Minnesota Pollution Control Agency (MPCA): Lake Monitoring Program, Chemistry, 1999-2012

The MPCA monitors approximately 100 lakes each year. Each lake is sampled monthly from May
to September for a period of two years. The primary focus is on collection of total phosphorus
(nutrient), chlorophyll-a (pigment in algae), and Secchi depth (distance light will travel in
water). With this information, it is possible to determine the condition of the lake, commonly
referred to as the “trophic status. Staff also collects information on water color,
suspended solids, temperature, dissolved oxygen and a number of other parameters. After a lake
has been monitored for a minimum of two years, the water chemistry data are used to assess its
condition. The water quality data and the results of the condition assessment are incorporated
in a variety of products, including lake assessment reports, status and trend/update reports and
fact sheets. The MPCA uses a Standard Operating Procedure (SOP), posted on the state Pollution
Control Agency website, when conducting its lake monitoring.