows them to collect more detailed information on their lake – Tier 2. Participants in Tier 2 collect water samples once per month May through August at Site 1.

The water quality sample is taken at one foot below the surface of the water, is poured off into the appropriate containers and shipped to the laboratory where it is analyzed for ammonia, nitrate-nitrite nitrogen, total Kjeldahl nitrogen (TKN), total phosphorus, alkalinity, chloride, total suspended solids and volatile suspended solids. 

NOTE: Additional options may be added for experienced Tier 2 volunteers; such as, dissolved oxygen monitoring or chlorophyll sampling.

Tier 3

After a volunteer has completed at least one year of Tier 2 monitoring and has met monitoring consistency and accuracy requirements, they become eligible for Tier 3. Volunteers in Tier 3 are chosen by Illinois EPA based on the volunteer’s interest in becoming a Tier 3 volunteer, the volunteer’s monitoring history and demonstrated proficiency, and if there is an opening in the rotation. Another requirement for Tier 3 eligibility is the lake being monitored must be 20 acres or more. This is because the water quality standard for total phosphorus only applies to lakes at least 20 acres in size. Since the data collected in this tier are being used by the Agency for making use-support decisions, lake size is a factor when applying water quality standards to these decisions.

The monitoring tasks for Tier 3 are similar to those of Tiers 1 and 2. A Tier 3 volunteer is expected to monitor their lake’s Secchi disk transparency twice per month from May through October, as well as, collect water quality and chlorophyll samples once per month from May through August and October. However, there are additional monitoring tasks reserved for only Tier 3 volunteers. For example, in Tier 3, the volunteer may be required to collect water quality and chlorophyll samples at up to three sites on their lake (instead of just one as in Tier 2). Additional depths may also be requested for water quality sampling and particular sites.


The filter is sent to the laboratory for analysis.

Finally, Tier 3 volunteers collect and record dissolved oxygen and temperature profiles at each of their sites, twice per month in conjunction with Secchi disk transparency monitoring.