As the City of Lakes, Minneapolis is known for its ample and beautiful lakes. Without a dedicated effort to preserve and protect these urban waters, our lakes would not be the valuable resources that they are today. The Minneapolis Park & Recreation Board’s (MPRB) lake water quality monitoring program was implemented in 1991 as part of a diagnostic study for the Chain of Lakes Clean Water Partnership. We currently monitor 13 lakes within the City of Minneapolis:

Lake Conditions

We make some monitoring data available throughout the season so you have an idea of lake conditions:

  • The Lake Aesthetic and User Recreational Index (LAURI) is a summary of conditions that affect recreation on each lake.
  • Updated Secchi disk readings indicate the current clarity of each lake.
  • We monitor beaches during the summer to determine if there are any health risks to swimmers. Weekly data indicates:
    • E. coli levels
    • Current water temperature
    • Open/closed status of the beaches

Aquatic Invasive Species

Aquatic invasive species are often the most visible sign of change in lakes, and many problem species are very difficult to remove or even limit. We carefully monitor these species in cooperation with various state agencies and work to limit their spread where possible.

Water Clarity

About Secchi Disk Readings

secchi diagram

To measure water transparency with a Secchi disk, the disk is lowered from the shaded side of a boat until it cannot be seen. The depth of the water is recorded at the point where the disk reappears upon raising it from its original depth beyond visibility. It is important to remember that the Secchi measurement is a simple, approximate measurement of water clarity and can be influenced by various factors such as time of day, reader's eyesight, water color and suspended particles in the water. Therefore, Secchi disk readings should be used as a comparative tool to determine trends between lakes and over time.

  • Increased water clarity may be due to reduced nutrient inputs, seasonal algal cycles, decreased sediment inputs, and zooplankton grazing on algae.
  • Decreased water clarity may be due to large algal blooms, increased soil erosion inputs, wind circulation of sediments and nutrients, stormwater inputs, or a decrease in zooplankton.

Secchi readings for the lakes are done during the regular lake sampling schedule, with some lakes sampled every other year.

Recent Secchi Disk Readings

Brownie Lake

September 13, 2016

Secchi Depth (feet): 4.4

+
More



Lake Calhoun

September 27, 2016

Secchi Depth (feet): 8.5

+
More



Cedar Lake

September 27, 2016

Secchi Depth (feet): 4.6

+
More



Lake Harriet

September 28, 2016

Secchi Depth (feet): 10.4

+
More



Lake Hiawatha

September 29, 2016

Secchi Depth (feet): 5.1

+
More



Lake of the Isles

September 27, 2016

Secchi Depth (feet): 4.2

+
More


Loring Pond

September 26, 2016

Secchi Depth (feet): 6.2

+
More



Lake Nokomis

September 29, 2016

Secchi Depth (feet): 2.0

+
More



Powderhorn Lake

September 26, 2016

Secchi Depth (feet): 2.0

+
More



Spring Lake

September 14, 2015

Secchi Depth (feet): 2.6

+
More



Wirth Lake

September 28, 2016

Secchi Depth (feet): 5.5

+
More


LAURI

Lake Aesthetic and User Recreation Index (LAURI)

The Lake Aesthetic and User Recreation Index (LAURI) was designed to give recreational users a source of information about conditions affecting their use of city lakes.  The goal is to have an accurate, science based and easily understandable recreational indicator for the public.  The  LAURI has five indices:

+
Public Health Index (E. coli measured at public swimming beaches)


+
Water Quality Index (water clarity/Secchi depth)


+
Habitat Quality (aquatic plant and fish diversity)


+
Recreational Access (availability and ease of public access)


+
Aesthetic Considerations (color and odor of water, garbage and debris)


Brownie Lake 2016

lauri graph for brownie lake

Lake Calhoun 2016

lauri graph for lake calhoun

Cedar Lake 2016

lauri graph for cedar lake

Diamond Lake 2016

lauri graph for diamond lake

Lake Harriet 2016

lauri graph for lake harriet

Lake Hiawatha 2016

lauri graph for lake hiawatha

Lake of the Isles 2016

lauri graph for lake of the isles

Loring Pond 2016

lauri graph for loring pond

Lake Nokomis 2016

lauri graph for lake nokomis

Powderhorn Lake 2016

lauri graph for powderhorn lake

Wirth Lake 2016

lauri graph for wirth lake

Citywide 2016

lauri graph citywide

Monitoring

Long-term monitoring is important because lakes can change from year to year due to wet or dry weather and we can only see trends when we put years of data together. Analysis of this data tells us if the water quality is improving or not.

View the MPRB Water Resources Report for detailed annual monitoring data, data collection methods, and more.